Reference List Abbe, G. R. 1992. Population structure of the eastern oyster, Crassostrea virginica (Gmelin, 1791), on two oyster bars in central Chesapeake Bay: further changes associated with shell planting, recruitment, and disease. Journal of Shellfish Research 11: 421-430. Ref ID: 95 Abbe, G. R. and Breitburg, D. L. 1992. The influence of oyster toadfish (Opsanus tau) and crabs (Callinectes sapidus and Xanthidae) on survival of oyster (Crassostrea virginica) spat in Chesapeake Bay - Does spat protection always work. Aquaculture 107: 21-31. Ref ID: 315 Abstract: Field experiments were conducted in central Chesapeake Bay to determine whether oyster toadfish Opsanus tau (Linnaeus), mud crabs (mostly Panopeus herbstii Milne-Edwards), and blue crabs (Callinectes sapidus Rathbun) influence the survival of juvenile oysters (Crassostrea virginica (Gmelin)), and whether interactions among these species modify their individual effects. Mesh-lined steel cages were used to manipulate toadfish and blue crab access to oyster spat and mud crabs. Oyster survival in the presence of toadfish was no different than in caged or uncaged controls. Spat set on cultch tended to have slightly lower survival in cages with only blue crabs than in other treatments. Survival of both cultchless spat and spat set on shells was negatively correlated with numbers of mud crabs in some, but not all, sets of replicates. Mud crabs were more abundant in August than in September each year and were also more abundant in 1988 than in 1987. Both temporal and habitat factors were probably responsible for the patterns of mud crab abundances. Results of 2 years of experimental studies suggest that the oyster toadfish is not an effective means of oyster predator control in the subtidal area of the Chesapeake Bay studied. These results contrast with those of studies conducted on oyster spat elsewhere and with tests of the use of toadfish to protect juvenile hard clams Abramsky, Z., Rosenzweig, M. L., and Pinshow, B. 1991. The shape of a gerbil isocline measured using principles of optimal habitat selection. Ecology 72: 329-340. Ref ID: 15 Ackerman, J. D., Ethier, C. R., Allen, D. G., and Spelt, J. K. 1992. Investigation of zebra mussel adhesion strenght using rotating disks. Journal of Environmental Engineering - ASCE 118: 708-724. Ref ID: 622 Abstract: Zebra mussels adhere tenaciously and gregariously to hard surfaces, thereby fouling water-processing facilities and equipment. At present, there are few data on zebra mussel adhesion strength to common substrates. A rotating disk test system (RDTS) was used to measure the adhesion strength of small mussels (almost-equal-to 1 mm) to four materials [polyvinylchloride (PVC), polymethylmethacrylate (PMMA), stainless steel (SS), and aluminum (AL)]. Adhesion strength varied significantly with material but only marginally with residence time (one, two, seven, 14, 21, and 28 days). The estimated shear stress required to remove 95% of mussels (tau95%) averaged 62 +/- 5 Pa (mean +/- standard error, n = 6 disks) on PVC, 50 +/- 3 Pa on PMMA, 48 +/- 4 Pa on SS, and 31 +/- 1 (n = 4) Pa on AL. Tau95% peaked on the second day (85 Pa on PVC, 65 Pa on PMMA, 57.5 Pa on SS, 32.5 Pa on AL), then decreased to a constant level. Ultimately, this research should provide insight into material selection and designs that minimize attachment and facilitate removal of zebra mussels. Ackerman, J. D., Cottrell, C. M., Ethier, C. R., Allen, D. G., and Spelt, J. K. 1996. Attachment strength of zebra mussels on natural, polymeric, and metallic materials. Journal of Environmental Engineering - ASCE 122: 141-148. Ref ID: 614 Abstract: Zebra mussel (Dreissena polymorpha and D. bugensis) fouling has increased operating and maintenance costs for marine and industrial facilities. An understanding of zebra mussel attachment strength on various substrates of different surface roughness is useful for the development of control strategies. Mussel attachment strength was inferred directly through tensile loading experiments using a calibrated force scale, and indirectly through fluid detachment using a wall jet. The results of both techniques were consistent and yielded statistically significant differences for different substrate types (natural greater than or equal to metallic > polymeric). Attachment varied significantly with material (P < 0.01) and with surface roughness within a material (P < 0.05). The lowest attachment strengths were measured on (in increasing order of attachment strength) smooth polytetrafluoroethylene, polymethylmethacrylate, and aluminum. The strongest attachment was measured on rough limestone/dolomite cobble, and mild steel of all roughnesses. Zebra mussel attachment strength was intermediate on, marine concrete, marine plywood, polyvinylchloride, stainless steel, and coal tar epoxy coated mild steel. These results provide preliminary design guidelines for the control of zebra mussels. Ahmed, M. 1971. Oyster species of west Pakistan. Pakistan Journal of Zoology 3: 229-237. Ref ID: 52 Ahmed, M., Barkati, S., and Sanaullah. 1987. Spatfall of oysters in the Gharo-Phittisalt water creek system near Karachi (Pakistan). Pakistan Journal of Zoology 19: 245-252. Ref ID: 45 Aldridge, D. C., Elliott, P., and Moggridge, G. D. 2004. The recent and rapid spread of the zebra mussel (Dreissena polymorpha) in Great Britian. Biological Conservation 119: 253-261. Ref ID: 648 Allen, S. K. Jr. and Downing, S. L. 1986. Performance of triploid Pacific oysters, Crassostrea gigas (Thunberg). I. Survival, growth, glycogen content, and sexual maturation in yearlings. Journal of Experimental Management 102: 197-208. Ref ID: 140 Allen, S. K. Jr. and Bushek, D. 1992. Large-scale production of triploid oysters, Crassostrea virginica (Gmelin), using "stripped" gametes. Aquaculture 103: 241-251. Ref ID: 128 Abstract: Successful production of triploid oysters requires precise control of the timing of fertilization of eggs. Logistically, using stripped gametes is the most practical method for producing triploids because the time of fertilization can be easily controlled. We examined several factors that may affect the survival and yield of triploid C virginica from stripped gametes in large scale spawnings. Triploidy was induced by inhibiting polar body II with cytochalasin B. Fourteen replicates containing from 17 to 49 million (M) eggs were treated. Survival and percent triploidy of 48-h-old larvae were not correlated; mean survival was 22% and mean triploidy was 79%. About 72% of 138 spat examined were triploid, indicating that the estimate of triploidy at 48 h was accurate. Overall, 400.8 M eggs yielded about 17.8 triploid spat, an efficiency of 4.4%. All linear regression models incorporating the treatment variables were non-significant. Variability may be random, a reflection of egg quality, or both. Allen, S. K. Jr. and Gaffney, P. M. 1993. Genetic confirmation of hybridization between Crassostrea gigas (Thunberg) and Crassostrea rivularis (Gould). Aquaculture 113: 291-300. Ref ID: 138 Abstract: Of the numerous reports of hybridization attempts in the genus Crassostrea, none has been confirmed genetically. Three replicates of a 2 x 2 factorial mating of Crassostrea gigas x C. rivularis (C. arakiensis) were produced to examine the viability of this cross. Fertilization rate, yield of 48-h-old larvae, and survival of fertilized eggs was lower in the hybrids than pure crosses. All crosses showed similar larval growth rates, except C. rivularis x C. gigas, which grew more slowly. Genetic control of eyed larval size was indicated by the intermediate size of hybrids compared to pure crosses. Spat were obtained from most cultures and were shown by protein electrophoresis to be hybrids. Contaminants were also present, underscoring the need for genetic confirmation in studies on bivalve hybridization. Allen, S. K. Jr., Gaffney, P. M., Scarpa, J., and Bushek, D. 1993. Inviable hybrids of Crassostrea virginica (Gmelin) with C. rivularis (Gould) and C. gigas (Thunberg). Aquaculture 113: 269-289. Ref ID: 139 Abstract: Interspecific hybridization may provide important tools for selective breeding programs in oyster culture, especially for enhancement of disease resistance, and may have a bearing on debates concerning the introduction of non-native species. Factorial crosses of C. virginica with C. rivularis (C. arakiensis) and C. gigas were made, producing control and hybrid larvae. Larval survival and growth were documented. After several replicated experiments it became apparent that diploid hybrids were inviable, and so triploid hybrids were also tested and found to be equally inviable. Feeding studies with hybrids were initiated to determine if lack of growth and viability were related to capture of food. Overall, hybrids of C. virginica with C. rivularis and C. gigas can be readily produced, but are inviable after 8-10 days and grow little. With regard to the species examined here, previous reports of successful hybridization should be questioned. Introduction of C. gigas to the native range of C. virginica will not have direct genetic effects on C. virginica. Amemiya, I. 1928. Ecological studies of Japanese oysters, with special reference to the salinity of their habitat. Journal of the College of Agriculture, Imperial University of Tokyo 9: 334-381. Ref ID: 642 Anderson, R. S., Brubacher, L. L., Ragone-Calvo, L., Unger, M. A., and Burreson, E. M. 1998. Effects of tributyltin and hypoxia on the progression of Perkinsus marinus infections and host defense mechanisms in oyster Crassostrea vriginica (Gmelin). Journal of Fish Diseases 21: 371-379. Ref ID: 519 Andow, D. A. and Hilbeck, A. 2004. Science-based risk assessment for nontarget effects of transgenic crops. BioScience 54: 637-649. Ref ID: 568 Andrews, J. D. 1951. Seasonal patterns of oyster setting in the James River and Chesapeake Bay. Ecology 32: 752-758. Ref ID: 482 Andrews, J. D. and Hewatt, W. G. 1957. Oyster mortality studies in Virginia. II. The fungus disease caused by Dermocystidium marinum in oysters of Chesapeake Bay. Ecological Monographs 27: 1-25. Ref ID: 481 Andrews, J. D. 1966. Oyster mortality studies in Virginia. V. Epizootiology of MSX a protistan pathogen of oysters. Ecology 47: 19. Ref ID: 495 Andrews, J. D. 1979. Oyster diseases in Chesapeake Bay. Marine Fisheries Review 41: 45-53. Ref ID: 479 Andrews, J. D. 1980. A review of introductions of exotic oysters and biological planning for new importation. Marine Fisheries Review 42: 1-11. Ref ID: 187 Andrews, J. D. 1982. Anaerobic mortalities of oysters in Virginia caused by low salinities. Journal of Shellfish Research 2: 127-132. Ref ID: 159 Andrews, J. D. 1996. History of Perkinsus marinus, a pathogen of oysters in Chesapeake Bay 1950-1984. Journal of Shellfish Research 15: 13-16. Ref ID: 37 Abstract: The pathogen Perkinsus marinus (Dermo) was discovered in Chesapeake Bay in 1950. It was already widely distributed in the Bay and caused annual mortality below the mouth of the Rappahannock River. Annual mortality in trayed oysters at the Virginia Institute of Marine Science (VIMS) varied annually from 24% to 57% at this most favorable site for the disease. Over 2 million bushels of seed oysters from the James River public beds were transplanted annually to private beds in 4 major growing areas. These were Hampton Roads, lower Bay proper, Mobjack Bay at mouth of York River, and the Rappahannock River. The introduction of Haplosporidium nelsoni (MSX) in 1959 resulted in killing most oysters throughout the Bay, and private planting was abandoned. Extreme dry weather during the decade of the 1980s allowed both diseases to spread widely throughout the Bay, and the oysters became scarce everywhere. MSX retreated to its endemic area below the mouth of the Rappahannock River when salinities returned to average levels. Dermo destroyed oysters in the seed area of the James River, and it has persisted there tenaciously with low mortality. Market-oyster production dropped from 2 to 3 million bushels annually during the 1950s to 6,000 in 1993. No seed oysters are available, and planting of private beds has ceased. Recovery is slow, and the oyster industry in Virginia was destroyed. ANON. 1900. The geographical distribution of Crassostrea virginica, C. gigas, and C. rivularis. Virginia Marine Bulletin 28: 11. Ref ID: 44 Ashby, S. L., Boyd, W. A., and Kennedy, R. H. 1998. Assessing The Potential for Zebra Mussel Habitat at U.S. Army Corps of Engineer Water Resource Projects Using Techniques and Water Quality Data., US Army Engineer Waterways Experimental Station (WES), Vicksburg, MS Ref ID: 121 Asif, M. 1978. Variations in allometric growth in the shells of Crassostrea rivularis (Gould), Saccostrea glomerata (Gould), and S. cuccullata (Born) from the coast of Karachi. Pakistan J.Sci.Ind.Res. 23: 46-49. Ref ID: 70 Asif, M. 1978. Some observations on interspecific cross in three species of oysters from the coast of Karachi. Pakistan Journal of Zoology 10: 217-221. Ref ID: 137 Asif, M. 1979. Hermaphroditism and sex reversal in the four common oviparous species of oysters from the coast of Karachi. Hydrobiologia 66: 49-55. Ref ID: 76 Atkinson, P. W., Clark, N. A., Bell, M. C., Dare, P. J., Clark, J. A., and Ireland, P. L. 2003. Changes in commercially fished shellfish stocks and shorebird populations in the Wash, England. Biological Conservation 114: 127-141. Ref ID: 613 Abstract: The Wash, in eastern England, supports internationally important populations of 11 species of shorebird. A major commercial shellfishery provides potential conflict between fishermen and nature conservation interests. During the 1990s, high fishing mortality and low recruitment substantially reduced the stocks of cockle (Cerastoderma edule) and mussel (Mytilus edulis). Population models. constructed from estimates of survival and recruitment, indicated that declines in the availability of cockles and mussels were associated with changes in oystercatcher (Haemotopus ostralegus) survival between 1970 and 1998, including three periods of mass mortality, and also the recruitment of juvenile birds to both oystercatcher and knot (Calidris canutus) populations. Emigration of knot may also have taken place. Cockle recruitment was dependent on climatic conditions, whereas mussel populations tended to be stable. The decline in mussel stocks, due to over-fishing, increased the vulnerability of the oystercatcher population to mass-mortality episodes in poor cockle years. The key to preventing major oystercatcher kills in future is to ensure sufficient mussels are available in poor cockle years. Recent cultivation of mussels in inter-tidal areas has been beneficial and is an important management tool for maintaining bird populations. (C) 2003 Elsevier Ltd. All rights reserved Austin, H. M., Evans, D., and Haven, D. S. 1996. A retrospective time series analysis of oyster, Crassostrea virginica, recruitment (1946-193). Journal of Shellfish Research 15: 565-582. Ref ID: 81 Abstract: Temporal patterns of eastern oyster, Crassostrea virginica (Gmelin 1791), spatfall in the Virginia tributary rivers to the Chesapeake Bay showed a decline in all rivers from 1946 through the early 1970s, with a subsequent leveling off. The decline was most severe in the James and less so moving north to the York and Rappahannock Rivers; it was least severe in the Potomac River. Yearling patterns generally mirrored the spat. Cluster analyses grouped the bars naturally by up- and downriver spatfall patterns. They also clustered this way when between-river comparisons were made. Spatfall showed a significant cross-correlation with yearlings a year later in all Virginia rivers, which suggests that the ''yearling'' designation was accurate and that spat counts may be used to predict yearling abundance. The relation of spat to later seed was significant for the James River at 2 and 3 y, but none was found between spat and market oyster. James River seed demonstrated a slightly significant relation to market oyster 4 y later. Regression analyses between spat counts and spring and summer water temperatures and river discharge produced little explanation of spat variation. There was, however, a significant relation between spat count and the Palmer Drought Index. The drought index is a combination of rainfall, soil type, and evapotranspiration. When the period of the greatest change in the drought index was correlated with spatfall, there was found to be a significant 2- to 4-y lag. We suggest that this reflects a response by the ecosystem to changing environmental conditions. Baird, D. and Ulanowicz, R. E. 1989. The seasonal dynamics of the Chesapeake Bay. Ecological Monographs 59: 329-364. Ref ID: 196 Baker, P. 1994. Competence to settle in oyster larvae, Crassostrea virginica: wild versus hatchery-reared larvae. Aquaculture 122: 161-169. Ref ID: 403 Abstract: Competency to settle in larvae of the oyster Crassostrea virginica is defined as proportional settlement of a given number of larvae within 24 h. It is distinguished from apparent competency, which is based on observed morphological characteristics. Competency of pediveliger larvae in lower York River, Chesapeake Bay, Virginia (taken by plankton pump from near the bottom of the water column) was 81.1% in 1990, and 79.9% in 1992. Larvae taken from midwater samples and near-surface samples showed a competency of 70.0 and 58.9%, respectively, but these values were not significantly different from the 1992 near-bottom samples. There were no handling effects, or larval density effects, on competency, based on assays using hatchery-reared larvae. Settlement over three trials of hatchery-reared larvae ranged from about 7% to 32% in 24 h. These percentages are much lower than those for York River larvae, but similar to daily settlement reported by commercial oyster hatcheries elsewhere Baker, P. 1997. Settlement site selection by oyster larvae, Crassostrea virginica: Evidence for geotaxis. Journal of Shellfish Research 16: 125-128. Ref ID: 294 Abstract: Settlement of larval oysters, Crassostrea virginica, with respect to upper and lower surfaces of natural substrates, was studied in the field and in the laboratory. Enclosures were used to retain pediveligers of Crassostrea under controlled field conditions: until they settled. About 62% of these larvae settled onto rough (outer) surfaces of natural oyster shell substrate; this closely marched the proportion of substrate oriented with the rough surface downward. In the laboratory, about 83% of larvae settled onto the lower surfaces of similar shell substrates, in the absence of light, regardless of how the shell substrate was positioned. Both field and laboratory results suggest that geotaxis is a stronger settlement orientation cue than either phototaxis or rugotaxis, in Crassostrea Baker, P. and Mann, R. 1998. Response of settling oyster larvae, Crassostrea virginica, to specific portions of the visible light spectrum. Journal of Shellfish Research 17: 1081-1083. Ref ID: 77 Abstract: Settlement site choice was used to rest the ability of competent-to-settle oyster (Crassostrea virginica) larvae to detect specific portions of the visible light spectrum. Larvae were permitted to settle on illuminated or shaded sides of vertically oriented settlement substrates. Five light treatments were used, including white light (400-700 nm), three fractions of white light; red light (600-700 nm), green light (450-575 nm, peak at 525 nm), blue light (400-500 nm, peal; at 425 nm); and total darkness. In total darkness, no settlement preference for either side of the substrates was detected. In all light treatments, larvae settled in significantly higher numbers onto shaded surfaces than illuminated surfaces. Crassostrea virginica larvae respond to most portions of the visible light spectrum, unlike many previously studied marine invertebrate larvae. This ability may reflect the diverse light conditions in the largely estuarine habitat of this species. Baker, P. and Mann, R. 2003. Late stage bivalve larvae in a well-mixed estuary are not inert particles. Estuaries 26: 837-845. Ref ID: 256 Abstract: Depth-specific sampling at a single location was used to examine the vertical distribution of pediveliger larvae of bivalve mollusks in the York River, an estuary of Chesapeake Bay, Virginia. The water column at the sampling site was usually well mixed, lacking consistent temperature or salinity gradients for larvae. Four species showed strong vertical stratification when collected simultaneously at three depths. Pediveliger stage larvae of a clam (Cyrtopleura costata), an oyster (Crassostrea virginica), and a shipworm (Bankia gouldi) were most abundant near the benthos, and least abundant near the surface. A mussel (Geukensia demissa), showed the reverse trend, with most pediveliger larvae near the surface. Tidal stage had a slight effect on two species (C. costata and C virginica), but only to increase the relative abundance of larvae near the benthos during flood tide. Otherwise, neither tidal phase nor light levels (night versus day) had detectable effects on distribution patterns. Sampling very close to the sediment-water interface provided no evidence that pediveliger larvae spent a significant proportion of their time in this location. While the behavior of pre-competent bivalve larvae may tend to retain them within an estuary, that of competent-to-metamorphose pediveliger larvae does not appear to have that function. Pediveliger larvae may regulate their depth to best locate potential settlement substrate. Such an hypothesis is consistent with adult habitat zones of at least some of these species in Chesapeake Bay. Removing competent-to-settle larvae from analyses of larval distributions in estuaries will enhance or clarify depth distribution patterns observed for earlier-stage larvae Baker, S. M. and Mann, R. 1992. Effects of hypoxia and anoxia on larval settlement, juvenille growth, and juvenille survival of the oyster Crassostrea virginica. Biological Bulletin 182: 265-269. Ref ID: 72 Abstract: The effects of hypoxia (1.5 mg O2 l-1, 20% of air saturation) and anoxia (<0.07 mg O2 l-1, <1% Of air saturation) on oyster (Crassostrea virginica) larval settlement, juvenile growth, and juvenile survival were studied. Settlement was reduced significantly (P < 0.05) in hypoxic treatments, as compared to normoxic treatments (7.3 mg O2 h-1, 100% of air saturation), and almost no settlement took place in anoxic treatments. After 96 h, 38% and 4% of the larvae placed in hypoxic and anoxic treatments had settled, while 79% settled in normoxic treatments. In the first 144 h after settlement, juveniles in hypoxic treatments grew one third as much as those in normoxic treatments, while juveniles in anoxic treatments did not grow at all. Median mortality times of recently settled juveniles in hypoxic and anoxic treatments were 131 h and 84 h, respectively. We conclude that hypoxic and anoxic waters have potentially detrimental effects on oyster settlement and recruitment. Baker, S. M. and Mann, R. 1994. Feeding ability during settlement and metamorphosis in the oyster Crassostrea virginica (Gmelin, 1791) and the effects of hypoxia on postsettlement ingestion rates. Journal of Experimental Marine Biology and Ecology 181: 239-253. Ref ID: 400 Abstract: The feeding ability of oyster (Classostrea virginica Gmelin) larvae during Settlement and metamorphosis was observed. Also examined were the effects of hypoxia (1.9 mg O-2.1(-1), 25% of air saturation) and microxia (<0.4 mg O-2.1(-1), <5% of air saturation) on ingestion rates of post-settlement oysters. Velar feeding occurred during the searching and crawling stages of settlement, but not during cementation. In newly settled larvae, 16% engaged in velar feeding while 84% did not feed. All later metamorphic phases fed, although the mode of particle capture was unclear. Under normoxic conditions mean rates of cell ingestion by post-settlement oysters (268-651 mu m in shell height) ranged from 600 to 3000 cells.h(-1) individual(-1). In response to hypoxic treatments, post-settlement oysters with shells heights of 469 +/- 103 mu m and 651 +/- 131 mu m maintained their normoxic rates of ingestion but oysters with shell heights of 436 +/- 60 mu m reduced their ingestion rates to 54-61% of normoxic rates. These oyster sizes differed in the extent of gill development and proliferation. In response to microxic treatments, ingestion rates were 1% to 14% of normoxic rates and decreased with body size. We conclude that oysters have the ability to feed at nearly all stages of settlement and metamorphosis and that hypoxic conditions will affect the feeding activities of only the youngest post-settlement oysters while microxic conditions will affect all post-settlement oysters Baldwin, B. S. and Newell, R. I. E. 1991. Omnivorous feeding by planktotrophic larvae of the eastern oyster Crassostrea virginica. Marine Ecology-Progress Series 78: 285-301. Ref ID: 623 Abstract: In order to better understand the particle diet of planktotrophic larvae of the eastern oyster Crassostrea virginica (Cmelin) we measured their ingestion of naturally occurring food organims. By using a dual radioisotope (H-3 and C-14) labeling technique in conjunction with plankton size fractionation procedures we demonstrate that oyster larvae feed upon bacteria, phagotrophic protozoans and phototrophs present in the diverse summer plankton assemblages of Chesapeake Bay, USA. Prodissoconch II oyster larvae cleared 0.2 to 30-mu-m C-14-labeled plankton (primarily phototrophs) at a rate of 0.0825 ml larva 1 h-1, and 0.2 to 30-mu-m H-3-labeled plankton (heterotrophic bacteria and phagotrophic protozoans) at a rate of 0.0017 ml larva-1 h-1. This calculated clearance rate for 0.2 to 30-mu-m heterotrophs was low due to the predominance of small (0.2 to 0.8-mu-m), poorly retained bacteria in this size class. Oyster larvae consumed a wide size range of food particles (0.2-0.8-mu-m to 20-30-mu-m) and selectively ingested 20 to 30-mu-m organisms. In other feeding experiments, oyster larvae cleared laboratory cultured heterotrophic flagellates (12-mu-m) at a rate of 0.0640 ml larva-1 h-1 and cultured heterotrophic ciliates (12 x 20-mu-m) at a rate of 0.1093 ml larva-1 h-1. The inclusion of heterotrophic food organisms in the diet of C. virginica may enhance its growth and development by providing energy and nutrients that supplement those of ingested phytoplankton. We suggest that because oyster larvae ingest non-phytoplankton cells, estimates of standing stocks of phytoplankton may not always be a reliable measure of food supply. Baldwin, B. S. and Newell, R. I. E. 1995. Feeding rate responses of oyster larvae (Crassostrea virginica) to seston quantity and composition. Journal of Experimental Marine Biology and Ecology 189: 77-91. Ref ID: 615 Abstract: The functional response of oyster larvae [Crassostrea vilginica (Gmelin)] to in situ food variability was examined by measuring their feeding rates for samples of seston (Chesapeake Bay, USA) that differed in both particle amount and composition. Feeding rates and patterns were compared to those of larvae fed the cultured alga Isochrysis sp. (clone T-ISO), Larval feeding patterns appeared to be consistent with a Holling's Type 3 functional response for both natural particles and T-ISO. The incipient limiting concentrations of suspended particle volume where ingestion rates became maximal were similar for natural plankton (range 20 x 10(5) to 33 x 10(5) mu m(3) . ml(-1)) and T-ISO (19 x 10(5) mu m(3) ml(-1)) and were also similar to previously reported values for other species of bivalve larvae fed cultured algae. Incipient limiting concentrations for natural suspensions corresponded to 20-100% of ambient concentrations. Larval ingestion rates for seston collected over different times and from different locations appeared to be at saturated levels (range about 90 x 10(3) to 120 x 10(3) mu m(3) . larva(-1). h(-1)) but it is not clear whether larval growth is food-limited in Chesapeake Bay, Ingestion rates for these seston samples were similar despite considerable differences in the particle size structure and plankton composition of these samples. Larval ingestion rates for seston were greater than maximal ingestion rates of T-ISO (about 28 x 10(3) mu m(3) . larva(-1) h(-1)) and higher than previously reported maximal rates for bivalve larvae fed cultured foods, suggesting that oyster larvae perceived differences in the nutritional quality of natural and cultured foods. These experiments suggest that in nature, the ingestion rates of oyster larvae appear to be most strongly regulated by food quantity (volume) and nutritional quality and not particle size or numerical abundance. Baldwin, B. S. and Newell, R. I. E. 1995. Relative importance of different size food particles in the natural diet of oyster larvae (Crassostrea virginica). Marine Ecology-Progress Series 120: 135-145. Ref ID: 624 Abstract: We examined the feeding activity of planktotrophic larvae of the eastern oyster Crassostrea virginica on different size particles suspended in surface waters of 2 subestuaries of Chesapeake Bay, USA. Particle suspensions were characterized using particle counters and microscopic observations. At both sites, particle assemblages were dominated (in terms of particle number and volume) by particles (predominantly plankton cells) with equivalent spherical diameters < 5 mu m. Feeding experiments demonstrated that small (< 150 mu m shell length) and large (> 200 mu m) oyster larvae typically ingested particles between 0.5 and 12 mu m. However, in the presence of blooms of large (10 to 30 mu m) dinoflagellates, small and large larvae extended their maximum ingested particle size to about 16 and 30 mu m, respectively. These results indicate that oyster larvae generally exploit foods within the characteristic particle biomass peak present in these estuaries and opportunistically feed upon periodic blooms of large plankton cells. Larvae derived a large percentage (range 20 to 90%) of the total ingested particle volume from picoplankton-size (here defined as 0.5 to 3 mu m) particles. These small particles constituted a larger percentage of the material ingested by small larvae than that ingested by large larvae. By comparison, both sizes of larvae derived about 2 to 40 % and about 5 to 20 % of total ingested food volume from 3 to 5 pm and 5 to 10 Fun particles, respectively. In experiments with abundant dinoflagellates > 10 mu m in size, both sizes of larvae derived 20 to 30 % of their total ingested volume from these particles. Banks, M. A., Hedgecock, D., and Waters, C. 1993. Discimination between closely related Pacific oyster species (Crassostrea) via mitochondrial DNA sequences coding for lareg subunit rRNA. Molecular Marine Biology and Biotechnology 2: 129-136. Ref ID: 180 Banks, P. D. and Brown, K. M. 2002. Hydrocarbon effects on fouling assemblages: the importance of taxonomic differences, seasonal, and tidal variation. Marine Environmental Research 53: 311-326. Ref ID: 492 Abstract: Effects of hydrocarbon-contaminated substrata on recruitment of three species of fouling organisms were studied along the Louisiana gulf coast. Clay tiles (232 cm(2)) were exposed to crude oil, 10% water soluble fraction of crude oil, or 25 g/kg artificial seawater, and placed out at two locations, in two seasons, and at two tidal levels in an estuary near Port Fourchon, Louisiana. Bryozoan (Membranipora savartii) recruitment was significantly reduced in all experiments on crude oil-exposed tiles. However, oysters (Crassostrea virginica) and barnacles (Balanus eburneus) exhibited recruitment facilitation, and oysters grew to larger size, on crude oil-exposed tiles in 1-4 of the five experiments. When oyster larvae were exposed to the same treatments in the laboratory, settlement was, however, significantly depressed on crude oil-exposed tiles as compared with controls, although oyster size was larger on crude-oil exposed tiles. Recruitment on tiles exposed to the water soluble fraction of crude oil was similar to control tiles in nearly all experiments for all taxa. We suggest naturally occurring biofilms (which hydrocarbons facilitate) may promote or inhibit recruitment, depending on the taxon, because hydrocarbons facilitated recruitment only in field experiments, not in lab experiments without biofilms. However, stronger currents in the field experiments may have more rapidly diluted hydrocarbons, and hydrocarbon effects were not large in comparison with natural seasonal and tidal variation in recruitment. (C) 2002 Elsevier Science Ltd. All rights reserved Barber, B. J., Ford, S. E., and Wargo, R. N. 1991. Genetic variation in the timing of gonadal maturation and spawning of the eastern oyster, Crassostrea virginica (Gmelin). Biological Bulletin 181: 216-221. Ref ID: 506 Abstract: The gonadal cycles of four groups of eastern oysters, Crassostrea virginica (Gmelin), including native stocks collected that year and inbred strains (reared in Delaware Bay for 5-6 generations) from both Long Island Sound and Delaware Bay, were compared in Delaware Bay in 1987. Inbred stains resembled their respective native stocks; both Long Island groups initiated gonadal development and spawning about one month earlier and spawned over a shorter duration than both Delaware Bay groups. Analysis of covariance revealed that the effect of time on gonadal development was statistically different (P less-than-or-equal-to 0.05) for all between-location group comparisons, but not for the two within-location comparisons. Thus, after six generations of inbreeding in Delaware Bay, Long Island oysters maintained their characteristic pattern of gonadal development and spawning, indicating the existence of genetically different environmental requirements for gonadal maturation between the two locations Barber, B. J., Ford, S. E., and Littlewood, D. T. J. 1991. A physiological comparison of resistant and susceptible oysters Crassostrea virginica (Gmelin) exposed to the endoparasite Haplosporidium nelsoni (Haskin, Stauber and Mackin). Journal of Experimental Marine Biology and Ecology 146: 101-112. Ref ID: 539 Abstract: Physiological rates of oysters Crassostrea virginica (Gmelin) selected and unselected for resistance to the endoparasite MSX Haplosporidium nelsoni (Haskin, Stauber & Mackin) were compared between June 1988 and May 1989 in lower Delaware Bay, USA. Prevalence of the parasite in the unselected (susceptible) group was 80% by July 1988, whereas no infections were detected in the selected (resistant) group until August 1988, and prevalence never exceeded 21%. In September 1988, cumulative mortality was 80% for the susceptible oysters compared to only 3% for the resistant oysters. Clearance rate was significantly (P < 0.001) greater in the resistant group than in the susceptible group in July and August 1988, but similar in June and September 1988 and May 1989. Oxygen consumption rate was significantly greater in the resistant group in June (P < 0.003) and August (P < 0.028) 1988, but similar in both groups in July and September 1988 and May 1989. During July and August 1988, when H. nelsoni was proliferating most rapidly and causing the greatest mortality of susceptible oysters, the difference between energy potentially taken in as food and energy respired was significantly (P < 0.002) greater in the resistant group than in the susceptible group. Although the greater degree of infection experienced by the susceptible oysters may have contributed to the differences in physiological rates, there was no consistent relationship between intensity of infection and physiological function. Alternatively, we suggest that "resistance" in the selected strain may be the result of a physiological response, perhaps induced by H. nelsoni, that inhibits development, as well as a basic metabolic adjustment to parasitism Barber, B. J., Mann, R., and Allen, S. K. Jr. 1992. Optimization of triploid induction for the oyster Crassostrea virginica (Gmelin). Aquaculture 106: 21-26. Ref ID: 126 Abstract: Standard techniques developed for producing triploid oysters (Crassostrea gigas) in the northwestern United States cause > 90% mortality of Crassostrea virginica, which is unacceptably high considering the scale of most east coast hatcheries. We examined the effect of cytochalasin B (CB) concentration, timing of treatment after fertilization, and duration of treatment on survival and triploid induction of C. virginica embryos. Survival to D-stage was inversely related to CB concentration and length of treatment. Induction of triploidy was CB-dose dependent. Optimal treatment of 0.25 mg/l CB for 10-15 min beginning when half the embryos were observed to be undergoing meiosis-I yielded mean survival to D-stage of 84% of control values with a mean of 96% triploid production. Barber, B. J. and Mann, R. 1994. Growth and mortality of eastern oysters, Crassostrea virginica (Gmelin, 1791), and Pacific oysters, Crassostrea gigas (Thunberg, 1793) under challenge from the parasite, Perkinsus marinus. Journal of Shellfish Research 13: 109-114. Ref ID: 527 Abstract: Stocks of oysters Crassostrea virginica and C. gigas were produced in the Virginia Institute of Marine Science (VIMS) hatchery in April 1991 and grown in two quarantined flumes receiving water from the York River, VA. From July 1991 through November 1992, growth and mortality of both species were compared. Also, beginning in June 1992 one flume (containing one group of each species) was ''dosed'' (oysters infected with P. marinus added) and the other flume remained ''undosed'' (no infected oysters added). Disease prevalence and intensity, mortality, and shell height were compared both within (between undosed and dosed groups) and between species. Mean shell height of C. gigas was significantly greater (P less-than-or-equal-to 0.05) than that of C. virginica in all but four monthly samples. In November 1992 (at age 19 months), mean shell height of C. gigas was 55 mm and that of C. virginica was 41 mm. Cumulative mortality of C. gigas was 70% compared to 59% for C. virginica. Mortality of C. gigas occurred primarily in April-May and September 1992 in conjunction with salinity below 20 ppt; mortality of C. virginica was greatest in September-November 1992 in conjunction with infection by P. marinus. Prevalence and intensity of P. marinus infections were greater in C. virginica than in C. gigas. The dosed C. virginica group had 100% prevalence with heavy infections by August 1992; maximum prevalence in the dosed C. gigas group was 80% with only 1 heavy infection throughout the study. There were no differences in mean shell height between dosed and undosed groups of either species. Mortality in the dosed C. virginica group was significantly greater (P less-than-or-equal-to 0.05) than in the undosed group in September and October 1992. Thus even though C. gigas is more tolerant of P. marinus and grows faster than C. virginica, a high non-disease mortality may be indicative of a lack of adaptability of C. gigas to the environmental factors prevailing in lower Chesapeake Bay Barber, B. J. 1996. Gametogenesis of eastern oysters, Crassostrea virginica (Gmelin, 1791), and Pacific oysters, Crassostrea gigas (Thunberg, 1793) in disease-endemic lower Chesapeake Bay. Journal of Shellfish Research 15: 285-290. Ref ID: 218 Abstract: Gametogenic cycles were compared for oysters, Crassostrea virginica and C. gigas, held in flumes receiving water from the York River, VA, where two protozoan parasites, Haplosporidium nelsoni and Perkinsus marinus, are endemic. Gametogenesis in C. virginica was characterized by a general lack of development, maturation, and spawning. Only two C. virginica developed mature gametes, and none showed evidence of spawning. From July onward, most individuals exhibited gamete resorption. In contrast, gamete development, maturation, and spawning were well defined and synchronous in C. gigas. Mature individuals predominated in June, and spawned individuals predominated in July. Mean gonadal area indices (GAI) were significantly different (P less than or equal to 0.001) between months and species. Mean oocyte areas were significantly different (P less than or equal to 0.001) between months. Significant month x species interactions (P less than or equal to 0.001) for both GAI and oocyte areas supported the differences in gametogenic cycles observed between species by the use of subjective staging. Among mature females, C. gigas had both a significantly greater (P less than or equal to 0.001) GAI and mean oocyte area than C. virginica. Combined prevalence of the parasites H. nelsoni and P. marinus increased from 0 to 86.7% in C. virginica between May and August. Infection intensity increased from epithelial infections to systemic infections from June through September. These parasites were never detected in C. gigas. The difference in gametogenic cycles observed between oyster species could be related to differences in susceptibility to the parasites H. nelsoni and P. marinus, genetic differences in gametogenic cycles, or a combination of both factors. This study establishes the ability of C. gigas to produce gametes and spawn in the environment prevailing in lower Chesapeake Bay Barber, B. J., Carnegie, R. B., Davis, C. V., and Mook, W. 1996. Effect of timing of seed deployment on growth and mortality of oysters, Crassostrea virginica, affected by Juvenile Oyster Disease (JOD). Journal of the World Aquaculture Society 27: 443-448. Ref ID: 553 Abstract: Mortality of oysters, Crassostrea virginica, caused by Juvenile Oyster Disease (JOD) has been a chronic problem the northeastern United States since 1988. To assist in identifying potential health management options, the effect of time of spawning and deployment of oysters on resultant growth and mortality was examined in the Damariscotta River, Maine. Broodstock oysters from a line selected for fast growth were spawned at 2-wk intervals between 28 March and 19 July 1995. Duplicate groups of juvenile oysters from each spawn were deployed in floating trays between 23 May and 31 August. Mortality and size of all cohorts were determined from late June to early December. Cumulative mortality of oysters was related to the timing of deployment. Cohorts placed in the river before June or after mid-August had cumulative mortalities of 20% or less. Oysters deployed between 8 June and 18 August had cumulative mortalities ranging from 64-96%. Growth of all cohorts was rapid immediately after deployment but decreased once JOD began to have an effect. Final size of oysters was directly related to age. This study determined that seed oysters placed in the Damariscotta River between June and mid-August will experience high mortality and low growth. Potential management options to reduce JOD impact include 1) early spawning and deployment in May, ensuring that a mean shell height >25 mm is reached prior to August and 2) late spawning and deployment after mid-August to avoid exposure to JOD Barber, B. J., Davis, C. V., and Crosby, M. A. 1998. Cultured oysters, Crassostrea virginica, genetically selected for fast growth in the Damariscotta River, Maine, are resistant to mortality caused by Juvenile Oyster Disease (JOD). Journal of Shellfish Research 17: 1171-1175. Ref ID: 525 Abstract: Growth and mortality of hatchery-produced juvenile oysters, Crassostrea virginica, selected for fast growth were compared with unselected, wild oysters at sites in Maine (Damariscotta River) and Massachusetts (North Bay) where Juvenile Oyster Disease (JOD) is enzootic. Over the course of the study, JOD occurred primarily in Maine, even though prevailing temperature and salinity at both sites were conducive for JOD development. From July to November 1996, mean shell height of selected oysters was greater than that of wild oysters at both sites. At the end of the study, mean shell height of both selected and wild oysters was greater in Massachusetts than in Maine. Mean cumulative mortality of both groups was greater in Maine than Massachusetts. Only in Maine was mean cumulative mortality of wild oysters greater than that of selected oysters. Differences in growth and mortality of oysters between sites were due primarily to the differential timing and severity of JOD occurrence. In addition, the difference in survival between selected and wild oysters in Maine was not related to differences in size between groups at the time of initial exposure to JOD. Thus, we conclude that occurrences of JOD are site specific (not dependent on source of seed), and that under challenge from JOD, selected oysters not only grow faster than wild (unselected) oysters, but exhibit a genetically based tolerance of this disease Barber, R. D., Kanaley, S. A., and Ford, S. E. 1991. Evidence for regular sporulation by Haplosporidium nelsoni (Msx) (Ascetospora, Haplosporidiidae) in spat of the American oyster, Crassostrea virginica. Journal of Protozoology 38: 305-306. Ref ID: 247 Abstract: The spore stage of Haplosporidium nelsoni, the ascetosporan parasite causing multinucleated sphere unknown (MSX) disease in oysters, Crassostrea virginica, has been reported so rarely (< 0.01% of infected oysters) that a second host has been postulated. However, recent intensive sampling of young (< 1 year) oysters in Delaware Bay, U.S. suggests that spore formation occurs regularly in this group and that spores are produced in at least 75-45% of all infections reaching the advanced stage. Sporulation was seasonal, occurring over two to three weeks in late June/early July and again in late summer/early fall. Our data indicate that sporulation by H. nelsoni in oysters is more common than previously suspected, occurring in a segment of the host population that may not have been sufficiently sampled in the past, and that a direct life cycle should be reconsidered Barille, L., Heral, M., and Barille-Boyer, A.-L. 1997. Ecophysiological deterministic model for Crassostrea gigas in an estuarine environment. Aquatic Living Resources 10: 31-48. Ref ID: 11 Abstract: An ecophysiological deterministic model of growth, reproduction and interactions between the bivalve and its estuarine environment was established for the Japanese oyster Crassostrea gigas. The environmental variables used in the model are: total particulate matter, particulate organic matter, particulate inorganic matter, chlorophyll, phaeopigments, proteins, lipids and carbohydrates. Rates of clearance, filtration, ingestion, absorption and respiration along with efficiencies of retention, selection and absorption are modelled with endogenous (dry weight of the animal, energy allocation between growth and reproduction) and exogenous variables (temperature, food quality and quantity). The model simulate the temporal evolution of two compartments: somatic and storage-gonad. Absorbed energy is allocated to soma up to a maximum somatic growth. This maximum decreases with age and never exceeds 0.02 g.d(-1).oyster(-1). Energy in excess is allocated to the storage-gonad compartment. The model identify storage and gametogenesis periods and correctly predicts spawning intensity. In this model, the oyster selectively reject inorganic from organic particles, enriching the ingested ration. Within potentially nutritive particles, fewer particles containing phytopigments are rejected compared with detritic particles. Absorption efficiency is represented as a function of organic content in the ingested ration. Microphytes are absorbed with an efficiency which fluctuates from 20 to 60%. The model predicts negative absorption for detritic material to take into account metabolic faecal losses. Theses formulations provide information about the temporal evolution of the amount of microphytes and detritic matter biodeposited as pseudofaeces and faeces. Barkati, S. and Khan, R. M. 1987. Relative growth in three oyster species. Pakistan J.Sci.Ind.Res. 1987: 8-624. Ref ID: 71 Abstract: 627 Bartol, I. K. and Mann, R. 1997. Small-scale settlement patterns of the oyster Crassostrea virginica on a constructed intertidal reef. Bulletin of Marine Science 61: 881-897. Ref ID: 288 Abstract: The construction of three-dimensional, intertidal reefs resembling those widely present during colonial times in the Chesapeake Bay, but now absent due to years of overharvesting, may provide a more ecologically advantageous environment for oyster settlement and subsequent survival than present subtidal, two-dimensional habitats. We examined settlement processes on a constructed, 210 x 30 m intertidal reef composed of oyster shell. The reef was destructively and non-destructively sampled weekly throughout the summer and fall at tidal heights ranging from 30 cm above to 90 cm below mean low water (MLW) and at two substrate levels (reef surface and 10 cm below the reef surface). Settlement at the surface of the reef community and within the reef interstices down to depths of 10 cm was statistically similar, and settlement was generally greatest subtidally; however, there were localized areas within the reef community where conditions were beneficial for intertidal settlement and where differences in intertidal/subtidal settlement rates were not detectable. These results suggest that microscale variations in tidal elevation and substrate depth strongly affect settlement processes and should not be ignored when constructing reefs Bartol, I. K., Mann, R., and Luckenbach, M. 1999. Growth and mortality of oysters (Crassostrea virginica) on constructed intertidal reefs: effects of tidal height and substrate level. Journal of Experimental Marine Biology and Ecology 237: 157-184. Ref ID: 522 Abstract: Intertidal oyster reefs, 3-dimensional structures created by years of successive settlement of larval oysters on adult oyster shells, provide levels of surface and interstitial heterogeneity that are rare in marine ecosystems. Surprisingly, little is known about the ecological benefits for oysters (Crassostrea virginica) in these aerially exposed, structurally complex systems. In this study a 210 m x 30 m intertidal reef was constructed. During three, 28-day sampling periods in the summer and early fall, growth and mortality of two size classes of oysters placed in cages at three tidal heights (25 cm above mean low water (MLW), MLW, and 90 cm below MLW) and at two substrate levels (reef surface and 10 cm below the reef surface) within the reef setting were examined. Mid-intertidal oysters residing within the reef interstices grew faster and enjoyed greater survival than mid-intertidal oysters at the reef surface during certain times of the year. Conversely, subtidal oysters inhabiting subsurface environments did not grow faster than surface dwelling subtidal oysters, but some oysters within the reef fabric (larger size class) experienced significantly higher survival. Along a tidal continuum, oysters at the reef surface grew best in subtidal locations, yet experienced the lowest mortalities in the low intertidal zone (MLW). Reef heterogeneity, which allows for residence along both interstitial and tidal gradients, may provide physical and biological refugia for oysters and furnish ideal spatial platforms for growth. Therefore, location within the reef habitat has a significant impact on the biology and ecology of C. virginica. (C) 1999 Elsevier Science BN. All rights reserved Bayne, B. L., Svensson, S., and Nell, J. A. 1999. The physiological basis for faster growth in the Sydney rock oyster, Saccostrea commercialis. Biological Bulletin 197: 377-387. Ref ID: 136 Abstract: Sydney rock oysters were sampled from a mass selection experiment for growth (the "selected" category) and from a control ("not selected") population and held in the laboratory at three ration levels. We evaluated three models to explain faster rates of growth by selected oysters. Selection resulted in oysters feeding at up to twice the rate and with greater metabolic efficiency than controls. A field experiment confirmed that selection leads to faster rates of feeding across a wide range of food concentrations. Selected oysters also grew more efficiently, at a smaller cost of growth (C-g): mean values for C-g were 0.43 J . J(-1) in selected individuals and 0.81 J . J(-1) in the controls. In contrast, oysters in both categories showed similar metabolic rates at maintenance, i.e., at a ration supporting zero growth. There was no evidence that differential energy allocation affected the balance between total metabolic requirements above and below zero net energy balance. By experimenting with selected and control oysters of different sizes and ages, then standardizing the data for size, we found no effects of age on the differences due to selection. Faster-growing oysters feed more rapidly; invest more energy per joule ingested; show a higher net growth efficiency; and are able to allocate less energy per unit of tissue growth, than slower-growing individuals. Bisker, R. and Castagna, M. 1987. Predation on single spat oysters Crassostrea virginica (Gmelin) by blue crab Callinectes sapidus Rathbun and mub crabs Panopeus herbstii Milne-Edwards. Journal of Shellfish Research 6: 37-40. Ref ID: 201 Bobo, M. Y., Richardson, D. L., Coen, L. D., and Burrell, V. G. 1997. A Report on the Protozoan Pathogens Perkinsus marinus (Dermo) and Haplosporidium nelsoni (MSX) in South Carolina Shellfish Populations. Technical Report Number 86, South Carolina Department of Natural Resources, Charleston, SC Ref ID: 191 Boles, L. C. and Lipcius, R. N. 1997. Potential for population regulation of the zebra mussel by finfish and the blue crab in North American estuaries. Journal of Shellfish Research 16: 179-186. Ref ID: 524 Abstract: We conducted a series of descriptive and manipulative experiments aimed at quantifying the abundance, natural mortality, and effectiveness of predators in controlling the zebra mussel, Dreissena polymorpha, in the Hudson River Estuary. First, we measured distribution, abundance, and mortality rates of a zebra mussel population in the middle portion of the Hudson River Estuary, NY. Rocks were collected along a depth gradient in the field and sampled for the density and size structure of the resident mussels over the growth season. Next, we either allowed access (controls) or denied access (predator exclusion) to predators in field experiments with rocks harboring a known number of zebra mussels to estimate natural mortality. Finally, we conducted manipulative field experiments to test the effectiveness of the blue crab, Callinectes sapidus, at consuming zebra mussels by presenting similar rocks to crabs in field enclosures. Field sampling in June, July, and August 1993 indicated a dense (similar to 30,000 mussels/m(2)) population composed of a single cohort of 1 + year-class mussels. Sampling in August 1994 indicated a decline in D. polymorpha density. Mussel density increased dramatically with depth less than 2 m below the spring low tide mark. in cage experiments, blue crabs caused mortality rates that were an order of magnitude higher than those measured for the local predator guild, which was primarily composed of finfish. Localized extinctions of zebra mussels within one growth season were predicted in areas where blue crab densities approach 0.1 crabs/m(2) Bologna, P. A. X. and Heck, K. L. 2000. Impacts of seagrass habitat architecture on bivalve settlement. Estuaries 23: 449-457. Ref ID: 271 Abstract: We investigated the effects of differing spatial scales of seagrass habitat architecture on the composition and abundance of settling bivalves in a sub-tropical seagrass community. The density of newly settled bivalves was generally greater at Thalassia testudinum grass bed edge (( 1 m) compared to interior portions of the bed (> 10 m). Deviation from this generalized pattern occurred when high densities of newly settled tulip mussels (Modiolus americanus) were recorded from the interior of the meadow, associated with aggregations of adult mussels. Bivalve settling densities appear to reflect settlement shadows of passively delivered larvae, bedload transport of newly settled individuals from unvegetated regions, as well as gregarious settlement among adult conspecifics. We also investigated the impact of seagrass patch shape and size on settlement by using artificial seagrass units (ASU) in separate short-term and long-term experiments. We found a positive relationship between ASU perimeter and bivalve abundance, suggesting that larval encounter rates with seagrass habitat may determine initial settlement patterns. Using ASUs we also investigated the relative role seagrass epiphytes play in determining the density of settling bivalves. Results showed greater settling densities where epiphytic secondary structure was elevated compared to controls, and bivalve density was significantly greater when ASUs were fouled with a natural community of epiphytes, suggesting that both microstructure and biofilms positively influenced bivalve settlement. We conclude that structural components of seagrass habitats increase bivalve settlement at multiple spatial scales, including epiphytic micro-structure, small-scale patch shape and size, and large-scale within habitat differences Branch, G. M. 1984. Competition between marine organisms: Ecological and evolutionary implications. Oceanography and Marine Biology: An Annual Review 64: 429-593. Ref ID: 499 Brandt, S. B. and Mason, D. M. 2003. Effects of nutrient loading on Atlantic menhaden (Brevoortia tyrannus) growth rate potential in the Patuxent River. Estuaries 26: 298-309. Ref ID: 605 Breese, W. P. and Malouf, R. E. 1975. Hatchery Manual for the Pacific Oyster. ORESU-H-75-002, Oregon State University Sea Grant College Program, Corvallis, OR Ref ID: 164 Breese, W. P. and Malouf, R. E. 1977. Hatchery rearing techniques for the oyster Crassostrea rivularis Gould. Aquaculture 12: 123-126. Ref ID: 53 Breitburg, D. L. 1991. Settlement patterns and presettlement behavior of the naked goby, Gobiosoma bosci, a temperate oyster reef fish. Marine Biology 109: 213-221. Ref ID: 466 Abstract: Dispersion, distribution, development and feeding incidence of larvae of the naked goby, Gobiosoma bosci (Lacepede), were examined for linkages between larval behavior while near the reef surface and later patterns of settlement and recruitment. Field sampling and experiments were conducted during the summers of 1988 and 1989 in the Flag Pond oyster reef along the western shore of the Chesapeake Bay near Camp Conoy, Maryland, USA. Results indicated that prior to settlement most demersal larvae aggregate in shoals and exhibit distinct microhabitat preferences on the reef. In a field experiment, larvae settled both during the day and at night. Dispersion at settlement was aggregated, suggesting that demersal shoaling influences settlement patterns in this species. The distribution of demersal larvae also indicated that larval swimming behavior is sufficiently strong to permit active control of position on reefs. Large demersal larvae settled rapidly when brought to the laboratory, but small larvae in demersal shoals appeared to require additional growth and morphological development prior to settlement. Development of the pelvic fins, used by juveniles and adults for perching on the substrate, may be a good indicator of competence to settle in this species. The adaptive significance of demersal shoaling by small larvae of the naked goby, and the fate of these larvae, remains perplexing because the low feeding rates found for larvae shoaling near the reef surface should slow or prevent the growth and development required prior to settlement. Observations made by other authors indicate that demersal shoaling and the use of water directly overlying reefs may be common behaviors of temperate and tropical reef fishes Breitburg, D. L. 1992. Episodic hypoxia in Chesapeake Bay: interacting effects of recruitment, behavior, and physical disturbance. Ecological Monographs 62: 525-546. Ref ID: 461 Abstract: Physical disturbance can be an important force at the individual, population, and community levels of organization. The effects of disturbance may differ for mobile and sessile organisms, however, because of differences in the potential for escape and postdisturbance recolonization by survivors. I used field sampling and laboratory experiments to examine how episodic movement of severely oxygen-depleted (hypoxic) bottom water into nearshore habitat in the Chesapeake Bay affects population density, recruitment, and reproduction of a mobile species-the naked goby (Gobiosoma bosc), a benthic oyster bed fish. Oxygen depletion is a common physical disturbance in freshwater, estuarine, and coastal aquatic systems. In this study, episodic hypoxia influenced mortality, size structure of the population, reproductive behavior, and spatial distribution.Intrusion of severely hypoxic water occurred in late July and early August during the 2-yr study. These intrusions coincided temporally with peak periods of recruitment, and caused the most severe drops in dissolved oxygen concentrations in deep and mid-depth areas of the oyster reef, where recruitment was highest. Laboratory experiments suggested that newly settled recruits require higher oxygen concentrations for survival than do older individuals. Field samples also indicated that these new recruits are less able to escape to more highly oxygenated shallow water refuges when an intrusion occurs. Thus, the spatial and temporal patterns of recruitment and disturbance, and physiological requirements, combine to result in extremely high mortality of new recruits during severe intrusions.In contrast to effects on new recruits, some large juveniles and adults success fully migrate inshore when oxygen levels decline. In both field samples and laboratory experiments, adult males continued to guard eggs and shelters until dissolved oxygen closely approached lethal levels. Calculations based on size-specific physiological tolerances and swimming speeds suggest that the occurrence of lethal conditions in the fluctuating environment may be more predictable to larger individuals than to new recruits. This predictability may increase the possibility of an appropriate response to low oxygen disturbances by large juveniles and adults.After the disturbance abates, surviving individuals recolonize abandoned areas. This ability of mobile animals to recolonize a disturbed area as adults or juveniles, rather than solely through reproduction, may lead to differences in postdisturbance ecological interactions and differences in selection for colonizing ability between mobile and sessile species Breitburg, D. L., Palmer, M. A., and Loher, T. 1995. Larval distributions and the spatial patterns of settlement of an oyster reef fish: responses to flow and structure. Marine Ecology-Progress Series 125: 45-60. Ref ID: 450 Abstract: A combination of larval behavior and physical factors influence the spatial patterns of settlement of marine organisms. Of particular importance to the settlement process is the blend of passive transport and active responses to water flow near the settlement habitat. Field experiments with the naked goby Gobiosoma bose, a benthic oyster reef fish, indicated that larvae aggregate in low-flow areas on the downcurrent sides of rocks, and shift position with changing flow directions. Larger aggregations of larvae were found in downcurrent positions at rocks that created larger low-flow zones, and during parts of the tidal cycle with higher ambient flow velocities. Settlement occurred in a highly aggregated pattern that reflected larval distributions, Most settlement measured in a field experiment was adjacent to downcurrent sides of rocks rather than in other positions near rocks, or away from structures that would decrease downcurrent now velocities. These results suggest that the active response of fish larvae to either direct or indirect effects of now on reefs may be important to fine-scale spatial patterns of settlement. Because zooplankton densities downcurrent of rocks were similar to, or lower than, densities upcurrent and lateral to rocks, spatial distributions of prey are unlikely to explain larval distributions. Instead, active preference for low-flow areas may enable fish larvae to maintain their position on oyster reefs, the preferred settlement habitat Breitburg, D. L., Sanders, J. G., Gilmour, C. C., Hatfield, C. A., Osman, R. W., Riedel, G. F., Seitzinger, S. B., and Sellner, K. G. 1999. Variability in responses to nutrients and trace elements, and transmission of stressor effects through an estuarine food web. Limnology and Oceanography 44: 837-863. Ref ID: 367 Abstract: Aquatic systems are increasingly exposed to multiple stressors from anthropogenic sources. These stressors can vary in the consistency and magnitude of responses they elicit in biota and in how the presence of additional stressors modifies their effects. Understanding how the biological environment and temporal dynamics influence responses to stressors, and how stressors interact, is important to predicting their effects in the natural environment. We examined temporal variability in responses of an experimental estuarine food web to elevated trace elements and nutrients, as well as non-additive effects of the combination of these two stressors. Experiments were conducted four times during spring through autumn 1996 in 20 1-m(3) mesocosms. We measured a range of system-, population-, and individual-level parameters to quantify responses of phytoplankton, bacterioplankton, heterotrophic nanoflagellates, copepods, fish, and benthic invertebrates to trace element and nutrient additions.The response to trace element additions was more variable both temporally and among phytoplankton and higher trophic level taxa than was the response to nutrient additions. Most taxa increased, either significantly or showed a trend toward increasing, in response to nutrient additions in all four mesocosm runs. In contrast, the direction as well as the magnitude of responses to trace element additions varied considerably among taxa and experimental runs. Two distinct types of nutrient x trace element interactions were important. First, temporal dynamics of nutrient ratios appeared to affect the temporal pattern of toxicity of trace elements to phytoplankton. Second, in the June mesocosm run when trace element additions reduced production, abundance, or growth of many organisms, these reductions were often proportionately greater in nutrient addition tanks than where no nutrients were added. Our results suggest that considerable temporal and taxonomic variation in responses to trace element loadings are likely to be seen in field settings even under constant loadings to the system and that trace elements may mask the magnitude of the response to high nutrient loadings in eutrophic systems. More generally, the presence of multiple stressors may either increase or dampen the temporal and spatial variability seen in aquatic systems, depending on the interactions among stressors and the influence of background environmental conditions and sensitive species on the expression of stressor effects Breitburg, D. L., Coen, L. D., Luckenbach, M. W., Mann, R., Posey, M., and Wesson, J. A. 2000. Oyster reef restoration: Convergence of harvest and conservation strategies. Journal of Shellfish Research 19: 371-377. Ref ID: 530 Abstract: Oyster reef restoration, protection, and construction are important to meeting harvest, water quality, and fish habitat goals. However, the strategies needed to achieve harvest and conservation goals have often been considered to be at odds. We argue that these goals are. in fact, compatible and that the same strategies will promote a sustainable harvest of the resource, increased filtration of estuarine waters, and increased provision of structured habitat for finfish, crabs, and other organisms that utilize oyster reefs or receive benefit indirectly from them. Creation or designations of unharvested sites (refuge sites) are key components of these strategies. Unharvested reefs have the potential to provide vertical relief, which is typically destroyed by harvest practices, to act as a source of larvae, which potentially increases the supply of harvestable oysters, and to protect those individuals most likely to have some resistance to disease. Furthermore. proper monitoring and design of refuge and restoration efforts are critical to providing information needed to improve the success of future restoration efforts, and will simultaneously enhance the basic information needed to understand the ecology of oysters and their role in estuarine and coastal systems Brousseau, D. J. 1995. Gametogenesis and spawning in intertidal oysters (Crassostrea virginica) from western Long Island Sound. Journal of Shellfish Research 14: 483-487. Ref ID: 82 Abstract: Four intertidal populations of the eastern oyster, Crassostrea virginica were sampled monthly in western Long Island Sound from March 1993-February 1994. Patterns of gametogenesis and spawning were determined from histological preparations of gonadal tissue. At all sites 1 period of gametogenesis occurred, with rapid maturation of the gonad during May and June. Spawning was remarkably synchronous; all individuals collected showed evidence of gamete release. Most animals were spawning in August and early September, although limited spawning did occur in July. Temperature does not appear to be a critical factor for stimulating spawning in oysters from this part of the Sound. These findings were compared with those of Loosanoff and others for subtidal oyster beds from the same region. Brousseau, D. J. 1996. Epizootiology of the parasite, Perkinsus marinus (Dermo) in intertidal oyster populations from Long Island Sound. Journal of Shellfish Research 15: 583-587. Ref ID: 215 Abstract: The recent reported occurrence of Perkinsus marinus in oysters from Long Island Sound prompted this study of the epizootiology of the parasite in this region. The monthly prevalence and infection intensity of P. marinus were determined for three intertidal populations of eastern oysters, Crassostrea virginica, during the period of 1993-1996. Total numbers of infected oysters were highest at the Bridgeport site, followed by the Westport and Milford locations. Disease prevalence was greater in 1995 than in 1994 at all sites studied. Numbers of infected oysters and parasite burdens peaked in the late fall and declined dramatically in the winter/early spring. Prevalence was highest (20-100%) at the Bridgeport, CT, site in every month sampled, and the weighted prevalence (Mackin's scale: 0-5) reached a maximum of 3.2 in November 1994. Temperature and salinity data available for the Bridgeport location indicate that conditions were reportedly favorable for parasite proliferation (greater than or equal to 20 degrees C; > 10 ppt) from June through September Brousseau, D. J. and Baglivo, J. A. 2000. Modeling seasonal proliferation of the parasite, Perkinsus marinus (Dermo) in field populations of the oyster, Crassostrea virginica. Journal of Shellfish Research 19: 133-138. Ref ID: 532 Abstract: A temperature-disease course model was developed to predict the effect of seasonal water temperature chan cs on disease progression of Dermo in field populations of Crassostrea virginica. A linear model was used to describe the relationship between weighted prevalence (disease intensity) and lagged cumulative temperature, where cumulative temperature was used as an estimate of cumulative harm. The model developed for Long Island Sound showed the strongest relationship between cumulative temperature and disease intensity when a lag time of 53 days was used. Point and interval estimates for the day(s) of the year when a mean weighted prevalence of 2 (Mackin Index) is expected ar four sites in Long Island Sound are given. This model allows the grower/manager to predict Dermo intensity in shellfish beds if field water temperature patterns are known. Such information can be used to select oyster growout beds and determine optimal time to harvest Brousseau, D. J., Filipowicz, A., and Baglivo, J. A. 2001. Laboratory investigations of the effects of predator sex and size on prey selection by the Asian crab, Hemigrapsus sanguineus. Journal of Experimental Marine Biology and Ecology 262: 199-210. Ref ID: 346 Abstract: Laboratory studies have shown that the nonindigenous Asian shore crab, Hemigrapsus sanguineus, readily consumes three species of commercial bivalves: blue mussels, Mytilus edulis, soft-shell clams, Mya arenaria, and oysters, Crassostrea virginica. Although crabs: can eat bivalves of a wide size range, they preferred the smaller prey (less than or equal to 10 mm SL). Prey critical size limits exist for M. edulis and C. virginica, but not M. arenaria, possibly because of differences in shell characteristics among the three species. Crabs preferred M. arenaria over both M. edulis and C. virginica, and M. edulis was strongly preferred over C. virginica in pairwise comparison tests. Experiments to determine feeding rates on mussels showed that H. sanguineus can consume large numbers of mussels daily (12.7 +/- 11.6 mussels day(-1); sexes pooled: N = 59). Mussel consumption rates increased with size of the predator and male crabs consumed more mussels than did similarly sized female crabs. The high densities of Hemigrapsus that occur in the wild, their effectiveness as predators of juvenile bivalves and their large appetites suggest an important role for these predators in restructuring the: prey communities in habitats into which they have been introduced. (C) 2001 Elsevier Science B.V. All rights reserved Brown, K. M. and Swearingen, D. C. 1998. Effects of seasonality, length of immersion, locality and predation on an intertidal fouling assemblage in the Northern Gulf of Mexico. Journal of Experimental Marine Biology and Ecology 225: 107-121. Ref ID: 538 Abstract: Recruitment of the intertidal fouling assemblage was studied by placing out tiles at four sites along the Louisiana Gulf of Mexico coast in fall, spring and summer, for immersion periods of one, two and three months. The dominant species were the barnacle Balanus eburneus (Gould), which recruited in all three seasons, but at highest densities in the spring; the oyster Crassostrea virginica (Gmelin), which recruited only in fall, and the bryozoan Membranipora savartii, which recruited in spring and fall. Thus, the species that recruited varied with the season, as in earlier studies of colonization of free space in intertidal fouling assemblages. However, unlike previous studies, barnacle abundances or oyster and bryozoan percentage cover tended to decrease with length of immersion. To determine if these post-settlement decreases were caused by predation, we enclosed tiles in mesh cages to exclude predators, and replicated experiments at both coastal and estuarine sites to determine site-specific differences in recruitment. Barnacles recruited at higher rates at coastal sites and oysters at estuarine sites, as predicted by the literature. For barnacles, densities after one month of colonization were lower on open or partially caged tiles than on caged tiles, supporting the hypothesis that predators, like blue and mud crabs, or southern oyster drills, may regulate barnacle abundance. Caging did not increase the percentage cover of either oysters or bryozoans. Oyster abundance may be limited by larval supply, as oyster recruitment never reached above 5% cover. Small predators, Like flatworms, which were not excluded by cages, may also be important for the latter two prey. (C) 1998 Elsevier Science B.V Brown, K. M. and Stickle, W. B. 2002. Physical constraints on the foraging ecology of a predatory snail. Marine and Freshwater Behaviour and Physiology 35: 157-166. Ref ID: 598 Abstract: We studied the effects of aerial exposure and high summer temperatures on the southern oyster drill (Stramonita haemastoma), feeding on the American oyster, Crassostrea virginica . In the laboratory, oyster drill feeding rates and growth were highest at 25 and 30degreesC, some mortality occurred at 35degreesC, all snails died at 40 and 45degreesC, and the 28-day LC50 was 35.7degreesC. In a second experiment where both water temperature (25 vs . 33degreesC) and aerial exposure were varied, only simulated tidal exposure lowered oyster drill feeding and growth rates. In field cage experiments, oyster drills had reduced feeding rates and growth at intertidal sites, but snail growth rates increased in late summer with warmer water temperature. We therefore conclude that aerial exposure, not high temperature, is the major factor limiting oyster drill feeding and growth in intertidal oyster reefs. Field experiments with partial cages also suggested that ambient predation rates were much higher at a subtidal than at a nearby intertidal site. Because southern oyster drills have depressed feeding, growth, and possibly lower fitness in intertidal oyster reefs during the summer, this reduced predation risk may provide a refuge for intertidal oysters Brown, K. M., Peterson, G. W., Banks, P. D., Lezina, B., Ramcharan, C., and McDonough, M. 2003. Olfactory deterrents to black drum predation on oyster leases. Journal of Shellfish Research 22: 589-595. Ref ID: 595 Abstract: Black drum (Pogonias cromis) predation is a serious threat to oyster production on Louisiana leases, and leaseholders hypothesize that black drum carcasses suspended above leases deter predation. We conducted experiments under laboratory and field conditions to test whether the scent of dead con-specifics deterred black drum predation. Preliminary experiments indicated that fish >70 cm total length were effective predators, and oysters <70 g wet total weight were preferred, and we used these sizes in subsequent experiments. Salinity did not affect feeding rates. Experiments in 30,000 L raceways indicated that scent did not significantly lower feeding rates. Parametric analyses of factorial experiments on oyster leases at two sites in Barataria Bay, Louisiana, during the fall and spring (periods of the year when fish feeding is most intense), indicated that scent reduced feeding rates by 10% to 20%, but only at one site in one season. Nonparametric analyses corroborated seasonal differences indicated by parametric analyses, but not the scent effect. We therefore conclude that scent from dead con-specifics is not an effective control strategy under most conditions. Dredge hauls during experiments suggested mortalities to all predators ranging from 63.1% to 92.5% within the first 4 weeks after seeding. The relative mortalities to black drum, southern oyster drills (Stramonita haemastoma) or possibly Perkinsus marinus infections varied among sites, as did temporal patterns of mortality within and among seasons Brumbaugh, R. D., Sorabella, L. A., Johnson, C., and Goldsborough, W. J. 2000. Small scale aquaculture as a tool for oyster restoration in Chesapeake Bay. Marine Technology Society Journal 34: 79-86. Ref ID: 561 Abstract: Since the early 1990s, efforts to restore the Chesapeake Bay's devastated oyster stocks have focused on the construction of small (similar to 2 ha.) intertidal shell reefs designed to mimic historic 3-dimensional reef habitat. The reefs are managed as oyster sanctuaries to allow adult oysters to accumulate, grow, and spawn over time. To enhance the effectiveness of this strategy, the Chesapeake Bay Foundation initiated a program in 1997 to train students and volunteers to grow large numbers of hatchery-produced oysters for stocking sanctuary reefs in selected tributaries. In 1998, a significant increase in spat settlement was documented in the Lynnhaven River, a small tributary where volunteer-grown oysters were transplanted onto a sanctuary reef providing further direction for restoration efforts. Since then, the program has expanded to include more than 500 citizens and 120 school classes on a Bay wide scale. This paper describes the strategy for restoring oysters in two small Virginia tributaries using volunteers, specifically middle and high school students, to grow broodstock (i.e., reproductively mature) oysters for transplanting onto state-managed sanctuary reefs using small-scale aquaculture techniques. To date, volunteers enlisted in a program dubbed the Chesapeake Bay Foundation "Oyster Corps" have grown and stocked more than 250,000 hatchery-produced oysters in Virginia's portion of Chesapeake Bay. Small scale aquaculture techniques have provided a simple, yet effective, means of involving the public in a restoration effort designed to increase oysters by a factor of 10 by the year 2010 Brumbaugh, R. D., Sorabella, L. A., Garcia, C. O., Goldsborough, W. J., and Wesson, J. A. 2000. Making a case for community-based oyster restoration: An example from Hampton Roads, Virginia, USA. Journal of Shellfish Research 19: 467-472. Ref ID: 599 Abstract: The eastern oyster (Crassostrea virginica) remains at historically low levels throughout the Chesapeake Bay. Recent efforts to restore oysters in the bay have focused on establishing a series of sanctuaries, or no-take zones, to increase oyster broodstock in selected tributaries. Oyster parasites continue to affect the rate of recovery in these tributaries; however, innovative management strategies, advances in aquaculture technology, and the availability of disease-tolerant broodstock from the lower Chesapeake Bay are providing ways to involve the public directly in restoration of this resource. A 1996 management decision to transplant large wild-caught oysters onto an oyster broodstock sanctuary reef in the Great Wicomico River, Virginia, was followed by greatly increased abundance of juvenile oysters throughout that river in 1997. Using that result as a model for strategic oyster reef restoration, citizens and school students have been enlisted to grow large numbers of hatchery-produced native oysters for restocking other sanctuary reefs throughout Chesapeake Bay. Efforts to supplement natural oyster populations in Hampton Roads, Virginia, began in May 1998, with the transplanting of 65,000 hatchery-produced oysters grown by school students. The oysters were transplanted onto strategically located sanctuary reefs constructed in the Lynnhaven and Elizabeth rivers. Surveys of these reefs following the oysters' spawning season have revealed order-of-magnitude increases in the abundance of juvenile oysters on both reefs, and correspondingly high spat settlement rates on oyster grounds surrounding the reefs. These results demonstrate that stocking strategically located broodstock reefs with hatchery-produced oysters grown by citizens can be an effective strategy for oyster restoration in the Chesapeake Bay Buchanan, J. T., Roppolo, G. S., Supan, J. E., and Tiersch, T. R. 1998. Conditioning of eastern oysters in a closed, recirculating system. Journal of Shellfish Research 17: 1183-1189. Ref ID: 526 Abstract: Techniques were developed for holding and conditioning of eastern oysters, Crassostrea virginica (Gmelin), in a recirculating system. Oysters collected in February from public oyster grounds off the coast of Louisiana were maintained in a recirculating system for 8 wks. For conditioning, water temperature in the system was gradually raised with a heat pump from 14 degrees C, and held at 25 degrees C for 6 wks. Oysters were fed a diet of algal paste (Isochrysis galbana for the first 6 wks and Chaetocerus calcitrans for the last 2 wks). Water quality, mortality, Perkinsus marinus infection, gonad development, and physiologic condition (dry tissue-to-dry shell ratio, dry tissue-to-wet tissue ratio, digestive diverticula tubule ratio) were monitored. At weeks 7 and 8, the laboratory-held oysters were compared with field controls held at Grand Isle, Louisiana. Water quality in the system remained within target ranges. Mortality was low (18 of 300 oysters stocked) and not associated with P. marinus infection. In the laboratory at week 1, the gonads of all oysters sampled were classified as immature or in early development. By week 5, the gonads of 73% of oysters sampled were classified as mature. Physiologic condition decreased in the laboratory. Field controls reached a higher mean gametic stage and were in better physiologic condition at the end of the 8-wk study. These differences were attributed to differences in nutrition available between the field and laboratory. This study demonstrated that conditioning of Crassostrea virginica is possible in a closed, recirculating system, although improvements in nutrition would be useful Buchanan, J. T., La Peyre, J. F., Cooper, R. K., and Tiersch, T. R. 1999. Improved attachment and spreading in primary cell cultures of the eastern oyster, Crassostrea virginica. In Vitro Cellular & Developmental Biology-Animal 35: 593-598. Ref ID: 280 Abstract: At present, establishment of a cell line from bivalve molluscs has been unsuccessful, and in vitro work is limited to primary cell cultures. We sought to improve attachment and spreading of cells of the eastern oyster, Crassostrea virginica, to aid primary cultures and to assist development of a bivalve cell line. Our objectives were to examine the effects of substrate on ventricle cell viability, attachment, and spreading by testing of collagen I, collagen IV, fibronectin, laminin, poly-D-lysine, and two types of uncoated tissue culture plates (Falcon(R) and Corning(R)). Experiments were conducted by incubating cells with the various substrates for 24 h and 5 d. An assay with a tetrazolium compound (MTS) was used to estimate cell numbers based on metabolic activity. Although differences in MTS assay values for substrate effect on cell viability were detected at 24 h and at 5 d (P > 0.0001), these were attributed to variations in metabolic activity due to different levels of attachment and spreading among treatments. Differences among treatments were detected in attachment and spreading at 24 h and 5 d (for all, P > 0.0001). At 24 h, poly-D-lysine induced the highest levels of attachment and spreading, no other factor performed better than the uncoated Falcon(R) substrate, and collagen I performed most poorly. At 5 d, poly-D-lysine and the uncoated Corning(R) substrate induced significantly higher levels of attachment and spreading than did the uncoated Falcon(R) substrate, and collagen I performed most poorly. From these results, poly-D-lysine best promoted cell attachment and spreading. Fibronectin (at 24 h) and laminin (at 5 d) warrant further study Along with improvements in medium composition, future work should involve screening of other attachment factors and combinations of factors, including those of bivalve origin Buchanan, J. T., Cheng, T. C., La Peyre, J. F., Cooper, R. K., and Tiersch, T. R. 2001. In vivo transfection of adult eastern oysters Crassostrea virginica. Journal of the World Aquaculture Society 32: 286-299. Ref ID: 554 Abstract: The eastern oyster Crassostrea virginica provides a commercially valuable industry along the eastern and Gulf coasts of the United States. Recently this industry has been damaged by disease problems, creating an interest in the use of gene transfer (transfection) to improve disease resistance. We transfected adult oysters with two genes, red-shifted green fluorescent protein (rsGFP), commonly used as a reporter gene, and the lytic peptide cecropin B (cepB), known to have antimicrobial properties. Oysters were transfected by injecting DNA mixed with SuperFect (TM), reagent (Qiagen Inc.) into the adductor muscle sinus. Oysters were assigned to three groups of 15: the first was injected with rsGFP complexed with transfecting reagent; the second was injected with cepB complexed with transfecting reagent; and the third was injected with saline (control group). Hemolymph was collected at 4 and 10 d after injection. DNA was extracted for analysis by polymerase chain reaction (PCR), and hemocytes were examined by flow cytometry and fluorescence microscopy for detection of green fluorescence due to rsGFP expression. The rsGFP gene was detected by PCR in hemocytes from 14 of 15 oysters at day 4, and in 15 of 15 oysters at day 10. The cepB gene was detected by PCR in 12 of 15 oysters at day 4 and in 14 of 15 oysters at day 10. No oysters from the control group were positive for either gene at days 4 or 10. Green fluorescence was detected by How cytometry at significantly higher levels (P < 0.05) in oysters injected with rsGFP than in other oysters at day 4, but not at day 10. This report indicates the ability to introduce DNA into adult eastern oysters with subsequent gene expression. Future work will involve developing these techniques for enhanced disease resistance in oysters Buchanan, J. T., Nickens, A. D., Cooper, R. K., and Tiersch, T. R. 2001. Transfection of eastern oyster (Crassotrea virginica) embryos. Marine Biotechnology 3: 322-335. Ref ID: 597 Abstract: There is a need for research in disease resistance and microbial elimination in the eastern oyster Crassosostrea virginica. Gene transfer may lead to advances in this area, and a means of selecting transfected larvae would be useful. We transfected 3-hour-postfertilization embryos with the bacterial gene aminoglycoside phosphotransferase II (neo(r)), which confers resistance to neomycin and related antibiotics such as G418. The antibiotic G418 was examined as a potential selective agent. A neutral red assay was used to determine survival after 48 hours of exposure to various concentrations of G418 (0-4 mg/ml). We examined the effects of electroporation and chemically mediated transfection of 3-hour- postfertilization embryos on survival to straight-hinge larvae. DNA alone was found to have no effect on survival (P > .05). For electroporation we found that increased voltage and pulse duration decreased survival (P < .05). Chemically mediated transfection did not significantly affect survival (P = .5172). Transgenic larvae were identified after electroporation and chemically mediated transfection. These larvae were reared for 24 hours and exposed to G418 at 0.3 mg/ml for 48 hours. Significant differences in survival between transfected and nontransfected larvae were detected for electroporation (P = .0147) and chemically mediated transfection (P = .037). Gene transfer was also confirmed with polymerase chain reaction and observation of expression of green fluorescent protein. This Study documents the first successful insertion and expression of foreign DNA in eastern oyster larvae Buckel, J. A. and Conover, D. O. 1997. Movements, feeding periods, and daily ration of piscivorous young-of-the-year bluefish, Pomatomus saltatrix, in the Hudson River estuary. Fishery Bulletin 95: 665-679. Ref ID: 666 Abstract: Young-of-the-year (YOY) bluefish, Pomatomus saltatrix, were collected during the summers of 1992 and 1993 in the Hudson River estuary with beach seine, surface trawl, and gill nets. The temporal and spatial patterns of catch-per-unit-of-effort (CPUE) and gut-fullness values were used to infer bluefish movement and feeding periods, respectively. Estimates of daily ration were made from gut-fullness values and previously published estimates of gastric evacuation rate. Nearshore beach-seine CPUE was highest during day collections and lowest at night. Offshore gill-net CPUE was highest during crepuscular or night periods and lowest during day sets. Hence, YOY bluefish appear to occupy nearshore environments during the day and move away from shore at night. Gut-fullness values for bluefish captured with beach seines were highest at diurnal and crepuscular periods and declined at night; however, there were indications of night feeding on some dates. The magnitude and pattern of daily ration estimates of YOY bluefish in the Hudson River estuary were similar to values measured in previous studies with other methods. Interannual differences in the magnitude of daily ration were observed and may be a result of day-today variation in feeding or differences in available prey type and size. Clupeids, striped bass, and bay anchovy were important prey in 1992, whereas striped bass, bay anchovy, and Atlantic silversides were the dominant prey of YOY bluefish in 1993. Improved understanding of the spatial and temporal patterns of bluefish feeding, as well as fine-scale temporal resolution of estimates of bluefish consumption rates, will aid in assessing the impact of YOY bluefish predation on fish populations within the Hudson River estuary. Buckel, J. A., Fogarty, M. J., and Conover, D. O. 1999. Foraging habits of bluefish, Pomatomus saltatrix, on the US east coast continental shelf. Fishery Bulletin 97: 758-775. Ref ID: 654 Abstract: After spending summer months in estuaries, spring- and summer-spawned young-of-the-year (YOY) bluefish, Pomatomus saltatrix, migrate out to continental shelf waters of the Mid-Atlantic Eight in early autumn. Adult bluefish are found on the continental shelf throughout summer and fall. Both juveniles and adults have high food consumption rates and are generally piscivorous. To determine principal prey types on the shelf, dietary analyses were performed on YOY and adult bluefish collected from National Marine Fisheries Service autumn bottom trawl surveys in 1994 and 1995. Both spring- and summer-spawned YOY bluefish diets were dominated by bay anchovy. However, the significantly larger size of the spring-spawned cohort was associated with the consumption of other prey species such as squid, butterfish, striped anchovy, and round herring. Summer-spawned bluefish were significantly smaller in 1995 than in 1994; diet and prey size comparisons suggest that body size had a dramatic influence on the amount of piscivorous feeding in the summer-spawned cohort. Adult bluefish diet was dominated by schooling species such as squid, butterfish, and clupeids. Cannibalism was virtually nonexistent. Daily ration estimates of YOY bluefish on the shelf(4-12% body wt/d) were similar to estuarine estimates in late summer. It is estimated that during the month of September, YOY bluefish in aggregate consumed 6.0 to 6.8 billion bay anchovies in 1994 and from 2.2 to 5.3 billion in 1995. The effect of this predatory loss on population dynamics of bay anchovy and the fish community on the continental shelf is unknown. Budd, K. and Arts, A.-M. 2000. Review of Biosecurity Influences of the Last Decade., Prepared for Parliamentary Commissioner for the Environment Ref ID: 117 Bundy, M. H., Breitburg, D. L., and Sellner, K. G. 2003. The responses of Patuxent River upper trophic levels to nutrient and trace element induced changes in the lower food web. Estuaries 26: 365-384. Ref ID: 616 Abstract: As a result of human activities, coastal waters can be exposed to multiple stressors that affect primary producers and their interactions with higher trophic levels. Mesocosm experiments were conducted during spring and summer 1996-1998 to investigate the responses of natural populations of primary producers to multiple stressors and the potential for these responses to be transmitted to higher trophic levels (i.e., copepods, bivalves, anemones, and fish). ne effects of two stressors, elevated nutrient and trace element loadings, were examined individually and in combination. Nutrient additions had a positive effect on biomass, productivity, and abundance of primary producers (Breitburg et al. 1999; Riedel et al. 2003). Growth or abundance of consumers increased with nutrient additions, but the magnitude of the response was reduced relative to that of their prey. Responses to trace element additions varied seasonally and among taxa. The responses of zooplankton and bivalves to stressor additions were affected by the biomass and changes in species composition of phytoplankton assemblages. The presence of fish predators did not alter zooplankton responses to stressor additions. These results suggest that the extent to which nutrient and trace element effects are transmitted from primary producers to higher trophic levels depends on the capacity of consumers to respond to stressor-induced changes in abundance and species composition of prey, on the absolute abundance of prey, and on the ability of predators to feed on alternative prey. The magnitude of the effects of stressors on estuarine food webs may depend on seasonal variability in species composition of phytoplankton assemblages, whether sensitive species dominate, and whether these species are important prey for secondary consumers. Because spatial and temporal patterns in nutrient and trace element loadings to the estuary can affect species composition of primary producers, it is critically important to examine the magnitude, timing, and spatial relationships of loadings of multiple stressors to coastal waters in order to understand the impacts of these stressors on higher trophic levels. Buroker, N. E., Hershberger, W. K., and Chew, K. K. 1979. Population genetics of the family Ostreidae. II. Interspecific studies of the genera Crasostrea and Saccostrea. Marine Biology 54: 171-184. Ref ID: 172 Burreson, E. M. and Calvo Ragone, L. M. 1996. Epizootiology of Perkinsus marinus disease of oysters in Chesapeake Bay, with emphasis on data since 1985. Journal of Shellfish Research 15: 17-34. Ref ID: 35 Abstract: Since 1987 Perkinsus marinus has been the most important pathogen of the eastern oyster, Crassostrea virginica, in Chesapeake Bay because of its widespread distribution and persistence in low salinity areas. The pathogen became established on all oyster beds in the Chesapeake Bay as a result of natural spread during the consecutive drought years from 1985 to 1988 or by movement of infected oysters during the same period. Elevated salinities resulting from drought conditions and concomitant warm winters allowed P. marinus to proliferate in what were historically low salinity areas. Oyster mortality was high on most beds and landings of market oysters declined to record low levels in both Maryland and Virginia during the late 1980s and early 1990s. The seasonal periodicity of P. marinus is primarily controlled by temperature. Both prevalence and intensity of infections begin to increase in June as temperature increases above 20 degrees C and overwintering infections begin to proliferate. Maximum values of prevalence and intensity occur in September immediately following maximal summer temperatures. Infection regression occurs during winter and spring as temperature declines resulting in minimum prevalence and intensity values in April and May. Prevalence and intensity of P. marinus infections in oysters from the James River, VA, over a five year period were significantly correlated with temperature when temperature data were lagged three months. Temperature explained 39% of the variability in prevalence and 46% of the variability in intensity. The relationship between temperature and annual variability in P. marinus abundance is somewhat obscure, in part because of the difficulty separating salinity and temperature effect. Nonetheless, data from 1988 to 1994 from the James River, VA, suggest that abnormally warm winters have a more significant Impact on summer P. marinus abundance than abnormally cold winters. Salinity is the primary environmental factor that controls local distribution and intensity of P. marinus infections. Long-term oyster disease monitoring along a salinity gradient in the James River, VA, revealed a statistically significant relationship between salinity and P. marinus prevalence and intensity. P. marinus infections remain light in intensity and no oyster mortality results if salinity is consistently less than 9 ppt. However, infections may persist for years in low salinity areas. If summer/fall salinities range from 9 to 15 ppt some infections may progress to moderate and heavy intensity, but oyster mortality is relatively low. If summer/fall salinities are consistently greater than 15 ppt, moderate and heavy infections may be numerous and oyster mortality may be high. Field studies in the York River, VA, suggest that new P. marinus infections are acquired from July through early October, but peak infection acquisition occurs during late August and is correlated with oyster mortality. The early infection process in oysters and the role of zoospores in transmission dynamics in nature are poorly understood. No direct link between oyster defense mechanisms and control of P. marinus infections has been established. If oyster defense mechanisms do modulate P. marinus infections, the components have not been identified. There is little evidence to support the common perception that pollution is responsible for the dramatic increase in P. marinus abundance since 1985. Pathogen abundance is clearly correlated with salinity increases resulting from drought conditions in the late 1980s, although there may be subtle effects of toxicants or poor water quality on the host/parasite interaction. Burreson, E. M., Calvo, L. M. R., Lapeyre, J. F., Counts, F., and Paynter, K. T. 1994. Acute osmotic tolerance of cultured cells of the oyster pathogen Perkinsus marinus (Apicomplexa, Perkinsida). Comparative Biochemistry and Physiology A-Physiology 109: 575-582. Ref ID: 559 Abstract: Cultured Perkinsus marinus cells were exposed for 24 hr to salinities of 0, 3, 6, 9, 12 and 22 ppt at temperatures of 1, 5, 10, 15 and 28 degrees C in artificial seawater (ASW) and to the same salinities at 28 degrees C in ASW with the osmotic concentration adjusted with sucrose to the equivalent of 22ppt. At 28 degrees C mortality increased as salinity decreased below 22ppt. Mortality was greater than 99% at 0 ppt and greater than 90% at 3 ppt. Mortality was 70% at 6 ppt, 43% at 9 ppt and 20% at 12 ppt. Mortality was low (<5%) and equal to that at 22 ppt in all treatments where osmotic concentration was maintained with sucrose. Mortality occurred rapidly, within 5 min of exposure to experimental conditions. In the region where mortality was most sensitive to salinity changes (6-12 ppt), lower temperature caused an increase in mortality, but the temperature effect was significant only at 9 ppt Burreson, E. M. 1994. Further evidence of regular sporulation by Haplosporidium nelsoni in small oysters, Crassostrea virginica. Journal of Parasitology 80: 1036-1038. Ref ID: 399 Abstract: During a held study to determine the susceptibility of the Pacific oyster Crassostrea gigas to Chesapeake Bay oyster pathogens, sporulation of Haplosporidium nelsoni was observed in eastern oysters Crassostrea virginica being used as controls. The C. virginica were obtained from 2 sources on 19 May 1993, a wild population in the upper Rappahannock River, Virginia (59.6 mm mean shell height) and a hatchery-reared population from Chesapeake Mariculture that was held in the Wye River, Maryland (42.2 mm mean shell height); they were deployed in the York River, lower Chesapeake Bay on 29 June 1993. Both groups of C. virginica became heavily infected with H. nelsoni in early July 1993. Sporulation was observed in both groups on 8 September but was most prevalent in the smaller Maryland oysters where it reached 36% of infected oysters. Oysters of 72.3 mm mean shell height deployed at the same location in May 1993 also became heavily infected with H. nelsoni, but no cases of sporulation were observed in these larger oysters. These results provide further evidence that sporulation of H. nelsoni occurs regularly only in oysters approximately 1 yr old or less Burreson, E. M., Alvarez, R. S., Martinez, V. V., and Macedo, L. A. 1994. Perkinsus marinus (Apicomplexa) as a potential source of oyster Crassostrea virginica mortality in coastal lagoons of Tabasco, Mexico. Diseases of Aquatic Organisms 20: 77-82. Ref ID: 594 Abstract: Poorly documented, but apparently sporadic oyster Crassostrea virginica mortality in the coastal lagoons Carmen, Machona and Mecoacan at the southern extreme of the Gulf of Mexico in Tabasco, Mexico, has been attributed by local oystermen to pollution resulting from oil refinery operations. In September 1992 we sampled oysters in these lagoons to investigate the potential for disease-induced mortality from the oyster pathogen Perkinsus marinus. Prevalence of P. marinus was 100% at Lodazal, a high salinity (31 ppt) site in Carmen lagoon and 60% at Rio San Felipe, a low salinity (15 ppt) site. At Los Jimenez, a high salinity (32 ppt) site in Machona lagoon with previous high mortality, prevalence of P. marinus was 90% and weighted prevalence, a measure of intensity, was 3.1, a high value associated with heavy infections and mortality. Samples collected at the Buena Vista aquaculture facility in Mecoacan lagoon revealed 60 to 100% prevalence of P. marinus, although most infections were low intensity. P. marinus is a potential source of oyster mortality in these coastal lagoons; more intensive sampling is necessary to determine the mortality attributable to P. marinus Bushek, D. and Allen, S. K. 1996. Races of Perkinsus marinus. Journal of Shellfish Research 15: 103-107. Ref ID: 224 Abstract: The existence of parasite races is an integral component of host-parasite interactions with significant implications for host-parasite coevolution, ecology, and management. Despite nearly 50 years of research, few studies have considered the existence or implications of races of Perkinsus marinus. Nonetheless, several field and laboratory observations indicate races exist that vary in virulence or environmental tolerance. One of the keys to understanding and managing P. marinus lies in the identification and characterization of races. A related and equally important key is elucidation of its genetic population structure. This paper discusses our current knowledge concerning P. marinus races and population structures Bushek, D. and Allen, S. K. 1996. Host-parasite interactions among broadly distributed populations of the eastern oyster Crassostrea virginica and the protozoan Perkinsus marinus . Marine Ecology-Progress Series 139: 127-141. Ref ID: 541 Abstract: The protozoan oyster parasite Perkinsus marinus causes extensive mortality in eastern oyster (Crassostrea virginica) populations during summer and fall across much of the oyster's distribution. Despite more than 40 yr of research on this particular parasite, no study has unequivocally demonstrated a genetic basis for host resistance to P. marinus nor has it been determined whether or not there are races of Fl marinus that vary in virulence. Using recently developed techniques to culture P. marinus in vitro, we examined the resistance of 4 genetically distinct oyster populations that had different natural histories of exposure to P. marinus and the virulence of 4 geographically distinct isolates of P. marinus. Offspring were produced from each oyster population and reared in a common environment, then exposed to each isolate of P. marinus. Oysters showed levels of resistance roughly corresponding to the duration parental populations had been exposed to P. marinus (Texas > Virginia > New Jersey = Maine), indicating that those populations which have been exposed to P. marinus for more than 40 yr have developed some resistance. Parasites isolated from the Atlantic coast (Mobjack Bay, VA and Delaware Bay, NJ, USA) produced heavier infections than those isolated from the Gulf of Mexico coast (Barataria Bay, LA and South Bay Laguna Madre, TX, USA), indicating that Atlantic isolates were more virulent than Gulf isolates. These data indicate that resistant races of the eastern oyster exist, and imply the existence of virulent parasite races. No statistically significant interaction was detected between oyster populations and parasite isolates. Relative infection intensities among oyster populations remained more or less constant across parasite isolates and vice versa. The lack of a significant interaction between host populations and parasite isolates indicated that mechanisms of resistance and virulence were general, not race-specific Bushek, D., Allen, S. K., Alcox, K. A., Gustafson, R. G., and Ford, S. E. 1997. Response of Crassostrea virginica to in vitro cultured Perkinsus marinus: Preliminary comparisons of three inoculation methods. Journal of Shellfish Research 16: 479-485. Ref ID: 209 Abstract: The recent development of in vitro culture methods for the oyster pathogen Perkinsus marinus (Mackin, Owen & Collier) provides a bountiful supply of axenic parasites for biological investigation. Understanding how this parasite interacts with its host, Crassostrea virginica (Gmelin), is of paramount importance. Here we report and discuss the results of several preliminary experiments on the response of C. virginica to in vitro-cultured P. marinus and the early fate of these cultured cells. In three separate experiments, doses of 10(2)-10(7) parasites per oyster of in vitro-cultured parasites were used to challenge healthy oysters (mean wet tissue weight = 13.8 g) via feeding, shell cavity injection, or adductor muscle injection. After 7 wk, no oysters from the feeding trial were infected. Most oysters in the shell cavity and adductor muscle injection trials had detectable infections, but variability was high. Mean infection intensity increased with dosage, but the effect of dosage was not significant in all trials, probably because of low sample size. The cultured parasites produced infection intensities that appeared to be markedly lower than those reported for natural cells under similar experimental dosing conditions. Sixty-two percent of shell cavity and adductor muscle injections, excluding controls, produced infections with fewer than 100 parasites per oyster, the lowest dosage used in this study. In another experiment, the early fate of cultured cells was investigated for each inoculation method by sampling rejecta over 4 days after dosing. On average, 4% of fed cells, 7% of cells injected into the shell cavity, and 13% of cells injected into the adductor muscle were recovered. Eighty-two percent of discarded parasites, many in phagocytes; were found on Day 1 postinoculation. Oysters were sacrificed on Day 4 to determine total body parasite burdens. Regardless of delivery method, total recovery of parasites (discarded and total parasite burden) was low compared with the dose administered: 4% from feedings, 12% from shell cavity injections, and 21% from adductor muscle injection. Finally, transmission electron microscopy of hemocytes removed at 2, 6, and 18 h postinoculation appeared to indicate that hemocytes can digest in vitro-cultured parasites, possibly explaining the low recovery rates and indicating a mechanism for the apparently low pathogenicity of cultured P. marinus Bushek, D., Holley, R. A., and Reece, K. S. 2000. Use of micromanipulation and "feeder layers" to clone the oyster pathogen Perkinsus marinus. Journal of Eukaryotic Microbiology 47: 164-166. Ref ID: 509 Abstract: Genetic and biochemical characterization of microbes often requires the use of clonal cultures. A method to clone the oyster parasite Perkinsus marinus is described. Individual cells are isolated via micromanipulation and maintained above an actively proliferating "feeder layer" of P. marinus on a 0.45-mu m membrane. Extracellular products released from the proliferating feeder layer can diffuse across the membrane and bathe the isolated cell, stimulating it to proliferate. The method is relatively simple and should be applicable to most protists that can be cultured in the laboratory Bushek, D., Ford, S. E., and Chintala, M. M. 2002. Comparison of in vitro-cultured and wild-type Perkinsus marinus. III. Fecal elimination and its role in transmission. Diseases of Aquatic Organisms 51: 217-225. Ref ID: 593 Abstract: Perkinsus marinus, a pathogen of the eastern oyster Crassostrea virginica, is transmitted directly among oysters. Previous studies found viable R marinus parasites in the feces and pseudofeces of oysters within hours of injection with parasites, suggesting that the parasite may be voided from live oysters and subsequently dispersed in the water column. The experiments described here were designed to quantify P. marinus shed in the feces and pseudofeces of experimentally infected oysters. The results indicated that parasites were shed in 2 phases. A 'decreasing' phase occurred within 2 wk of challenge and before net parasite proliferation began in the host. An 'increasing' phase occurred after R marinus had begun replicating. The quantity of R marinus recovered in the feces and pseudofeces of exposed oysters was only about 5% of the dose administered. In vitro-cultured R marinus were eliminated at a greater rate than wild-type R marinus and the fraction discharged was not associated with culture phase. Oysters that were continuously dosed with R marinus in their food gradually lost the ability to discard the parasite in pseudofeces. The quantity of R marinus shed in feces of infected oysters was correlated with both the P. marinus body burden and subsequent survival time, suggesting that noninvasive fecal counts could predict infection intensity and survival. The results indicate that in an epizootic, shedding of R marinus via feces is relatively small compared to the potential number released by cadavers of heavily infected oysters, but that fecal discharge may be important in transmission before infections become lethal Butler, R. W. and Kirbyson, J. W. 1979. Oyster Predation by the Black Oystercatcher in British-Columbia. Condor 81: 433-435. Ref ID: 610 Cabraal, R. A. and Wheaton, F. W. 1981. Estimating Maryland Chesapeake Bay oyster population using Leslie and Delury equations. Transactions of the Asae 24: 519-523. Ref ID: 476 Cahn, A. R. 1950. Oyster Culture in Japan. Fishery Leaflet 383, republication of Report No. 134, US Fisheries and Wildlife Service, Washington, DC Ref ID: 42 Cai, Y., Deng, C., and Lui, Z. 1992. Studies on the ecology of Crassostrea rivularis (Gould) in Zhanjiang Bay. Trophic Oceanology 11: 37-43. Ref ID: 41 Calabrese, A. and Davis, H. C. 1970. Tolerances and requirements of embroys and larvae of bivlve molluscs. Helgolander wissenschaftliche Meeresuntersuchungen 20: 553-564. Ref ID: 181 Calvo, G. W., Fagan, R. J., Greenhawk, K. N., Smith, G. F., and Jordan, S. J. 1996. Spatial distribution and intensity of Perkinsus marinus infections in oyster recovery areas in Maryland. Journal of Shellfish Research 15: 318-389. Ref ID: 30 Abstract: The project described here reports on the status and spatial variability of Perkinsus marinus in three oyster recovery areas (ORAs) during 1994. The objectives of the study were to examine spatial variability in P. marinus infections among oyster bars along single tributaries and within single oyster bars. In addition, the study was conducted to compare estimates of prevalence based on intensive and spatially accurate patent-tong sampling with estimates of prevalence based on traditional dredge sampling of 30 oysters. For comparative purposes, patent-tong and dredge sampling were both conducted in each of four oyster bars, within 35 days, during September-October 1994. In June 1994, a pilot study was conducted to test the use of long range navigation (LORAN) and global positioning system (GPS) for the accurate deployment of patent-tongs and to compare hemolymph and tissue Ray fluid thioglycollate medium assays. In summary, results from this investigation support three conclusions: (1) During fall 1994, the variation of P. marinus prevalence, among and within oyster bars in sampled ORA tributaries, was small (<30%) but statistically significant; (2) traditional dredge samples of 30 oysters per bar provided estimates of prevalence remarkably similar (within 5%) to the ones obtained from patent-tong samples of an average of 340 oysters per bar; (3) RFTM assays conducted in the spring showed that hemolymph, rectum, and combined gill and palp samples gave equivalent determinations of prevalence. Calvo, G. W., Luckenbach, M. W., Allen, S. K. Jr., and Burreson, E. M. 1999. Comparative field study of Crassostrea gigas (Thunberg, 1973) and Crassostrea virginica (Gmelin, 1791) in relation to salinity in Virginia. Journal of Shellfish Research 18: 465-473. Ref ID: 46 Abstract: To evaluate and compare the performance of triploid juvenile C. gigas (mean shell height = 19.2 mm) and triploid juvenile Crassostrea virginica (mean shell height = 31.7 mm), 600 oysters of each species were deployed for 1 year in floating mesh cages at three replicate sites within low, medium, and high salinity regimes (respectively, <15%, 15-25%, > 25%) in the Chesapeake Bay and the Atlantic Coast of Virginia. The comparative performance of the two oyster species varied with salinity. At low salinity sites, cumulative mortality of C. virginica (10%) was significantly (P < .05) lower than that of C. gigas (63%), and over-all mean growth rate of C. virginica (2.9 mm mo(-1)) was significantly (P < .05) higher than that of C. gigas (1.6 mm mo(-1)). At medium salinity sites, survival and growth rate of C. virginica and C. gigas were nor significantly (P > .05) different. Both species experienced moderately high cumulative mortality at the medium salinity sites-35% for C. virginica and 53% for C. gigas-but considerable variation among sires was observed. Ar high salinity sites, mean cumulative mortality was similarly low (<11%) for both species; whereas, over-all mean growth rate of C. gigas (7.1 mm mo(-1)) was significantly (P < .05) higher than that of C. virginica (3.6 mm mo(-1)). At all sites, C. gigas was less susceptible than C. virginica to Perkinsus marinus infections. Infections by Haplosporidium nelsoni were present in C. virginica and absent in C. gigas. Infestations by mud-worm Polydora spp. were more prevalent and severe for C. gigas than for C. virginica at low and medium salinity sites in October 1997, but similar for both species at other times and locations. Condition index was significantly (P < .05) higher for C. virginica than for C. gigas at low salinity in May 1998, but similar for both species for other times and locations. Crassostrea virginica outperformed C. gigas in low salinity sires in the Chesapeake Bay, C. gigas outperformed C. virginica at high salinity sites in the Atlantic Coast, and performance was similar for both species at medium salinity sites in the Chesapeake Bay. Calvo, G. W., Luckenbach, M. W., Allen, S. K. Jr., and Burreson, E. M. 2000. A Comparative Field Study of Crassostrea ariakensis and Crassostrea virginica in Relation to Salinity in Virginia. Special Report in Applied Marine Science and Ocean Engineering No. 360 Ref ID: 54 Calvo, G. W., Luckenbach, M. W., Allen, S. K. Jr., and Burreson, E. M. 2001. A comparative field study of Crassostrea ariakensis (Fujita 1913) and Crassostrea virginica (Gmelin 1791) in relation to salinity in Virginia. Journal of Shellfish Research 20: 221-229. Ref ID: 59 Abstract: We examined survival, growth, and disease susceptibility of triploid Crassostrea ariakensis (= rivularis) and compared results with that of diploid Crassostrea virginica. Two hundred and fifty oysters (age = 2 yr, mean shell height = 60-64 mm) of each species were deployed at duplicate sites, (Chesapeake Bay, and the Atlantic Coast of Virginia) within low, medium, and high salinity regimes respectively (< 15%, 15-25%, > 25%). Over the course of the study, from June 1998 to September 1999, C. virginica exhibited low survival, modest growth and high disease susceptibility. In contrast, C. ariakensis exhibited high survival, high growth rate, and low disease susceptibility. At low salinity sites, final mean cumulative mortality of C. virginica (81%) was significantly higher than that of C. ariakensis (14%). At medium and high salinity sites, all C. virginica died before the end of the study whereas final mean cumulative mortality in C ariakensis was 13 to 16%. After 1 year of deployment, mean shell height of C. virginica at low, moderate, and high salinity sites was respectively 70, 80 and 73 mm. In comparison, mean shell height of C. ariakensis was respectively 93, 121 and 137 mm. At low salinity sites, mean growth rate of C virginica was not significantly different from that of C ariakensis. At medium and high salinity sites, mean growth rate of C virginica was significantly lower than that of C ariakensis. Prevalence and intensity of Perkinsus marinus infections were significantly higher in C. virginica than in C. arlakensis. During the second summer of disease exposure, prevalence in C. virginica was 100% at all sites whereas in C ariakensis it ranged from 0 to 28%. Heavy intensity of infections were prevalent in C. virginica whereas infections in C. ariakensis were limited to light intensity. Haplosporidium nelsoni (MSX) was present in C. virginica, but absent in C. ariakensis. Mud worms (Polydora spp.) were present in both oyster species, but infestations were low and did not appear to affect condition or growth. In summary, wide salinity tolerance and low disease susceptibility were associated with high survival and growth of C. ariakensis in Chesapeake Bay and the Atlantic Coast of Virginia. Cano, J., Rosique, M. J., and Rocamora, J. 1997. Influence of environmental parameters on reproduction of the european flat oyster (Ostrea edulis L.) in a coastal lagoon (Mar Menor, southeastern Spain). Journal of Mollsucs Studies 63: 187-196. Ref ID: 83 Abstract: The influence of environmental parameters (temperature, dissolved oxygen, suspended matter, chlorophyll a) on the condition indices and gametogenic cycle of the European flat oyster (Ostrea edulis L.) was analyzed in the Mar Menor (Murcia, Spain) between January 1990 and December 1992. The highest condition index values were recorded during the prespawning season at temperatures between 11-12 degrees C. Condition index values gradually decreased from 14 degrees C, coinciding with the appearance of the first larvae in the plankton. Condition index values were lowest in summer. Multiple regression analysis revealed that the condition indices were correlated mainly with temperature and to a lesser extent, with dissolved oxygen, chlorophyll a and suspended matter. Absolute chlorophyll concentrations were low and presented a negative correlation with the condition index values, though this correlation was less pronounced than that of temperature. Gametogenesis was continuous all year round, but spawning took place only at temperatures of 14 degrees C or higher, and larvae were present in the plankton to 28 degrees C. The low absolute values of chlorophyll a and suspended matter found in the oligotrophic Mar Menor did not seem to affect the gametogenesis, spawning or the larval development of the oysters, which feed on picoplankton, principally composed of dinoflagellates and bacteria. Carlton, J. T. 1989. Man's role in changing the face of the ocean: biological invasions and implications for conservation of near-shore environments. Conservation Biology 3: 265-273. Ref ID: 182 Carlton, J. T. 1992. Introduced marine and estuarine mollusks of North America: an end-of-the-20th-century perspective. Journal of Shellfish Research 11: 489-505. Ref ID: 109 Carlton, J. T. 1999. Molluscan invasions in marine and estuarine communities. Malacologia 41: 439-454. Ref ID: 171 Abstract: The distributions of many species of marine and estuarine mollusks have been altered dramatically by human movements over the past 2,000 and more years. Vectors have included vessels, mariculture, the aquarium trade, intentional or accidental releases into the wild, and canals. Most marine mollusk distributions are held to be "natural" prior to the 19th century, whereas mollusk distributions during or since the 19th century are held to be potentially subject to human modification. However, that pre-19th century invasions occurred is clear, suggesting that the antiquity of human-mediated mollusk introductions has been extensively underestimated. The Asian oyster Crassostrea gigas was introduced to Europe by the 1500s, the Northern Hemisphere mussel Mytilus may have arrived in the Southern Hemisphere by the early 1500s, and shipworms have similarly been widespread by shipping. A subset of 38 Northern Hemisphere introduced mollusks reveals distinct geographic patterns: 63% originate in the North Atlantic Ocean/Mediterranean area, while 37% originate in the North Pacific Ocean. Within the Atlantic Ocean, the western Atlantic is a significantly stronger donor area, accounting for 75% of those North Atlantic taxa that have dispersed globally. Similarly, the western Pacific Ocean is also a strong donor region, exporting 93% of all those originating in the Pacific. Ecologically, in San Francisco Bay, California, the introduced infaunal or near-surface bivalves Mya, Gamma, Venerupis, Musculista and Potamocorbula may be sufficiently abundant as to control water column productivity. The European snail Littorina littorea (Linnaeus, 1758) has had vast and complex impacts on intertidal hard and soft bottom communities from Canada to the mid-Atlantic America. In general, far more attention must be paid to experimentally demonstrating the impacts of invasive species. Carriker, M. R. 1992. Introductions and transfers of molluscs: risk considerations and implications. Journal of Shellfish Research 11: 507-510. Ref ID: 103 Case, T. J. 1991. Invasion resistance, species build-up and community collapse in metapopulation models with interspecies competition. Biological Journal of the Linnean Society 42: 239-266. Ref ID: 122 Chai, A. L., Homer, M. L., Tsai, C. F., and Goulletquer, P. 1992. Evaluation of oyster sampling efficiency of patent tongs and an oyster dredge. North American Journal of Fisheries Management 12: 825-832. Ref ID: 645 Chew, K. K. 1984. Recent advances in the cultivation of molluscs in the Pacific United States and Canada. Aquaculture 39: 69-81. Ref ID: 603 Chew, K. K. 1990. Global bivalve shellfish introductions. World Aquaculture 21: 9-22. Ref ID: 104 Chew, K. K. 1993. Ecological changes related to declines of oyster stocks in Chesapeake Bay. Aquaculture Magazine 19: 73-76. Ref ID: 546 Choi, K., Powell, E. N., Lewis, D. H., and Ray, S. M. 1994. Instantaneous reproductiver effort in female American oysters, Crassostrea virginica, measured by a new immunoprecipation assay. Biological Bulletin 186: 41-61. Ref ID: 580 Christmas, J. F. and Jordan, S. J. 1987. Biological monitoring of selected oyster bars in the lower Choptank river. Pages 125-139 in G. B. Mackiernan, editor. Dissolved Oxygen Processes in the Chesapeake Bay: Processes and Effects. Maryland Sea Grant Publications: UM-SG-TS-87-03, College Park, MD. Ref ID: 650 Christmas, J. F., McGinty, M. R., Randle, D. A., Smith, G. F., and Jordan, S. J. 1997. Oyster shell disarticulation in three Chesapeake Bay tributaries. Journal of Shellfish Research 16: 115-123. Ref ID: 649 Christmas, J. F. Jr. and Jordan, S. J. 1991. Choptank River Oyster Mortality Study. CBRM-HI-91-1, Maryland Department of Natural Resources, Annapolis, MD Ref ID: 591 Chu, F. E., Volety, A. K., and Constantin, G. 1996. A comparison of Crassostrea gigas and Crassostrea virginica: effects of temperature and salinity on susceptibility to the protozoan parasite, Perkinsus marinus. Journal of Shellfish Research 15: 375-380. Ref ID: 31 Abstract: The susceptibility of diploid and triploid (2N and 3N) Crassostrea gigas to Perkinsus marinus was compared, in the laboratory, with that of Crassostrea virginica al three test temperatures (10, 15, and 25 degrees C) at 20-22 ppt and at three test salinities (3, 10, and 20 ppt) at a temperature of 19-22 degrees C. Experimental oysters were challenged twice with freshly isolated P, marinus meronts, after acclimation to test temperatures and salinities. Although infection prevalence and intensity increased with temperature (p = 0.0001) and salinity in P. marinus-challenged oysters of both oyster species: they were highest in C. virginica groups. Infection intensity was significantly (p = 0.001) higher in P. marinus-challenged C. virginica than C. gigas (2N and 3N) at all temperatures; however, infection prevalence was not statistically different at any temperature treatment. In all salinity treatments, prevalence and infection intensity were significantly higher (p = 0.0001) in P. marinus-challenged C. virginica than 2N and 3N C. gigas. Because high infection prevalence and intensity were found in non-challenged C. virginica, part of the recorded prevalence and intensity in challenged C. virginica was probably attributed to latent infection carried over from the field. High mortality occurred in both 2N and 3N C. gigas during temperature and salinity adjustment, particularly at 25 degrees C and 3 psu. Chu, F. E. 1996. Laboratory investigations of susceptibility, infectivity, and tramission of Perkinsus marinus in oysters. Journal of Shellfish Research 15: 57-66. Ref ID: 34 Abstract: The protozoan parasite, Perkinsus marinus (Dermo), has caused significant mortality in the eastern oyster, Crassostrea virginica, along the east coast of the United States and the Gulf of Mexico, since the 1950s. Because of its current expanded distribution and increased abundance, P. marinus is now considered more prevalent in the mid-Atlantic waters and the Chesapeake Bay in particular, than another protozoan pathogen, Haplosporidium nelsoni (MSX). The susceptibility, infectivity/pathogenicity, and transmission of P. marinus in eastern oysters were investigated in numerous laboratory studies, The influence of environmental factors such as temperature, salinity, and pollution on the interaction between the host oyster and the parasite were also examined. Three P. marinus life stages, the meront, prezoosporangia, and biflagellated zoospore, were found effective in transmitting the disease. The meront stage was more effective than the prezoosporangia stage in transmitting the disease in eastern oysters, suggesting that the meront is the primary transmission agent in nature. A dose of 10-10(2) freshly isolated P. marinus cells oyster(-1) was required to cause infection by direct shell cavity injection. P. marinus susceptibility and disease progression were positively correlated with temperature, salinity, and number of infective cells the oyster encountered. Temperature appeared to be the most important factor, followed by the infective cell dose, and then salinity in determining the subsequent disease development in oysters. There was no significant interaction between temperature, salinity, and infective cell dose on the prevalence of disease in oysters. However, the interaction between either temperature and salinity or between temperature and P. marinus dose significantly intensified the disease. The Pacific oyster, Crassostrea gigas, was less susceptible, but not completely resistant, to P. marinus compared to the eastern oyster, C. virginica. However, the Pacific oyster was intolerant of high temperature (>15 degrees C) and low salinity (<10 ppt), thus vulnerable to high mortality under high temperature and low salinity environmental conditions. Pollution has the potential to enhance P. marinus susceptibility and infection in oysters. Chu, F. L. E. and Lapeyre, J. F. 1993. Perkinsus marinus susceptibility and defense-related activities in eastern oysters Crassostrea virginica: temperature effects. Diseases of Aquatic Organisms 16: 223-234. Ref ID: 237 Abstract: The relationship of potential defense-related cellular and humoral activities and the susceptibility of eastern oysters Crassostrea virginica to the parasite Perkinsus marinus were examined at 10, 15, 20 and 25-degrees-C. Oysters were acclimated at experimental temperatures for 20 d and then challenged with P. marinus. Total hemocyte counts (TC) and percentage of granulocytes (PG) 20 d after temperature acclimation were higher in oysters dt high than at low acclimation temperature. Higher protein (P) and lysozyme (L) concentrations were found in oysters at 10 and 15-degrees-C. No significant differences in hemagglutination (H) titers due to temperature acclimation were observed. Infection prevalence 46 d after challenge by P marinus was 100, 91, 46 and 23% respectively, for oysters at 25, 20, 15 and 10-degrees-C. Disease intensity increased with temperature. OysterS dt higher temperatures had greater PG and TC and hemocyte phagocytic activity. No difference was found in TC and PG between control and challenged oysters within each temperature treatment. Bleeding may to some extent reduce TC and PG in oysters. P did not vary much among temperatures. No reduction of P in oysters was found due to P. marinus challenge and infection. L tended to be higher in oysters at lower than at higher treatment temperatures. The oysters at 10-degrees-C had the highest L concentration and lowest P. marinus infection. But, it is not known whether the high extracellular L in oysters at 10-degrees-C is attributable to the low P marinus susceptibility in these oysters. There was no significant difference in condition index (CI) between control and challenged oysters and between infected and uninfected oysters. However, CI decreased with increasing temperatures. The H titers were not associated with any measured variables. The greater TC, PG, and phagocytic capability in oysters at higher temperatures did not result in fewer or less intense P. marinus infections Chu, F. L. E. and Hale, R. C. 1994. Relationship between pollution and susceptibility to infectious disease in the eastern oyster, Crassostrea virginica. Marine Environmental Research 38: 243-256. Ref ID: 233 Abstract: Infectious disease epizootics seriously affect many populations of marine organisms. Pollution has been hypothesized to contribute to some aquatic epizootics, although this link has not been adequately examined To further evaluate this hypothesis, the effect of a complex mixture of sediment derived pollutants on the susceptibility of the eastern oyster, Crassostrea virginica, to an infectious disease was investigated. The disease studied is caused by the protozoan parasite Perkinsus marinus (Dermo) and results in significant oyster mortalities in the mid-Atlantic region of the United States. Oysters were exposed to 0, 15 and 30% dilutions of water soluble fractions, generated from sediments collected from the Elizabeth River, a heavily, polluted subestuary of the Chesapeake Bay, USA. Oysters were then challenged with P. marinus meronts. Pollutant exposure enhanced preexisting P. marinus infections and increased the oysters' susceptibility to experimentally induced infection, in a dose-dependent manner Chu, F. L. E. and Volety, A. K. 1997. Disease processes of the parasite Perkinsus marinus in eastern oyster Crassostrea virginica: Minimum dose for infection initiation, and interaction of temperature, salinity and infective cell dose. Diseases of Aquatic Organisms 28: 61-68. Ref ID: 213 Abstract: Experiments were conducted to: (1) test the response of oysters to different doses of the oyster parasite Perkinsus marinus and to 2 stages, meronts or prezoosporangia; and (2) investigate the synergistic effects of temperature, salinity and infective cell concentration on P. marinus infection in oysters. A dose-dependent response of P. marinus infection was found in oysters inoculated with 0, 10, 10(2), 10(4), and 10(5) meronts or prezoosporangia per oyster and maintained at 22 to 25 degrees C and 14 to 21 ppt for 8 to 12 wk. The minimum dose required to infect oysters was 10(2) meronts or prezoosporangia per oyster through shell cavity inoculation. Interactive effects between temperature, salinity, and infective cell dose on P. marinus prevalence was insignificant in the experiment, in which oysters were challenged by 0, 2.5 x 10(3) or 2.5 x 10(4) meronts per oyster and held at 9 temperature-salinity regimes (10, 15 and 25 degrees C at 3, 10 and 20 ppt). However, there was a significant positive interaction relevant to infection intensity between temperature and salinity, and between temperature and meront dose. Temperature was the most important factor followed, respectively, by the infective cell dose and salinity in determining the susceptibility to P. marinus in oysters. Reduced condition index was observed in moderately to heavily infected oysters and in oysters at 25 degrees C Chu, F. L. E. 1999. Environmental factors and the infectious disease caused by the protozoan parasite, Perkinsus marinus, in eastern oysters (Crassostrea virginica). Bulletin of the European Association of Fish Pathologists 19: 265-268. Ref ID: 600 Abstract: Temperature and salinity are two important factors limiting the distribution and abundance of Perkinsus marinus, a protozoan parasite of Eastern oysters (Crassostrea virginica). Results of laboratory studies ale consistent with field observations and clearly demonstrate that P. marinus susceptibility and disease advancement are positively correlated with temperature, salinity and in situ number of infective cells. Laboratory findings also suggest that environmental degradation may enhance the epizootic, although disease caused by P. marinus in oysters is known to be predominantly exacerbated by elevated temperature and salinity. Oysters cellular defence mechanisms appear ineffective in defence against P. marinus. Also, pollutant esposure caused no significant effects on defence-related activities measured in oysters Chu, F. L. E., Volety, A. K., Hale, R. C., and Huang, Y. Q. 2002. Cellular responses and disease expression in oysters (Crassostrea virginica) exposed to suspended field - contaminated sediments. Marine Environmental Research 53: 17-35. Ref ID: 515 Abstract: Exposure of oysters to water soluble fractions derived from field-contaminated sediments (FCS) containing predominantly lower molecular weight organic aromatic compounds, has been previously demonstrated to enhance pre-existing infections caused by the protozoan parasite, Perkinsus marinus (Dermo), and the prevalence of experimentally induced infections. To further explore the role of pollution on the onset and progression of disease, effects of suspended FCS from an estuarine creek in Virginia, USA, dominated by higher molecular weight polycyclic aromatic hydrocarbons (PAHs) on cellular responses and Dermo disease expression in oysters (Crassostrea virginica) were examined. Sediments were collected from a PAH polluted estuarine creek in Virginia, USA. To test effects on cellular response, oysters from Maine were exposed daily to 0, 1.0, 1.5, or 2.0 g suspended FCS (corresponding to 0, 70.2, 105, or 140 mug PAHs, respectively) for 5, 10, 20, and 40 days. Hemocyte activities and plasma lipid, protein and lactate dehydrogenase (LDH) levels were then measured. Exposure stimulated neutral red uptake, MTT reduction, and H-3-leucine incorporation in oyster hemocytes at various exposure times, but did not affect the plasma protein, lipid and LDH levels. To test effects on Dermo expression, oysters from a Dermo enzootic area, with an initial estimated infection prevalence of 39%, were exposed daily to 0, 1.0, 1.5, or 2.0 g suspended FCS (corresponding to 0, 75.0, 113, or 150 mug PAHs, respectively) for 30 days. Exposure enhanced disease expression in oysters. However, no significant change was noted in any measured cellular or humoral parameters. (C) 2001 Elsevier Science Ltd. All rights reserved Chu, F. L. E., Lund, E., Soudant, P., and Harvey, E. 2002. De novo arachidonic acid synthesis in Perkinsus marinus, a protozoan parasite of the eastern oyster Crassostrea virginica. Molecular and Biochemical Parasitology 119: 179-190. Ref ID: 266 Abstract: The capability of synthesizing fatty acids de novo in the meront stage of the oyster protozoan parasite, Perkinsus marinus, was investigated employing stable-isotope-labeled precursors (1,2 C-13-acetate and palmitic-d(31) acid). Fatty acid methyl esters derived from 1,2 C-13-acetate and palmitic-d(31) acid were analyzed using gas chromatography/mass spectrometry and gas chromatography/flame ionization detection. Results revealed that in vitro cultured P. marinus meronts utilized C-13-acetate to synthesize a range of saturated and unsaturated fatty acids. The saturated fatty acids 14:0, 16:0, 18:0, 20:0, 22:0, 24:0 and the unsaturated fatty acids, 18:1(n-9), 18:21(n-6), 210:1(n-9), 20:2(n-6), 210:21(n-9), 210:3(n-6), 210:4(n-6) were found to contain C-13, after 7, 14, and 21 days incubation with the precursor. This indicates that meronts can synthesize fatty acid de novo using acetate as a substrate. Meronts efficiently elongated 16:0-d(31) to 18:0, 20:0, 22:0, 24:0, but desaturation activity was limited, after 7 and 14 days cultivation. Only a small quantity of 18:1-d(29) was detected. This suggests that meronts cannot directly convert exogenous palmitic acid or its products of elongation to unsaturated counterparts. The ability to synthesize 20:4(n-6) from acetate is particularly interesting. No parasitic protozoan has been reported to be capable of synthesizing long chain essential fatty acids, such as 20:4(n-6) de novo. Future study will be directed to determine whether the observed in vitro activities indeed reflect the in vivo activities, when meronts are associated with the host. (C) 2002 Elsevier Science B.V. All rights reserved Cigarria, J., Fernandez, J., and Magadan, L. P. 1998. Feasibility of biological control of algal fouling in intertidal oyster culture using periwinkles. Journal of Shellfish Research 17: 1167-1169. Ref ID: 494 Abstract: The effectiveness of the use of periwinkles (Littorina littorea L.) to control the fouling algae in oyster bags was tested at the Eo estuary in northwest Spain. Growth was higher for Japanese oysters (Crassostrea gigas Thunberg) when cultured with than without periwinkles (87.74 g vs 60.07 g of mean wet weight). This biological control of fouling shortens the growth period and thus reduces production cost. The system appears to be one of the most effective and most environmental friendly methods of limiting the negative effect of the seaweeds in intertidal oyster culture Cloern, J. E. 1982. Does the benthos control phytoplankton biomass in south San Francisco Bay? Marine Ecology-Progress Series 9: 191-202. Ref ID: 635 Coakley, J. M. 2004. Growth of eastern oyster, Crassostrea virginica, in Chesapeake Bay. University of Maryland, College Park. Ref ID: 566 Abstract: I applied modern techniques of modal analysis to track size modes in Eastern oyster, Crassostrea virginica, populations longitudinally through time, from which I inferred age-classes to establish size-at-age relationships for individual oyster bars and across Maryland's Chesapeake Bay. Average shell lengths of putative age-0 through age- 5 oysters range from 22.93 (±6.67, n=194) mm to 84.46 (±8.27, n=4) mm. Growth rates declined with age-class from a mean of 28.97mm/yr to -0.85mm/yr, and the maximum and minimum individual growth rates were 0.78 and 53.0 mm/yr, respectively. I estimated von Bertalanffy growth parameters across all sites as L ‡=90.85mm, k=0.55, and to=-0.51. Two processes likely account for the small asymptotic length: size-selective mortality, both natural and fishery-related, and underlying Dermo infections in the population. On average, I estimated oysters take 3 years to reach a marketable size within Chesapeake Bay. As an alternative to modal length frequency analysis, annuli in chondrophore sections of known-age oysters in Chesapeake were examined. It was determined that annuli formation was unrelated to chronological age. Cochennec, N., Renault, T., Boudry, P., Chollet, B., and Gerard, A. 1998. Bonamia-like parasite found in the Suminoe oyster Crassostrea rivularis reared in France. Diseases of Aquatic Organisms 34: 193-197. Ref ID: 40 Abstract: Considering the economic importance of the Pacific oyster Crassostrea gigas to the French shellfish industry, the appearance of major diseases in this species could cause dramatic decreases in production. Suminoe oysters, of the non-indigenous species Crassostrea rivularis (Gould), were introduced into France to test their ability to adapt to local conditions. These oysters were imported after careful examination, and were maintained in laboratory quarantine. Some mortalities occurred 7 mo after importation. Histological and electron microscope examinations of 9 dead specimens revealed a parasite presumed to be a Bonamia-Like protozoan. This is the first report concerning a parasite of the genus Bonamia in a species belonging to the genus Crassostrea. Thus, C. rivularis is not considered to be a suitable substitute for C, gigas in France. Coen, L. D., Luckenbach, M. W., and Breitburg, D. L. 1999. The role of oyster reefs as essential fish habitat: a review of current knowledge and some new perspectives. American Fisheries Society Symposium 22: 438-454. Ref ID: 151 Coen, L. D. and Luckenbach, M. W. 2000. Developing success criteria and goals for evaluating oyster reef restoration: Ecological function or resource exploitation? Ecological Engineering 15: 323-343. Ref ID: 273 Abstract: Habitat restoration encompasses a broad range of activities, emphasizing very different issues, goals, and approaches depending on the operational definition of 'restoration'. This is particularly true for many shellfish (molluscan) dominated systems (e.g. oyster reefs, mussel beds, vermetid gastropod reefs). In contrast to other well-studied biogenic habitats, such as seagrasses, mangroves, or salt marshes, bivalves are directly consumed as a resource. Hence resource extraction has direct consequences for habitat health. Restoration objectives have typically included reduction of public health risks through improved water quality to increase harvest. Restoration or enhancement of populations of commercially exploited shellfish depressed by overharvesting and/or reduced environmental quality remains the principal motivation behind most shellfish 'restoration' efforts. Direct and indirect ecosystem services (e.g. filtering capacity, benthic-pelagic coupling, nutrient dynamics, sediment stabilization, provision of habitat, etc.) derived fi om oyster habitat have been largely ignored or underestimated. Only recently, the restoration of lost ecological function associated with shellfish communities has been included in our discussions and related research examining habitat development and function through a scientific approach. The former area has been reviewed extensively and will not be out focus here. In this review, we examine some of the restoration efforts made in the name of fisheries enhancement, address their effectiveness, and discuss some of the issues associated with realizing the broader goal of ecological restoration. We note the importance of linking success criteria to specific goals and make the case for. a gl cater need in clarifying the ecological functions of shellfish and shellfish habitats. We recognize the limitations of existing datasets and summarize ongoing attempts to address oyster habitat restoration throughout the broad geographic distribution of the American oyster, Crassostrea virginica (Gmelin). In many ways this topic parallels the ongoing debate over 'attraction versus production' associated with artificial reef management. We consider how local conditions (e.g. tidal range, bottom topography, turbidity, salinity) and resulting habitat traits affect restoration strategies. We also discuss the underappreciated value of shellfish populations from those areas designated as closed to harvesting due to their intrinsic worth as habitat/larval reserves. The necessity of ecosystem (adaptive) management strategies emerges from this discussion. Finally, this overview supports our contention that shellfish habitat should be included in discussions of 'essential fish habitats' (or EFH). (C) 2000 Elsevier Science B.V. All rights reserved Coman, G. J., Crocos, P. J., Preston, N. P., and Fielder, D. 2002. The effects of temperature on the growth, survival and biomass of different families of juvenile Penaeus japonicus Bate. Aquaculture 214: 185-199. Ref ID: 534 Abstract: Variation in the growth, survival and change in total biomass (termed biomass increase) of different families of juvenile Penaeus japonicus was investigated over a range of temperatures in controlled laboratory experiments. In the first experiment, the effects of temperature on six families of juveniles were examined over a broad range of temperatures (24 to 30 degreesC). In the second experiment, the effects of temperature on six more families of juveniles were examined over a narrower range of temperatures (27.5 to 31.2 degreesC). Over the broad temperature range, mean growth and biomass increase were highest at 27 degreesC and mean survival was highest at 24 degreesC. Mean growth was lowest at 24 degreesC, whilst survival and biomass increase were lowest at 30 degreesC. However, there was a significant interaction between family and temperature, with some families tolerating a broader range of temperatures than others. As a result, the ranking of families in relation to growth, survival and biomass increase changed at each temperature. This effect was more pronounced for survival than for growth. Over the narrower range, temperature significantly affected growth, survival and biomass increase, but there was no significant interaction between family and temperature. Growth, survival and biomass increase were significantly lower at 31.2 than at 27.5 and 29.2 degreesC. These results suggest that if grow-out conditions for P. japonicus vary by more than a few degrees, interactions between family and temperature could affect the efficiency of selection. The results also suggest that the family x temperature interaction may have a more pronounced effect on survival than on growth. Crown Copyright (C) 2002 Published by Elsevier Science B.V. All rights reserved Connor, J. L. 1980. Distribution and seasonality of macroalgae on oyster communities of central Chesapeake Bay. Botanica Marina 23: 711-717. Ref ID: 477 Cook, T., Folli, M., Klinck, J., Ford, S., and Miller, J. 1998. The relationship between increasing sea-surface temperature and the northward spread of Perkinsus marinus (Dermo) disease epizootics in oysters. Estuarine Coastal and Shelf Science 46: 587-597. Ref ID: 207 Abstract: From its initial discovery in the Gulf of Mexico in the late 1940s until 1990, Perkinsus marinus, the parasite responsible for Dermo disease in the eastern oyster, Crassostrea virginica was rarely found north of Chesapeake Bay. In 1990-92, an apparent range extension of the parasite led to epizootic outbreaks of the disease over a 500 km range north of Chesapeake Bay. One of the hypotheses for the range extension argues that small, undetected numbers of parasites were already present in northern oysters as the result of repeated historical introductions, and that a sharp warming trend in 1990-92 stimulated the disease outbreak. This argument was based on trends in air temperature. The present study examined this hypothesis by analysing water temperatures, rather than air temperatures, for five stations located in areas affected by the recent epizootics. At all five stations, there was a strong increasing trend in winter sea-surface temperature (SST) between 1986 and 1991. At four of the five stations, there was a smaller increasing trend in winter temperatures after 1960. There were no consistent or obvious trends in summer (August) temperatures. In Delaware Bay, which has a 40 year history of monitoring for oyster diseases, occasional findings of P. marinus in oysters were correlated with warming episodes that were especially notable in the winter (February) record. Empirical orthogonal function (EOF) analysis showed that winter temperatures varied consistently at the stations examined and were associated with variations in P. marinus prevalence. Associations using EOF analysis with August temperatures were much weaker. The SST record is consistent with the hypothesis that increasing winter water temperatures have been important in the recent outbreak of P. marinus epizootics in the north-eastern U.S.A. (C) 1998 Academic Press Limited Cox, C. and Mann, R. 1992. Temporal and spatial changes in fecudnity of eastern oysters, Crassostrea virginica (Gmelin, 1791) in the James River, Virginia. Journal of Shellfish Research 11: 49-54. Ref ID: 75 Cranfield, H. J., Carbines, G., Michael, K. P., Dunn, A., Stotter, D. R., and Smith, D. J. 2001. Promising signs of regeneration of blue cod and oyster habitat changed by dredging in Foveaux Strait, southern New Zealand. New Zealand Journal of Marine and Freshwater Research 35: 897-908. Ref ID: 427 Abstract: Epifaunal reefs in Foveaux Strait are oyster (Ostrea chilensis Philippi, 1845) habitat. One hundred and thirty years of oyster dredging has diminished the complexity and distribution of these reefs. Commercial densities of blue cod (Parapercis colias (Forster in Bloch and Schneider, 1801)) were discovered on epifaunal reef habitat in 1989 and became the focus of a major blue cod fishery. We document habitat changes that followed the closing of the oyster fishery in 1993 and interactions between the blue cod and oyster fisheries after the oyster fishery was reopened in 1996. Evidence from blue cod fishers and oyster surveys suggests that the benthic habitat of some oyster beds regenerated in the absence of dredging and that the relative density of blue cod, and then oysters, rebuilt to commercial levels. Benthic habitat was modified once more when oyster dredging restarted and the relative density of blue cod on oyster beds fell again. The observations suggest that rotational fishing of oysters could mitigate the effects of dredging on habitat and that marine protected areas could expedite habitat recovery. Increasing habitat complexity and blue cod density on a reef of oyster shells formed by an oyster fisher suggests that habitat enhancement might remedy effects of dredging. The questions raised by the observations could be answered by management experiments on the scale of the fisheries Crawford, C. M., Macleod, C. K. A., and Mitchell, I. M. 2003. Effects of shellfish farming on the benthic environment. Aquaculture 224: 117-140. Ref ID: 497 Crosby, M. P., Roberts, C. F., and Kenney, P. D. 1991. Effects of immersion time and tidal position on insitu growth rates of naturally settled eatern oysters, Crassostrea virginica (Gmelin 1791). Journal of Shellfish Research 10: 95-103. Ref ID: 498 Culloty, S. C., Cronin, M. A., and Mulcahy, M. F. 2003. Possible limitations of diagnostic methods recommended for the detection of the protistan, Bonamia ostreae in the European flat oyster, Ostrea edulis. Bulletin of the European Association of Fish Pathologists 23: 67-71. Ref ID: 487 Abstract: Screening of heart smears is one of the OIE recommended methods for diagnosis of the protistan Bonamia ostreae in the native oyster, Ostrea edulis. Within a recent study, 130 oysters were brought to the laboratory from Lake Grevelingen, a Bonamia-endemic area as part of a planned experiment. A sub-sample of 30 oysters was screened using heart smears, to determine baseline prevalence of infection at time zero, and no infection was observed. The remaining oysters were maintained in the laboratory and screened over a six-month period, but three weeks after the trial began two oysters out of 100 had Class 4 infections, and further infection was observed over the remaining months. These results indicate that oysters found at the beginning of the trial to be free of Bonamia, using a standard method i.e. heart smears, were in fact infected. The oysters may have been experiencing a latent infection; latent infections cannot be detected by presently recommended screening techniques. Alternatively the sample size used may have been too small. The results raise concerns about limitations of the diagnostic methodology for Bonamia ostreae for research and regulatory purposes Dalby, J. E. and Young, C. M. 1992. Role of early postsettlement mortality in setting the upper depth limit of ascidians in Florida epifaunal communities. Marine Ecology-Progress Series 80: 221-228. Ref ID: 503 Abstract: At 3 sites in Florida, USA, the communities of marine sessile invertebrates are dominated by oysters (Crassostrea virginica) in the mid-intertidal zone, and by ascidians (several species) in the low intertidal and subtidal zones. Our experiments tested the hypotheses that the upper depth limit of ascidians is set by (1) predation by oysters on larvae, (2) larval zonation, and (3) early post-settlement mortality. Hypothesis 1 was tested by monitoring ascidian recruitment on the shells of dead and living oysters placed in both the oyster and ascidian zones. Because recruitment of all ascidian species was confined to oysters placed in the ascidian zone, we concluded that the upper depth limit of these ascidians cannot be due solely to predation on larvae by oysters. Hypotheses 2 and 3 were tested by monitoring the recruitment of ascidians on settling plates fixed in the 2 zones, and on plates floating at 2 depths in the water column. In the 'fixed' experiments, recruitment of all ascidian species was confined to the ascidian zone. In the 'floating' experiments, the number of recruits of Diplosoma glandulosum did not differ between shallow and deep plates, and recruitment of Styela plicata was confined to shallow plates. Thus, we concluded that early post-settlement mortality is a major factor setting the upper depth limit of these 2 species. We vertically transplanted 2 ascidians (S. plicata, Botryllus planus) and found that the survivorship of both was greater in the ascidian zone than in the oyster zone. Thus, further support was gained for the post-settlement mortality hypothesis Dame, R. F. 1987. The net flux of inorgnic matter by an intertidal oyster reff. Continental Shelf Research 7: 1421-1424. Ref ID: 596 Dame, R. F. and Libes, S. 1993. Oyster reefs and nutrient retention in tidal creeks. Journal of Experimental Marine Biology and Ecology 171: 251-258. Ref ID: 625 Abstract: The role of oyster reefs in nutrient cycling and grazing within an estuarine ecosystem was observed by experimentally manipulating six tidal creeks. Reactive nutrient concentrations were significantly different in creeks with oysters when compared to creeks from which oysters had been removed. This evidence supports the hypothesis that oyster reefs function as nutrient retention mechanisms in these systems. There were no significant differences in Chlorophyll a concentrations among the creeks. This suggests that despite the increased grazing pressure exerted by these filter feeders plankton productivity may be enhanced in creeks with oysters. Dauer, D. M., Tourtellotte, G. H., and Ewing, R. M. 1982. Benthic Studies of the Lower Chesapeake Bay .2. Oyster Shells and Artificial Worm Tubes - the Role of Refuges in Structuring Benthic Communities of the Lower Chesapeake Bay. Internationale Revue der Gesamten Hydrobiologie 67: 661-677. Ref ID: 474 Davis, C. V. and Barber, B. J. 1994. Size-dependent mortality in hatchery-reared populations of oysters, Crassostrea virginica, Gmelin-1791, affected by juvenile oyster disease. Journal of Shellfish Research 13: 137-142. Ref ID: 588 Abstract: Recurring mortalities of hatchery reared juvenile oysters in the Damariscotta River, Maine, caused by juvenile oyster disease (JOD), prompted a monitoring program to track growth and survival of juvenile eastern oysters, Crassostrea virginica, during the summer of 1993. Three cohorts of oysters ranging in initial mean shell height from 12.1 to 25.9 mm were deployed on July 16 in growout trays adjacent to a commercial shellfish nursery operation. Mortalities commenced August 18 and continued beyond September 21, 1993 in all three cohorts. Dying oysters displayed cupping of the left valve, unequal shell growth with the left valve outgrowing the right, tissue emaciation, mantle retraction and conchiolin deposition on the inner shell surfaces. Cumulative mortality was highly correlated to mean cohort size (shell height). The smallest size class (Cohort 3) suffered the highest cumulative mortality (56.2%); the largest size class (Cohort 1) experienced relatively low cumulative mortality (13.6%). The results of this study suggest that the impacts of JOD can be minimized by attaining mean shell height of >25 mm prior to mid-July (requires early spawning) or by deploying seed after mid-August (requires overwintering) Davis, C. V. and Barber, B. J. 1999. Growth and survival of selected lines of eastern oysters, Crassostrea virginica (Gmelin 1791) affected by juvenile oyster disease. Aquaculture 178: 253-271. Ref ID: 528 Abstract: Juvenile oyster disease (JOD) has had severe impacts on eastern oyster, Crassostrea virginica, culture in the northeastern United States in recent years. JOD mortalities in Maine have resulted in juvenile crop losses exceeding 90%. Previous research has demonstrated an inverse relationship between oyster size and JOD-induced mortality; thus the use of genetically selected broodstock along with specific management options may help manage JOD-related mortality. The goals of this project were to determine the size specificity and temporal and spatial variability of JOD outbreaks with respect to several lines selected for fast growth. Two lines (including within line unselected controls) having undergone two generations of selection for faster growth, along with an unselected wild line, were deployed during the 1994-1995 growing seasons at two sites in the Damariscotta River, ME, an estuary historically impacted by JOD. Periodic monitoring of size (shell height and live weight) and mortality of replicate cohorts was conducted to track oyster growth and incidence of JOD-induced mortalities. Due to the asynchrony of spat deployment between the cohorts, differences among lines were not feasible to evaluate, but within two lines (Flowers G(2) and Milford G(2)), selected sublines both outgrew the within line controls and had lower rates of JOD-induced mortality. The reduced mortality in the selected sublines presumably resulted from their faster growth and hardiness thus enabling the cohort to reach a refuge size/age sooner and reduce its susceptibility to JOD. (C) 1999 Elsevier Science B.V. All rights reserved de Montaudouin, X., Audemard, C., and Labourg, P.-J. 1999. Does the slipper limpet (Crepidula fornicata, L.) impair oyster growth and zoobenthos biodiviersity? A revisited bypothesis. Journal of Experimental Marine Biology and Ecology 235: 105-124. Ref ID: 29 Abstract: The Prosobranch Gastropod Crepidula fornicata was introduced into Great Britain at the end of the 19th century from North America, upon imported oysters Crassostrea virginica. Since then, it has invaded sheltered coasts of the North West Atlantic and Mediterranean Sea. C. fornicata proliferation has often generated social conflicts due to three main causes: (1) trophic competition with other suspension feeders, e.g. the cultivated oyster Crassostrea gigas; (2) spatial competition with macrozoobenthos; and (3) enhancement of silt and clay sedimentation. The effects of C. fornicata on C. gigas growth and on macrozoobenthic density and diversity have been documented through field experiments in an oyster park of Arcachon Bay (France). Densities of C. gigas and biomass of C. fornicata were manipulated over a period of 247 days within field enclosures at low water level to test: (1) oyster growth, condition index and mortality; (2) zoobenthic community alterations (abundance, biomass, species richness). From this small-scale experiment, it was shown that none of these investigated parameters was significantly affected by the presence of C. fornicata. However, faunal assemblages were modified in enclosures compared to external bare sands, due to adding a hard substrata over a soft sediment. DeBrosse, G. A. and Allen, S. K. 1996. The suitability of land-based evaluations of Crassostrea gigas (Thunberg, 1793) as an indicator of performance in the field. Journal of Shellfish Research 15: 291-295. Ref ID: 535 Abstract: The introduction of Crassostrea gigas to the mid-Atlantic requires prior knowledge of their likely ecological response, according to the International Council for Exploration of the Seas Committee guidelines. Without at least an experimental introduction, however, such knowledge is unattainable. Are comparisons of survival: growth, disease resistance, etc., conducted in land-based tanks suitable for estimating the performance of C. gigas in the field? In June 1991, equal numbers of spat from three crosses-MSX-resistant Crassostrea virginica (eastern), C. gigas form Miyagi, and C. gigas form Hiroshima-were split into two replicates and reared in upwellers for the first summer and in a land-based tank for the second. After the first season, C. virginica had the highest mortality (65, 36, and 13% for eastern, Miyagi, and Hiroshima, respectively) and average spat size was about 30% greater in both C. gigas groups. For the second year, the three crosses were transferred to a 16,000-L tank; two replicates of eastern oyster were also placed in Delaware Bay. Cumulative mortality for the second season (through 11/92) was eastern, 60%; Miyagi, 73%; Hiroshima, 93%; and eastern in Delaware Bay, 37%. In the tank, Miyagi oysters grew fastest, followed by Hiroshima and eastern; however, eastern oysters grown in the field were larger than all tank-reared groups. All oysters in the tank were infested with Polydora websteri, C. gigas heavily and eastern oysters lightly; eastern oysters grown in the field were virtually free of infestation. These data indicate that tank-based comparisons are unlikely to yield a true measure of performance in the local environment Dekshenieks, M. M., Hofmann, E. E., and Powell, E. N. 1993. Environmental effects on the growth and development of eastern oyster, Crassostrea virginica (Gmelin, 1791), larvae: a modeling study. Journal of Shellfish Research 12: 241-254. Ref ID: 9 Abstract: The effects of temperature, food concentration, salinity and turbidity on the growth and development of Crassostrea virginica larvae were investigated with a time-dependent mathematical model. Formulations used in the model for larval growth are based upon laboratory data. Simulations were done using temperature conditions characteristic of Laguna Madre, Galveston Bay, Apalachicola Bay, North Inlet and Chesapeake Bay. These simulations show that the duration of the planktonic larval phase, which is determined by larval growth rate, decreases at lower latitudes in response to warmer water temperatures. Also, oysters in the more southern locations have a longer spawning season during which the oyster population can produce more larvae. Simulations were done for Galveston Bay and Chesapeake Bay using idealized time series of food supply that included higher concentrations in the spring, summer or fall. Additional simulations considered the effects of increased food supply in both spring and fall seasons. The results show that shifting the period of enhanced food supply from March-April to April-May, when temperatures are warmer, reduces the minimum larval planktonic period from 44 to 34 days. Shifting the fall bloom from August-September to September-October, however, does not appreciably change the minimum larval planktonic period. The final set of simulations considered the effect of low salinity events and turbidity on the planktonic period of the larvae of Crassostrea virginica. By imposing a simulated low salinity (5 ppt) event of one month duration in August, the larval planktonic time is increased by about 39% over normal August salinities. Turbidity concentrations less than 0.1 g l-1 result in slightly decreased planktonic times. These model results show clearly the importance of ambient environmental conditions in determining the planktonic time of larvae of Crassostrea virginica, and hence their ultimate recruitment to the adult oyster population. Dekshenieks, M. M., Hofmann, E. E., Klinck, J. M., and Powell, E. N. 1996. Modeling the vertical distribution of oyster larvae in response to envrionmental conditions. Marine Ecology Progress Series 136: 97-110. Ref ID: 10 Abstract: A size-structured, time and vertically-dependent model was used to investigate the effects of water column structure on the distribution of larvae of the oyster Crassostrea virginica. Formulations used to model larval growth and behavior are based upon laboratory studies. Simulated vertical larval distributions obtained for conditions representative of a well-mixed, partially stratified and strongly stratified water column illustrate the effect that salinity and temperature gradients have on moderating larval swimming and hence on larvae vertical location. For well-mixed conditions, smaller larvae are dispersed throughout most of the water column. For strongly stratified conditions, the smaller-sized larvae cluster within the region of strong salinity change. Intermediate-sized larvae cluster within or directly below the region of strong salinity change. The oldest larvae are found near the bottom for all salinity conditions since their location is determined primarily by sinking rate. Additional simulations show that diurnal salinity changes interact with larval behavioral responses to create patchy larval distributions. Finally, simulations show that the inclusion of an upwelling or downwelling velocity can overwhelm the behavioral responses of smaller larvae and result in much different vertical distributions. The simulated vertical larval distributions show that changes in larval migratory behavior which are brought about by changes in the vertical salinity gradient can significantly alter larval distribution patterns. These, when combined with horizontal advective flows, have important implications for larval dispersal. Dekshenieks, M. M., Hofmann, E. E., Klinck, J. M., and Powell, E. N. 1997. A modeling study of the effects of size- and depth-dependent predation on larval survival. Journal of Plankton Research 19: 1583-1598. Ref ID: 560 Abstract: The form of the predation pressure experienced by larval stages of marine invertebrates is largely unknown. However, it is believed that the type, timing and rate of larval predation are critical in determining recruitment to adult populations. In this study, a time and depth-dependent model of the growth and behavior of larvae of the Eastern oyster, Crassostrea virginica, was used to investigate the effects of different forms of size-and depth-dependent predation on larval survivorship. The simulated larval survival for a cohort experiencing size-dependent predation showed that the greatest percent of the cohort survived to competent settlement size when the predation pressure decreased with increasing larval size. Additional simulations that included different types of depth-dependent predation showed that the interaction between vertical larval migration behavior and predation determined the percent of the cohort that survived to settlement size. The simulated distributions show that a higher percent of larvae survive when the predation pressure is concentrated in the surface waters. A lower percent of larvae survive to competent settlement size when the predation pressure is concentrated near the bottom. The different forms of size-and depth-dependent predation result in variations in the number of larvae present in the water column during each larval development stage. Thus, different forms of predation impact the number of larvae available for dispersal throughout the marine environment. These results have important implications concerning the exchange of genetic material between populations Dekshenieks, M. M., Hofmann, E. E., Klinck, J. M., and Powell, E. N. 2000. Quantifying the effects of environmental change on an oyster population: A modeling study. Estuaries 23: 593-610. Ref ID: 504 Abstract: Three models are combined to investigate the effects of changes in environmental conditions on the population structure of the Eastern oyster, Crassostrea virginica. The first model, a time-dependent model of the oyster population as described in Powell et al. (1992, 1994, 1995a,b, 1996, 1997) and Hofmann et al. (1992, 1994, 1995), tracks the distribution, development, spawning, and mortality of sessile oyster populations. The second model, a time-dependent larval growth model as described in Dekshenieks et al. (1993), simulates larval growth and mortality. The final model, a finite element hydrodynamic model, simulates the circulation in Galveston Bay, Texas. The coupled post-settlement-larval model (the oyster model) runs within the finite element grid at locations that include known oyster reef habitats. The oyster model was first forced with 5 yr of mean environmental conditions to provide a reference simulation for Galveston Bay. Additional simulations considered the effects of long-term increases and decreases in freshwater inflow and temperature, as well as decreases in food concentration and total seston on Galveston Bay oyster populations. In general, the simulations show that salinity is the primary environmental factor controling the spatial extent of oyster distribution within the estuary. Results also indicate a need to consider all environmental factors when attempting to predict the response of oyster populations; it is the superposition of a combination of these factors that determines the state of the population. The results from this study allow predictions to be made concerning the effects of environmental change on the status of oyster populations, both within Galveston Bay and within other estuarine systems supporting oyster populations Dew, J. R., Berkson, J. M., Hallerman, E. M., and Allen, S. K. Jr. 2003. A model for assessing the likelihood of self-sustaining populations resulting from commercial production of triploid Suminoe oysters (Crassostrea ariakensis) in Chesapeake Bay. Fishery Bulletin 101: 758-768. Ref ID: 199 Abstract: Culture of a non-native species, such as the Suminoe oyster (Crassostrea ariakensis), could offset the harvest of the declining native eastern oyster (Crassostrea virginica) fishery in Chesapeake Bay. Because of possible ecological impacts from introducing a fertile non-native species, introduction of sterile triploid oysters has been proposed. However, recent data show that a small percentage of triploid individuals progressively revert toward diploidy, introducing the possibility that Suminoe oysters might establish self-sustaining populations. To assess the risk of Suminoe oyster populations becoming established in Chesapeake Bay, a demographic population model was developed. Parameters modeled were salinity, stocking density, reversion rate, reproductive potential, natural and harvest-induced mortality, growth rates, and effects of various management strategies, including harvest strategies. The probability of a Suminoe oyster population becoming self-sustaining decreased in the model when oysters are grown at low salinity sites, certainty of harvest is high, minimum shell length-at-harvest is small, and stocking density is low. From the results of the model, we suggest adopting the proposed management strategies shown by the model to decrease the probability of a Suminoe oyster population becoming self-sustaining. Policy makers and fishery managers can use the model to predict potential outcomes of policy decisions, supporting the ability to make science-based policy decisions about the proposed introduction of triploid Suminoe oysters into the Chesapeake Bay. Dittman, D. E., Ford, S. E., and Haskins, H. H. 1998. Growth patterns in oysters, Crassostrea virginica, from different estuaries. Marine Biology 132: 461-469. Ref ID: 68 Abstract: We analyzed a data set collected over 15 yr, containing growth data from strains of eastern oysters, Crassostrea virginica (Gmelin, 1791), initiated from parent populations in Long Island Sound, Delaware Bay, and lower Chesapeake Bay. The long-term growth data proved to be a powerful tool for examining patterns of growth differentiation among separated populations of C. virginica. The oyster strains had been grown in a common environment in lower Delaware Bay for up to seven generations. We found that the oyster strains with origins in Long Island Sound were significantly larger over several generations than oyster strains from Delaware Bay and Chesapeake Bay. Chesapeake Bay oyster strains were larger than Delaware Bay oyster strains at 1.5 yr old, but Delaware Bay oysters were larger at 2.5 yr. Year-to-year variation in environmental conditions had a strong significant effect on absolute oyster size and the relative sizes of the oyster strains. Persistent differences between oyster strains from different origins over several generations support a hypothesis that these estuarine populations have experienced long-term genetically-based population differentiation. This result is consistent with hypotheses of population differentiation of oysters based on observations of local reproductive timing. Dittman, D. E., Ford, S. E., and Padilla, D. K. 2001. Effects of Perkinsus marinus on reproduction and condition of the eastern oyster, Crassostrea virginica, depend on timing. Journal of Shellfish Research 20: 1025-1034. Ref ID: 544 Abstract: The protistan parasite Perkinsus marinus has been responsible for high mortality of eastern oysters, Crassostrea virginica, along the Atlantic and Gulf Coast of the United States. It also causes sublethal effects, although an impact on reproduction has heretofore been difficult to demonstrate. We examined the effect of P. marinus infection on growth, reproduction (as measured by relative gonadal size, and the proportional representation of gametogenic tissue and gametes in the gonad), and condition index of eastern oysters. Oysters of known age and genetic history were exposed to P. marinus infection and sampled at 2-4 week intervals over an 11-month period during the 1990-1991 epizootic in Delaware Bay. During this time, 50 to 100% of the oysters had detectable infections and nearly 55% died. Shell growth rates were inhibited as infections intensified during initial exposure in autumn 1990, but resumed in the spring and remained high, even after infection became heavy. The effect on reproduction varied with the stage of the gametogenic cycle. The relative gonadal size and the proportion of gametogenic tissue in the gonad. as well as the condition index, were most strongly depressed during the spring gametogenic period; however. there was no significant effect of parasite burden when the oysters were reproductively mature and ready to spawn. Data suggested that infected oysters, recovered, produced gametes, and spawned in early summer. Other studies have found inconsistent evidence of sublethal deleterious effects of P. marinus on reproduction. By sampling throughout the year and employing oysters of known genetic background, of the same age, reared in a common environment. and for which the timing of initial infection was known, we were able to show that P. marinus does have significant negative effects on oyster reproduction, measurable primarily during gametogenesis. rather than at spawning Doering, P. H. and Oviatt, C. A. 1986. Application of filtration rate models to field populations of bivalves: an assessment using experimental mesocosms. Marine Ecology-Progress Series 31: 265-275. Ref ID: 602 Drake, J. M. 2004. Allee effects and the risk of biological invasion. Risk Analysis 24: 795-802. Ref ID: 639 Dumbauld, B. R., Armstrong, D. A., and Mcdonald, T. L. 1993. Use of oyster shell to enhance intertidal habitat and mitigate loss of dungeness crab (Cancer magister) caused by dredging. Canadian Journal of Fisheries and Aquatic Sciences 50: 381-390. Ref ID: 457 Abstract: Juvenile Dungeness crab (Cancer magister) recruit to intertidal areas in estuaries along the Pacific Northwest coast of the United States in May and June of each year and survive best through their first summer in shell or eelgrass habitat. Experiments were initiated in Grays Harbor, Washington, to investigate the potential of using shell to enhance intertidal crab habitat as a means to augment the crab resource and mitigate losses from the subtidal population that occur during dredging. Experimental plots (225 M2) were constructed prior to crab settlement at each of three intertidal locations using three configurations of oyster shell (heavy layer, light scattering, and small piles of shell). Resulting crab densities were comparable with those found in naturally occurring shell with high numbers (20-60 crab.m-2) observed during settlement that declined to a relatively stable density of 10 crab.m-2 in July and August. Crab survival was highest in both heavy and pile configurations, but the heavy shell configuration remained intact the longest. This enhancement experiment has become the impetus for a large-scale (8 ha) mitigation program in 1992 as part of a dredging project completed in 1990 in Grays Harbor Durbin, A. G. and Durbin, E. G. 1998. Effects of menhaden predation on plankton populations in Narragansett Bay, Rhode Island. Estuaries 21: 449-465. Ref ID: 608 Durve, V. S. 1986. On the ancestry and distribution pathways of three species of Indian oysters. Indian Journal of Marine Sciences 15: 56-58. Ref ID: 43 Eberhardt, L. L. 1998. Applying difference equations to wolf predation. Canadian Journal of Zoology 76: 380-386. Ref ID: 18 Abstract: Parameters for generalized Lotka-Volterra equations, expressed as difference equations, have been estimated from actual data on wolves and their prey. The functional response is represented by a single constant, while the numerical response is expressed as a ratio-dependent limitation on predator abundance. Parameters for the Lotka-Volterra equations were estimated by multiple-regression fits to data on moose (Alces alces) and wolves (Canis lupus) on Isle Royale, and from other sources. Observed prey-predator ratios are highly variable, but much of the variability may arise from nonequilibrium conditions. A. multiple-prey model has been developed by assuming that utilization rates vary in proportion to relative current biomass. If analyses are to be useful, the: dynamic, nonlinear nature of predator-prey systems requires that a system of equations be developed, along with extensive series of observations of actual abundances of predator and prey. Ebersole, E. L. and Kennedy, V. S. 1995. Prey preferences of blue crabs Callinectes sapidus feeding on three bivalve species. Marine Ecology-Progress Series 118: 167-177. Ref ID: 396 Abstract: Individual blue crabs Callinectes sapidus were allowed to forage on 3 bivalve species (soft clam Mya arenaria; Atlantic rangia clam Rangia cuneata; hooked mussel Ischadium recurvum), with 2 of the 3 species made available together at one time in 2201 aquaria. In 3 separate sets of experiments, we examined the blue crab's consumption and preferences between 2 bivalve species of different profitabilities [(net energy intake)/(handling time); J s(-1)]: M. arenaria and R, cuneata, M. arenaria and I. recurvum, and R, cuneata and I. recurvum. These experiments also examined the effects of 3 additional factors on prey consumption and prey preference: prey location (near to or distant from point of introduction of crab), prey refuge availability (shallow or deep sand for the clams; detached or clustered for the hooked mussel), and prey density (high or low numbers). Profitability curves correctly predicted that the blue crab preferred the highly profitable soft clam over the less energetically profitable Atlantic rangia clam. When the difference between prey profitabilities was not as great (i.e. between the soft clam and the hooked mussel, and between the Atlantic rangia clam and the hooked mussel) profitability alone was not a clear predictor of blue crab preference. Prey refuge availability significantly affected prey preference; deep sand provided (1) a greater refuge for the soft clam than for the Atlantic rangia clam and (2) a greater refuge for the soft clam than clustering provided for the hooked mussel. Prey location and refuge availability interacted to affect prey preference, in that prey location significantly affected prey consumption in shallow sand (more near prey than distant prey were eaten), but not in deep sand. Prey density generally affected total prey consumption, but not prey preference Eckman, J. E. 1996. Closing the larval loop: linking larval ecology to the population dynamics of marine benthic invertebrates. Journal of Experimental Marine Biology and Ecology 200: 207-237. Ref ID: 577 Eggleston, D. B., Elis, W. E., Etherington, L. L., Dahlgren, C. P., and Posey, M. H. 1999. Organism responses to habitat fragmentation and diversity: Habitat colonization by estuarine macrofauna. Journal of Experimental Marine Biology and Ecology 236: 107-132. Ref ID: 286 Abstract: Ecologists increasingly recognize that their choice of spatial scales may influence greatly their interpretation of ecological systems, and that small changes in the patchiness of habitat resources can produce abrupt, sometimes dramatic shifts in distribution and abundance patterns of a species. Moreover, identification of scale- and habitat-dependent ecological patterns are central to management efforts aimed at predicting the response of organisms to the increasing threat of habitat fragmentation. We used habitat plots containing artificial seagrass, oyster shell, and a mixture of seagrass and shell, placed on unstructured seafloor for 14 days in Back Sound, North Carolina, USA to examine the interactive effects of patch size, habitat diversity and experimental site on colonization by assemblages of estuarine macrofauna. We tested three a priori predictions of the general hypothesis that macrofaunal colonization is scale- and habitat-dependent: (1) colonization (per unit area) will be higher in small patches than in large ones; (2) small macrofauna will show a stronger response to habitat patchiness at a given scale than large macrofauna; and (3) colonization by estuarine macrofauna will be higher in habitat plots containing a mixture of seagrass and oyster shell compared to monotypic plots. Macrofauna responded to habitat patchiness in a complex manner that varied according to habitat type, experimental site, species, taxon, functional group, and animal body size (small: 500 mu m-2 mm; large: > 2 mm). Of the five out of seven response variables where we observed a significant patch size effect, grass shrimp (Palaemonidae sp.) and small, mobile crustaceans (i.e., amphipods and isopods) were the only taxonomic or functional groups whose densities were higher in small (0.25 m(2)) than large (1 m(2)) patches, as predicted. Moreover, there was a disproportionate reduction in macrofaunal abundance and diversity in small patches of oyster shell compared to seagrass and mixed habitat treatments; this pattern was significant for both the total density and numbers of small species but not for large macrofauna. The total density and number of macrofaunal species was not higher in the mixed habitat treatment compared to seagrass or oyster shell. Our study demonstrates that an organism's response to habitat patchiness is dependent upon species, tars, functional group, and animal body size, and that an organism's response is further modified by habitat type. The patterns observed in this study highlight the importance of scale- and habitat-dependent responses by mobile organisms to complex benthic habitats, and, because of the disproportionate reduction in faunal density and diversity in small versus large patches of oyster shell, heightens concern over the negative impacts to biodiversity through large-scale fragmentation of subtidal oyster reefs in certain regions. (C) 1999 Elsevier Science B.V. All rights reserved Engle, J. B. 1956. The years of study on oyster setting in a seed area in upper Chesapeake Bay. Proceedings of the National Shellfisheries Association 46: 88-99. Ref ID: 551 Everett, R. A., Ruiz, G. M., and Carlton, J. T. 1995. Effect of oyster mariculture on submerged aquatic vegetation: an experimental test in a Pacific Northwest estuary. Marine Ecology-Progress Series 125: 205-217. Ref ID: 451 Abstract: The effects of commercial culture of oysters, Crassostrea gigas, on submerged aquatic vegetation (SAV), Zostera marina, were examined with replicated field experiments in the South Slough estuary, Oregon, USA. Both stake and rack methods of oyster culture resulted in significant decreases in the abundance of SAV compared to undisturbed reference areas. SAV cover in both stake and rack treatments was less than 25 % of that in reference plots after 1 yr of culture, and was absent from rack treatments after 17 mo of culture. Field experiments using marked plants revealed no difference in growth between plants in stake and reference plots. Comparisons of sediment surface topography demonstrated that oyster culture resulted in significantly greater sediment deposition in stake plots and greater erosion in rack plots. Silt-clay fractions and carbon content of sediments tended to increase with stake culture and decrease with rack culture, but only for carbon content at racks were the differences significant between culture and reference plots. Stake culture likely affected SAV via increased sedimentation and direct physical disturbance during placement and harvest, while increased erosion and perhaps shading resulted in the marked decrease in SAV coincident with rack culture. These results indicate the potential for significant loss of SAV from estuarine ecosystems where these methods of oyster culture and SAV coincide Faisal, M., MacIntyre, E. A., Adham, K. G., Tall, B. D., Kithary, M. H., and La Peyre, J. F. 1998. Evidence for the presence of protease inhibitors in eastern (Crassostrea virginica) and Pacific (Crassostrea gigas) oysters. Comparative Biochemistry and Physiology Part B 121: 161-168. Ref ID: 186 Abstract: The plasma of eastern (Crassostrea virginica) and Pacific (Crassostrea gigas) oysters were compared for levels of inhibitory activities against a variety of proteases. Representatives of the serine, cysteine, metallo and aspartic protease mechanistic classes were analyzed, including extracellular proteases produced by two oyster-associated pathogens; Perkinsus marinus and Vibrio io vulnificus. In comparison to C. virginica, C. gigas plasma exhibited significantly higher specific inhibition levels (ng protease inhibited/mu g plasma protein) for papain (P < 0.001), pepsin (P < 0.001), P. marinus protease (P < 0.001), trypsin (P = 0.015), and V. vulnificus protease (P <0.001). Plasma of C. gigas did not inhibit the metalloprotease thermolysin. Instead, a significant increase in substrate hydrolysis was seen in wells containing plasma and thermolysin in comparison to wells containing thermolysin only. A similar trend was noted for thermolysin with the eastern oyster samples. These studies indicate the presence of protease inhibitors in the plasma of Crassostrea spp., which may have an impact upon host defense mechanisms, in addition to other physiological roles. Fayer, R., Farley, C. A., Lewis, E. J., Trout, J. M., and Graczyk, T. K. 1997. Potential role of the eastern oyster, Crassostrea virginica, in the epidemiology of Cryptosporidium parvum. Applied and Environmental Microbiology 63: 2086-2088. Ref ID: 547 Fayer, R., Graczyk, T. K., Lewis, E. J., Trout, J. M., and Farley, C. A. 1998. Survival of infectious Cryptosporidium parvum oocysts in seawater and Eastern oysters (Crassostrea virginica) in the Chesapeake Bay. Applied and Environmental Microbiology 64: 1070-1074. Ref ID: 375 Abstract: Oocysts of Cryptosporidium parvum placed in artificial seawater at salinities of 10, 20, and 30 ppt at 10 degrees C and at 10 ppt at 20 degrees C were infectious after 12 weeks, Those placed in seawater at 20 ppt and 30 ppt at 20 degrees C were infectious for 8 and 4 weeks, respectively, These findings suggested that oocysts could survive in estuarine waters long enough to be removed by filter feeders such as oysters, Thereafter, 30 Eastern oysters, Crassostrea virginica, were collected,vith a dredge or with hand tongs at each of six sites within Maryland tributaries of the Chesapeake Bay in May and June and in August and September of 1997, Hemocytes and gill washings from all oysters were examined for the presence of Cryptosporidium oocysts and Giardia cysts by immunofluorescence microscopy utilizing a commercially available kit containing fluorescein isothiocyanate-conjugated monoclonal antibodies, Giardia was not detected by this method from any of the 360 oysters examined, Presumptive identification of Cryptosporidium oocysts was made in either hemocytes or gill washings of oysters from all six sites both times that surveys were conducted, In addition, during August and September, for each of the six sites, hemocytes from the 30 oysters were pooled and gill washings from the oysters were pooled, Each pool was delivered by gastric intubation to a litter of neonatal mice to produce a bioassay for oocyst infectivity, Intestinal tissue from two of three mice that received gill washings from oysters collected at a site near a large cattle farm and shoreline homes with septic tanks was positive for developmental stages of C. parvum, These findings demonstrate for the first time that oysters in natural waters harbor infectious C. parvum oocysts and can serve as mechanical vectors of this pathogen Fayer, R., Lewis, E. J., Trout, J. M., Graczyk, T. K., Jenkins, M. C., Higgins, J., Xiao, L. H., and Lal, A. A. 1999. Cryptosporidium parvum in oysters from commercial harvesting sites in the Chesapeake Bay. Emerging Infectious Diseases 5: 706-710. Ref ID: 362 Abstract: Oocysts of Cryptosporidium parvum, a zoonotic waterborne pathogen, can be removed by bivalve molluscs from contaminated water and retained on gills and in hemolymph. We identified oocysts of C. parvum in oysters from seven sites in the Chesapeake Bay area. These findings document the presence of C. parvum infectious for humans in oysters intended for human consumption Fayer, R., Trout, J. M., Lewis, E. J., Xiao, L., Lal, A., Jenkins, M. C., and Graczyk, T. K. 2002. Temporal variability of Cryptosporidium in the Chesapeake Bay. Parasitology Research 88: 998-1003. Ref ID: 336 Abstract: Although Cryptosporidium has been found worldwide in molluscan shellfish from waters contaminated with human and animal feces, little or no relate environmental data have been obtained. In the present study, oysters (Crassostrea virginica) were collected eight times over 3 years from seven sites in the Chesapeake Bay or its tributaries, with accompanying data on water temperature, salinity, rainfall, and streamflow. Oyster gill washings were examined by immunofluorescence microscopy for Cryptosporidium oocysts. Of 1,590 oysters collected, 19.6% had detectable oocysts. Of 53 collections, oocysts were detected 81 % of the time. The time when the greatest percentage of oysters at most sites had detectable oocysts coincided with the time of greatest weekly and monthly rainfall, greatest streamflow into the Bay, and lowest water temperatures. In 28% of 53 collections, C. parvum genotypes I and 2 and C. baileyi were identified by PCR and gene sequencing. Oocyst infectivity was confirmed from 37.5% of 40 collections by initiating C. parvum genotype 2 infections in mice Fegley, S. R., Ford, S. E., Kraeuter, J. N., and Haskin, H. H. 2003. The persistence of New Jersey's oyster seedbeds in the presence of oyster disease and harvest: The role of management. Journal of Shellfish Research 22: 451-464. Ref ID: 484 Abstract: New Jersey's Delaware Bay oyster fishery developed along a pathway common to many fisheries. Perennially large harvests led to depletion of the oyster resource, which led to increasing, but ineffective, harvest restrictions and cumbersome management. In the 1950s, two events altered the management structure. In the beginning of the decade, a university researcher dedicated himself to having oystermen and the state regulatory agency use information from research and monitoring programs directly in their decision making. He achieved limited success until a previously unknown oyster disease, eventually called MSX, occurred that threatened to drive the oyster fishery to extinction. The presence of MSX led oyster harvesters to become dependent on the information provided by the university. In addition, the regulatory agency and its regulations had to be responsive to short-term changes in the intensity and prevalence of disease. A tripartite management structure developed in which: 1) the oystermen, researchers, and state regulatory agency acted cooperatively and 2) flexible guidelines were developed that could respond to annual variation in oyster abundance and disease. Several aspects of this management arrangement could prove useful in other fisheries Finelli, C. M. and Wethey, D. S. 2003. Behavior of oyster (Crassostrea virginica) larvae in flume boundary layer flows. Marine Biology 143: 703-711. Ref ID: 485 Abstract: Larval behaviors are increasingly recognized as determining factors in the water column distribution and subsequent settlement patterns of marine invertebrates. In particular, larvae within one or two body lengths of the seafloor (= interaction zone) may be better able to control their settlement location or respond to settlement cues. Here we examine temporal changes the behavior of larval oysters (Crassostrea virginica) swimming in the bottom 1 cm of a flume boundary layer. In addition, we present a novel behavior, called 'dive-bombing', that consists of an abrupt downward acceleration and subsequent contact with the bottom. Larvae were divided into two arbitrarily chosen size classes (those retained on a 153 mum screen and those retained on a 202 mum screen) to separate those that developed eyespots from those that did not develop eyespots. Behavior in a flume boundary layer was monitored from day 15 to day 21 post-fertilization. In the larger size class, the percentage of oyster larvae within close proximity (1 to 2 body lengths) of the flume bed steadily increased from 6% to 28% with larval age. In contrast, if larvae were restricted from reaching larger sizes through sieving this proportion remained constant at 12%. Dive-bombing was exhibited by a constant 4% of the larval population regardless of age or size. Kinematic analysis of swimming paths shows dive-bombing to be distinct from other swimming behaviors and from the passive sinking of dead larvae. For example, vertical acceleration at the initiation of dive-bombing is some 30-400 times that measured for other live or dead larvae. Our results indicate that larvae are capable of rapid acceleration and that they may be able to control their approach to the bottom under a much wider range of conditions than had previously been suspected Fitt, W. K. and Coon, S. L. 1992. Evidence for ammonia as a natural cue for recruitment of oyster larvae to oyster beds in a Georgia salt marsh. Biological Bulletin 182: 401-408. Ref ID: 314 Abstract: Competent veliger larvae of the oysters Crassostrea virginica and C. gigas exhibited settlement behavior when exposed to ammonia (NH3). The threshold for this response decreased with increasing larval age. The response of veligers to adult-conditioned seawater was correlated with the concentration of NH3 in the seawater. Although the concentrations of NH3 found in marsh water flowing over oyster beds on Sapelo Island, Georgia, were never high enough to elicit settlement behavior from oyster larvae, the concentrations found near the substrate were sufficient to induce settlement behavior in older larvae of C virginica. In addition, dilution occurs during sampling in the field and may lead one to underestimate, by a factor of 1.7 to 3.5, the actual concentration of NH3 associated with surfaces. In conclusion, NH3 may be an important environmental cue triggering settlement behavior of larval oysters, which, along with other substrate cues, leads to cementation and metamorphosis Foltz, D. W., Newkirk, G. F., and Zouros, E. 1983. Genetics of growth rate in the American oyster: absence of interactions among enzyme loci. Aquaculture 33: 157-165. Ref ID: 143 Foltz, D. W. and Chatry, M. 1986. Genetic heterozygosity and growth rate in Louisiana oysters (Crassostrea virginica). Aquaculture 57: 261-269. Ref ID: 135 Ford, S., Powell, E. N., Klinck, J. M., and Hofmann, E. E. 1999. Modeling the MSX parasite in eastern oysters (Crassostrea virginica) populations. I. Model development, implementation, and vertification. Journal of Shellfish Research 18: 475-500. Ref ID: 3 Abstract: A mathematical model simulating the host-parasite-environmental interactions of eastern oysters (Crassostrea virginica) and the pathogen, Haplosporidium nelsoni, which causes MSX disease, has been developed. The model has 2 components. One replicates the infection process within the oyster and the other simulates transmission. The infection-development component relies on basic physiological processes of both host and parasite, modified by the environment, to reproduce the observed annual prevalence cycle of H. nelsoni. Equations describing these rates were constructed using data from long-term field observations, and field and laboratory experiments. In the model, salinity and temperature have direct effects upon in vivo parasite survival and proliferation as well as on transmission rates. Cold winters depress transmission rates for 1 or 2 years after the event, even if temperatures return to normal. Warm winters have no effect on transmission in subsequent years. Hemocyte activity, parasite density, and the overall environmental quality provided to the parasite by the host also influence the modeled infection process. Hemocytes scavenge and eliminate parasites that die over the winter or that degenerate as a result of failed sporulation. Replication rates of H. nelsoni are slowed at high parasite densities. The environmental quality provided by the host, which is a function of oyster food availability and the oyster's potential growth efficiency, affects doubling times and also determines whether the parasite completes its life cycle by forming spores. Sport production is related to a threshold environmental quality, which occurs only in small oysters because of their high growth efficiency. Simulations that use environmental conditions characteristic of Delaware Bay reproduce the observed seasonal H. nelsoni cycle, consequent oyster mortality, and spore production in juvenile oysters. The oyster-H. nelsoni model provides a quantitative framework for guiding future laboratory and field studies as well as management efforts. Ford, S. E. and Haskin, H. H. 1987. Infection and mortality patterns in strains of oysters Crassostrea virginica selected for resistance to the parasite Haplosporidium nelsoni (MSX). Journal of Parasitology 73: 368-376. Ref ID: 589 Ford, S. E., Figueras, A. J., and Haskin, H. H. 1990. Influence of selective breeding, geographic origin, and disease on gametogenesis and sex ratios of oysters, Crassostrea virginica, exposed to the parasite Haplosporidium nelsoni (Msx). Aquaculture 88: 285-301. Ref ID: 248 Ford, S. E. 1996. Range extension by the oyster parasite Perkinsus marinus into the northeastern United States: Response to climate change? Journal of Shellfish Research 15: 45-56. Ref ID: 222 Abstract: From its discovery in 1949 until 1990, the oyster parasite Perkinsus marinus, cause of Dermo disease in the eastern oyster Crassostrea virginica, was found primarily from Chesapeake Bay south along the Atlantic Coast of the United States and into the Gulf of Mexico. In 1990 and 1991, the parasite suddenly appeared in locations from Delaware Bay, NJ, to Cape God, MA, a range extending more than 500 km north of Chesapeake Bay. An earlier incursion of the parasite into Delaware Bay in the 1950s, associated with importation of large numbers of infected oysters from Chesapeake Bay, did not cause detectable mortalities or result in the establishment of a significant parasite population. The parasite was no longer detected after imports of infected oysters ceased. In contrast, the epizootic that began in Delaware Bay in 1990 resulted in high disease prevalence and intensity, and caused heavy mortalities, but was not linked to similar imports. Several hypotheses for the sudden appearance of the parasite in the northeastern United States are considered: 1) the parasite was transmitted via infected oysters introduced from enzootic southern areas into northern waters; 2) a change in the genetic structure of either host or parasite increased the parasite's ability to invade and proliferate in the northeast; 3) the environment in the northeastern United States became more favorable for parasite activity; or 4) some combination of these three. The simplest explanation consistent with available data is that the pathogen was repeatedly introduced, by many means over many years, into various northeast locations where it remained undetected and was stimulated to proliferate into an epizootic by a recent extreme warming trend. Above average winter, rather than summer, temperatures were associated with the 1990s epizootic. Also, cold winters, not cool summers, were correlated with the disappearance of P. marinus from Delaware Bay in the 1950s. Stopping or materially slowing the epizootic will probably require a series of consecutive cold (i.e., average or below average temperatures) winters and cool springs that will delay and restrict the proliferation of parasites during the following summer. Eliminating the parasite from its new range may be difficult even with cooler temperatures, however, as the development of low temperature-adapted parasites could occur now that large populations are established in a region where selection pressure exists for this trait Ford, S. E. and Borrero, F. J. 2001. Epizootiology and pathology of juvenile oyster disease in the eastern oyster, Crassostrea virginica. Journal of Invertebrate Pathology 78: 141-154. Ref ID: 569 Abstract: Juvenile Oyster Disease (JOD) causes mortalities of small cultured oysters, Crassostrea virginica. The present study was an intensive epizootiological and pathological investigation of JOD in eight sequentially deployed cohorts at sites on Long Island, New York. JOD symptoms and mortalities began in all groups at about the same time. Lesions on the mantle were detected histologically about 1 week before the principal symptom, a conchiolin deposit on the inner shell, appeared. Mortality began about 1 week later and reached 60-90% in oysters <25 mm. Mantle lesions were highly correlated with subsequent conchiolin-deposit prevalence and with total mortality. Larger juveniles (25-40 mm) were affected by the disease and produced conchiolin deposits, but mortalities did not exceed 30%. Mortalities were consistently related to size, but not necessarily to age or length of "exposure" in the field. There was no indication that JOD was linked to a particular broodstock or hatchery. Wild spat deployed at experimental sites showed JOD symptoms before the hatchery-produced groups did and cohorts maintained inside a hatchery experienced essentially no JOD. Histological examination of cohorts experiencing high mortalities failed to reveal an obvious etiological agent, but showed a disease pattern similar to that described for other bivalve diseases with a bacterial etiology. Similarities and differences between this and other studies of JOD suggest that one or more bacterial species is responsible for JOD, but that a trigger, probably temperature, is also involved and may vary from site to site. (C) 2001 Elsevier Science (USA) Francis, R. I. C. C. and Shotton, R. 1997. "Risk" in fisheries management: a review. Canadian Journal of Fisheries and Aquatic Science 54: 1699-1715. Ref ID: 113 Abstract: ''Risk'' has appeared more frequently in the fisheries management literature in recent years. The reasons for this are partly internal (scientists seeking better ways to advise fishery managers) and partly external (e.g., adoption of the precautionary approach). Though terminology varies, there is consensus that there are two stages in dealing with risk. The first (here called risk assessment) is the formulation of advice for fisheries managers in a way that conveys the possible consequences of uncertainty. This advice is in the form of an evaluation of the expected effects of alternative management options, rather than recommendations. Risk assessment has been undertaken in many fisheries, and there is general agreement as to how it should be done (although technical details differ). The second stage (risk management) is the way fishery managers take uncertainty into account in making decisions. Much fisheries risk management is informal, i.e., nonquantitative, undocumented, and loosely linked (if at all) with a risk assessment. The major reason for this is that the objectives of fisheries management are often conflicting and are rarely stated in a way that provides explicit direction to managers or scientists. Frechette, M., Aitken, A. E., and Page, L. 1992. Interdependence of food and space limitations of a benthic suspension feeder: consequences for self-thinning relationships. Marine Ecology Progress Series 83: 55-62. Ref ID: 20 Frechette, M. and Despland, E. 1999. Impaired shell gaping and food depletion as mechanisms of asymmetric competition in mussels. EcoScience 6: 1-11. Ref ID: 24 Abstract: We studied the effect of two different mechanisms in generating asymmetric competition in mussels. In the control group, unrestricted growth was assessed from mussels growing individually. In the second and third groups, the setup was adjusted such that mussels were grouped in pairs, but with shells either not touching (testing for a closeness effect: exploitation competition), or touching so that total space for gaping tvas reduced by 50% (testing for constraint effect: interference competition). Taken together, shell constraint and closeness resulted in growth reduction only in the two smallest size classes tested. Therefore competition was asymmetric. Closeness was the only significant factor. The asymmetric nature of exploitation competition was probably due to more severe small-scale depletion in seston around small mussels, since numerical simulations suggested that without small-scale patterns in seston depletion, exploitation competition is symmetric. Our simulations also suggest i) that had it been significant, interference would have resulted in asymmetric competition, and ii) behavioral periodic shell closure of large mussels may have provided a mechanism for alleviating the effect of shell constraint on small mussels, but that the required amplitude of behavioral gap reduction is about 50%. Asymmetric competition in mussel populations appears to be attributable to small-scale spatial structure in seston depletion, unless crowding is so severe that other mechanisms come into play. Freire-Santos, F., Gomez-Couso, H., Ortega-Inarrea, M. R., Castro-Hermida, J. A., Oteiza-Lopez, A. M., Garcia-Martin, O., and Ares-Mazas, M. E. 2002. Survival of Cryptosporidium parvum oocysts recovered from experimentally contaminated oysters (Ostrea edulis ) and clams (Tapes decussatus). Parasitology Research 88: 130-133. Ref ID: 342 Abstract: Samples of two species of shellfish that form part of the human food chain (the oyster Ostrea edulis and the marine clam Tapes decussatus) were experimentally contaminated with Cryptosporidium parvum oocysts. Changes in the viability of oocysts subsequently recovered from the shellfish were evaluated by means of an immunofluorescent antibody technique (IFAT) and inclusion/exclusion of the fluorogenic vital dye propidium iodide. There was a sharp decrease in oocyst viability during the first 4 days, with 15-25% viable oocysts remaining thereafter. In addition the infectivity of these oocysts at 10 and 31 days post-contamination was demonstrated using a suckling murine model French McCay, D. P., Peterson, C. H., DeAlteris, J. T., and Catena, J. 2003. Restoration that targets function as opposed to structure: replacing lost bivalve production and filtration. Marine Ecology Progress Series 264: 197-212. Ref ID: 161 Friedland, K. D., Ahrenholz, D. W., and Guthrie, J. F. 1989. Influence of plankton on distribution patterns of the filter-feeder Brevoortia tyrannus (Pisces: Clupeidae). Marine Ecology-Progress Series 54: 1-11. Ref ID: 606 Gaffney, P. M. and Allen, S. K. Jr. 1992. Genetic aspects of introductions and transfers of molluscs. Journal of Shellfish Research 11: 535-538. Ref ID: 101 Gaffney, P. M. and Allen, S. K. Jr. 1993. Hybridization among Crassostrea species: a review. Aquaculture 116: 1-13. Ref ID: 134 Abstract: Numerous attempts at hybridization in the genus Crassostrea have been reported. Most suffer from one or more of the following: (1) ambiguities in the classification of oysters; (2) contamination of experimental cultures by extraneous gametes or larvae; (3) the absence of control experiments for assessing the quality of gametes as well as larval viabilities; (4) the absence of genetic confirmation of hybrid status. We conclude that to date there is no unequivocal evidence for the existence of viable interspecific hybrids among Crassostrea species. Examples of taxonomic ambiguities that cloud interpretation of hybridization experiments include the frequent misclassification of the Kumamoto oyster (C. sikamea) as the Pacific oyster (C. gigas), the probably unjustified distinction between C. gigas and the Portuguese oyster C. angulata, and the lumping of C. iredalei with C. rivularis. Low-level contamination of cultures is a common occurrence that may account for many reports of successful hybridization. Experimental controls are essential to properly assess gamete quality and zygote growth and survival, yet are often not included. Finally, few reports provide genetic confirmation that the zygotes produced are actually hybrids. To date, most genetic analyses have demonstrated that putative interspecific hybrid oysters were not hybrids. Use of adequate controls and genetic analysis of parents and offspring are essential to hybridization experiments, and are demonstrated elsewhere. Gaffney, P. M. and Bushek, D. 1996. Genetic aspect of disease resistance in oysters. Journal of Shellfish Research 15: 135-140. Ref ID: 129 Abstract: Like other phenotypic traits, resistance to disease is generally subject to underlying genotypic variability. This may come about indirectly, as a result of variation in overall physiology or in life history characteristics, or may be more directly attributable to variation in cellular or biochemical mechanisms. We summarize here our current understanding of genetic influences on physiological and life history variation in Crassostrea and review the evidence available to date on intra- and interspecific generic variation in disease resistance, with emphasis on Perkinsus marinus and MSX. We also describe our current view of population structure in Crassostrea virginica, and how it may affect the evolution of disease resistance. Finally, we explore approaches to the development of disease-resistant oysters that capitalize on the generic variability inherent in C. virginica and within the genus Crassostrea. Gallager, S. M., Mann, R., and Sasaki, G. C. 1986. Lipid as an index of growth and viability in three species of bivalve larvae. Aquaculture 56: 81-103. Ref ID: 189 Gallagher, E. D., Gardner, G. B., and Jumars, P. A. 1990. Competition amoung the pioneers on a seasonal soft-bottom benthic succession: field experiments and analysis of the Gilpin-Ayala competition model. Oecologia 83: 427-442. Ref ID: 26 Gang, L., Yaping, H., and Ning, Q. 1988. Population gene pools of big-size cultivated oysters (Crassostrea) along the Guangdong and Fujian Coast of China. Proceedings on Marine Biology of the South China Sea 51-69. Ref ID: 192 Gangnery, A., Chabirand, J. M., Lagarde, F., Gall, P. L., Oheix.J., Bacher, C., and Buestel, D. 2003. Growth model of tje Pacific oyster, Crassostrea gigas, cultured in Thau Lagoon (Mediterranee, France). Aquaculture 215: 267-290. Ref ID: 585 Gangnery, A., Bacher, C., and Buestel, D. 2004. Modelling oyster population dynamics in a Mediterranean coastal lagoon (Thau, France): sensitivity of marketable production to environmental conditions. Aquaculture 230: 323-347. Ref ID: 586 Garnier-Gere, P. H., Naciri-Graven, Y., Bougrier, S., Magoulas, A., Heral, M., Kotoulas, G., Hawkins, A. J. S., and Gerard, A. 2002. Influences of triploidy, parentage, and genetic diversity on growth of the Pacific oyster Crassostrea gigas reared in contrasting natural environments. Molecular Ecology 11: 1499-1514. Ref ID: 576 Glancy, T. P., Frazer, T. K., Cichra, C. E., and Lindberg, W. J. 2003. Comparative patterns of occupancy by decapod crustaceans in seagrass, oyster, and marsh-edge habitats in a Northeast Gulf of Mexico estuary. Estuaries 26: 1291-1301. Ref ID: 667 Abstract: Decapod crustaceans occupying seagrass, salt marsh edge, and oyster habitats within the St. Martins Aquatic Preserve along the central Gulf coast of Florida were quantitatively sampled using a 1-m(2) throw trap during July-August 1999 and March-April 2000. Relative abundance and biomass were used as the primary measures to compare patterns of occupancy among the three habitat types. Representative assemblages of abundant and common species from each habitat were compared using Schoener's Percent Similarity Index (PSI). In all, 17,985 decapods were sampled, representing 14 families and 28 species. In the summer sampling period, mean decapod density did not differ between oyster and seagrass habitats, which both held greater densities of decapods than marsh-edge. In the spring sampling period oyster reef habitat supported greater mean decapod density than both seagrass and marsh-edge, which had similar densities of decapods. Habitat-specific comparisons of decapod density between the two sampling periods indicated no clear seasonal effect. In summer 1999, when seagrasses were well established, decapod biomass among the three habitats was not significantly different. During spring 2000, decapod biomass in oyster (41.40 g m(-2)) was greater than in marsh-edge (4.20 g m(-2)), but did not differ from that of seagrass (9.73 g m(-2)). There was no significant difference in decapod biomass between seagrass and marsh-edge habitats during the spring 2000 sampling period. The assemblage analysis using Schoener's PSI indicated that decapod assemblages associated with oyster were distinct from seagrass and marshedge habitats (which were similar). The results of this study suggest that in comparison to seagrass and marsh-edge habitats, oyster reef habitats and the distinct assemblage of decapod crustaceans that they support represent an ecologically important component of this estuarine system. Godley, B. J., Smith, S. M., Clark, P. F., and Taylor, J. D. 1997. Molluscan and crustacean items in the diet of the loggerhead turtle, Caretta caretta (Linnaeus, 1758) [Testudines: Chelonidae] in the eastern Mediterranean. Journal of Molluscan Studies 63: 474-476. Ref ID: 626 Goss-Custard, J. D., Stillman, R. A., West, A. D., Caldow, R. W. G., Triplet, P., Durell, S. E. A. L., and McGrorty, S. 2003. When enough is not enough: shorebirds and shellfishing. Proceedings of the Royal Society of London Series B-Biological Sciences 271: 233-237. Ref ID: 611 Abstract: In a number of extensive coastal areas in northwest Europe, large numbers of long-lived migrant birds eat shellfish that are also commercially harvested. Competition between birds and people for this resource often leads to conflicts between commercial and conservation interests. One policy to prevent shellfishing from harming birds is to ensure that enough food remains after harvesting to meet most or all of their energy demands. Using simulations with behaviour-based models of five areas, we show here that even leaving enough shellfish to meet 100% of the birds' demands may fail to ensure that birds survive in good condition. Up to almost eight times this amount is needed to protect them from being harmed by the shellfishery, even when the birds can consume other kinds of non-harvested prey Gosselin, L. A. and Qian, P.-Y. 1997. Juvenile mortality in bethic marine inverebrates. Marine Ecology Progress Series 146: 265-282. Ref ID: 89 Abstract: Thirty years ago, Thorson (1966; Neth J Sea Res 3;267-293) calculated that juvenile mortality in marine bivalves could exceed 98.6%. Subsequently, juvenile mortality rates have been assumed to be high and to influence the evolution of life history traits. However, there have been no attempts to establish whether high juvenile mortality is common or to determine if interspecific trends in juvenile mortality exist. To address this issue, we reviewed 30 studies of age-specific mortality among bivalves, gastropods, barnacles, ascidians, bryozoans and echinoderms. High juvenile mortality is widespread among benthic marine invertebrates, with 20 of the 30 studies reporting levels of juvenile mortality >90%. Mortality is particularly high during the first moments of juvenile life, and can exceed 30% during the first day. Pooling survivorship data from all species revealed a general trend, with survivorship decreasing exponentially during the first days or weeks of juvenile life until, by the age of 4 mo, virtually all cohorts were reduced to <20% of their initial numbers; mortality remained low thereafter. We suggest that extreme vulnerability at the onset of juvenile life is a shared trait that is largely responsible for the survivorship trend. Natural variation within this trend would be largely due to variation in intensity of mortality factors. Predation and desiccation are well-documented causes of juvenile mortality, but the current lack of data on factors such as ultraviolet radiation, diseases, and 'internal' causes (energy depletion, developmental and physiological defects) precludes a ranking of factors as selective pressures. Methods used to quantify juvenile mortality vary considerably in the level of resolution they can achieve within the early juvenile period. Studies of early juvenile mortality should ideally monitor the fate of individuals from the onset of juvenile life, using sampling intervals less than or equal to 1 d. Mapping and imaging techniques can provide accurate results for sessile organisms, whereas mark and recapture can be effective for motile animals with limited dispersal. Early juvenile mortality has been shown to influence population abundance and distribution as well as community structure. Juvenile mortality is also expected to be an important determinant of age at maturity, but only among species maturing within 4 mo of postlarval life since mortality remains low after the age of 4 mo. A compilation of data on age at first reproduction in 92 species revealed a bimodal grouping of species: 22% of species maturing within 45 d after beginning juvenile life, and 60% maturing after at least 1 yr. The influence of juvenile mortality on age at maturity will differ substantially among these 2 groups and will therefore not be equal or directly comparable among all species, Given the magnitude of early juvenile mortality and the similarities in mortality patterns across diverse taxa and habitats, a better understanding of early juvenile mortality should help researchers to understand how population parameters are regulated and help elucidate the significance of traits that characterize populations and species. Gottlieb, S. J. and Schweighofer, M. E. 1996. Oysters and the Chesapeake Bay ecosystem: a case for exotic species introduction to improve environmental quality. Estuaries 19: 639-650. Ref ID: 194 Abstract: Restoration of the Chesapeake Bay ecosystem has been a priority for residents and governments of the bay watershed for the past decade. One obstacle in the efforts to ''save the bay'' has been continuing nutrient enrichment from agricultural and sewer runoff. The attainability of a mandated 40% nutrient reduction goal has yet to be seen. Furthermore, disappearance of certain organisms may have had an adverse effect on the resilience of the ecosystem. The Eastern oyster (Crassostrea virginica), once abundant in Chesapeake Bay, was a vital part of the food web, processing excess phytoplankton and depositing materials on the bottom. Over harvesting and disease have decimated the native oyster population. The introduction of an exotic species, the Japanese oyster (Crassostrea gigas), may be a way to reestablish a robust oyster community in the bay. The literature on the role of bivalve molluscs in estuarine ecosystems shows: that they are an essential part of healthy estuaries around the world. A comparison of C. virginica and C. gigas in terms of temperature and salinity tolerance and resistance to disease shows that C. virginica is ideally adapted to conditions in Chesapeake Bay, but it is unable to stave off the endemic diseases, whereas C. gigas is adapted to conditions in the lower bay only but is much less susceptible to the same diseases. We conclude that the potential introduction of C. gigas to Chesapeake Bay would be limited by the Japanese species' physiological requirements but that the revitalization of a bivalve population is imperative to the restoration of ecosystem function. Goulletquer, P., Heral, M., and Prou, J. 1994. Combined effects of temperature and salinity on larval survival of the eastern oyster in the Maryland portion of the Chesapeake Bay. Haliotis 23: 71-86. Ref ID: 500 Grabowski, J. H., Powers, S. P., Peterson, C. H., Powers, M. J., and Green, D. P. 2003. Consumer ratings of non-native (Crassostrea gigas and Crassostrea ariakensis) vs. native (Crassostrea virginica) oysters. Journal of Shellfish Research 22: 21-30. Ref ID: 57 Abstract: Given suggestions that a non-native oyster be used to replace the depleted native oyster, consumer preference evaluations were conducted to determine how two non-native oysters, Crassostrea gigas and C. ariakensis, when grown in North Carolina estuaries, were rated by consumers. Tests compared the taste, appearance, and/or aroma of both raw and cooked non-native oysters to similarly prepared native oysters, C. virginica. In the first series of tests, consumers exhibited a slight preference for raw C. virginica over raw C. gigas. When cooked, both species were rated equal. In the second series of tests, a larger group of participants ranked the taste, appearance, and aroma of C. virginica, C. gigas, and C. ariakensis. Participants that tasted raw oysters collectively preferred C. virginica over both non-native species. This preference remained strong regardless of the frequency with which participants consumed oysters. Preferences for appearance and aroma varied; however, ratings never indicated a preference for either non-native species over C. virginica. Participants as a whole preferred the taste of cooked C. virginica better than C. gigas, whereas a taste preference did not exist between cooked C. virginica and C. ariakensisis. Given that participants collectively preferred the taste of both raw and cooked C. virginica to C. gigas, the suitability of C gigas for substitution in either the raw or steamed oyster market is questionable. For oysters of similar length (80 to 110 mm), dry tissue weight of C. ariakensis was twice that of C. virginica. This higher per-oyster yield suggests that C. ariakensis might be more suitable for a steamed or packaged oyster market where oysters are sold by meat weight rather than by number. However, these markets often command much lower prices, perhaps rendering unfeasible the aquaculture of this introduced oyster. Before large-scale introduction of non-native oyster species occurs, consumer preferences should be incorporated into economic evaluations that include additional economic (oyster prices, market demand and supply functions) and biological information (growth and survivorship). Profitability expectations generated by the model then need to be weighed against the potential ecological risks and ecosystem benefits of aquaculture or introduction to the wild for each non-native oyster species. Grabowski, J. H. 2004. Habitat complexity disrupts predator-prey interactions but not the trophic cascade on oyster reefs. Ecology 85: 995-1004. Ref ID: 160 Grabowski, J. H. and Powers, S. P. 2004. Habitat complexity mitigates trophic transfer on oyster reefs. Marine Ecology-Progress Series 277: 291-295. Ref ID: 655 Abstract: Structured habitats within several aquatic systems have been characterized as having higher abundances of both predators and their prey. Understanding this somewhat paradoxical phenomenon requires teasing apart how habitat complexity influences predator-prey dynamics. To determine whether habitat complexity influences predator foraging efficiency, we measured predator foraging rates within structurally simple and complex habitats. We selected as our test system mud crabs feeding on juvenile hard clams within biogenic reefs formed by the eastern oyster. At low and intermediate crab densities, foraging rates of mud crabs were similar between simple and complex habitats. However, at high crab densities foraging rates were higher for crabs in the complex reefs than in the simple reefs. In addition to providing refuge to both intermediate predators and their prey, habitat complexity appears to enhance predator foraging efficiency by reducing interference competition among predators. In systems where interference competition among densely populated predators may be intense, complex habitats may not provide survival benefits to all trophic levels. Grabowski, J. H., Peterson, C. H., Powers, S. P., Gaskill, D., and Summerson, H. C. 2004. Growth and survivorship of non-native (Crassostrea gigas and Crassostrea ariakensis) versus native eastern oysters (Crassostrea virginica). Journal of Shellfish Research 23: 781-793. Ref ID: 676 Abstract: The decline of wild populations of the eastern oyster Crassostrea virginica from fishing impacts and disease combined with limited success in its culture has stimulated discussion among coastal managers about the risks and benefits of introducing non-native oysters in Maryland, Virginia, and North Carolina. Field experiments in 1999 to 2000 and 2001 to 2002 comparing growth, survivorship, and prevalence of disease in 2 non-native oysters, C. gigas and C. ariakensis, versus C. virginica in North Carolina estuaries demonstrated that in high-salinity (>25parts per thousand) waters, performance of C. gigas in culture greatly surpassed that of both of the other oysters (with growth 162.4% higher than C. virginica and 54.1% higher than C. ariakensis and survivorship 33.1% higher than C. virginica and 22.3% higher than C. ariakensis). C. ariakensis survivorship at these high salinity sites was highly variable and unpredictable even when using environmental covariates, and at salinities below similar to10parts per thousand this species did not grow, rendering its culture nonviable at low salinity. However, in waters of intermediate salinity (15% to 25%), C. ariakensis outgrew both of the other 2 oysters (35.9% higher than C. gigas and 24.5% higher than C. virginica) and exhibited 42.1% higher survivorship than C. gigas. Although survivorship of C. virginica and C. ariakensis did not differ significantly at intermediate salinities, only C. virginica failed to achieve legally harvestable sizes and, based on its increasingly high susceptibility to death from disease with age, is likely to have experienced much greater mortality by the time of complete grow-out. Experimental elevation above the bottom augmented growth and survivorship of C. ariakensis most strongly, whereas C. gigas was not influenced by rack height. Before large-scale introduction of any non-native oyster occurs, the quantitative biologic results should first be incorporated into economic evaluations that weigh expected profitability and ecosystem benefits against the potential ecologic risks of introduction (both for wild release and for aquaculture of triploids). Grant, J. 1996. The relationship of bioenergetics and the environment to the field growth of cultured bivalves. Journal of Experimental Marine Biology and Ecology 200: 239-256. Ref ID: 69 Greer, J. and Terlizzi, D. 1999. Exotics in the Chesapeake Bay. UM-SGEP-99-01, Maryland Sea Grant College Program, College Park, MD Ref ID: 106 Griffiths, C. L. and Hockey, P. A. R. 1987. A model describing the interactive roles of predation, competition, and tidal elevation in structuring mussel populations. South African Journal of Marine Science 5: 547-556. Ref ID: 23 Guinez, R. and Castilla, J. C. 1999. A tridimensional self-thinning model for multilayered intertidal mussels. The American Naturalist 154: 341-357. Ref ID: 19 Abstract: Intertidal mussels usually form complex multilayered matrices with density-dependent effects on survival and growth, and self-thinning scaling between biomass (B) and density (N) is expected. This article develops a tridimensional model of space-driven self-thinning that in addition to B-N explicitly includes the degree of packing of the mussels, measured as the number of layers (L). The structure of our model (B-N-L) encompasses previous bidimensional models (B-N) of self-thinning as special cases and enables comparisons between mono- and multilayered populations. We contrast the predictions of the bi- and tridimensional models using data obtained from Perumytilus purpuratus mussel beds on the rocky shores of central Chile monitored during a 28-mo period. The tridimensional model suggests that density dependence is much more frequent than hitherto indicated by bidimensional models. We propose that our space-driven tridimensional model may be applied nor only to mussels but also to other species where spatial overlapping configurations occur. Guo, X., DeBrosse, G. A., and Allen, S. K. Jr. 1996. All-triploid Pacific oysters (Crassostrea gigas Thunberg) produced by mating tetraploids and diploids. Aquaculture 142: 149-161. Ref ID: 125 Abstract: To document the reproductive characteristics of tetraploids and determine whether they can be used for triploid production, factorial crosses were made between diploids (D) and tetraploids (T), producing DD, DT, TD and ?T groups (female listed first). A normal triploid group was also produced by blocking polar body II with cytochalasin B (3nCB). Survival to spat in TD and DT groups was about the same as in normal diploids, and significantly higher than in the 3nCB and TT groups, As determined by flow cytometry, all surviving oysters from DT and TD crosses were triploids, and only 46% of oysters from the 3nCB group were triploids. ?T crosses produced primarily tetraploids despite low survival. At 8 and 10 months of age, triploid oysters from DT and TD groups were 13-51% larger than normal diploids, possibly due to polyploid gigantism. These results suggest that mating tetraploids and diploids is the best method for triploid production, and triploids produced in this way are better suited for aquaculture than those produced by altering meiosis and are ideal for population control. Guo, X. and Allen, S. K. Jr. 1997. Sex and meiosis in autotetraploid Pacific oyster, Crassostrea gigas (Thunberg). Genome 40: 397-405. Ref ID: 133 Abstract: Sex and meiosis were studied in induced autotetraploids of the Pacific oyster (Crassostrea gigas Thunberg) and were compared with sex and meiosis in autotriploids and normal diploids. Tetraploid oysters reached sexual maturity at 1 year of age in an approximately 1:1 sex ratio. In contrast with the abnormally high frequency of hermaphrodites among triploids, tetraploids had about the same level of hermaphrodites as normal diploids. Fecundity of tetraploids was comparable to that of normal diploids, differing from the greatly reduced fecundity of triploids. Homologous chromosomes synapsed predominantly as trivalents in eggs from triploids and as quadrivalents in eggs from tetraploids. After fertilization, eggs from tetraploids and triploids went through two meiotic divisions, as normal eggs did. The average gamete chromosome number was 10.0 for diploids and 19.9 for tetraploids. The distribution of gamete chromosome numbers from triploids suggested that the extra chromosome in the trivalent segregated randomly during anaphase I. In tetraploids, however, the two extra chromosomes in the quadrivalents did not segregate independently and, instead, they preferentially cosegregated to opposite poles producing balanced gametes. These results suggest that mechanisms may exist to weigh, balance, and equally distribute quadrivalents, possibly through mitotic force and tension. Errors in chromosome balancing in normal meiosis may result in nondisjunction, which is the primary cause of human aneuploidy. Guo, X., Ford, S. E., and Zhang, F. 1999. Molluscan aquaculture in China. Journal of Shellfish Research 18: 19-31. Ref ID: 179 Abstract: Molluscan aquaculture in China has been growing rapidly in the past decade. China produced 6.4 million metric tons (MMT) of mollusks from aquaculture in 1996, an eightfold increase over that of 1986, At least 32 species of marine mollusks are cultured commercially in China. The 1996 production included 2.3 MMT of oysters, 1.6 MMT of clams (mostly Ruditapes, Meretrix, razor clams, and blood cockles), 1 MMT of scallops, 0.4 MMT of mussels, 700 tons of abalone, and 20 tons of marine pearls. Shandong province is the largest producer of cultured mollusks, followed by Guangdong, Fujian, Liaoning, Guangxi, and Zhejiang provinces (ranked 2-6, respectively). As a generalized pattern, molluscan aquaculture in China is characterized by scallops, abalone, and Manila clams in the northern provinces (Shandong and Liaoning), oysters and pearl oysters in the south (Fujian, Guangdong, and Guangxi), and various clam species in the middle (Zhejiang and Jiangsu). The production technology ranges from simple gathering and stocking of wild seeds for several clam species to sophisticated hatchery and growout operations for abalone and pearl oysters. The rapid development of intensive mariculture during the past decade may have exceeded the carrying capacity of some areas and contributed to deterioration of the culture environment. Abalone and scallop cultures in the north have been seriously affected by diseases and mortalities in recent years. Hallerman, E. M. and Kapuscinski, A. R. 1995. Incorporating risk assessment and risk management into public policies on genetically modified finfish and shellfish. Aquaculture 137: 9-17. Ref ID: 112 Abstract: Genetically modified finfish and shellfish pose economic benefits to aquaculture, but also pose ecological and genetic risks to ecosystems receiving such organisms. Realization of benefits with minimization of risks posed by a new technology can be addressed through the processes of risk assessment and risk management. Public policies adopted by individual countries will reflect differences in the outcome of risk assessment and risk management processes resulting from differences among the receiving ecosystems and sets of human values at issue. A number of countries and international institutions have begun development of policies for oversight of genetically modified aquatic organisms. In the United States, a working group commissioned by the U.S. Department of Agriculture incorporated risk assessment and risk management principles into draft performance standards for safely conducting research with genetically modified finfish and shellfish. The performance standards address research with a broad range of aquatic GMOs, and compliance is intended to be voluntary. In contrast, the Canadian policy mandates adherence to specified guidelines for experiments with transgenic aquatic organisms; establishment as national policy is expected soon. Based upon the recently-adopted Gene Technology Act, Norwegian policy does not preclude use of genetically engineered aquatic organisms in the aquaculture industry, but the Norwegian government seems unlikely to support such use. Policies on aquatic GMOs have been adopted by leading international institutions concerned with fisheries management or aquaculture. The philosophy and technical content of oversight policies have important implications for scientists involved in research with aquatic GMOs. Hand, R. E., Nell, J. A., and Thompson, P. A. 2004. Studies on triploid oysters in Australia XIII. Performance of diploid and triploid Sydney rock oyster, Saccastrea glomerata (Gould, 1850), progeny from a thrid generation breeding line. Aquaculture 233: 93-107. Ref ID: 574 Harding, J. M. and Mann, R. 1999. Fish species richness in relation to restored oyster reefs, Pianktank River, Virginia. Bulletin of Marine Science 65: 289-299. Ref ID: 496 Harding, J. M. 1999. Selective feeding behavior of larval naked gobies Gobiosoma bosc and blennies Chasmodes bosquianus and Hypsoblennius hentzi: preferences for bivalve veligers. Marine Ecology-Progress Series 179: 145-153. Ref ID: 627 Abstract: In the tidal creeks of North Inlet, a high salinity salt marsh estuary near Georgetown, South Carolina, USA, the Eastern oyster Crassostrea virginica is an abundant component of the benthic macrofauna that exerts controls on microbial communities by its grazing and nutrient regenerative activities, The effects of oyster activity on North Inlet microbial food web structure were studied using: (1) water samples collected from tidal creeks with oyster reefs versus tidal creeks without oyster reefs (removed as part of a large-scale field manipulation study); and (2) flow-through flumes. In pair-wise comparisons of creeks with similar hydrography and morphology, the only microbial group found to vary significantly with the presence of oyster reefs was the phototrophic nanoflagellates (pflags), which were 1.25- to 2.25-fold less abundant in creeks with oyster reefs during the summer phytoplankton bloom, Because heterotrophic nanoflagellates (hflags) did not vary in these same comparisons, we hypothesized that preferential feeding for pflags by oysters was responsible for the reduction in pflag abundance. The hypothesis was tested during March and July 1999 using flumes with flowing creek water containing either live oysters or dead oyster shells, Significant reductions in pflags and some types of diatoms were measured in the outflow from live oysters, but oyster effects on other microbial components (hflags, cyanobacteria, and heterotrophic bacterio-plankton) were not evident. The flume study demonstrated preferential feeding by oysters on pflags using naturally occurring microbial assemblages, The differences in pflag abundance in creeks with oyster reefs versus creeks without oyster reefs suggests that this grazing activity can affect the structure of natural microbial communities. Harding, J. M. and Mann, R. 2000. Estimates of naked Goby (Gobiosoma bosc), striped blenny (Chasmodes bosquianus) and Eastern oyster (Crassostrea virginica) larval production around a restored Chesapeake Bay oyster reef. Bulletin of Marine Science 66: 29-45. Ref ID: 587 Abstract: Naked gobies (Gobiosoma bose) and striped blennies (Chasmodes bosquianus) rely on oyster reefs for nesting sites, feeding grounds, and refugia from predation by upper level piscivores. Seasonal densities of Eastern oysters (Crassostrea virginica), naked gobies, and striped blennies on Palace Bar Reef, Piankatank River, Virginia were quantified and used to develop species-specific larval production estimates. Densities of oyster adults, juveniles, and articulated shell valves (the result of recent mortality) did not significantly change from November 1995 to November 1996. Naked goby and striped blenny densities varied with substrate type and season; peak fish densities for both species were observed in August 1996. Areas where shell substrate dominated the bottom supported fish densities up to 14 times greater than those observed in habitat areas lacking shell. Larval production and recruitment estimates for Palace Bar Reef oysters are of the same order of magnitude as observed field densities. Benthic fish production estimates are within an order of magnitude of adult densities and are similar to previous recruitment estimates for Chesapeake Bay naked gobies. Species-specific production estimates for both oysters and fishes are sufficient to sustain observed adult densities on Palace Bar Reef, Piankatank River, Virginia Harding, J. M. and Mann, R. 2001. Oyster reefs as fish habitat: opportunistic use of restored reefs by transient fishes. Journal of Shellfish Research 20: 951-959. Ref ID: 148 Abstract: Under the Magnuson-Stevenson Fisheries Management Act of 1996, cur-rent Fisheries management practice is focused on the concept of Essential Fish Habitat (EFH). Application of the EFH concept to estuarine habitats relates directly to ongoing oyster reef restoration efforts. Oyster reef restoration typically creates complex habitat in re.-ions where such habitat is limited or absent. While healthy oyster reefs provide structurally and ecologically complex habitat for many other species from all trophic levels including recreationally and commercially valuable transient finfishes, additional data is required to evaluate oyster reef habitats in the context of essential fish habitat. Patterns of transient fish species richness, abundance, and size-specific habitat use were examined along an estuarine habitat gradient from complex reef habitat through simple sand bottom in the Piankatank River, Virginia. There was no clear delineation of habitat use by transient fishes along this cline of estuarine habitat types (oyster reef to sand bar). Atlantic croaker (Micropogonias undulatus). Atlantic menhaden (Brevoortia tyrannus), bluefish (Pomatomus saltatrix), silver perch (Bairdiella chrysoura), spot (Leiostomus xanthurus), spotted seatrout (Cynoscion regalis), striped bass (Morone saxatilis), and weakfish (Cynoscion nebulosus) were found in all habitat types examined. In general, the smallest fish were found on the sand bar. the site with the least habitat heterogeneity. As habitat complexity increased along the gradient from oyster shell bar through oyster reef, transient fish size and abundance increased. Opportunistic habitat use by this Suite of generalists relates variations in habitat quality as related to habitat-specific productivity and Suggests that oyster reefs may be important but not essential habitat for these fishes. Harding, J. M. and Mann, R. 2001. Diet and habitat use by bluefish, Pomatomus saltatrix, in a Chesapeake Bay estuary. Environmental Biology of Fishes 60: 401-409. Ref ID: 431 Abstract: Bluefish, Pomatomus saltatrix, are recreationally valuable finfish along the Atlantic seaboard and in the Chesapeake Bay. Diet and habitat use patterns for bluefish life history intervals in Chesapeake Bay estuaries are poorly described although it is widely acknowledged that this apex piscivorous species relies on estuarine habitat for feeding and nursery grounds after oceanic spawning and inshore migration of larvae. Bluefish diet, distribution, and abundance patterns were examined in relation to oyster reef, oyster bar, and sand bottom habitat in the Piankatank River, Virginia. Bluefish from all sites were predominantly piscivorous and were more abundant at reef sites than non-reef sites. Bluefish caught in association with the oyster reef consumed a wider diversity of prey items than fish from other sites; diet diversity may contribute to bluefish success during periods when small pelagic food fish abundance is reduced. Bluefish estuarine habitat use is positively correlated with the presence of oyster shell habitat and the complex trophic communities centering on oyster reefs Harding, J. M. 2001. Temporal variation and patchiness of zooplankton around a restored oyster reef. Estuaries 24: 453-466. Ref ID: 617 Abstract: Zooplankton abundance and distribution patterns were determined for six seasonally important invertebrate taxa (bivalve veligers, gastropod veligers, polychaete larvae, barnacle nauplii, calanoid copepod adults and nauplii) and a diurnally important taxon (decapod zoea) around a restored oyster reef in the Piankatank River, Virginia. Data were collected on spatial scales of hundreds of meters and seasonal (May through October), diel (day-night), and tidal (3 h) temporal scales. Significant seasonal and diel patterns in abundance were observed for all taxa. Tidal-influences alone appear to be less important than seasonal and diel patterns for most taxa but the interaction of tidal and diel cues may have caused the observed diel zooplankton distribution patterns in both June and August 1996. Zooplankton taxa around the oyster reef were distributed non-randomly (patchily) regardless of their horizontal location with regard to the reef. Seasonal pulses in zooplankton abundance relate directly to life history patterns and reproductive cycles for individual taxa. Reef benthic fauna have the capacity to directly influence the composition and absolute abundance of the overlying zooplankton community and indirectly influence oyster reef community trophic dynamics. Harding, J. M. and Mann, R. 2003. Influence of habitat on diet and distribution of striped bass (Morone saxatilis) in a temperate estuary. Bulletin of Marine Science 72: 841-851. Ref ID: 418 Abstract: Striped bass (Morone saxatilis) are recreationally and commercially valuable finfish along the Atlantic seaboard of North America including the Chesapeake Bay estuary. Habitat use patterns for striped bass in relation to biogenic habitat types in Chesapeake Bay tributaries are poorly described although it is widely acknowledged that these piscivorous fishes use estuarine habitat for nursery and feeding grounds during development. Striped bass diet and distribution patterns were examined in relation to a gradient of biogenic habitats ranging from complex three-dimensional oyster reef through flat oyster bar to sand bottom habitat in the Piankatank River, Virginia. Striped bass were more abundant at both sites with oysters and oyster shell substrate than at the site with sand substrate. Striped bass in association with the three-dimensional oyster reef were larger and consumed more teleosts (e.g., naked gobies) than fish at either of the non-reef sites. Striped bass estuarine habitat use is positively correlated with the presence of oyster reef habitat that includes physical structure and food resources via complex trophic communities centered on the oyster reef Harding, J. M. 2003. Predation by blue crabs, Callinectes sapidus, on rapa whelks, Rapana venosa: possible natural controls for an invasive species? Journal of Experimental Marine Biology and Ecology 297: 161-177. Ref ID: 255 Abstract: Blue crabs Callinectes sapidus are voracious predators in Chesapeake Bay and other estuarine habitats. The rapa whelk Rapana venosa is native to Asian waters but was discovered in Chesapeake Bay in 1998. This predatory gastropod grows to large terminal sizes (in excess of 150 mm shell length (SL)) and has a thick shell that may contribute to an ontogenetic predation refuge. However, juvenile rapa whelks in Chesapeake Bay may be vulnerable to predation by the blue crab given probable habitat overlap, relative lack of whelk shell architectural defenses, and the relatively large size of potential crab predators. Feeding experiments using three size classes of blue crab predators in relation to a size range of rapa whelks of two different ages (Age 1 and Age 2) were conducted. Blue crabs of all sizes tested consumed Age 1 rapa whelks; 58% of all Age 1 whelks offered were eaten. Age 2 rapa whelks were consumed by medium (67% of whelks offered were eaten) and large (70% of whelks offered were eaten) blue crabs but not by small crabs. The attack methods of medium and large crabs changed with whelk age and related shell weight. Age 1 whelks were typically crushed by blue crabs while Age 2 whelk shells were chipped or left intact by predators removing prey. Rapa whelks less than approximately 35 turn SL are vulnerable to predation by all sizes of blue crabs tested. Rapa whelk critical size may be greater than 55 mm SL in the presence of large blue crabs indicating that a size refugia from crab predation may not be achieved by rapa whelks in Chesapeake Bay until at least Age 2 or Age 3. Predation by blue crabs on young rapa whelks may offer a natural control strategy for rapa whelks in Chesapeake Bay and other estuarine habitats along the North American Atlantic coast. (C) 2003 Elsevier B.V All rights reserved Hart, D. R. and Gardner, R. H. 1997. A spatial model for the spread of invading organisms subject to competition. Journal of Mathematical Biology 35: 935-948. Ref ID: 16 Abstract: A spatially explicit integrodifference equation model is studied for the spread of an invading organism against an established competitor. Provided the invader is initially confined to a bounded region. the invasion spreads asymptotically as a travelling wave whose speed depends on the strength of the competitive interaction and on the dispersal characteristics of the invader. Even an inferior, but established, competitor can significantly reduce the invasion speed. The invasion speed is also influenced by the exact shape of the dispersal kernel (especially the thickness of the tail) as well as the mean dispersal distance for each generation. Hartman, K. J. and Brandt, S. B. 1995. Predatory demand and impact of striped bass, bluefish, and weakfish in the Chesapeake Bay: applications of bioenergetics models. Canadian Journal of Fisheries and Aquatic Sciences 52: 1667-1687. Ref ID: 674 Abstract: We applied bioenergetics models for dominant Chesapeake Bay piscivores, striped bass (Morone saxatilis), bluefish (Pomatomus saltatrix), and weakfish (Cynoscion regalis), along with site-specific data on diets, growth, and energy density, to examine trophic linkages and the relationship of predatory demand to prey supply. Atlantic menhaden (Brevoortia tyrannus), bay anchovy (Anchoa mitchilli), and spot (Leiostomus xanthurus) accounted for 65-99% of the annual biomass of piscivore diets (excluding age-0 striped bass that ate mostly invertebrates). The diets of young piscivores were dominated by anchovy, but menhaden and spot became increasingly important to older fish. Young (age < 2) striped bass ate mostly benthic prey. Older striped bass fed increasingly on pelagic sources, primarily menhaden, but bluefish and weakfish increased benthic resource use from 10% at age 0 to 50% by age 2. Comparison of consumption (supply) to demand (potential consumption) measured the suitability of Chesapeake Bay for predator production. Bluefish came closest to achieving their demand for prey, suggesting that they are more successful predators than either striped bass or weakfish. Results suggest that Chesapeake Bay may be a better nursery than production area for older fish, and prey supply (not temperature) may account for the movements and use of the estuary by older piscivores. Hartwell, S. I., Wright, D. A., Takacs, R., and Hocutt, C. H. 1991. Relative respiration and feeding rates of oyster and brackish water clam in variously contaminated waters. Marine Pollution Bulletin 22: 191-197. Ref ID: 412 Abstract: Oysters (Crassostrea virginica) and brackish water clams (Rangia cuneata) were acclimated in situ to water from two different Chesapeake Bay tributaries. Following acclimation, their respiratory and feeding rates were determined in approximately 1 l. recirculating chambers. Mean oyster respiration rate varied between 0.58-2.21 mg O2 g-1 h-1, depending upon acclimation water quality. Mean clam respiratory rates varied between 0.028-0.251 mg O2 g-1 h-1. The weight specific respiration rate of the clams was 0.106 + 0.213 log10 dry wt. Mean feeding rate for oysters ranged between 4.25-9.63 l g-1 h-1. Mean feeding rates for clams varied between 0.38 and 0.72 l g-1 h-1. The weight specific feeding rate of the clams was 0.563 + 0.519 log10 dry wt. R. cuneata was shown to be a potentially useful species for monitoring environmental pollution in the fresh-saltwater interface of estuaries Hastings, A. 1996. Models of spatial spread: a synthesis. Biological Conservation 78: 143-148. Ref ID: 123 Abstract: I review models describing the dynamics of range expansion (spatial spread) of invading organisms, emphasizing two apparently robust results. First, there appears to be a linear rate of spread with time, and second, this rate is proportional to the per capita growth rate of the population wizen the invading species is rare. Both results hold for a variety of single-species and two-species models. I then present two models, one stochastic, and one with an Allee effect, that demonstrate that the constant linear rate of spread may only hold after an initial period of slower spread. Finally, I emphasize that the dependence of the rate of spread on the per capita growth rate need only hold when this is maximized when the species is rare. This last observation may have important implications for understanding the rate of spread for precisely those species which are likely to cause the most disruption to the communities they invade. Haven, D. S., Whitcomb, J. P., and Kendall, P. C. 1981. The Present and Potential Productivity of the Baylor Grounds in Virginia. Volume I. Rappahannock, Corrotoman, Great Wicomico, Piankatank, York and Poquoson Rivers, and Mobjack Bay and Its Tributaries., Special Report Number 243 in Applied Marine Science and Ocean Engineering, Virginia Institute of Marine Science and School of Marine Science, The College and William and Mary, Gloucester Point, VA Ref ID: 592 Hawkins, A. J. S., Magoulas, A., Heral, M., Bougrier, S., Naciri-Graven, Y., Day, A. J., and Kotoulas, G. 2000. Separate effects of triploidy, parentage, and genomic diversity upon feeding behaviour, metabolic efficieny, and net energy balance in the Pacific oyster Crassostrea gigas. Genetic Research of Cambridge 76: 273-284. Ref ID: 573 Hayes, K. R. 1997. A Review of Ecological Risk Assessment Methodologies. Technical Report Number 13, Centre for Research on Introduced Marine Pests, Australia Ref ID: 115 Hedgecock, D., Chow, V., and Waples, R. S. 1992. Effective population numbers of shellfish broodstocks estimated from temporal variance in allelic frequencies. Aquaculture 108: 215-232. Ref ID: 407 Abstract: Effective population number (N(e)) can be estimated from temporal changes in the frequencies of selectively neutral alleles in isolated populations. The utility and limitations of this temporal method for aquaculture broodstocks are examined using published allozyme data for 16 shellfish stocks and their will progenitors. Estimates of N(e) for these broodstocks are all less than 1 00, and 1 3 are less than 50. For eight stocks, estimated N(e) agrees with records of breeding numbers (N(b)), but in the remaining eight cases, N(b) lies outside of the 95% confidence interval for estimated N(e).Assumptions of the temporal method are evaluated. First, two independent tests, one based on the distribution of temporal variances at individual loci, the other on the expected loss of alleles from finite populations, suggest that allozymes behave as selectively neutral genetic markers suitable for estimating genetic drift and N(e). Second, migration into a stock can have diverse effects on estimates of N(e), depending on the genetic similarity of immigrants and the captive broodstock population. Exchange among diverged hatchery stocks of Kuruma shrimp appears to have inflated temporal change, reducing estimated N(e); on the other hand, additions of wild hard clams to a hatchery stock appear to have retarded temporal change, increasing estimated N(e). Four cases in which N(b) is smaller than the lower confidence limit of estimated N(e) are explained by contamination among stocks propagated simultaneously in the same hatchery. Finally, comparison of captive broodstocks with contemporary samples from natural sources confounds genetic drift that has occurred in both lineages; genetic drift is not negligible in some natural populations, leading to uncertainty in some N(e) estimates.For four cases in which N(b) is much larger than estimated N(e), variance in reproductive success is proposed as the most likely explanation of loss of genetic diversity over time. The extremely high fecundities and variable fertilities of aquatic organisms must be taken into account in broodstock management, particularly if hatchery products are used to enhance natural populations. The temporal method, when correctly applied and interpreted, provides new insight into the genetics of aquaculture broodstock populations Hedgecock, D., Li, G., Banks, M. A., and Kain, Z. 1999. Occurrence of the Kumamoto oyster Crassostrea sikamea in the Ariake Sea, Japan. Marine Biology 133: 65-68. Ref ID: 50 Abstract: The Kumamoto oyster Crassostrea sikamea is distinguished from the closely related Pacific oyster C. gigas by concordant differences in 16S rDNA, allozymes, and a one-way gametic incompatibility. After repeated failures to find this oyster in its native habitat, we speculated in 1994 that "the Kumamoto oyster may be extinct in Japan". In September 1996, we sampled small, deep-cupped oysters from the Ariake Sea and typed these for 16S rDNA and ITS-1 DNA markers previously shown to be diagnostic for the three most common oysters in the Ariake Sea, C. gigas, C. sikamea and C. ariakensis. Our earlier suggestion of the demise of C. sikamea proved incorrect. Of the 256 oysters sampled, 181 (71%) were C. gigas, 53 (21%) were C. sikamea, and 22 (9%) were C. ariakensis; no interspecific hybrids were observed. The distributions of C. sikamea and C. ariakensis are clumped in the,Ariake Sea: C. sikamea occurs on the eastern and northern shores, C. ariakensis occurs only in the northern part. These results emphasize the value of molecular markers for discriminating these morphologically plastic species both in the field and in aquaculture. Herbold, B. and Moyle, P. B. 1986. Introduced species and vacant niches. American Naturalist 128: 751-760. Ref ID: 105 Hershberger, W. K., Predue, J. A., and Beattie, J. H. 1984. Genetic selection and systematic breeding in Pacific oyster culture. Aquaculture 39: 237-245. Ref ID: 132 Hilgerloh, G., O' Halloran, J., Kelly, T. C., and Burnell, G. M. 2001. A preliminary study on the effects of oyster culturing structures on birds in a sheltered Irish estuary. Hydrobiologia 465: 175-180. Ref ID: 636 Abstract: This study investigated the species composition, numbers and behaviour of birds in an intertidal oyster culture area in Cork Harbour . These data were compared to a nearby area free of aquaculture within the same estuary in March 1999. Species which occurred in the aquaculture free area were also observed in the trestle-area. The most abundant species were oystercatcher Haematopus ostralegus, redshank Tringa totanus, dunlin Calidris alpina, curlew Numenius arquata, black-headed gull Larus ridibundus and common gull Larus canus. Oystercatcher, curlew, black-headed gull and common gull occurred in significantly lower numbers in the trestle area, while for redshank and dunlin the differences were not significant. The percentage of birds feeding did not differ between the two areas. Oystercatcher, redshank, dunlin and curlew mostly fed in both areas. In contrast, black-headed gull and common gull generally did not feed, but surveyed the area. Whether the trestles were covered by oyster bags or not did not have any effect on the number of birds except for the dunlin. Dunlin were significantly more frequent beneath the trestles with bags compared with those without bags. In general, the percentage of birds feeding did not differ between areas. Interspecies differences occurred with regard to the position occupied by birds at the trestles. Oystercatcher, redshank and curlew spent more time underneath the trestles. Dunlin, black-headed gulls and common gulls did not differ in numbers underneath or on top of the trestles. These preliminary observations at a single time period give some insight as to the potential interactions between shellfish aquaculture and intertidal birds Hofmann, E., Powell, E., Bochenek, E. A., and Klinck, J. 2004. A modelling study of the influence of environment and food supply on survival of Crassostrea gigas larvae. ICES Journal of Marine Science 61: 596-616. Ref ID: 581 Abstract: A biochemically based model was developed to simulate the growth, development, and metamorphosis of larvae of the Pacific oyster (Crassostrea gigas). The unique characteristics of the model are that it: (1) defines larvae in terms of their protein, neutral lipid, polar lipid, carbohydrate, and ash content; (2) tracks weight separately from length to follow larval condition; and (3) includes genetic variation in growth efficiency and egg quality to better simulate cohort population dynamics. The model includes parameterizations for filtration, ingestion, and respiration, which determine larval growth rate, and processes controlling larval mortality and metamorphosis. Changes in larval tissue composition occur as the larva grows and in response to the biochemical composition of the food. Simulations of larval growth indicate that departures of temperature, salinity, or food content from optimum levels reduce larval cohort survival, either because of metabolic constraints that result in death, unsuccessful metamorphosis, or increased predation resulting from increased larval lifespan. Temperatures and salinities near optimal values improve larval survival at low food concentration by increasing ingestion rate or growth efficiency. Also, survival at a given food concentration can vary widely depending on food composition, which determines food quality. The simulations suggest that the ratio of carbohydrate + lipid-to-protein may best describe the overall food quality, with optimal food compositions being characterized by ratios near 1.2 to 1.4 over a range of food concentrations. In contrast, food compositions containing too much or too little protein reduce larval survival, even at saturating food concentrations. In simulations emphasizing genetic variability within the cohort, larvae with high growth efficiency originating from large eggs out-perform other egg quality-growth efficiency combinations over a wide range of temperature, salinity, and food contents. As a consequence, suboptimal temperature, salinity, or food content compresses genetic variation by uniformly favouring larvae from large eggs with a high growth efficiency. However, the larval survival obtained from simulations that use a range of food qualities is representative of a much broader range of genetic types. Thus, the simulations support the supposition that food quality is an important variable controlling the survival and genetic variability of C. gigas larval cohorts. Hofmann, E. E., Powell, E. N., Klinck, J. M., and Wilson, E. A. 1992. Modeling oyster populations III. Critical feeding periods, growth, and reproduction. Journal of Shellfish Research 11: 399-416. Ref ID: 5 Hofmann, E. E., Klinck, J. M., Powell, E. N., Boyles, S., and Ellis, M. 1994. Modeling oyster populations II. Adult size and reproductive effort. Journal of Shellfish Research 13: 165-182. Ref ID: 6 Abstract: A time-dependent model of energy flow in post-settlement oyster populations is used to examine the factors that influence adult size and reproductive effort in a particular habitat, Galveston Bay, Texas, and in habitats that extend from Laguna Madre, Texas to Chesapeake Bay. The simulated populations show that adult size and reproductive effort are determined by the allocation of net production to somatic or reproductive tissue development and the rate of food acquisition, both of which are temperature dependent. For similar food conditions, increased temperature reduces the allocation of net production to somatic tissue and increases the rate of food acquisition. This temperature effect, however, is mediated by changes in food supply. Within the Gulf of Mexico, oyster size declines from north to south because increased temperature decreases the allocation of net production to somatic growth. An increase in food supply generally results in increased size as more energy is used in somatic growth; however, at low latitudes, as food supply increases, adult size decreases because the allocation of more net production to reproduction outweighs the effect of increased rates of food acquisition. Variations in temperature and food supply affect reproductive effort more than adult size because the rate of energy flow through the oyster is higher in warmer months when most net production is allocated to reproduction and small changes in temperature substantially change the spawning season. The wide range of reproductive effort expected from small changes in temperature and food supply suggest that comparisons of adult size and reproductive effort between oyster populations can only be made within the context of a complete environmental analysis of food supply and associated physical parameters and an energy flow model. Hofmann, E. E., Powell, E. N., Klinck, J. M., and Saunders, G. 1995. Modeling diseased oyster populations I. Modeling Perkinsus marinus infections in oysters. Journal of Shellfish Research 14: 121-151. Ref ID: 523 Abstract: The endoparasite, Perkinsus marinus, is one of the primary factors affecting the abundance and productivity of populations of the Eastern oyster, Crassostrea virginica. The environmental and biological factors that control the prevalence and infection intensity of P. marinus were examined with a coupled oyster population-parasite model. The simulations show that food availability to the host and temperature control on the growth and developmental rates of the host and parasite are the environmental factors that regulate the parasite. In addition, a feedback between the density of the parasite in the host and the parasite's division rate partially controls infection intensity.Simulations that use summer temperatures typical of temperate estuaries show increased parasite growth rate which results in more of the net production of the oyster population going to reproduction, thereby reducing the ability of the oyster to outgrow the parasite. As a result, disease prevalence and infection intensity are maximal during the summer throughout the range of environments tested with the model. The simulations suggest that oyster mortality from P. marinus, as a fraction of the adult population, may be most pronounced for mid-latitude systems. The increased reproductive potential of oyster populations living at lower latitudes balances increased mortality from disease. Thus, disease prevalence and infection intensity average higher in the simulated populations that correspond to the central part of the latitudinal range of the oyster.The timing and magnitude of food supply for the oyster greatly affects the degree of mortality produced by the parasite in the simulated populations. In the early spring, the oyster has not switched to a reproductive mode, and more of the net production goes to somatic tissue development. Hence, if increased food is available in the early spring (a March to April spring bloom), mortality due to the parasite decreases in the simulated oyster population. The simulations suggest that the primary defense for the oyster is to simply outgrow P. marinus.The simulated oyster populations remain at moderate to moderately heavy infections for extended periods during the summer for two reasons. First, increasing density of the parasite results in a decreased rate of parasite division, which decreases the rate of oyster host mortality. Second, the rate at which infected individuals reach a lethal infection level is slowed enough that less heavily-infected oysters grow up to replace those that die. These simulation results show that, unlike many host-parasite systems, high infection rates in oysters do not necessarily result in high host mortality. The simulations further suggest that the rates of P. marinus division and mortality must vary regionally among oyster populations and that some lability in disease resistance by the oysters must be present.The results from the oyster population-P, marinus model imply that environmental changes, such as temperature variability, which may result from climatic effects, can potentially alter the prevalence and infection levels of the parasite in oyster populations. Sensitivity of the host-parasite system to the recent history of environmental change provides a mechanism for exaggerating the effects of extreme years, such as times of reduced food supply or extended periods of warm temperature. Thus, any management strategy for diseased oyster populations must take into account environmental conditions, the physiology of the oyster and the parasite, as well as the previous history of the disease in the population Hofmann, E. E. and Powell, T. M. 1998. Environmental variability effects on marine fisheries: Four case histories. Ecological Applications 8: S23-S32. Ref ID: 376 Abstract: The changing nature of marine fisheries requires management approaches that recognize and include ecosystem and environmental effects. Therefore, we review some examples of exploited fishery stocks in which environmental control is a major contributor to structuring the abundance and distribution of the stock. Four examples, taken from studies of northern cod (Gadus morhua), cod and haddock (Melanogrammus aeglefinus) larvae, the eastern oyster (Crassostrea virginica), and Antarctic krill (Euphausia superba), are given that clearly illustrate environmental control on the fishery. From these examples, we argue that future management strategies for exploited fisheries must include effects of environmental variability. In particular, management strategies must be flexible enough to include delayed responses to environmental variations that result from the transfer of perturbations from larger to smaller scales and vice versa. This capability requires an understanding of where linkages between the physical environment and the species of interest occur. Development of this knowledge requires input from a variety of disciplines, coordinated research programs, and considerable cooperation at national and international levels Hofmann, E. E., Ford, S., Powell, E., and Klinck, J. 2001. Modeling studies of the effect of climate variability on MSX disease in eastern oyster (Crassostrea virginica) populations. Hydrobiologia 460: 195-212. Ref ID: 571 Abstract: Eastern oysters (Crassostrea virginica) often undergo epizootics of MSX (Multinucleated Spore Unknown) disease, which is caused by the protozoan pathogen, Haplosporidium, nelsoni, The disease has been present in oyster populations in the mid-Atlantic United States since the 1950s. During the 1980s and 1990s, it became established further north along the east coast of the United States. To investigate the factors underlying the northward progression of MSX disease, a model that simulates the host-parasite-environmental interactions was used. The model is physiologically-based and is Structured around the transmission, proliferation and death rates of the parasite. Environmental conditions of temperature, salinity and oyster food supply provide the external forcing that results in variations in the biological rates. For (his study, environmental data sets, both average and extreme, were obtained at a site in upper Chesapeake Bay for 1986 through 1995. This site is in the middle of one of the most productive oyster growing regions on the cast coast of the United States; thus, both short- and long-term changes in the environment measured here realistically reflect conditions experienced by important oyster populations. The effect of short-term high-salinity (drought) or low-salinity (wet) conditions on MSX disease prevalence and intensity was relatively small because the average salinity regime already favors maximum parasite activity at this site. Even the extreme low salinity events were not low enough to significantly inhibit the parasite. Similarly, simulations using short-term high-temperature extremes For the same site showed only minor deviations from the average pattern because average temperatures were already high enough to support parasite development. In contrast, the measured low temperature conditions, applied for a single year, caused a dramatic reduction in parasite activity, which extended over a 2-year period. Additional simulations show that overall food supply to the host is of little consequence in determining the basic disease pattern; however, the timing of maximum food supply provided to the host, relative to specific times in the parasite life cycle, is important in determining whether or not the parasite attempts sporulation or undergoes density-independent growth. Simulations that test a sequence of changing environmental conditions show that when a year with cold winter temperatures (less than 3 degreesC) is followed by a year of low salinity (less than 15 ppt), prevalences and intensities of MSX disease are greatly reduced, with the disease becoming almost absent in (lie oyster populations however, the disease returns when average environmental conditions return. Simulations using progressive cooling or warming conditions indicate that winter temperatures consistently lower than 3 degreesC limit the long-term development of MSX disease. These simulations support the suggestion that climate warming is a contributing factor to the northward spread of MSX disease Hoshino, T. 1981. Oysters in Japan. Journal of Science of the Hiroshima University, Series B, Division 1 (Zoology) 29: 207-347. Ref ID: 55 Houde, E. D. 1977. Food concentration and stocking density effects on survival and growth of laboratory-reared larvae of bay anchovy Anchoa mitchili and lined sole Achirus lineatus. Marine Biology 43: 333-341. Ref ID: 609 Hunt, H. L. and Scheibling, R. E. 1997. Role of early post-settlement mortality in recruitment of benthic invertebrates. Marine Ecology Progress Series 155: 269-301. Ref ID: 88 Abstract: Newly settled invertebrates usually are subject to high rates of mortality (Type ill survivorship). Therefore, knowledge of early post-settlement events is critical in determining if and when patterns of abundance and distribution of juveniles reflect settlement patterns. Causes of mortality of early juvenile invertebrates include delay of metamorphosis, biological disturbance, physical disturbance and hydrodynamics, physiological stress, predation, and competition. Predation is the best documented cause of early mortality, particularly for mobile species. Other possible causes which have not yet been investigated are developmental abnormalities, insufficient energy reserves, disease and. parasitism. In most studies of sessile invertebrates, early post-settlement mortality did not obscure the relationship between recruit and settler abundance. This relationship appears to be more variable among mobile species for which migration also can modify the distribution of settlers. There is still insufficient data to support general conclusions about the conditions under which recruitment rate can be predicted from settlement rate. Studies have found evidence of the effects of both settlement and early post-settlement mortality on the distribution of some sessile species at small spatial scales, but mortality appears to have less influence at larger scales. Much of the present knowledge of the early postsettlement period has come from studies of barnacles and ascidians and more information is needed for other groups of benthic marine invertebrates, particularly mobile species. The relative importance of mortality during the early post-settlement period compared to other life history stages can only be determined in studies which examine several stages. Jackson, J. B. C., Kirby, M. X., Berger, W. H., Bjorndal, K. A., Botsford, L. W., Bourque, B. J., Bradbury, R. H., Cooke, R., Erlandson, J., Estes, J. A., Hughes, T. P., Kidwell, S., Lange, C. B., Lenihan, H. S., Pandolfi, J. M., Peterson, C. H., Steneck, R. S., Tegner, M. J., and Warner, R. R. 2001. Historical overfishing and the recent collapse of coastal ecosystems. Science 293: 629-638. Ref ID: 512 Abstract: Ecological extinction caused by overfishing precedes all other pervasive human disturbance to coastal ecosystems, including pollution, degradation of water quality, and anthropogenic climate change. Historical abundances of large consumer species were fantastically large in comparison with recent observations. Paleoecological, archaeological, and historical data show that time lags of decades to centuries occurred between the onset of overfishing and consequent changes in ecological communities, because unfished species of similar trophic level assumed the ecological roles of overfished species until they too were overfished or died of epidemic diseases related to overcrowding. Retrospective data not only help to clarify underlying causes and rates of ecological change, but they also demonstrate achievable goals for restoration and management of coastal ecosystems that could not even be contemplated based on the limited perspective of recent observations alone. Jordan, S. J. 1995. Population and disease dynamics of Maryland oyster bars: a multivariate classification analysis. Journal of Shellfish Research 14: 459-468. Ref ID: 13 Abstract: Cluster analysis was applied to size frequency, spatfall, mortality, and disease prevalence data collected from 64 oyster bars in Maryland's Chesapeake Bay during 1990-1993. Six population types were identified. Salinity and prevalence of Perkinsus marinus and Haplosporidium nelsoni infections were important variables explaining cluster membership (stepwise discriminant analysis). Six similar population types were identified by cluster analysis of the same data set with P. marinus and H. nelsoni prevalence, mortality, spatfall, relative abundance of small and market oysters, and mean shell height as the population attributes. Both analyses pointed to recruitment, along with mortality from parasitic infections, as defining oyster population structure. Mapping cluster membership of each oyster bar over the 4 years provided a simple way to visualize year to year changes in many variables describing the oyster population. Jordan, S. J., Greenhawk, K. N., McCollough, C. B., Vanisko, J., and Homer, M. L. 2002. Oyster biomass, abundance, and harvest in northern Chesapeake Bay: trends and forecasts. Journal of Shellfish Research 21: 733-741. Ref ID: 154 Abstract: We applied time series of fishery-dependent and fishery-independent data to develop indices of relative biomass and estimates of absolute abundance and biomass for the Maryland oyster population. The principal objectives for this work were to specify a baseline and determine trends relative to the Chesapeake Bay Program's goal to achieve a 10-fold increase in the standing stock of oysters in the Bay from a 1994 baseline. Population biomass varied by 3-fold from 1986-2001, with most of the variation caused by changes in the stock of market-sized oysters. There were also important spatial differences in population structure and trends over a gradient of salinity. Lagged correlations between small oyster biomass and either market-sized oyster biomass or landings were not statistically significant but suggested that most of the market-sized oysters and those harvested were four to five years old. The index of relative biomass for market-sized oysters proved to be a useful predictor of annual harvests in Maryland. We used this relationship to estimate absolute abundance and biomass of oysters for the time series. The latter estimates may be biased negatively with respect to true abundance and biomass because of biases in both the fishery and the fishery-independent monitoring program. The index of relative biomass will be a suitable measure of population status relative to the oyster restoration goal only so long as the population remains at relatively low levels. Because the index has a theoretical maximum of about 75% of the 10-fold goal, a quantitative estimator will be required for higher population levels. Jordan, S. J. and Coakley, J. M. 2004. Long-term projections of eastern oyster populations under various management scenarios. Journal of Shellfish Research 23: 63-72. Ref ID: 501 Jorde, D. G. and Owen, R. B. 1990. Foods of black ducks, Anas rubripes, wintering in marine habitats of Maine. Canadian Field Naturalist 104: 300-302. Ref ID: 675 Abstract: Diet and foraging habitats of Black Ducks (Anas rubripes) wintering along the central coast of Maine were studied during 1983 and 1984. Marine invertebrates accounted for 96% of diet. Amphipods (Gammarus oceanicus), periwinkles (Littorina spp.), and Blue Mussels (Mytilus edulis) were the principal foods eaten. Jorgensen, C. B. 1996. Bivalve filter feeding revisited. Marine Ecology-Progress Series 142: 287-302. Ref ID: 302 Abstract: Recent developments concerning the nature of bivalve filter feeding are reviewed and interpretations of data are examined. No convincing evidence was found for: (1) a function of mucus in the normal feeding mechanism; (2) sorting of suspended particles according to food value; (3) low rates of water processing in nature; (4) physiological control of water pumping and filtration efficiency according to nutritional needs. Recent findings are consistent with the view that the capacity for water processing is evolutionarily adapted to the concentrations of suspended food, primarily phytoplankton, that prevail in the biotope during the productive seasons of the year. 'Scope for growth', computed from measurements of the energy balance parameters, is extensively used to assess effects of environmental factors, including pollutants, on the physiology and energetics, particularly of mussels. Estimates tend, however, to underrate the values they are believed to reflect due to neglect of negative effects of the experimental conditions on the filter-pump. Possible effects of the experimental conditions on filtration rates should therefore be established before a calculated 'scope for growth' can be extrapolated to the habitat which the experiment simulates Jung, S. and Houde, E. D. 2004. Production of bay anchovy Anchoa mitchilli in Chesapeake Bay: application of size-based theory. Marine Ecology-Progress Series 281: 217-232. Ref ID: 656 Abstract: To evaluate and quantify productivity of abundant bay anchovy Anchoa mitchilh in the Chesapeake Bay ecosystem, daily stock biomass, production, and contribution to predators of young-of-the-year (YOY) bay anchovy were estimated from May 1995 to October 2000, based on tri-annual midwater trawl collections. Empirical allometric relationships were applied to develop size-dependent growth and mortality estimates. Estimated annual mean stock biomass of YOY bay anchovy was lowest in 1996 (17 x 10(3) metric tons [t] wet weight) and highest in 2000 (64 x 10(3) t). Estimated YOY production varied inter-annually by a factor of 4, ranging from 167 x 10(3) t in 1996 to 697 x 10(3) t in 2000. Daily stock biomass levels usually peaked in mid September, while daily production and contribution to predators peaked from mid July to late September. The annual production to mean biomass (P/(B) over bar) ratio, which included the very productive larval stage, was high and ranged from 9.02 to 13.23. Analysis of environmental factors indicated that water temperature and dissolved oxygen were important controllers of growth rate. Inter-annual variability in length-specific mortality was inversely related to mean salinity in the summer and fall, suggesting that salinity controls abundances and spatial distributions of predators on bay anchovy. Results imply that annually variable hydrological conditions and secondary productivity may drive observed variability in recruitment and production of YOY bay anchovy by inducing small but decisive differences in growth and predation mortality on early-life stages. Jung, S. and Houde, E. D. 2004. Recruitment and spawning-stock biomass distribution of bay anchovy (Anchoa mitchilli) in Chesapeake Bay. Fishery Bulletin 102: 63-77. Ref ID: 657 Abstract: Recruitment of bay anchovy (Anchoa mitchilli) in Chesapeake is related to variability in hydrological conditions and to abundance and spatial distribution of spawning stock biomass (SSB). Midwater-trawl surveys conducted for six years, over the entire 320-km length of the bay, provided information on anchovy SSB, annual spatial patterns of recruitment, and their relationships to variability in the estuarine environment. SSB of anchovy varied sixfold in 1995-2000; it alone explained little variability in young-of-the-year (YOY) recruitment level in October, which varied ninefold. Recruitments were low in 1995 and 1996 (47 and 31 x 10(9)) but higher in 1997-2000 (100 to 265 x 10(9)). During the recruitment process the YOY population migrated upbay before a subsequent fall-winter downbay migration. The extent of the downbay migration by maturing recruits was greatest in years of high freshwater input to the bay. Mean dissolved oxygen (DO) was more important than freshwater input in controlling distribution of SSB and shifts in SSB location between April-May (prespawning) and June-August (spawning) periods. Recruitments of bay anchovy were higher when mean DO was lowest in the downbay region during the spawning season. It is hypothesized that anchovy recruitment level is inversely related to mean DO concentration because low DO is associated with high plankton productivity in Chesapeake Bay. Additionally, low DO conditions may confine most bay anchovy spawners to the downbay region, where production of larvae and juveniles is enhanced. A modified Ricker stock-recruitment model indicated density-compensatory recruitment with respect to SSB and demonstrated the importance of spring-summer DO levels and spatial distribution of SSB as controllers of bay anchovy recruitment. Ke, C. and Wang, W. 2001. Bioaccumulation of Cd, Se, and Zn in an estuarine oyster (Crassostrea rivularis) and a coastal oyster (Saccostrea glomerata). Aquatic Toxicology 56: 33-51. Ref ID: 183 Abstract: We compared the bioaccumulation of Cd, Se, and Zn in an estuarine oyster (Crassostrea rivularis) and a coastal oyster (Saccostrea glomerata) from both the dissolved and particulate phases. A bioenergetic-based kinetic model was used to predict the exposure pathways of metals in the oysters. The assimilation efficiencies (AEs) of metals, determined for four species of phytoplankton and natural sediment, were in the range of 30-75% for Cd, 25-75% for Se, and 30-80% for Zn, respectively, in the two oysters. There was little difference in metal AE between the two oysters and among the three metals on the same particle type. Metal uptake rate constant, determined from the log-log relationship between metal influx. rate and metal concentration in the dissolved phase, was higher for Cd and Zn in the estuarine oyster C. rivularis than in the coastal oyster S. glomerata. The uptake rate constants quantified for Cd, Se, and Zn were the highest among different bivalve species studied so far. The calculated metal absorption efficiency from the dissolved phase was similar to those found in other bivalve species. The measured efflux rate constant in the estuarine oyster C. rivularis was in the range of 0.01-0.03 day(-1) for Cd, Se, and Zn, and were comparable to those found in mussels and clams. In contrast, the efflux rate constant of Cd and Zn in the coastal oyster S. glomerata was 0.003-0.004 day(-1), which may be responsible for the high Cd and Zn concentrations in the oysters. The bioenergetic-based kinetic model predicts that under most circumstances likely experienced by oysters in nature, the majority of Se and Zn in the two oysters stem from uptake from the dietary phase. Dissolved uptake contributes significantly to metal accumulation only when the metal concentration factor (CF) in the particles is in the lower portion of the range typically found in nature. Sensitivity analysis indicates that the metal CF is a critical parameter in determining the exposure pathways of metals in the oysters. Our study demonstrated that estuarine and coastal oysters differed in their strategies in accumulating a high metal concentration in their tissues. Keiner, C. 1998. W. K. Brooks and the oyster question: Science, politics, and resource management in Maryland, 1880-1930. Journal of the History of Biology 31: 383-424. Ref ID: 441 Kennedy, V. S. and Breisch, L. L. 1981. Maryland's Oysters Research and Management. UM-SG-TS-81-04, Maryland Sea Grant and the Tidewater Administration of the Department of Naturdal Resources of the State of Maryland, College Park, MD Ref ID: 99 Kennedy, V. S. and Krantz, L. B. 1982. Comparative gametogenc and spawning patterns of the oyster Crassostrea virginica (Gmelin) in the central Chesapeake Bay. Journal of Shellfish Research 2: 133-140. Ref ID: 184 Kennedy, V. S. and Breisch, L. L. 1983. Sixteen Decades of Political Management of the Oyster Fishery in Maryland's Chesapeake Bay. Journal of Experimental Management 16: 153-171. Ref ID: 94 Kennedy, V. S. 1983. Sex ratios in oysters, emphasizing Crassostrea virginica from Chesapeake Bay, Maryland. The Veliger 25: 329-338. Ref ID: 158 Kennedy, V. S. 1989. The Chesapeake Bay Oyster Fishery: Traditional Management Practices. UM-SG-RS-89-03, Sea Grant College Program, University of Maryland, College Park, MD Ref ID: 93 Kennedy, V. S., Newell, R. I. E., Krantz, G. E., and Otto, S. 1995. Reproductive capacity of the eastern oyster Crassostrea virginica infected with the parasite Perkinsus marinus . Diseases of Aquatic Organisms 23: 135-144. Ref ID: 78 Abstract: We studied the influence of the protozoan parasite Perkinsus marinus (Mackin, Owen & Collier) on reproduction in the eastern oyster Crassostrea virginica (Gmelin) from 2 sub-estuaries of central Chesapeake Bay, Maryland, in 1990 and 1991. One hypothesis was that increased levels of infection by P. marinus would result in smaller egg size and diminished lipid reserves within individual eggs. Our results did not reveal any consistent deleterious effects of P. marinus on these gametogenic characteristics, although some of our sample sizes were small and the average disease intensities were low, Our second hypothesis, that there would be a decline in reproductive output as a result of high levels of P. marinus infection, was supported for one estuary when those oysters were near their peak of reproductive condition (July). We found no evidence to support our third hypothesis that there would be a negative influence of infections during the 1990 reproductive season on subsequent reproductive output (summer 1991). Based on published evidence that P. marinus can inhibit oyster growth, we speculate that oysters infected at low intensities by P. marinus can divert energy from growth to reproduction. This differential energy partitioning allows infected oysters to produce fewer eggs than uninfected oysters but with no change in the amount of lipid reserves stored in each egg. Kennedy, V. S., Newell, R. I. E., and Eble, A. F. 1996. The Eastern Oyster Crassostrea virginica. Maryland Sea Grant College, Univeristy of Maryland. College Park, MD. Ref ID: 146 Kennedy, V. S. 1996. The ecological role of the eastern oyster, Crassostrea virginica, with remarks on disease. Journal of Shellfish Research 15: 177-183. Ref ID: 155 Abstract: Historical writings and the presence of pre-Colonial shell middens provide evidence that individual eastern oysters Crassostrea virginica (Gmelin, 1791) grew larger and formed more extensive reefs than they do under present-day conditions of harvesting, habitat destruction, and disease. Their diminished abundance has reduced their roles in providing hard substrate, in filtering the estuarine water column, and in affecting energy flow and nutrient flux. The poorly understood interactions among the abundant inhabitants of oyster assemblages have undoubtedly also been affected, although it is not clear how or by how much. The one important difference between the results of mortality from harvesting compared with mortality from disease may be that the shells of disease-stricken oysters remain on the oyster bar to continue to serve as substrate. There may be a connection between stress imposed by overfishing or habitat alteration and susceptibility of eastern oysters to disease. Kennedy, V. S. and Sanford, L. P. 1999. Characteristics of relatievly unexploited beds of the eastern oyster, Crassostrea virginica, and early restoration programs. Pages 25-46 in M. Luckenbach, R. Mann, and J. A. Wesson, editors. Oyster Reef Habitat Restoration: A Synopis and Synthesis of Approaches. Virginia Institute of Marine Science Press, Glouchester Point, VA. Ref ID: 647 Kesarcodi-Watson, A., Lucas, J. S., and Klumpp, D. W. 2001. Comparative feeding and physiological energetics of diploid and triploid Sydney rock oysters, Saccostrea commercialis. I. Effects of oyster size. Aquaculture 203: 177-193. Ref ID: 575 Kimmerer, W. J., Gartside, E., and Orsi, J. J. 1994. Predation by an introduced clam as the likely cause of substantial declines in zooplankton of San Francisco Bay. Marine Ecology-Progress Series 113: 81-93. Ref ID: 628 Kingsley, D. H. and Richards, G. P. 2003. Persistence of Hepatits a virus in oysters. Journal of Food Protection 66: 331-334. Ref ID: 563 Kirby, M. X. 2004. Fishing down the coast: Historical expansion and collapse of oyster fisheries along continental margins. Proceedings of the National Academy of Sciences of the United States of America 101: 13096-13099. Ref ID: 658 Abstract: Estuarine ecosystems have changed dramatically from centuries of fishing, habitat disturbance, sedimentation, and nutrient loading. Degradation of oyster reefs by destructive fishing practices in particular has had a profound effect on estuarine ecology, yet the timing and magnitude of oyster-reef degradation in estuaries is poorly quantified. Here, I evaluate the expansion and collapse of oyster fisheries in 28 estuaries along three continental margins through the analysis of historical proxies derived from fishery records to infer when oyster reefs were degraded. Exploitation for oysters did not occur randomly along continental margins but followed a predictable pattern. Oyster fisheries expanded and collapsed in a linear sequence along eastern North America (Crassostrea virginica), western North America (Ostreola conchaphila), and eastern Australia (Saccostrea glomerata). Fishery collapse began in the estuaries that were nearest to a developing urban center before exploitation began to spread down the coast. As each successive fishery collapsed, oysters from more distant estuaries were fished and transported to restock exploited estuaries near the original urban center. This moving wave of exploitation traveled along each coastline until the most distant estuary had been reached and overfished. Klinck, J. M., Powell, E. N., Kraeuter, J. N., Ford, S. E., and Ashton-Alcox, K. A. 2001. A fisheries model for managing the oyster fishery during times of disease. Journal of Shellfish Research 20: 977-989. Ref ID: 147 Abstract: Setting the yearly allocation for a fished stock is always an uncertain endeavor. Populations suffering significant mortality from disease require particularly careful management. Disease mortality is not a standard component of Fisheries models, however. Here, we develop a model for the management of fished oyster populations in which disease mortality is a controlling influence. The model requires a quantitative estimate of abundance by size class, some knowledge about growth rates to establish the size range recruiting into the fishery, and an estimate of the anticipated natural mortality rate. The latter is of considerable consequence because small changes in mortality rate effect large changes in predicted outcomes. The model permits investigation of scenarios that include a range of allocations, timing of fishing seasons, variation in fishing efforts within seasons to establish a preferred harvest level, variations in the distribution of fishing among beds to minimize overharvesting of disease-affected beds (area management), and rebuilding plans to increase total stock abundance after epizootic mortality or periods of overharvesting. The model is sufficiently general that it can be applied to any commercial shellfish species. Simulations show that appropriate timing of the fishing season with respect to the timing of disease mortality can more than double the yearly allocation to the fishery. Some harvested animals would otherwise have died from disease. Besides disease, the other model parameter that most affects simulation outcome is the abundance of submarket-size oysters that can be expected to recruit to the fishery in the simulated year. Population stability is strongly determined by the number of recruits available to replace the deaths that decimate the market-size population each year. The number of recruits is a function of survivorship in previous years, but also the anticipated growth rate that defines the size range of oysters at the beginning of the fishing year that can be expected to recruit to the fishery. This modeling exercise points to the critical need to understand population dynamics and survival of size classes below market size that are not often the targets of investigatory activities. Klinck, J. M., Hofmann, E. E., Powell, E. N., and Dekshenieks, M. M. 2002. Impact of channelization on oyster production: a hydrodynamic-oyster population model for Galveston Bay, Texas. Environmental Modeling & Assessment 7: 273-289. Ref ID: 557 Abstract: A hydrodynamic-oyster population dynamics model was developed to assess the effect of a change in ship channel configuration under different freshwater inflow regimes and different future hydrologies on oyster (Crassostrea virginica) populations in Galveston Bay, Texas. The population dynamics model includes the effects of environmental conditions, predators, and the oyster parasite Perkinsus marinus on oyster populations. The hydrodynamic model includes the effects of wind stress, river runoff, tides, and oceanic exchange on the circulation of the Bay. Simulations were run for low, mean, and high freshwater inflow conditions under the present (1993) hydrology and predicted hydrologies for 2024 and 2049 that include anticipated water diversion projects to satisfy the freshwater demands of population growth in metropolitan Houston, Texas. Simulation results show that oyster biomass was predicted to increase after enlargement of the ship channel. Oyster biomass is expected to increase on about 53% of total reef acreage when averaged over a 50-yr time span. Oyster reef acreage characterized by increased biomass after channel enlargement increases moderately under the present hydrology and the 2049 hydrology, but decreases slightly in 2024. Lower biomass in 2024 is due to reduced freshwater inflow and increased saltwater intrusion that pushes the optimal areas for oyster growth somewhat farther upbay than in 2049. Declines in oyster biomass, noted in most simulations in downbay reaches, were more than balanced by increased oyster biomass upbay. The differential between upbay and downbay reefs can be explained by an increase in mortality from Perkinsus marinus downbay and saltwater intrusion upbay that expands the area characterized by moderate salinities. The 20th century history of Galveston Bay is one of expansion of isohaline structure and increased oyster production as a result of anthropogenic modification of bay physiography. The salinity gradient of the 1990s, however, is not in equilibrium with the distribution of hard substrate required for oyster growth, that reflects an earlier equilibrium with the pre-1900s hydrodynamics. Increased saltwater intrusion is normally disadvantageous to oyster populations; but, in this case, channel enlargement further expands the salinity gradient upbay and outward (east and west) from the channel. As a result, in most years, oyster biomass is increased because moderate salinities cover more of the pre-1900s reef tracts where hard substrate is plentiful Kobayashi, M., Hofmann, E. E., Powell, E. N., Klinck, J. M., and Kusaka, K. 1997. A population dynamics model for the Japanese oyster, Crassostrea gigas. Aquaculture 149: 285-321. Ref ID: 7 Abstract: Relationships that describe the growth of the Japanese oyster, Crassostrea gigas, were developed using measurements made from June 1990 to January 1991 in mariculture fields located in Hinase waters of the Okayama Prefecture, Japan. These relationships show that shell length increase for Hinase oyster populations of 50-100mm in size was similar to that measured for C. gigas populations in the UK; however, the Hinase oysters were lighter for a given length than oysters found in Israel, Canada, Australia and Korea. Increases in live weight were greater in smaller oysters and lower for larger oysters than those observed for C. gigas populations in other areas. This suggests that the linear increase in live weight is a feature of artificially cultured C. gigas populations in Hinase waters. These data were used to calculate regressions between shell length and live weight, wet meat weight and dry meat weight, and dry meat weight and wet meat weight. Additionally, measurements of the gonadal condition of the C. gigas populations indicated that gonadal tissue development occurred when water temperatures were above 23 degrees C. These relationships were then used as input into a mathematical model that describes the time-dependent evolution of post-settlement oyster populations. A filtration rate relationship was developed for C. gigas, examined for general applicability, and used for the oyster population model. This relationship accounts for the faster growth of C. gigas relative to that of Crassostrea virginica. Similarly, two relationships for respiration rate were examined with the oyster population model. The relationships differed in the amplitude of the respiration rate, namely, one provided a rate 60% lower than the other for a given dry meat weight at 20 degrees C. The final biological process examined with the model was the reproductive efficiency, which determined the apportionment of net production to somatic and reproductive tissue growth. The simulated post-settlement oyster populations showed growth rates that agreed with those measured for field cultivated populations in Hinase waters when the lower respiration rate was used with a reproductive efficiency that varied from 0.0 to 0.8 between 23 and 27 degrees C. This modeling effort illustrates the changes that are needed to model the population dynamics of C. gigas in comparison with the similar species. C. virginica. Moreover, the model as now configured can be used to investigate effects of oyster density, local environmental conditions, including flow fields, the distribution of mariculture rafts, and cultivation practices on the growth and development of C. gigas. In addition, this model can provide a framework for predicting potential oyster yield from individual mariculture fields. Koehn, R. K. and Shumway, S. E. 1982. A genetic/physiological explaination for the differential growth rate among individuals of the American oyster, Crassostrea virginica (Gmelin). Marine Biology Letters 3: 35-42. Ref ID: 150 Kolar, C. S. and Lodge, D. M. 2002. Ecological predictions and risk assessment for alien fishes in North America. Science 298: 1233-1236. Ref ID: 119 Abstract: Methods of risk assessment for alien species, especially for nonagricultural systems, are largely qualitative. Using a generalizable risk assessment approach and statistical models of fish introductions into the Great Lakes, North America, we developed a quantitative approach to target prevention efforts on species most likely to cause damage. Models correctly categorized established, quickly spreading, and nuisance fishes with 87 to 94% accuracy. We then identified fishes that pose a high risk to the Great Lakes if introduced from unintentional ( ballast water) or intentional pathways ( sport, pet, bait, and aquaculture industries). Kraeuter, J. N., Ford, S., and Canzonier, W. 2003. Increased biomass yield from delaware bay oysters (Crassostrea virginica) by alternation of planting season. Journal of Shellfish Research 22: 39-49. Ref ID: 542 Abstract: The practice of moving oysters from low-salinity to high-salinity areas for improving growth and meat quality has been practiced for well over a century. In the Delaware Bay, the practice was abruptly changed when MSX (Haplosporidium nelsoni) caused large-scale oyster mortality in the higher salinity portions of the bay. Similar disruptions occurred in Chesapeake Bay and other areas. In time the Delaware Bay, the oyster industry learned how to operate around the disease. but in early 1990s, Dermo (Perkinsus marinus) began to cause serious mortality on transplanted oysters. Despite the historic and continuing movement of oysters within and between estuaries, there is little published scientific literature indicating optimum conditions for transplantation. We investigated the effects of transplantation front a low-salinity seed bed to a typical higher salinity leased ground. The transplants were designed to evaluate an early, the traditional spring, and two fall transplant dates on the subsequent disease levels, growth, and survival of the oysters in three size classes: market. submarket, and small. Environmental and oyster disease data suggest we conducted the experiment under nearly worse-case conditions, high Dermo, and low food (chlorophyll). There were no significant differences associated with the timing of transplant. We did not record significant growth on any size oyster and disease caused mortality exceeded 50% for early transplants. Smaller oysters experienced greater mortality than market size individuals. Despite these conditions, meat dry weight nearly doubled within 1 to 2 mo after transplant in all but the March transplant. Under these disease and environmental conditions the only economic gain would be from the doubling of the meat weight and associated better meat quality. No gain can be expected from submarket oysters growing into the market size classes Krantz, G. E. and Chamberlin, J. V. 1978. Blue crab predation on cultchless oyster spat. Proceedings of the National Shellfisheries Association 68: 38-41. Ref ID: 175 Krantz, G. E. 1993. Oyster recruitment in the Chesapeake Bay 1939 to 1993., Maryland Department of Natural Resources, Oxford, MD Ref ID: 590 Krantz, G. E. and Jordan, S. J. 1996. Management alternatives for protecting Crassostrea virginica fisheries in Perkinsus marinus enzootic and epizootic areas. Journal of Shellfish Research 15: 167-176. Ref ID: 36 Abstract: We review management of oyster stocks infected by Perkinsus marinus, comparing previously published recommendations with current practices, with emphasis on the public fishery in the Maryland portion of Chesapeake Bay. The epizootiology of perkinsiasis is described, particularly the spread of the disease into low salinity areas. We also describe recent attempts to develop a policy and management framework for restoration of oyster populations that have been depleted by P. marinus and Haplosporidium nelsoni. It is apparent from experiences in Gulf of Mexico estuaries, Long Island Sound, and Maryland that strong recruitment can, to some extent, offset the impacts of P. marinus on oyster fisheries. Although improved management practices so far have had very limited success in maintaining harvestable stocks in the Chesapeake, it is clear that the recruitment potential of oyster populations has not been diminished to a critical point. Strategies designed to enhance and supplement natural recruitment, along with maintaining growing areas as free from P. marinus infections as possible, currently offer the most promise for maintaining harvestable stocks. In combination, new developments in research, management, monitoring, and policy are cause for guarded optimism, both for larger, sustainable harvests and for restoration of some of the ecological functions of healthy oyster populations. La Peyre, M. K., Nickens, A. D., Volety, A. K., Tolley, G. S., and La Peyre, J. F. 2003. Environmental significance of freshets in reducing Perkinsus marinus infection in eastern oysters Crassostrea virginica: potential management applications. Marine Ecology-Progress Series 248: 165-176. Ref ID: 502 Abstract: The effects of extreme freshwater events on Perkinsus marinus-Crassostrea virginica interactions remain unexplored. The effects of freshwater events on R marinus infection in C. virginica and oyster survival were therefore examined in controlled laboratory experiments and a field study. For the laboratory experiments, oysters were collected in spring, summer and winter from an area in Louisiana where R marinus is endemic. Oysters were placed in 2 recirculating water systems at a salinity and temperature similar to their collection site. They were subjected to 2 salinity treatments (freshet and control). Freshet events were simulated by reducing the water to salinities of 0 to 1 ppt over a 48 h period, and maintained for a 21 d period. Control oysters were maintained at the initial salinity. Thirty oysters were sampled prior to the freshet event, and 30 oysters per treatment group (freshet, control) were sampled on Days 7, 14 and 21 after initiation of the freshet event. Oyster mortality, R marinus infection intensities, oyster condition index and oyster plasma osmolality were measured in weekly samples. All 3 simulated freshet events (i.e. spring, summer, winter) resulted in a significant reduction in P. marinus infection intensity, but failed to eliminate infection. The failure of the oyster plasma to reach very low osmolality (<50 mOsm kg(-1)) provides a likely explanation for the lack of complete P. marinus elimination. The field study involved sampling oysters monthly in the Caloosahatchee estuary, Florida, from September 2000 to February 2002, and determining P. marinus weighted prevalence and condition index of wild oysters, and growth and survival of caged juvenile oysters. The data strongly support the contention that the numerous freshwater releases to the Caloosahatchee River kept P. marinus infection intensities in oysters at low levels, resulting in an overall low weighted prevalence, low oyster mortality and good growth. Data from our field study appear to support the hypothesis that repetitive and well-timed freshet events can prevent infection of oysters with P. marinus or at least maintain P. marinus infections at non-lethal intensities (e.g. <10(6) parasites g(-1) wet tissue) in oyster populations. The use of an adaptive management approach involving control of freshwater inflows could be invaluable to the oyster industry in areas close to freshwater diversion projects Lackey, R. T. 1994. Ecological risk assessment. Fisheries 19: 14-18. Ref ID: 102 Lackey, R. T. 1996. Is ecological risk assessment useful for resolving complex ecological problems? Pages 525-540 in D. J. Stouder, P. A. Bisson, and R. J. Naiman, editors. Pacific Salmon and Their Ecosystems: Status and Future Options. Chapman and Hall. Ref ID: 118 Lam, K. and Morton, B. 2003. Mitochondrial DNA and morphological identification of a new species of Crassostrea (Bivalvia : Ostreidae) cultured for centuries in the Pearl River Delta, Hong Kong, China. Aquaculture 228: 1-13. Ref ID: 672 Abstract: The cultivation of a species of Crassostrea in the Pearl River Delta, China, is reputed to have a similar to 700-year history, the industry in Hong Kong currently being centred around the village of Lau Fau Shan in Deep Bay. The identity of the cultured species of Crassostrea in Hong Kong has been discussed for many years. The objective of this study was, therefore, to determine its specific identity by comparing the genetic distances of mitochondrial DNA sequences, that is, partial cytochrome oxidase I and 16S genes with those of other Crassostrea species. This is the first species of Ostreidae to be described genetically, in addition to shell characters. Phylogenetic analyses based on the cytochrome oxidase I and 16S data set show that Crassostrea hongkongensis is a genetically distinct taxon. The new species is genetically a sister taxon to Crassostrea nippona. Distinctive features of C hongkongensis include an elongated, resilifer-like ligamental area, a D-shaped adductor muscle scar with a straight or slightly convex dorsal margin, three colour patterns and thin, brownish yellow lamellae covering the uneroded right valve. This study highlights the significance of using molecular genetics, accompanied by morphology, in identifying species of the notoriously phenotypically plastic Ostreidae. Lam, K. and Morton, B. 2004. The oysters of Hong Kong (Bivalvia : Ostreidae and Gryphaeidae). The Raffles Bulletin of Zoology 52: 11-28. Ref ID: 670 Abstract: In this revision of the oysters of Hong Kong, twelve species of Ostreidae and Gryphaeidae are described in terms of their shell characters and habitats. Of these, Crassostrea ariakensis, Saccostrea mordax, Dendostrea crenulifera, Ostrea denselamellosa, Crassostrea lugubris and Crassostrea angulata are new records for Hong Kong. Since species identification based on shell characters alone are inadequate, the identities of Hong Kong C. lugubris and C. angulata were determined by subjecting their mitochondrial DNA cytochrome oxidase I (COI) gene sequences to phylogenetic analyses. Other species from Hong Kong such as Saccostrea cucullata, Saccostrea mordax, Planostrea pestigris, Dendostrea folium and Hyotissa imbricata are also identified, as is Crassostrea hongkongensis, a recently described new species. Langdon, C. J. and Robinson, A. M. 1993. Guide for the culture of the Suminoe oyster (Crassostrea rivularis)., Hatfield Marine Science Center, Oregon State University, Newport, Oregon Ref ID: 49 Langdon, C. J. and Robinson, A. M. 1996. Aquaculture potential of the Suminoe oyster (Crassostrea ariakensis Fugita 1913). Aquaculture 144: 321-338. Ref ID: 47 Abstract: Oyster production on the West coast of the USA is almost entirely dependent on the culture of the Pacific oyster Crassostrea gigas. Commercial production of the Suminoe oyster Crassostrea ariakensis is presently limited to a few bays in Washington, Oregon and California. The objective of the present study was to determine the aquaculture potential of the Suminoe oyster for the West coast, USA. Female Suminoe oysters became sexually mature about 3 months later than Pacific oysters in Yaquina Bay, OR. Suminoe oyster broodstock could be successfully conditioned at 20 degrees C for spawning from mid-March until mid-October. Larvae were cultured and successfully set by feeding them on a microalgal diet of the flagellate Pseudoisochrysis paradoxa (VA-12) during the first 7 days of culture and then a diet made up wholly or partly of the diatom species Chaetoceros calcitrans during subsequent weeks of culture. Growth and setting of larvae were greatest at a salinity of 15 to 20 ppt. No successful settlement occurred at 35 ppt salinity. Both Suminoe and Pacific oyster spat grew best at 25 degrees C and a salinity of 25 to 35 ppt. Growth of Suminoe oyster spat was less sensitive to sub-optimal temperature and salinity conditions than Pacific oysters. In grow-out trials conducted from 1989 to 1993 on the West coast, USA, final shell lengths of Suminoe oysters were significantly less than those of Pacific oysters, but there were no significant differences in tissue dry weights. Both Suminoe and Pacific oysters reached market size for the half-shell trade (60 to 70 mm shell length) 12 to 18 months after planting. Consumer acceptability tests indicated that Suminoe oysters were equal or superior to Pacific oysters in appearance, taste and texture. Lee, M. B. and Lee, E. H. 2003. Passage of a coccidial parasite (Eimeria acervulina) through the eastern oyster (Crassostrea virginica). Journal of Food Protection 66: 679-681. Ref ID: 564 Lehnert, R. L. and Allen, D. M. 2002. Nekton use of subtidal oyster shell habitat in a southeastern US estuary. Estuaries 25: 1015-1024. Ref ID: 261 Abstract: Subtidal accumulations of oyster shell have been largely overlooked as essential habitat for estuarine nekton. In southeastern U.S. estuaries, where oyster reef development is mostly confined to the intertidal zone, eastern oyster (Crassostrea virginica) shell covered bottoms are often the only significant source of hard subtidal structure. We characterized and quantified nekton use of submerged shell rubble bottoms, and compared it to use of intertidal reefs and other subtidal bottoms in the North Inlet estuary, South Carolina. Replicate trays (0.8 m(2)) filled with shell rubble were deployed in shallow salt marsh creeks, and were retrieved after soak times of 1 to 25 days from May 1998 to March 2000. Thirty six species of fishes, representing 21 families, were identified from the 455 tray collections. Water temperature, salinity, soak time and the presence of a shell substrate all affected the catch of fishes in the trays. Catches during the warmer months were two to five times greater than those during the winter. Fishes were present in 98% of the trays with an overall average of 5.7 fish m(-2). The assemblage was numerically dominated by small resident species including naked goby (Gobiosoma bosc), oyster toadfish (Opsanus tau), and crested blenny (Hypleurochilus geminatus). Transient species accounted for 23% of all individuals and 62% of the total biomass due to the presence of relatively large sheepshead (Archosargus probatocephalus) and black sea bass (Centropristis striata). Both the transient and resident species displayed distinct periods of recruitment and rapid growth from April to October. Lower abundances of juvenile gobies and blennies during 1998 were attributed to long periods of depressed salinity caused by high rainfall associated with El Nino conditions in spring. Crabs and shrimps, which were often more abundant than the fishes, accounted for comparable biomass in the tray collections. In comparisons of subtidal tray and trawl catches, trays yielded 10 to 1,000 fold higher densities of some demersal fish groups. Comparisons of intertidal and subtidal gear catches indicated that many species remain in the subtidal shell bottom at all stages of the tide. This study suggests that subtidal shell bottom may be essential fish habitat for juvenile seabass, groupers, and snappers and that it may be the primary habitat for a diverse assemblage of ecologically important resident fishes and crustaceans. Given the high levels of nekton use and the areal extent of oyster shell bottoms in eastern U.S. and Gulf estuaries, increased attention to protection and restoration of these areas appears justified Lehotay, S. J., Harman-Fetcho, J. A., and McConnell, L. L. 1998. Agricultural pesticide residues in oysters and water from two Chesapeake Bay tributaries. Marine Pollution Bulletin 37: 32-44. Ref ID: 440 Abstract: Little is known of the impact of agricultural activity on oysters in Chesapeake Bay tributaries. As a preliminary assessment of pesticide residues in oyster tissues, this study monitored more than 60 pesticides in oysters and overlying water in two tributaries of the Chesapeake Bay Paired water and oyster samples were collected throughout 1997 from the Patuxent and Choptank Rivers which discharge into opposite shores of the Chesapeake Bay in Maryland. In water, herbicides such as atrazine, simazine, cyanazine, and metolachlor were present throughout the year with individual water concentrations peaking as high as 430 ng/l in the late spring and summer and subsiding in the fall. These herbicides were not detected in the oysters even when concentrations were highest in the water. Another herbicide, trifluralin, was detected throughout the year at concentrations of less than 0.6 ng/l and 0.4 ng/g (wet weight) in water and oyster samples, respectively. Several insecticides, such as endosulfans I and II, endosulfan sulfate, chlorpyrifos, alpha- and gamma-HCH, p,p'-DDE, o,p'-DDT, trans-nonachlor, and trans-chlordane were also measured in bath oysters and water at low concentrations. Published by Elsevier Science Ltd Leitao, A., Boudry, P., Labat, J. P., and Thiriot-Quievruex, C. 1999. Comparative Karyological study of cupped oyster species. Malacologia 41: 175-186. Ref ID: 188 Abstract: Chromosomes of six cupped oyster species were studied using karyometric analysis after conventional Giemsa staining, and silver staining. Karyotypes of Crassotrea angulata (nine metacentric and one submetacentric chromosome pairs), C. sikamea (nine metacentric and one submetacentric chromosome pairs), C. virginica (eight metacentric and two submetacentric chromosome pairs), C. ariakensis (eight metacentric and two submetacentric chromosome pairs), C. gasar (six metacentric and four submetacentric chromosome pairs), and Saccostrea commercialis (eight metacentric and two submetacentric chromosome pairs) are distinguishable by the number and position of the submetacentric chromosome pair and by the location of nucleolus organizer regions. Comparative karyological analysis of these six cupped oysters and of C. gigas was made using a Principal Component Analysis and a Hierarchical Clustering Analysis. Crassostrea gasar appears isolated from the other oyster species. Then, two clusters are separated. The first one groups C. gigas, C. angulata and C. sikamea, in which C. gigas is plesiomorphic. The second one consists of C. ariakensis, C. virginica and S. commercialis. Results are discussed with regards to oyster species relationships based on other genetic characters and to hybridization possibilities. Lenihan, H. S. and Peterson, C. H. 1998. How habitat degradation through fishery disturbance enhances impacts of hypoxia on oyster reefs. Ecological Applications 8: 128-140. Ref ID: 517 Abstract: Oysters are ecosystem engineers that create biogenic reef habitat important to estuarine biodiversity, benthic-pelagic coupling, and fishery production, Prevailing explanations for the dramatic decline of eastern oysters (Crassostrea virginica) during the last century overlook ecosystem complexity by ignoring interactions among multiple environmental disturbances. To explain oyster loss, we tested whether (1) mortality of oysters on natural oyster reefs varies with water depth (3 m vs. 6 m), (2) harvesting by oyster dredges reduces the height of oyster reefs, and (3) bottom-water hypoxia/anoxia and reduction in reef height through fishery disturbance interact to enhance mortality of oysters in the Neuse River estuary, North Carolina, USA. The percentage of oysters found dead (mean +/- 1 SD) during a survey of natural reefs in May 1993 was significantly greater at 6-m (92 +/- 10%) than at 3-m (28 +/- 9%) water depth. Less than one season's worth of oyster dredging reduced the height of restored oyster reefs by similar to 30%. During stratification of the water column in summer, oxygen depletion near the seafloor at 6 m caused mass mortality of oysters, other invertebrates, and fishes on short, deep experimental reefs, while oysters and other reef associates elevated into the surface layer by sufficient reef height or by location in shallow water survived. Highly mobile blue crabs (Callinectes sapidus) abandoned burrows located in hypoxic/anoxic bottom waters but remained alive in shallow water, Our results indicate that interaction of reef habitat degradation (height reduction) through fishery disturbance and extended bottom-water hypoxia/anoxia caused the pattern of oyster mortality observed on natural reefs and influences the abundance and distribution of fish and invertebrate species that utilize this temperate reef habitat. Interactions among environmental disturbances imply a need for the integrative approaches of ecosystem management to restore and sustain estuarine habitat Lenihan, H. S., Micheli, F., Shelton, S. W., and Peterson, C. H. 1999. The influence of multiple environmental stressors on susceptibility to parasites: An experimental determineation with oysters. Limnology and Oceangraphy 44: 910-924. Ref ID: 166 Abstract: A large-scale field experiment was used to test whether exposure to a suite of potential environmental factors (flow speed, temperature, salinity, and low dissolved oxygen) influences the level of parasitic infection of the oyster Crassostrea virginica. The parasite was the protozoan Perkinsus marinus, which has decimated populations of oysters in estuaries of North America. The environmental factors were considered stressors because they influence the physiological condition of either the host or parasite. Between December 1994 and July 1995, flow speed, temperature, salinity, dissolved oxygen concentration (DO), Perkinsus infection, and mortality of oysters were monitored across 24 experimental oyster reefs in the Neuse River estuary, North Carolina. Eight reef treatments were created consisting of an orthogonal combination of three factors: water depth (3 m vs. 6 m deep), reef height (2 m vs. 1 m tall), and position on reef (base vs, crest). Principal component analysis revealed that there was clear separation of environmental factors among reefs and that a majority of the variation (96.2%) among treatments could be explained by two principal component axes (PCs): one (24.3% of variation explained) was formed by flow and the other (71.9% of variation explained) by temperature, salinity, and DO. Oysters with the highest proportion of individuals infected (prevalence), highest intensity of infection, and highest mortality were located at the base of reefs, where flow speeds and food quality were lowest and sedimentation rates highest. However, there was no significant effect of hydrographic conditions on Perkinsus infection or mortality of oysters, despite large differences in mean salinity, DO, and exposure to hypoxia-anoxia. Temperature did not vary among treatments. Correlation of disease responses (infection prevalence and intensity, and mortality) with the first two PCs showed that these response variables were significantly (and negatively) correlated with flow only. Oysters in low flow were hypothesized to have:the greatest susceptibility to Perkinsus infection because of their poor physiological condition. The restoration of oyster reefs increases reef height and thus flow speeds (by elevating oysters higher above the boundary and by actively influencing flow), thereby reducing the negative effects of disease by restoring reef morphology to its natural size. Lenihan, H. S. 1999. Physical-biological coupling on oyster reefs: How habitat structure influences individual performance. Ecological Monographs 69: 251-275. Ref ID: 516 Abstract: A large-scale field experiment was conducted to test whether the physical structure of biogenic reef habitat controls physical conditions (hydrodynamics and hydrographics) with subsequent influence on the performance (recruitment, growth, and survival) of a benthic suspension feeder. The experimental system consisted of restored subtidal oyster reefs inhabited by the eastern oyster Crassostrea virginica. To determine whether the size of reefs influences the flow environment and oyster performance, reefs of four heights-tall (2 m), short (1 m), dredged (0.6 m), and low (0.1 m)-were constructed at 3-m water depth in the Neuse River estuary, North Carolina, USA. To test whether oyster performance varies with water depth and hydrographic conditions, tall and short reefs were also constructed at 6-m water depth. Flow speed, sedimentation, temperature, salinity, dissolved oxygen, and the performance of oysters were measured as a function of reef height, position on reef, and water depth over a 10-mo period. Flow speed was found to increase on reefs with reef height and elevation on reefs. Rates of sediment deposition were seasonally highest where flow speed was lowest, at the bases of reefs, and seasonally decreased with increasing water depth. More than 90% of the surface area of low reefs was buried after only 16 mo of exposure in the estuary, indicating that reef height controls habitat quality (and quantity) indirectly through its effect on flow. Short reefs and the bases of tall reefs at 6-m depth were exposed to a total of 26 d of hypoxia/anoxia. No other reef treatment was exposed to >5 d of hypoxia.Physical conditions on experimental reefs had a profound influence on the performance of oysters as the flow environment alone explained 81% of variability in oyster growth and mortality. Recruitment of oysters over a 2-mo period was slightly higher on the front bases than the crests of reefs, but did not vary with reef height or water depth. After 10 mo, the shell growth and condition index of genetically similar, hatchery-raised oysters were greatest on the crests of tall and short reefs, where flow speed and quality of suspended food material were highest, and sediment deposition was lowest. Growth was greatest overall at the crests of tall reefs located at 6-m water depth where flow speed was high, and the numbers of days exposed to hypoxia/anoxia and variation in salinity were lowest. Total percentage mortality of oysters after 10 mo was greater on low reefs located at 3-m depth than on all other reef types and was greater on the bases than crests of tall, short, and dredged reefs. Predation by crabs and fishes accounted for 4-20% of total oyster mortality and showed no pattern across reef treatments. Results of this experiment indicate (1) that the physical structure and location of biogenic habitat controls local physical variables and (2) that, in turn, physical variables, especially flow speed, have a profound influence on the performance of a resident species. Realization that an ecological function of habitat is to indirectly control local population production through physical-biological coupling should improve our ability to conserve, restore, and manage habitat and associated species diversity. Better ecological engineering of restored oyster reef habitat is likely to improve fishery production and help maintain estuarine biodiversity Lenihan, H. S. and Micheli, F. 2000. Biological effects of shellfish harvesting on oyster reefs: resolving a fishery conflict by ecological experimentation. Fishery Bulletin 98: 86-95. Ref ID: 510 Abstract: We conducted a large-scale held experiment to test whether clam and oyster harvesting applied alone and in combination on intertidal oyster reefs have impacts on resident shellfish populations. This experiment was conducted to resolve a long-standing conflict between oyster (Crassostrea virginica (Gmelin, 1791)) and clam (Mercenaria mercenaria (Linneaus, 1758)) fishermen who contend that the other fishery causes high rates of mortality to their respective species. Intertidal oyster reefs located in two estuarine creeks near Wilmington, North Carolina, were harvested for clams only, oysters only, both clams and oysters, or were left undisturbed as controls. Experimental harvesting was conducted over a one-year period by a professional shellfisherman who used realistic fishing techniques (clam rakes and oyster tongs), intensity, and frequency. Harvesting impact on hard clam and oyster populations was assessed by sampling naturally occurring oysters before and after harvesting, and sampling both naturally occurring clams (all size classes) and transplanted, hatchery-raised clams (20-37 mm in length) alter harvesting. Clam and oyster harvesting had obvious negative effects on populations of oysters. There was a substantial decrease in the number of live oysters on clam-harvested and oyster-harvested reefs compared with unharvested, control reefs. Clam and oyster harvesting, applied together, reduced oyster densities and killed unharvested oysters ata level similar to that caused by each type of harvesting applied separately. The effects of the shellfish harvesting on populations of hard clams varied between the two sites (i.e. creeks). In both creeks, clam harvesting, alone and combined with oyster harvesting, significantly decreased the number of live, naturally occurring clams. Oyster harvesting alone decreased the number of live, naturally occurring clams only at one site. Clam harvesting also decreased the number of live, transplanted clams on reefs, but there was no effect of oyster harvesting, because the transplanted clams were juveniles too small to be harvested with oyster tongs. Overall, the combined effect of both types of harvesting applied together did not have a negative synergistic effect an clam and oyster populations. Consequently, both clamming and oyster harvesting should be permitted on some reefs, but maintaining large populations of oysters and clams on intertidal oyster reefs will require protection of some reefs from bath types of harvesting Lenihan, H. S., Peterson, C. H., Byers, J. E., Grabowski, J. H., Thayer, G. W., and Colby, D. R. 2001. Cascading of habitat degradation: Oyster reefs invaded by refugee fishes escaping stress. Ecological Applications 11: 764-782. Ref ID: 268 Abstract: Mobile consumers have potential to cause a cascading of habitat degradation beyond the region that is directly stressed, by concentrating in refuges where they intensify biological interactions and can deplete prey resources. We tested this hypothesis on structurally complex, species-rich biogenic reefs created by the eastern oyster, Crassostrea virginica, in the Neuse River estuary, North Carolina, USA. We (1) sampled fishes and invertebrates on natural and restored reefs and on sand bottom to compare fish utilization of these different habitats and to characterize the trophic relations among large reef-associated fishes and benthic invertebrates, and (2) tested whether bottom-water hypoxia and fishery-caused degradation of reef habitat combine to induce mass emigration of fish that then modify community composition in refuges across an estuarine seascape. Experimentally restored oyster reefs of two heights (1 m tall "degraded" or 2 m tall "natural" reefs) were constructed at 3 and 6 m depths. We sampled hydrographic conditions within the estuary over the summer to monitor onset and duration of bottom-water hypoxia/anoxia, a disturbance resulting from density stratification and anthropogenic eutrophication. Reduction of reef height caused by oyster dredging exposed the reefs located in deep water to hypoxia/anoxia for >2 wk, killing reef-associated invertebrate prey and forcing mobile fishes into refuge habitats. Refugee fishes accumulated at high densities on reefs in oxygenated shallow water, where they depleted epibenthic crustacean prey populations. Thus, physical disturbances can impact remote, undisturbed refuge habitats through the movement and abnormal concentration of refugee organisms that have subsequent strong trophic impacts. These results have implications for the design of Marine Protected Areas (MPAs), showing that reserves placed in proximity to disturbed areas may be impacted indirectly but may serve a critical refuge function on a scale that matches the mobility of consumers Lenihan, H. S. and Peterson, C. H. 2004. Conserving oyster reef habitat by switching from dredging and tonging to diver-harvesting. Fishery Bulletin 102: 298-305. Ref ID: 572 Lewis, E. J., Farley, C. A., Small, E. B., and Baya, A. M. 1996. A synopsis of juvenile oyster disease (JOD) experimental studies in Crassostrea virginica. Aquatic Living Resources 9: 169-178. Ref ID: 545 Abstract: In the late 1980's juvenile oysters, Crassostrea virginica, spawned and cultured in New England and New York, began experiencing up to nearly 100% mortalities in some batches of juveniles. The cause of these mortalities was not ascertained immediately, but examination of dead and dying oysters did not reveal a previously recognized disease syndrome. Early studies showed that it was not an environmental or genetic problem, thus we hypothesized that a new, transmissible disease agent caused the observed mortality. This was verified under laboratory conditions where the disease was readily transmissible. Transmission was enhanced by warm water temperatures, 22-26 degrees C, and salinities of 18-30 ppt. Also, the infectious agent was filterable and sensitive to erythromycin, supporting the hypothesis that the causative agent may be a protistan parasite in the 2-6 mu m size range. No evidence to support a viral or bacterial etiology was found Lewis, V. P. and Peters, D. S. 1994. Diet of juvenille and adult Altantic menhaden in estuarine and coastal habitats. Transactions of the American Fisheries Society 123: 803-810. Ref ID: 668 Abstract: The Atlantic menhaden Brevoortia tyrannus is a pelagic, obligate filter-feeding fish. Although much of the primary literature indicates that amorphous matter is a major component of the stomach contents of Atlantic menhaden, the diet of these fish is typically perceived to consist primarily of phytoplankton and zooplankton. This disparity between observation and perception results from the belief that amorphous matter in the stomachs is the remnants of plankton that were ingested alive or that it is detritus of low nutritional value and only incidentally ingested. In this study, we found that the stomach contents of juvenile and adult Atlantic menhaden in estuarine creeks were 81% amorphous matter, 17% phytoplankton, and 1% zooplankton, by dry weight. Sampling in two estuarine creeks in North Carolina revealed no seasonal change in diet. Stomachs of fish collected from coastal waters contained smaller amounts of amorphous matter (47%) and higher amounts of phytoplankton (36%) and zooplankton (18%) than stomachs of fish from estuarine creeks. The higher concentration of plankton in the diet of fish in coastal locations probably reflects the lower concentration of suspended amorphous matter and higher relative abundance of plankton typical of that environment. In stomachs that contained largely amorphous matter, the concentrations of ash (70%, dry weight) and humic compounds (38%, ash-free dry weight [AFDW]) were high and the carbohydrate content was moderately low (14%, AFDW). On the basis of reported concentrations of these compounds in plankton and amorphous aggregates, we conclude that the amorphous matter we found in the stomachs of Atlantic menhaden was not recently ingested living or moribund plankton, but was probably material that was produced in the environment by the aggregation of dissolved organics from various detrital sources, including decaying vascular plants. If vascular plants contribute to the production of amorphous matter, their role in coastal and estuarine energy flow and fishery production may be underestimated. Li, G., Hubert, S., Bucklin, K., Ribes, V., and Hedgecock, D. 2003. Characterization of 79 microsatellite DNA markers in the Pacific oyster Crassostrea gigas. Molecular Ecology Notes 3: 228-232. Ref ID: 190 Abstract: We characterized 79 microsatellite DNA markers, which were obtained from genomic libraries enriched for CA, GA, ATG and TAGA motif repeats, in the Pacific oyster Crassostrea gigas. For eight F-1 grandparents or great-grandparents of mapping families; the average heterozygosity, 0.705, and average number of alleles per locus, 5.7, did not vary among motif-repeat or motif-complexity categories. Non-amplifying polymerase chain reaction null alleles, which were confirmed by segregation in the mapping families, were detected at 41 (51.9%) of the 79 loci. Cross-species amplifications from C. angulata, C. sikamea, C. ariakensis and C. virginica showed a precipitous decline with distance from the focal species C. gigas. Lin, H. J. and Shao, K. T. 2002. The development of subtidal fouling assemblages on artificial structures in Keelung Harbor, northern Taiwan. Zoological Studies 41: 170-182. Ref ID: 491 Abstract: Effects of substratum, its submersion season, and submersion period on the development of subtical fouling assemblages were examined for a period of 18 mo in a subtropical harbor. Four types of artificial surfaces, including steel, stainless steel, cathodically protected steel, and concrete, were initially submersed in fall and spring, respectively, and sampled every 3-6 mo. There is little evidence that type of substratum influenced the development of fouling assemblages. However, richer taxa and greater biomass of fouling assemblages occurred on spring-than on fall-submersed plates. Fouling biomass reached a maximum at the end of the study period, but the taxa were richest at the end of 12 months. Classification and ordination analyses show that the species compositions of fouling assemblages were structured by submersion season and submersion period of the substratum, but not by the nature of the substratum itself. The oyster, Crassostrea gigas, dominated spring plates throughout the study period, but the assemblages on fall plates were highly variable. This indicates that submersion season and submersion period of the substratum are more important than type of substratum in the development of subtical fouling assemblages. However, the abundance and species composition on spring and fail plates became less dissimilar by the end of 12 mo. This suggests that development takes the same course even with different seasons of submersion, It is likely that the fouling species acted in individualistic manners, and the assemblages were composed simply of fouling species which arrived at that time. Our results demonstrate that the developmental process is greatly affected by seasonal fluctuations in larval abundance and historical components on a substratum Lipcius, R. N. and Stockhausen, W. T. 2002. Concurrent decline of the spawning stock, recruitment, larval abundance, and size of the blue crab Callinectes sapidus in Chesapeake Bay. Marine Ecology-Progress Series 226: 45-61. Ref ID: 659 Abstract: Conservation of exploited marine populations requires knowledge of interannual variation in the characteristics of and relationships between the spawning stock and recruitment, which determine Population resilience and persistence. We examined relationships between spawning stock abundance, postlarval recruitment, larval abundance, and female size of the blue crab in Chesapeake Bay, both within the Spawning grounds over a 13 yr interval (1988 to 2000) and within lower-bay tributaries over 20 yr (1979 to 1998). Our findings establish that there has been a concurrent, persistent and substantial reduction in the spawning stock, recruitment, larval abundance, and female size, Specifically, in 1992 to 2000: (1) spawning stock abundance declined by 81 female size by 8%, and spawning stock biomass by 84%; (2) mean size at maturity (L) diminished by 9%; (3) larval abundance and postlarval recruitment were lower by approximately 1 order of magnitude compared with earlier years. The decrease in these variables was rapid, occurring over 1 to 2 yr, and therefore indicative of a phase shift in the Spawning stock and recruitment, rather than a progressive diminution, We propose that the initial descent resulted from poor recruitment in 1991, despite high spawning stock and larval abundance, and that the poor recruitment in 1991, in concert with high fishing and natural mortality, subsequently led to a diminished spawning stock in 1992 and thereafter, We further suggest that the Spawning stock, larval abundance, and recruitment are unlikely to rebound to former high levels without significant reductions in fishing and natural mortality along with enhanced environmental conditions conducive to successful recruitment. The key consequences of a diminished spawning stock and recruitment are a heightened probability of recruitment failure and reduced resilience to demographic and environmental stochasticity. In addition, the relationships between spawning stock abundance (SSA) and larval abundance, SSA and postlarval recruitment, and SSA and female size were positive and significant. The demonstration of a concurrent decrease and significant association between spawning stock abundance and recruitment, larval abundance and female size is unique for the blue crab and for marine invertebrates in general, and indicates an urgent need to conserve the Spawning stock for long-term sustainable exploitation and population persistence. Lipton, D. W. and Kirkley, J. 1992. A Profile of the Oyster Industry of the Northeastern United States., report to the National Marine Fisheries Service, Northeast Region, 62 pp. Ref ID: 96 Lipton, D. W., Lavan, E. F., and Strand, I. E. 1992. Economics of molluscan introductions and transfers: the Chesapeake Bay dilemma. Journal of Shellfish Research 11: 511-519. Ref ID: 107 Liu, P. and Cui, X. 1999. A discrete model of competition. Mathematics and Computers in Simulation 49: 1-12. Ref ID: 22 Abstract: Sufficient conditions are derived for the global asymptotic stability of the positive equilibrium of the coupled system of difference equations with distributed delays modelling the dynamics of two competing species with discrete generations. The conditions obtained are the same as in the continuous case which are sufficient for the globally asymptotic stability of the positive equilibrium. Livingston, R. J., Howell IV, R. L., Niu, X., Lewis, F. G., and Woodsum, G. C. 1999. Recovery of oyster reefs (Crassostrea virginica) in a gulf estuary following disturbance by two hurricanes. Bulletin of Marine Science 64: 465-483. Ref ID: 87 Abstract: During the summer and fall of 1985, two hurricanes struck the Apalachicola Bay system, a center for oyster (Crassostrea virginica) production in the northeast Gulf of Mexico. The first storm, Hurricane Elena, physically destroyed the major oyster-producing reefs in the Apalachicola estuary in early September (9/1/85). This disturbance was followed a month later by considerable accumulations of spat on those reefs most affected by the storm. The second hurricane, Kate, struck the bay in late November(11/21/85) and probably contributed to the natural mortality of young-of-the-year oysters. However, overall oyster biomass did not seem to be affected by Kate. Subsequent oyster growth was substantial with full recovery of the oyster stock noted within a 12-mo period. A detailed evaluation was made of the response of this important estuarine population to these disturbances. The timing and nature of the disturbances relative to the natural history of the oyster were crucial to the overall recovery pattern of the population. Hurricane Elena occurred at the end of the oyster spawning activity in 1985. Effects of the storm probably increased habitat availability and reduced direct competition and predation such that the oyster population benefited from the successful recruitment. The subsequent storm, Kate, coming after the spawning period, was not as destructive to oyster populations as Elena and could have even enhanced growth of the survivors. Hurricanes are common along the Gulf coast during the spawning period of the oysters; it appears that C. virginica is well adapted for such natural disturbances. The observed response of the Apalachicola oyster population to successive disturbances has significant meaning in terms of the long-term ecological stability of estuarine populations and the evolutionary aspects of such biological response to temporally unstable habitats. In this case, such populations can be viewed as highly resilient under even the most extreme conditions of physical instability. However, the exact biological response to temporally irregular disturbances is highly dependent on the timing of such events relative to the natural history of population in question. Livingston, R. J., Lewis, F. G., Woodsum, G. C., Niu, X. F., Galperin, B., Huang, W., Christensen, J. D., Monaco, M. E., Battista, T. A., Klein, C. J., Howell, R. L., and Ray, G. L. 2000. Modelling oyster population response to variation in freshwater input. Estuarine Coastal and Shelf Science 50: 655-672. Ref ID: 558 Abstract: This paper describes the linkage of a three-dimensional hydrodynamic circulation model with descriptive and experimental biological data concerning oyster (Crassostrea virginica) population dynamics in the Apalachicola Estuary (Florida, U.S.A.). Our intent was to determine the direct and indirect role of Apalachicola River flow in the maintenance of oyster production. Results of a monthly field sampling programme conducted on the oyster reefs in the Apalachicola system during 1985-1986 were used to develop statistical models relating several life-history characteristics of oysters to physical-chemical aspects of water quality. The same life-history characteristics were related statistically to output from a circulation model of Apalachicola Bay. Highest oyster densities and overall bar growth were found in the vicinity of the confluence of high salinity water moving westwards from St George Sound and river-dominated (low salinity) water moving south and eastwards from East Bay. With the exception of models for oyster mortality, the predictive capability of results from the parallel modelling efforts was low. A time-averaged model was developed for oyster mortality during the summer of 1985 by running a regression analysis with averaged predictors derived from the hydrodynamic model and observed (experimental) mortality rates throughout the estuary. A geographic information system was then used to depict the results spatially and to compare the extent of expected mortality in 1985 and 1986. High salinity, relatively low-velocity current patterns, and the proximity of a given oyster bar to entry points of saline Gulf water into the bay were important factors that contribute to increased oyster mortality. Mortality was a major determinant of oyster production in the Apalachicola Estuary with predation as a significant aspect of such mortality. By influencing salinity levels and current patterns throughout the bay, the Apalachicola River was important in controlling such mortality. Oyster production rates in the Apalachicola system depend on a combination of variables that are directly and indirectly associated with freshwater input as modified by wind, tidal factors, and the physiography of the bay. River flow reduction, whether through naturally occurring droughts, through increased upstream anthropogenous (consumptive) water use, or a combination of the two, could have serious adverse consequences for oyster populations. By coupling hydrodynamic modelling with descriptive and experimental biological data, we were able to determine the effects of potential freshwater diversions on oyster production in Apalachicola Bay. (C) 2000 Academic Press Losee, E. 1979. Relationship between larval and spat growth rates in the oyster (Crassostrea virginica). Aquaculture 16: 123-126. Ref ID: 65 Luo, J., Hartman, K. J., Brandt, S. B., Cerco, C. F., and Rippetoe, T. H. 2001. A spatially-explict approach for estimating carrying capacity: an application for the Atlantic menhaden (Brevoortia tyrannus ) in Chesapeake Bay. Estuaries 24: 545-556. Ref ID: 607 Lutz, C. G. 2003. Asian oysters in the Chesapeake Bay - a new beginning? Aquaculture Magazine 29: 28-32. Ref ID: 548 MacKenzie, C. L. Jr. 1970. Causes of oyster spat mortality, conditions of oyster seetling beds, and recommendations for oyster bed management. Proceedings of the National Shellfisheries Association 60: 59-67. Ref ID: 90 MacKenzie, C. L. Jr. 1977. Development of an aquacultural program for rehabilitation of damaged oyster reefs in Mississippi. Marine Fisheries Review 39: 1-13. Ref ID: 152 MacKenzie, C. L. Jr. 1981. Biotic potential and environmental resistancee in the American oyster (Crassostrea virginica) in Long Island Sound. Aquaculture 22: 229-268. Ref ID: 92 MacKenzie, C. L. Jr. 1983. To increase oyster production in the northeastern United States. Marine Fisheries Review 45: 1-22. Ref ID: 163 Maguire, L. A. 2004. What can decision analysis do for invasive species management? Risk Analysis 24: 859-868. Ref ID: 638 Mann, R., Meehan, B., Rainer, J. S., Kennedy, V. S., Newell, R. I. E., and Van Heukelem, W. F. 1987. Influence of low oxygen tensions on larvae and post settlement stages of the oyster Crassostrea virginica. Pages 140-143 in G. B. Mackiernan, editor. Dissolved Oxygen Processes in the Chesapeake Bay: Processes and Effects. UM-SG-TS-87-03, Maryland Sea Grant Publisher, College Park, MD. Ref ID: 651 Mann, R. 1988. Distribution of bivalve larvae at a frontal system in the James River, Virginia. Marine Ecology Progress Series 50: 29-44. Ref ID: 203 Mann, R., Burreson, E. M., and Baker, P. K. 1991. The decline of the virginia oyster fishery in Chesapeake Bay: considerations for introduction of a non-endemic species, Crassostrea gigas (Thunberg, 1793). Journal of Shellfish Research 10: 379-388. Ref ID: 114 Mann, R., Campos, B. M., and Luckenbach, M. W. 1991. Swimming rate and responses of larvae of three mactrid bivalves to salinity discontinuitues. Marine Ecology Progress Series 68: 257-269. Ref ID: 202 Abstract: Straight-hinge, umbo and pediveliger larvae of the mactrid bivalves Spisula solidissima, Mulinia lateralis and Rangia cuneata were exposed to intense salinity discontinuities of 0, 5, 10 and 15 parts per thousand in vertically oriented swimming chambers. Larvae concentrated in the region of highest gradient, i.e. at the salinity discontinuity, regardless of species, stage of development or larval brood. S. solidisima larvae, initially swimming at 30 parts per thousand salinity, crossed discontinuities of both 5 and 10 parts per thousand but not of 15 parts per thousand. M. lateralis larvae, initially swimming at 25 parts per thousand salinity, also crossed a discontinuity of 5 parts per thousand but not of 10 or 15 parts per thousand. R. cuneata larvae, initially swimming at 10 parts per thousand salinity, generally preferred to remain at that salinity. Swimming and passive sinking velocities, defined as vertical distance traversed per unit time, were measured in different salinities under constant temperature and light. For all species, swimming rate changed with larval stage, highest velocity occurring at the umbo stage. Upward swimming rate of S. solidissima larvae ranged from 0.18 to 0.49 mm s-1 and increased with increasing salinity. Upward swimming rate of M. lateralis larvae ranged from 0.25 to 0.50 mm s-1, but was not consistently related to salinity. Upward swimming rate of R. cuneata larvae ranged from 0.18 to 0.53 mm s-1; swimming rate of pediveliger larvae increased consistently as salinity decreased. Downward swimming rates were similar to upward rates. No significant differences in downward swimming rate were detected in relation to salinity. Passive sinking was more frequent than active downward swimming in umbo and pediveliger larvae. Sinking rate increased with larval size of S. solidissima and M. lateralis larvae; however, R. cuneata straight-hinge larvae sank faster than umbo and pediveliger larvae. Species-specific differences in larval sinking and swimming are related to the different habitats occupied by adults. Larvae of S. solidissima, a marine stenohaline species, remained in high salinity water. Larvae of M. lateralis, a euryhaline species, use their preference for discontinuities or higher salinity water to assist retention in partially mixed estuaries. High sinking rate and short larval period of R. cuneata may offset the behavioural characteristic and aid in the retention of R. cuneata larvae in the low salinity zone of most partially mixed estuaries. Mann, R., Rainer, J. S., and Morales-Alamo, R. 1994. Reproductive activity of oysters, Crassostrea virginica (Gmelin, 1791) in the James River, Virginia during 1987-1988. Journal of Shellfish Research 13: 157-164. Ref ID: 80 Abstract: Reproductive activity in oysters, Crassostrea virginica Gmelin, in the James River, Virginia, was examined for 1987 from weekly estimates for fecundity and egg viability in oysters collected from Wreck Shoal, and for 1988 from weekly estimates of fecundity, egg viability, gonad volume fraction, gonad thickness, and mean egg size in oysters collected from Horsehead Reef. Maximum and mean fecundity values from Wreck Shoal oysters were higher than from Horsehead oysters. No relationship was evident between fecundity and egg viability at Horsehead Reef. A strong temporal relationship was observed between egg viability and peak oyster settlement in the James in both years of the study as estimated by off-bottom settlement substrates. In 1987 highest viability occurred from late June through mid August with peak settlement occurring from mid June through late August. In 1988 viable eggs were recorded from late July through the end of August; major settlement occurred from early August through mid September. Fishery independent estimates of oyster population abundance on Horsehead Reef, when combined with concurrent egg production and viability data, illustrate the losses that occur during the early life history stages of oysters in this location. Mann, R. and Evans, D. A. 1998. Estimation or oyster, Crassostrea virginica, standing stock, larval production, and advestive loss in relation to observed recruitment in the James River, Virginia. Journal of Shellfish Research 17: 239-253. Ref ID: 86 Abstract: Standing stock and demographic data for oysters, Crassostrea virginica, in the James River, Virginia are used to generate spatial estimates of egg production on a reef-specific basis. Subsequent estimates are made of losses related to density-dependent fertilization, natural mortality in the plankton, advective loss related to estuarine circulation, availability of substrate (both absolute amounts and after occlusion by fouling organisms), limited competency of pediveligers to metamorphose, and post settlement mortality to an age of 4 wk post metamorphosis. Reef-specific egg production is highly variable on a per unit basis within the James. In all reef systems fertilization losses approach two orders of magnitude, in some instances higher than estimated losses to advection over a 21-day development period. The combination of limited substrate availability compounded by substrate fouling suggests that increasing substrate availability at the rime of settlement would strongly facilitate an increase in population size. Final estimates from sequential calculations of surviving juvenile densities agree within one order of magnitude with field observations. Mann, R. and Harding, J. A. 2000. Invasion of the North American Atlantic coast by a large predatory Asian mollusc. Biologial Invasions 2: 7-22. Ref ID: 204 Mann, R. 2000. Restoring the oyster reef communities in the Chesapeake Bay: A commentary. Journal of Shellfish Research 19: 335-339. Ref ID: 355 Abstract: Restoration of the oyster Crassostrea virginica resource to the Chesapeake Bay is a widely supported goal. This manuscript explores the questions of why, how, and in what time frame this should be attempted. Restoration goals based simply on support of a commercial fishery fail to address the role of the oyster as a cornerstone species within the Chesapeake Bay and should only be considered in the context of a long-term sustainable fishery exploitation. The argument is proffered that a restored resource sustaining a fishery at the historical harvest level is unrealistic, because: (1) harvest probably exceeded biological production for much of the recorded history of exploitation; and (2) maximum production, a desired end for fishery support, occurs at approximately half the maximum (virgin, unexploited) biomass, and, thus, can only be achieved with disruption of the virgin complex community structure. Thus, the direct harvest economic value of a fishery based on a restored resource will not reach historical levels if there is an accompanying goal of long-term community development that is self-sustaining in the absence of restoration effort. The role of the oyster as a cornerstone organism and the pivotal link in benthic-pelagic coupling is examined in the context of current and projected watershed management problems, including agricultural and urban development with associated nutrient and sediment erosion issues, in the entire Chesapeake Bay watershed. Restoration efforts to date have focused on rebuilding three-dimensional reef structures, often with subsequent oyster broodstock enhancement, in predominantly small estuaries with retentive circulation to provide demonstration of increased resultant recruitment. Such examples are used to increase public awareness of the success of restoration processes and increase long-term participation in such programs by schools, nonprofit and civic organizations, and commercial and recreational fishing groups Marsden, J. E. and Lansky, D. M. 2000. Substrate selection by settling zebra mussels, Dreissena polymorpha, relative to material, texture, orientation, and sunlight. Canadian Journal of Zoology 78: 787-793. Ref ID: 514 Abstract: Zebra mussels (Dreissena polymorpha) invaded the Great Lakes in 1986 and are considered to be a nuisance species, because of their rapid population growth and their strong byssal attachment to a variety of man-made and natural surfaces. Research on possible antifouling materials or coatings has revealed few nontoxic substrates that even retard attachment of mussels. The influence of several substrate characteristics in combination (material, texture, orientation, and sunlight) on zebra mussel settlement was examined. Settlement of post-veliger mussels on experimental plates indicated that the mussels attached in higher numbers on upper versus lower horizontal surfaces, textured versus smooth surfaces, shaded versus sunlit surfaces, PVC versus Plexiglas, and plastic (PVC and Plexiglas) versus glass. Zebra mussels did not show strong preferences among several additional substrate materials (wood, Fiberglas, concrete, limestone, aluminum, and raw steel) but they strongly avoided galvanized steel. These results confirm field observations of locations in which mussels are most likely to be found. Information about zebra mussel substrate preferences may enhance the design of monitoring programs and the integrated management of mussels in vulnerable areas. Matthiessen, G. C. and Davis, J. P. 1992. Observations on growth rate and resistance to MSX (Haplosporidum nelsoni) amoung diploid and triploid eastern oysters (Crassostrea virginica (Gmelin, 1791)) in New England. Journal of Shellfish Research 11: 449-454. Ref ID: 67 Mazouni, N., Gaertner, J. C., and Deslous-Paoli, J. M. 2001. Composition of biofouling communities on suspended oyster cultures: an in situ study of their interactions with the water column. Marine Ecology-Progress Series 214: 93-102. Ref ID: 493 Abstract: This study was based on in situ experiments conducted in a shellfish lagoon (Thau, France) to determine the interactions between suspended oyster Crassostrea gigas Thunberg cultures and their environment at a seasonal scale. Three groups of descriptors were considered simultaneously during the course of the study: the taxonomic composition of an oyster culture unit (OCU), the nutrient and oxygen exchanges at the OCU-water interface (fluxes) and the water-column characteristics (water). We used a multiple factorial analysis (MFA) to assess in a single reference frame: (1) the seasonal organisation of the taxonomic groups which compose the OCU and (2) the interactions between this multispecific assemblage and the water column. We found strong seasonal variability in the OCU composition and the OCU interactions with the water column. Taxonomic richness of the biofouling was at a maximum in spring and minimum in August after a bottom anoxia. Among biofouling species, ascidians always constituted the dominant group. The annual pattern of coexistence observed between ascidians and oysters might be explained by resource partitioning, and also by a beneficial trophic interaction between these 2 groups. The structure of the OCU was based on a complex system of interactions, particularly in spring. During this season, the development on the OCU of macrofauna of soft substratum such as polychaetes reflected the presence of a suspended sediment compartment. The influence of the OCU on the water column was maximum in summer and minimum in winter. In the shellfish zone, the OCU plays a central role in nutrient renewal, particularly in summer when benthic fluxes are insufficient to satisfy phytoplankton nitrogen requirements. We estimate that the multispecific assemblages occurring on the oyster ropes (oysters and biofouling) have a potential annual DIN production of 2 x 10(7) mol yr(-1) and thus oyster cultures could have a determining influence on nitrogen recycling in the water column in the Thau lagoon Mcconnell, R. L. 1995. The human population carrying capacity of the Chesapeake Bay watershed: A preliminary analysis. Population and Environment 16: 335-351. Ref ID: 453 Abstract: Estimating human population carrying capacity for subglobal areas is problematic due to interregional transfers of energy, resources, pollution and waste. However, recent research on Chesapeake Bay sediment has permitted determination of time of onset of major episodes of Bay degradation, which may be used with census data to derive preliminary estimates of the watershed's carrying capacity.Chesapeake Bay, the United States' largest estuary, is experiencing increasing degradation despite a decade of studies and significant remedial activity. Since 1985, phosphorus emissions declined 18%, due mainly to a ban on phosphate detergent, but nitrogen increased at least 2%. Degrading influences, related to increasing fossil-fuel consumption and relentless population growth, include (1) over-harvesting of shellfish and fish species, (2) nitrogen emissions from sewage treatment plants, agriculture, fossil-fueled power plants and motor vehicles, (3) phosphorus emissions from sewage and agriculture, (4) debris, sewage, fuel spills and exhaust from 400,000 registered watercraft, (5) storm-water runoff, (6) sedimentation from land-use changes, (7) industrial discharges, (8) construction of dams and other barriers to anadromous fish migration, and (9) disposal of dredged material.Oyster harvests have declined over 95% in Virginia since the 1950s. Submerged aquatic vegetation (SAV), essential to fish and bottom-dwelling invertebrates, is estimated to cover only 10% of its pre-1950 distribution. Where remediation efforts have resulted in recolonization of SAV, species diversity is reduced 50-90%. Anoxic conditions are persistent in the Bay's deeper waters.New sediment data allow precise determination of time of onset of degration by recognizing changes in ratio of benthic to planktonic diatoms. These data, coupled with analyses of living resource populations, indicate that the most significant episode of Bay degradation commenced in the 1950s, and suggest that the human population carrying capacity for the watershed does not exceed 8 million without substantial changes in energy consumption and lifestyle. The watershed's present population of 16 million is projected to increase at]east 20% by 2020. furthermore, registration of motor vehicles may increase by one-third over the same interval. Coals of 40% reduction by 2000 of nitrogen and phosphorus emissions into the Bay set by the Chesapeake Bay Commission are unattainable without permanent changes in behavior affecting every facet of life in the watershed. The extent to which remediation efforts are successful in the Bay's watershed will help define much of the structure and nature of U.S. society in the twenty-first century McCormick-Ray, M. G. 1998. Oyster reefs in 1878 seascape pattern - Winslow revisited. Estuaries 21: 784-800. Ref ID: 439 Abstract: An analysis of Winslow's 1878 oyster survey data of Tangier Sound relates the Euclidean dimensions of oyster beds to plan-channel morphology, water depths, bottom slopes, and relief. Results show that at a regional scale the Tangier oyster beds followed a benthic seascape density pattern related to the main axial Tangier Sound Channel: its morphology, meanders, and east-west location. The north-south axis of the channel was intersected by estuarine flows into its central-eastern section, where meanders began with a tight meander around a western shoal, followed by wider second and third meanders. The location of the deepest axial depths of the channel's bottom indicates a lateral, side-to-side switching between opposite beds, and a vertical undulation in a deepening trend to 31 m at the apex: of the first meander. The depth then generally shallowed as the channel plan-form meandered southward to the sound's entrance. Oyster beds flanked the upper sides of the channel, their generally long and narrow linear axes oriented with that of the main channel in width-to-length ratios of < 0.4. Bed lengths increased from the north to the second meander, then decreased. The widest (2.3 km), longest (8.3 km), and largest (7 km(2)) beds laid opposite each other in the channel's second meander. Eastern beds were generally wider and larger than western beds, and water depths along their channel sides indicate a deepening trend from 3.6 m in the north to 16.5 m in the south, unlike western beds, which reached a maximum depth of 10.4 m north of the meanders. Minimum water depths on the shoal sides of beds varied little, described by mean values of 4.6 m (SD = 1.1) for eastern beds and 3.3 m (SD = 0.56) for western beds. Analysis of profiles indicates that the deeper southeastern beds had variable relief with longer and more gradual slopes into the channel than the shallower northwestern beds with flatter bed-tops and abrupt, steeper transitions into the channel. The profiles indicate variability of a single bed in distributions of oysters and bed morphologies to make analysis at the small scale difficult. However, at the regional scale, a seascape pattern emerges that relates the distributions of oysters to the channel and shoals. This re-examination of the historic database in the context of regional tidal channel patterns provides parameters for considering the interactive role of oysters with hydrodynamics and the structural importance of oyster reefs for land and seascape processes Melancon, E., Soniat, T., Cheramie, V., Dugas, R., Barras, J., and Lagarde, M. 1998. Oyster resource zones of the Barataria and Terrebonne estuaries of Louisiana. Journal of Shellfish Research 17: 1143-1148. Ref ID: 285 Abstract: A 1:100,000 scale map delineating the subtidal oyster resource zones within the Barataria and Terrebonne estuaries was developed. Strategies to accomplish the task included interviews with Louisiana oystermen and stare biologists to develop a draft map, field sampling to document oyster (Crassostrea virginica), Dermo (Perkinsus marinus), and oyster drill (Stramonita haemastoma) abundances, use of historical salinity data to aid in map verification, and public meetings to allow comment on a draft before final map preparation. Four oyster resource zones were delineated on the final map: a dry zone where subtidal oysters may be found when salinities increase, a wet zone where subtidal oysters may be found when salinities are suppressed, a wet-dry zone where subtidal oysters may be consistently found due to favorable salinities, and a high-salinity zone where natural oyster populations are predominantly found in intertidal and shallow waters. The dry zone is largely coincident with the brackish-marsh habitat, with some intermediate-type marsh. The wet-dry zone is found at the interface of the brackish and saline marshes, but extends further seaward than up-estuary. The wet zone and the high salinity zones are areas of mostly open water fringed by salt marshes. The dry zone encompasses 91,775 hectares, of which 48,788 hectares are water (53%). The wet zone encompasses 83,525 hectares, of which 66,958 hectares are water (80%). The wet-dry zone encompasses 171,893 hectares, of which 104,733 hectares are water (61%). The high salinity zone encompasses 125,705 hectares, of which 113,369 hectares are water (90%). There is a clear trend of increasing water habitat in the four zones over the past 30 years, and oysters are now cultivated on bottoms that were once marsh. The map should be useful in managing the effects upon oysters of freshwater diversions into the estuaries. It provides a pre-diversion record of the location of oyster resource zones and should prove helpful in the seaward relocation of oysters leases Meritt, D. W. 1977. Oyster spat settlement on natural clutch in the Maryland portion of the Chesapeake Bay (1939-1975). UMCEES Special Report no. 7, University of Maryland, Horn Point Laboratory, Cambridge, MD Ref ID: 200 Meritt, D. W. and Leffler, M. 2001. Oyster restoration in the Chesapeake Bay. Aquaculture Magazine 27: 87-88. Ref ID: 550 Mersmann, T. J., Buehler, D. A., Fraser, J. D., and Seegar, J. K. D. 1992. Assessing bias in studies of bald eagle food habits. Journal of Wildlife Management 56: 73-78. Ref ID: 673 Abstract: Although studies of bald eagle (Haliaeetus leucocephalus) food habits are numerous, few authors have quantified biases inherent in the techniques used. In our study of food habits of nonbreeding bald eagles on the northern Chesapeake Bay, we examined biases associated with pellet analysis, food remains analysis, and direct observation. We assessed these biases through controlled feedings of 2 captive bald eagles and through observations of free-ranging eagles. Fish fed to 2 captive bald eagles were underrepresented (P < 0.001) in egested pellets. Most bird and mammal food items were detected in greater-than-or-equal-to 1 pellet; however, species and carcass condition affected frequency of occurrence. Analysis of captive eagles' food remains overrepresented birds, medium-sized mammals, and large bony fish (P < 0.001); small mammals and small fish were underrepresented (P < 0.001). This bias increased over time due to greater persistence of some remains in shoreline plots. Direct observations of free-ranging eagles resulted in biases toward easily identified species such as eels and catfish, but also documented the use of small, soft-bodied fish, which were not well documented by the other techniques. Because of the variety of biases present, accurate assessment of bald eagle foods requires use of multiple techniques. Meyer, D. L. 1994. Habitat partitioning between the xanthid crabs Panopeus herbstii and Eurypanopeus depressus on intertidal oyster reefs (Crassostrea virginica) in southeastern North Carolina. Estuaries 17: 674-679. Ref ID: 309 Abstract: The abundances of the xanthid crabs Panopeus herbstii and Eurypanopeus depressus were examined relative to surface oyster shell cover, surface oyster cluster volume, subsurface shell content, substrate sand and silt composition, and oyster reef elevation. During August 1986 through July 1987, xanthid crabs were collected monthly from twelve 0.25 m2 x 15 cm deep quadrats, during low tide, from intertidal oyster reefs in Mill Creek, Pender County, North Carolina, USA, with respective quadrat details recorded. The abundance of P. herbstii, and to a lesser degree E. depressus, was positively correlated with surface shell cover. The abundance of E. depressus, and to a lesser degree P. herbstii, was positively correlated with surface cluster volume. The majority of P. herbstii inhabited the subsurface stratum of the oyster reef, whereas the majority of E. depressus inhabited the cluster stratum. Seasonality (i.e., temperature) appeared to influence the strata habitation of both species, with a higher incidence of cluster habitation during warmer months and a lower incidence during colder months. Crab abundance was not related to other factors examined, such as subsurface shell, substrate sand and silt composition, or elevation within the oyster reef. The analyses show that P. herbstii and E. depressus have partitioned the intertidal oyster reef habitat, with E. depressus exploiting surface shell clusters and P. herbstii the subsurface stratum Meyer, D. L. and Townsend, E. C. 2000. Faunal utilization of created intertidal eastern oyster (Crassostrea virginica) reefs in the southeastern United States. Estuaries 23: 34-45. Ref ID: 276 Abstract: Oyster cultch was added to the lower intertidal marsh-sandflat fringe of three previously created Spartina alterniflora salt marshes. Colonization of these created reefs by oysters and other select taxa was examined. Created reefs supported numerous oyster reef-associated faunas at equivalent or greater densities than adjacent natural reefs. Eastern oyster (Crassostrea virginica) settlement at one site of created reef exceeded that of the adjacent natural reefs within 9 mo of reef creation. After only 2 yr, harvestable-size C. virginica (>75 mm) were present in the created reefs along with substantial numbers of C. virginica clusters. The created reefs also had a higher number of molluscan, fish, and decapod species than the adjacent natural reefs. After 2 yr the densities of C. virginica, striped barnacle (Balanus amphitrite), scorched mussel (Brachidontes exustus), Atlantic ribbed mussel (Geukensia denissa), common mud c-rab (Panopeus herbstii), and Bat mud crab (Eurypanopeus depressus) within the created reefs were equivalent to that of adjacent natural reefs. From these data it is evident that created oyster reefs can quickly acquire functional ecological attributes of their natural counterparts. Because the demand far oysters continues to increase in the face of dwindling natural resources, habitat creation techniques need to evolve and these approaches need to consider the ancillary ecological benefits reef creation mw provide. Reef function as well as physical and ecological linkages of oyster reefs to other habitats (marsh, submerged aquatic vegetation, and bare bottom) should be considered when reefs are created in order to provide the best use of resources to maintain tbe integrity of estuarine systems Micheli, F. 1997. Effects of experience on crab foraging in a mobile and a sedentary species. Animal Behaviour 53: 1149-1159. Ref ID: 297 Abstract: The effects of experience on prey and prey-patch choice were compared between two species of marine predatory crabs. The blue crab, Callinectes sapidus Rathbun, is highly mobile and forages in a variety of estuarine and lagoonal habitats. The Atlantic mud crab, Panopeus herbstii H. Milne-Edwards, is smaller and less mobile and is found mostly in oyster reefs and on shelly bottoms. In the laboratory, crabs were offered a choice between two prey types (juvenile hard clams, Mercenaria mercenaria Linne, and juvenile oysters, Crassostrea virginica Gmelin) following a preliminary phase in which crabs were trained to feed on clams only, oysters only or a mixture of the two prey types. In field enclosures, crabs were offered a choice between patches of juvenile hard clams located in an inter-tidal salt marsh and in an adjacent unvegetated inter-tidal flat after they were trained to feed in either one of the two habitat types. Both in the laboratory prey-choice and the field prey-patch choice experiments, blue crabs modified their foraging behaviour depending on previous experience. The effect of experience on their foraging behaviour did not diminish after 24 hours. Experience had no significant effects on the foraging behaviour of mud crabs. Differences in the ecological contexts (e.g. in the variability of prey quality and availability) in which the two species forage may explain the greater effect of experience on the blue crab foraging behaviour, although alternative explanations cannot be ruled out. (C) 1997 The Association for the Study of Animal Behaviour Micheli, F. and Peterson, C. H. 1999. Estuarine vegetated habitats as corridors for predator movements. Conservation Biology 13: 869-881. Ref ID: 282 Abstract: The spatial proximity of one habitat to another can strongly influence population and community dynamics We investigated whether the proximity of intertidal oyster reefs to vegetated estuarine habitats, salt marshes, and seagrass beds, affects the abundance and community structure of benthic macroinvertebrates on reefs and predator-prey interactions between mobile predators and bivalves living on reefs. Benthic macroinvertebrate abundance was highest on reefs spatially separated from salt marshes. Macroinvertebrate species richness was highest on reefs separated from both salt marshes and seagrass beds. Comparisons of predation on juvenile bivalves transplanted to reefs for 7-12 days indicated that survivorship of clams was greatest on reefs spatially separated from both salt marshes and seagrass beds, whereas reef proximity to vegetated habitats dirt not affect the survivorship of oysters, The foraging behavior of blue crabs may explain patterns of macroinvertebrate abundance and clam survivorship among reefs with different proximity to vegetated habitats. In experiments conducted In 30-m(2) field enclosures, blue crabs had higher predation rates on hard clams transplanted onto artificial reefs adjacent to salt marshes or seagrass beds than on reefs separated from both habitats by unvegetated sand bottom. Thus, vegetated habitats appeared to act as corridors by facilitating the access of blue crabs to oyster reefs and enhancing the intensity of blue crab predation. Such an understanding of the effects of landscape characteristics of estuarine habitats on their value as habitats for estuarine organisms can be used to predict the consequences of habitat fragmentation on ecosystem function and to improve strategies for habitat and species conservation and restoration Micheli, F. 2004. Effects of predator foraging behavior on patterns of prey mortality in marine soft bottoms. Ecological Monographs 67: 203-224. Ref ID: 643 Abstract: This study links spatial and seasonal patterns of mortality of the hard clam, Mercenaria mercenaria (L.), in marine soft bottoms with the predation rates and habitat use of its main predator, the blue crab, Callinectes sapidus Rathbun. Patterns of predation on tethered juvenile clams exposed to the natural assemblage of predators were compared among different habitat types in fall and summer. Between-habitat patterns of predation on clams varied with season. In fall, predation on tethered clams was greater in subtidal sand bottoms and just inside the edge of intertidal salt marshes than in intertidal sand hats. In summer, predation on clams was similar in all habitats. Experiments conducted in held enclosures showed that: (a) individual crabs spent more time in the salt marsh habitat than in intertidal sand flats; (b) crab individuals placed in a sand bottom habitat had greater predation rates in high-density prey patches than in low-density patches; (c) individuals had greater predation rates in prey patches located just inside the edge of salt marshes than in intertidal sand flats, when prey density was held constant between the two habitats; (d) at intermediate and high crab densities predation mortality of clams was similar between vegetated and unvegetated habitats; (e) both individual crabs and groups of crabs consumed similar numbers of clams in the two habitat types when large predatory birds (mainly various species of terns, Sterna spp., herring gulls, Larus argentatus Coues, and ring-billed gulls, L. delawarensis Ord) were excluded from enclosures, but the crabs consumed more clams in the salt marsh than in the sand flat habitat in control enclosures where birds were not excluded. In the fall, when Herring and Ring-billed Gulls were abundant in the study area, preference by blue crabs for safer and more profitable habitats may explain the greater predation on clams in salt marshes than in intertidal sand flats. In the summer, when Herring and Ring-billed Gulls were rare and crab densities are 1.5-3 times greater than in the fall, competition with conspecifics may have caused crabs to disperse and feed in intertidal flats and may explain the general lack of differences in predation intensity among habitat types observed in the summer. Thus, patterns of predation and habitat use by blue crabs appeared to explain between-habitat and seasonal differences in predation mortality of clams. Focusing on the variation in the feeding rates of individual predators in response to external conditions can produce the mechanistic understanding of spatial and seasonal patterns of predation needed to understand and better predict the processes that structure benthic marine communities. Michener, W. K. and Kenny, P. D. 1991. Spatial and temporal patterns of Crassostrea virginica (Gmelin) recruitment: relationship to scale and substratum. Journal of Experimental Marine Biology and Ecology 154: 97-121. Ref ID: 85 Abstract: A series of experiments were performed in a euhaline (North Inlet, South Carolina) and mesohaline estuary (Wando River, South Carolina) to examine recruitment variability across several spatial and temporal scales. Crassostrea virginica (Gmelin) recruitment varied across all temporal and spatial scales with the exception of among reefs within restricted zones of the Wando River Estuary. Both biological and physical factors could be related to the variability observed at different scales. At the finest spatial scales, oyster larvae indicate a preference for crevices and shells or tests of other organisms as attachment sites. Higher recruitment on the shaded sides of plates in the high intertidal zone was consistent with observations documenting the preference of larvae for shaded attachment sites, adverse effects of direct exposure to light and heat, and sedimentation. Observations made at broader spatial scales (100s m) suggested that the availability of potential settlement surfaces may be the underlying factor contributing to the observed distribution of intertidal oyster reefs. Recruitment patterns were affected by choice and position of substrata. Sampling frequency was observed to influence the number of peak recruitment events observed within a season, estimates of total net recruitment, and the variability associated with recruitment observations made at different levels in the intertidal zone. Gregarious settlement behavior, sedimentation, and biophysical modification of the substrata were implicated in the regulation of recruitment patterns at shorter time scales. Competition and predation appeared to be important in regulating recruitment patterns at longer time scales, although the effects varied across the intertidal gradient. The physical and biotic processes which normally operate to structure intrareef spatial recruitment patterns were not observed to be as important in reefs which are physically restricted by tidal factors to very narrow zones within the intertidal gradient. Millican, P. F. and Helm, M. M. 1994. Effects of nutrition on larvae production in the European flat oyster, Ostrea edulis. Aquaculture 123: 83-94. Ref ID: 79 Abstract: The production of viable larvae of the European flat oyster, Ostrea edulis, was evaluated. Firstly, oysters pre-conditioned in fertilised sea water for 42 days prior to warm-water conditioning in the hatchery produced more broods of larvae than oysters pre-conditioned in unfertilised sea water. Secondly, larvae production was influenced by the diet provided to the broodstock during hatchery conditioning. The most productive treatments were either unfiltered sea water or filtered sea water supplemented with a mixture of Dunaliella tertiolecta and Tahitian Isochrysis, which produced 135 317 and 78 250 larvae per oyster, respectively. The least productive treatment was the single species diet of D. tertiolecta, where 10 820 larvae per oyster were released. These larvae showed a lower subsequent survival compared with larvae from other broodstock treatments. Compared with larvae released in the wild, the larvae from these experiments showed lower levels of total lipid. This result, together with the fact that hatchery-conditioned broodstock showed lower fecundity than wild stock, demonstrates that there remains considerable scope to improve the conditions for broodstock maintenance for aquaculture purposes. Minello, T. J., Able, K. W., Weinstein, M. P., and Hays, C. G. 2003. Salt marshes as nurseries for nekton: testing hypotheses on density, growth and survival through meta-analysis. Marine Ecology-Progress Series 246: 39-59. Ref ID: 660 Abstract: We examined the nursery role of salt marshes for transient nekton by searching the literature for data on density, growth, and survival of juvenile fishes and decapod crustaceans in marshes and using meta-analyses to test hypotheses. We analyzed density data from 32 studies conducted throughout the world, Based on fish density, habitat types could be ranked from highest to lowest as: seagrass > vegetated marsh edge, nonvegetated marsh, open water, macroalgae, oyster reefs > vegetated inner marsh. However, patterns of habitat use varied among the 29 fish species represented. For decapod crustaceans (seven species), habitat types were ranked: seagrass > vegetated marsh edge > nonvegetated marsh, vegetated inner marsh, open water, macroalgae > oyster reef. We identified only 5 comparative studies on transient nekton growth in salt marshes. Fish growth in nonvegetated salt marsh was not significantly different from growth in open water or in macroalgae beds but was significantly lower than in seagrass. Growth of decapod crustaceans was higher in vegetated marsh than in nonvegetated marsh. Nekton survival in salt marsh (11 studies analyzed) was higher than in open water, lower than in oyster reef/cobble and not significantly different from survival in seagrass. When density, growth and survival are all considered, the relative nursery value of salt marshes for nekton appears higher than open water but lower than seagrass. Vegetated marsh appears to have a higher nursery value than nonvegetated marsh; however, tidal dynamics and nekton movement among marsh components complicates these comparisons. The available data have a strong geographical bias; most studies originated in the northern Gulf of Mexico or on the Atlantic coast of the United States. This bias may be significant because there is some evidence that salt marsh nursery value is dependent on geography, salinity regimes and tidal amplitude. Moran, A. L. and Manahan, D. T. 2004. Physiological recovery from prolonged 'starvation' in larvae of the Pacific oyster Crassostrea gigas. Journal of Experimental Marine Biology and Ecology 306: 17-36. Ref ID: 582 Abstract: Previous studies of energy metabolism in larvae have described a developmental "point of no return" (PNR), a time by which larvae of planktotrophic marine species must feed in order to survive and grow. This study investigated the effects of long-term food deprivation on developing larvae of the oyster Crassostrea gigas with the goal of providing a biochemical and metabolic description of larvae at the PNR in this species. Mortality of unfed larvae was low for the first 14 days without the addition of phytoplankton foods. Even after 33 days without food, larvae were still swimming. Unfed larvae did not lose their ability to capture and digest algal cells when provided with food after 33 days. Growth, metabolic rate and biochemical constituents all increased at the same or greater rates in larvae whose feeding was delayed for 5, 8, 11, 14 or 17 days compared to larvae fed at 2 days old, when feeding was possible. These results show that larvae of C. gigas can survive long feeding delays while maintaining a constant rate of metabolism. These results suggest that oyster larvae have the capacity to survive 'starvation' using alternative sources of energy. If there is a "point of no return" beyond which larvae of C. gigas must feed on microalgae to survive, our findings suggest this point may be set by the availability of detrital material or dissolved organic carbon that can fuel maintenance metabolism for extended periods equivalent to over four times the predicted lifespan. Moroney, D. A. and Walker, R. L. 1998. Recruitment patterns of the eastern oyster, Crassostrea virginica, along a creek gradient in House Creek, Little Tybee Island, Georgia. Journal of Shellfish Research 17: 1085-1091. Ref ID: 284 Abstract: Our goal is to produce large, deep-cupped, single oysters, Crassostrea virginica, for the half-shell and steamer marker. However, oysters in Georgia are small and grow in clusters because of high recruitment rates and lack of appropriate substrate upon which oyster spat can settle. It was hypothesized that oyster recruitment would be lower at sites farther back into a tidal creek presumably because of high tidal flushing rates (40% exchange per tide). To test this hypothesis, spat collectors were deployed monthly at 10 sites along two branches of House Creek, Little Tybee Island, Georgia from April to November, 1996. The total number of oysters on each collector was enumerated and 30 oysters per site were measured for shell length. Significant differences in recruitment rates were observed between sites (p < .001). Generally, oyster spat recruitment was lowest at the most remote sites in a tidal creek and increased seaward. The recruitment rate at one site was higher than expected based on our hypothesis. However, the percent cover by adult oyster reefs at this site was also higher and may explain the higher recruitment rate. Therefore, our data supports the hypothesis. Based upon the results of this study, the most remote sites in a tidal creek with relatively low percent cover by adult oyster reefs should exhibit low recruitment rates. It may therefore be possible to reduce oyster clustering by culturing oysters in these areas for grow-out to market size Moroney, D. A. and Walker, R. L. 1999. The effects of tidal and bottom placement on the growth, survival, and fouling of the eastern oyster Crassostrea virginica. Journal of the World Aquaculture Society 30: 433-442. Ref ID: 66 Abstract: Oysters Crassostrea virginica in Georgia are naturally small and grow in clusters; however, it is more profitable to harvest large, single oysters. This study attempts to identify favorable tidal and bottom placements for the grow-out of large, single oysters in Georgia. Three bags, each containing 50 single oysters, were placed in four different tidal positions (subtidal on-bottom, subtidal off-bottom, intertidal on-bottom and intertidal off-bottom) at five sites in House Creek, Georgia. Measurements of oyster growth, survival and degree of oyster spat fouling were taken seasonally (every 3 mo). Oysters from on-bottom treatments exhibited significantly lower growth (P = 0.0364 intertidal only), survival (P = 0.0044) and degree of fouling (P = 0.0154) than oysters from the intertidal off-bottom treatment. However, the oysters placed intertidally off-bottom were heavily fouled during the recruitment period. It may be necessary to sacrifice some growth and survival by culturing oysters intertidally on-bottom during the recruitment period in order to reduce the degree of fouling. During the non-recruitment period, placing oyster culture bags intertidally off-bottom maximizes growth and survival. Morris Jr., J. G. 2003. Cholera and other types of vibriosis: a story of human pandemics and oysters on the half shell. Food Safety 37: 272-280. Ref ID: 518 Muniain-Mujika, I., Calvo, M., Lucena, F., and Girones, R. 2004. Comparative analysis of viral pathogens and potential indicators in shellfish. International Journal of Food Microbiology 83: 75-85. Ref ID: 570 Nakaoka, M. 1996. Dynamics of age- and size-structured populations in fluctuating environments: applications of stochastic matrix models to natural environments. Researches on Population Ecology 38: 141-152. Ref ID: 578 Nakaoka, M. 1997. Demography of the marine bivalve Yoldia notabilis in fluctuation enviroments: an analysis using stochastic matrix model. Oikos 79: 59-68. Ref ID: 579 National Research Council. 2004. Nonnative Oysters in the Chesapeake Bay. The National Academies Press. Washington DC. Ref ID: 652 Nelson, K. A., Leonard, L. A., Posey, M. H., Alphin, T. D., and Mallin, M. A. 2004. Using Transplanted oyster (Crassostrea virginica) beds to improve water quality in small tidal creeks: a pilot study. Journal of Experimental Marine Biology and Ecology 298: 347-368. Ref ID: 567 Neuhauser, C. and Pacala, S. W. 1999. An explicityly spatial version of the Lotka-Volterra model with interscpecific competition. The Annals of Applied Probability 9: 1226-1259. Ref ID: 28 Abstract: We consider a spatial stochastic version of the classical Lotka-Volterra model with interspecific competition. The classical model is described by a set of ordinary differential equations, one for each species. Mortality is density dependent, including both intraspecific and interspecific competition. Fecundity may depend on the type of species but is density independent. Depending on the relative strengths of interspecific and intraspecific competition and on the fecundities, the parameter space for the classical model is divided into regions where either coexistence, competitive exclusion or founder control occur. The spatial version is a continuous time Markov profess in which individuals are located on the d-dimensional integer lattice. Their dynamics are described by a set of local rules which have the same components as the classical model. Our main results for the spatial stochastic version can be summarized as follows. Local competitive interactions between species result in (1) a reduction of the parameter region where coexistence occurs in the classical model, (2) a reduction of the parameter region where founder control occurs in the classical model, and (3) spatial segregation of the two species in parts of the parameter region where the classical model predicts coexistence. Newell, R. I. E. and Jordan, S. J. 1983. Preferential ingestion of organic material by the American oyster Crassostrea virginica. Marine Ecology-Progress Series 13: 47-53. Ref ID: 601 Newell, R. I. E., Alspach, G. S. Jr., Kennedy, V. S., and Jacobs, D. 2000. Mortality of newly metamorphosed eastern oysters (Crassostrea virginica) in mesohaline Chesapeake Bay. Marine Biology 136: 665-676. Ref ID: 156 Abstract: Stocks of eastern oysters, Crassostrea virginica (Gmelin), in mesohaline Chesapeake Bay, USA, exhibit a high degree of inter-annual and spatial variability in recruitment. We found that cumulative oyster spatfall on off-bottom collector plates, measured throughout the summer in 14 years over a span of three decades, was highly positively correlated (r(2) = 0.8) with juvenile oyster recruitment on adjacent oyster bars. Total abundances of juvenile oysters on these bars were, however, generally 99.7% lower than predicted from cumulative seasonal larval settlement on collector plates. We propose that although the number of larvae metamorphosing was the key factor in determining the gross annual pattern of recruitment to these mesohaline oyster bars, the actual magnitude of recruitment was governed by post-settlement processes, such as competition for limited resources and predation. We tested the hypothesis that predation may be partly responsible for high post-settlement juvenile oyster mortality. We performed a series of 3-d field investigations over two summers (1989, 1990) at a mesohaline site, employing cages of various mesh sizes (400, 800, 1500 mu m) to protect hatchery-reared spat of 0.5 to 4.0 mm shell height. Mortality rates for spat held for 3 d in the estuary (17.8%) were significantly higher (P = 0.0001) for the smallest spat (0.5 to 2.0 mm) compared with those of 2.01 to 4.0 mm (4.2%). In 1990, but not in 1989, enclosure within 400 and 800 mu m mesh cages significantly (P = 0.004) increased survival during 3-d deployments (9.4 and 10.1%, respectively) compared with spat unprotected by mesh cages (21.9%). In a series of laboratory predation studies that used the entire community of invertebrates that could penetrate the cages, microscopic juvenile polyclad flatworms, Stylochus ellipticus, were the only organisms that we observed crawling into living oysters and feeding on oyster tissue. Large flatworms (50 to 200 mm(2)) are known to be important predators on oysters, but this ability of flatworms that were so small (< ca. 5 mm(2)) and translucent as to be almost invisible without magnification to feed on immediate post-metamorphic oysters has not been documented previously. Our results suggest that the rate of mortality due to predation in mesohaline Chesapeake Bay is much reduced once spat survive for 2 to 3 weeks post-metamorphosis. Thus, it is likely that predation in the 1 to 2 week period immediately after settlement may be a crucial factor in the structuring of eastern oyster populations. Newell, R. I. E., Cornwell, J. C., and Owens, M. S. 2002. Influence of simulated bivalve biodeposition and microphytobenthos on sediment nitrogen dynamics: A laboratory study. Limnology and Oceanography 47: 1367-1379. Ref ID: 262 Abstract: Suspension-feeding eastern oysters, Crassostrea virginica, were once abundant in Chesapeake Bay and may then have exerted top-down control on phytoplankton and also reduced turbidities, thereby increasing light available to benthic plants. Alternatively, oysters may have simply recycled inorganic nutrients rapidly back to the water column, with no long-lasting reduction in phytoplankton biomass resulting from oyster feeding activity. To help distinguish between these scenarios, we explored changes in nitrogen fluxes and denitrification in laboratory incubations of sediment cores held under oxic and anoxic conditions in response to loading by pelletized phytoplankton cells, an experimental analog for oyster feces and pseudofeces. When organics were regenerated under aerobic conditions, typical of those associated with oyster habitat, coupled nitrification-denitrification was promoted, resulting in denitrification of similar to20% of the total added nitrogen. In contrast, under anoxic conditions, typical of current summertime conditions in main-stem Chesapeake Bay where phytoplankton is microbially degraded beneath the pycnocline, nitrogen was released solely as ammonium from the added organics. We postulate that denitrification of particulate nitrogen remaining in oyster feces and pseudofeces may enhance nitrogen removal from estuaries. In aerobic incubations with sufficient light (70 mumol m(-2) s(-1)), a benthic microalgal/cyanobacterial community grew that not only absorbed the inorganic nitrogen released from the added organics but also fixed N-2. This result suggests that an ecosystem dominated by benthic primary production may develop in shallow waters when reduced turbidity associated with bivalve feeding increases light penetration to a level that can sustain benthic microalgal production Newkirk, G. F. and Haley, L. E. 1983. Selection for growth rate in the european oyster, Ostrea edulis: repsonse of second generation groups. Aquaculture 33: 149-155. Ref ID: 131 Nie, Z. 1991. The culture of marine bivalve mollusks in China. Pages 261-275 in W. Menzel, editor. Estuarine and Marine Bivalve Mollusk Culture. CRC Press, Inc., Boca Raton, FL. Ref ID: 174 Nol, E. 1989. Food-Supply and Reproductive-Performance of the American Oystercatcher in Virginia. Condor 91: 429-435. Ref ID: 612 Nunes, J. P., Ferreira, J. G., Gazeau, F., Lencart-Silva, J., Zhang, X. L., Zhu, M. Y., and Fang, J. G. 2003. A model for sustainable management of shellfish polyculture in coastal bays. Aquaculture 219: 257-277. Ref ID: 489 Abstract: A multi-species model for shellfish polyculture in coastal embayments is presented, and an application of the model to a test site (Sanggou Bay, Northern China) used for large-scale longline cultivation of the Chinese scallop Chlamys farreri, the Pacific oyster Crassostrea gigas and the kelp Laminaria japonica is described.The model integrates a bay-scale ecological simulation with individual-based modelling of scallops and oysters, and upscales the individual processes for the target species (scallops and oysters) by means of a multi-cohort population dynamics model. Human interaction with the target cohorts over a number of years is explicitly simulated. The model has been used to estimate the exploitation carrying capacity for scallops and oysters in the system, the harvest potential for different seeding and harvesting scenarios, and the impacts on the ecosystem of different polyculture management strategies.Although an increase in seeding to 2 X and 15 x standard seeding for scallops and oysters respectively optimizes the yield of both, thus corresponding to the exploitation carrying capacity, the ratio of harvest/seed is lowered, which may make the fishery less attractive from an economic point of view.Progressive increases in seeding lead to a collapse of the fishery: this occurs at >15 x standard seeding for scallops, and at >30 x for oysters. In parallel, there are profound modifications at the ecosystem level, which were studied by means of a mass balance carried out on the model. Under standard conditions, there is a net export of primary production from the bay to the Yellow Sea, but at 15-20 x increase in seeding, the bay becomes a net phytoplankton importer, due to phytoplankton clearance by cultivated shellfish.The model simulates a period of 6 years in about 2 min, and was shown to be a useful tool for polyculture management over multiannual periods; a development of the socioeconomic component will allow feedbacks between economic consequences of different cultivation scenarios and ecosystem responses to be explicitly considered. The application of this type of model may be of use in promoting a more holistic approach to shellfish aquaculture management. (C) 2003 Elsevier Science B.V. All rights reserved O'Beirn, F. X., Heffernan, P. B., Walker, R. L., and Jansen, M. L. 1996. Young-of-the-year oyster, Crassostrea virginica, reporduction in coastal Georgia. Estuaries 19: 651-658. Ref ID: 73 Abstract: Young-of-the-year (YOY) oysters (Crassostrea virginica) in the Gulf of Mexico mature sexually and spawn in their first year. This study determined whether YOY oysters in the southeastern United States also mature and spawn in their first year. In 1991 and 1993, 300 YOY oysters were marked in May and 20-30 were sampled in subsequent months along with 20 adult controls. Two sites were chosen in 1991 (House Creek and Skidaway River) and one in 1993 (Skidaway River). At House Creek, YOY oysters were mature and spawned in September. YOY oysters at Skidaway spawned in October. Adult oysters did not appear to spawn in 1991. In 1993, the adult oysters spawned in August and September whereas, the YOY oysters spawned heavily in October. Oyster recruitment in coastal Georgia extends through October. The potential contribution of YOY oysters to this late season set is substantial, given that the YOY oysters are relatively large (approximate to 4 cm) and are found in greater numbers than the adults. Oysters are capable of having two, if not more, generations within one year, prior to exposure of disease-causing organisms. Also, this particular reproductive strategy would increase the oysters suitability as a test subject in population genetic studies. O'Beirn, F. X., Heffernan, P. B., and Walker, R. L. 1996. Recruitment of the eastern oyster in coastal Georgia: patterns and recommendations. North American Journal of Fisheries Management 16: 413-426. Ref ID: 644 O'Beirn, F. X., Walker, R. L., and Jansen, M. L. 1998. Microgeographical variations in gametogenesis and sex ratio in the eastern oyster at two marsh sites in Georgia. Transactions of the American Fisheries Society 127: 298-308. Ref ID: 153 Abstract: This study examined gametogenesis of the eastern oyster Crassostrea virginica along an intertidal gradient. Twenty eastern oysters were taken from two tidal heights (high-intertidal, HI, and low-intertidal, LI) on a mostly biweekly basis from two sites (House Creek and Skidaway River) in Wassaw Sound, Georgia, from June 1993 to September 1994. Gametogenic condition was evaluated by histological staging of the gonads and by subsequent image analysis. No retardation in gametogenic maturation and spawning activity was seen in the HI eastern oysters when compared with the LI eastern oysters. Also, the HI eastern oysters tended to maintain higher gametogenic variables throughout the year than the LI eastern oysters. At the Skidaway River site, HI female eastern oysters had significantly higher reproductive variables than the LI eastern oysters. Multiple spawning events occurred at each tidal height. We concluded that no retardation in gametogenesis occurred in HI eastern oysters, and being located high in the intertidal zone appeared to enhance the reproductive ability of the oysters. Sex ratios differed at the different tidal heights. Female: male abundance ratios were greater in HI areas (3.45:1 at House Creek and 3.12:1 at Skidaway River) than in LI areas (1.95:1 at House Creek and 1.85:1 at Skidaway River). The higher proportion of males and smaller-sized eastern oysters found in the LI zone at both sites probably indicated a younger population of eastern oysters. Younger or smaller animals could have resulted from stressors on the eastern oysters induced by nonlethal predatory activity, siltation, and disease. O'Beirn, F. X., Luckenbach, M. W., Nestlerode, J. A., and Coates, G. M. 2000. Toward design criteria in constructed oyster reefs: Oyster recruitment as a function of substrate type and tidal height. Journal of Shellfish Research 19: 387-395. Ref ID: 529 Abstract: Restoration of degraded oyster reef habitat generally begins with the addition of substrate that serves as a reef base and site for oyster spat attachment. Remarkably, little is known about how substrate type and reef morphology affect the development of oyster populations on restored reefs. Three-dimensional, intertidal reefs were constructed near Fisherman's Island, Virginia: two reefs in 1995 using surfclam (Spisula solidissima) shell and six reefs in 1996 using surfclam shell, oyster shell, and stabilized coal ash. We have monitored oyster recruitment and growth quarterly at three tidal heights (intertidal, mean low water, and subtidal) on each reef type since their construction Oyster recruitment in 1995 exceeded that observed in the two subsequent years. High initial densities on the 1995 reefs decreased and stabilized at a mean of 418 oyster/m(2). Oyster settlement occurred on all reef types and tidal heights in 1996; however, postsettlement mortality on the surfclam shell and coal ash reefs exceeded that on the oyster shell reefs, which remained relatively constant throughout the year (mean = 935 oysters/m(2)). Field observations suggest that predation accounts for most of the observed mortality and that the clam shell and coal ash reefs, which have little interstitial space, suffer greater predation. Oyster abundance was consistently greatest higher in the intertidal zone on all reefs in each year studied. The patterns observed here lead to the preliminary conclusion that the provision of spatial refugia (both intertidal and interstitial) from predation is an essential feature of successful oyster reef restoration in this region. In addition, high levels of recruitment can provide a numerical refuge, whereby the oysters themselves will provide structure and increase the probability of an oyster population establishing successfully on the reef Ofoighil, D. O., Gaffney, P. M., and Hilbish, T. J. 1995. Differences in mitochondrial 16S ribosomal gene sequences allow discrimination among American [Crassostrea virginica (Gmelin)] and Asian [C. gigas (Thunberg) C. ariakensis (Wakiya)] oyster species. Journal of Experimental Marine Biology and Ecology 192: 211-220. Ref ID: 178 Abstract: Limited field trials for potentially disease resistant Asian cupped oysters were recently initiated in the central Atlantic coastal region of North America. We have developed a simple and sensitive genetic assay that unambiguously distinguishes the native Crassostrea virginica (Gmelin) from two of its exotic Asian congeners, C. gigas (Thunberg) and C. ariakensis (Wakiya). Homologous fragments (443 nt) of the mitochondrial rRNA large subunit were amplified from, and sequenced for, these three commercially important species of oysters. C. virginica exhibits 85.5 and 84% sequence similarity to C. gigas and C. ariakensis (respectively) and contains seven additional nucleotides in the amplified 16S gene fragment. The two Asian species do not differ in gene length and display 95.1% sequence similarity. Numerous endonuclease restriction site differences are apparent among the three oyster species and we present a polymerase chain reaction/ restriction fragment length polymorphism strategy that can distinguish these species. This methodology will prove valuable in monitoring the ecological consequences, at all life history stages, of trial introductions of Asian Crassostrea species into this region. Oliver, L. M., Fisher, W. S., Ford, S. E., Calvo, L. M. R., Burreson, E. M., Sutton, E. B., and Gandy, J. 1998. Perkinsus marinus tissue distribution and seasonal variation in oysters Crassostrea virginica from Florida, Virginia and New York. Diseases of Aquatic Organisms 34: 51-61. Ref ID: 556 Abstract: Perkinsus marinus infection intensity was measured in eastern oysters Crassostrea virginica collected in October and December 1993, and March, May, and July 1994 from 3 U.S. sites: Apalachicola Bay (FL), Chesapeake Bay (VA), and Oyster Bay (Mr'). Gill, mantle, digestive gland. adductor muscle, hemolymph, and remaining tissue (including gonadal material and rectum) were dissected from 20 oysters from each site at each collection time. Samples were separately diagnosed for P. marin us infections by incubation in Ray's Fluid Thioglycollate Medium (RFTM) and subsequent microscopic quantification of purified enlarged hypnospores. At all sampling times and sites, average P. marinus infection intensity (g wet wt tissue(-1) or ml hemolymph(-1)) was lowest in hemolymph samples, and generally highest in the digestive gland. Perkinsus marinus prevalence was 100% at both FL and NY sites for each of the 5 collection times, and, for the VA site, was less than 100% in only 1 month (May 1994). Seasonal intensity patterns and mean total body burdens differed among the sites. Average body burden was highest in VA during October and progressively declined to a minimum in May. This decline was probably due to mortality of heavily infected oysters and diminution of parasite activity associated with colder temperatures and reduced salinities. Intensities varied little during the months of October and December at both the FL and NY sites. Minimum average intensities were observed in March in FL oysters and May in NY oysters. Relatively high P. marinus infection levels that persisted throughout the winter in NY oysters compared with VA oysters could reflect constant high salinity in Long Island Sound which favors parasite activity, and also rapid decline in temperature in the fall that may have prevented epizootic oyster mortalities Orr, R. L., Cohen, S. D., and Griffin, R. L. 1993. Generic Non-Inigenous Pest Risk Assessment Process: The Generic Process for Estimating Pest Risk Associated with the Introduction of Non-Indigenous Organisms., Planning and Risk Analysis Systems, Policy and Program Development, Animal and Plant Health Inspection Service, United States Department of Agriculture, Washington, DC Ref ID: 116 Ortega, S. 1981. Environmental stress, competition, and dominance of Crassostrea virginica near Beaufort, North Carolina, USA. Marine Biology 62: 47-56. Ref ID: 169 Ortega, S. and Sutherland, J. P. 1992. Recruitment and growth of the eastern oyster, Crassostrea virginica, in North Carolina. Estuaries 15: 158-170. Ref ID: 62 Abstract: The effects of location, salinity, and depth on recruitment and growth of the eastern oyster Crassostrea virginica in Pamlico and Core sounds, North Carolina, were investigated from 1988 to 1990. We measured length and density of spat settling on oyster cultch deployed at deep (approximately 3 m) and shallow (approximately 1 m) depths at six sites in areas with low salinity and six sites in areas with high salinity. These data were compared with similar data taken at some of these sites by the North Carolina Division of Marine Fisheries since 1981 as part of their cultch planting program. Recruitment was generally greater in the high salinity sites, compared to the low salinity sites. Recruitment was less at shallow depths compared to deeper depths. In all three years the highest recruitment occurred in August and September, corresponding to the months of maximum water temperature. Recruitment was highly variable in space and time, but appeared to diminish from 1988 to 1990. Recruitment was reduced by sedimentation and a variety of sessile organisms. All sites appeared to have a similar potential for growth. Osman, R. W., Whitlatch, R. B., and Zajac, R. N. 1989. Effects of resident species on recruitment into a community: larval settlement versus post-settlement mortality in oyster Crassostrea virginica. Marine Ecology Progress Series 54: 61-73. Ref ID: 91 Paraso, M. C., Ford, S. E., Powell, E. N., Hofmann, E. E., and Klinck, J. M. 1999. Modeling the MSX parasite in eastern oyster (Crassostrea virginica) populations. II. Salinity effects. Journal of Shellfish Research 18: 501-516. Ref ID: 521 Abstract: An oyster population model coupled with a model for Haplosporidium nelsoni, the causative agent of the oyster disease MSX, was used with salinity time-series constructed from Delaware River flow measurements to study environmentally-induced variations in the annual cycle of this disease in Delaware Bay oyster populations. Model simulations for the lower Bay (high salinity) sire reproduced the annual cycle observed in lower Delaware Bay. Simulations at both upper Bay (low salinity) and lower Bay sites produced prevalences and intensities that were consistent with field observations. At all sites, low freshwater discharge resulted in increased disease levels, whereas high freshwater discharge produced decreased levels. At upper Bay sites, simulated changes in runoff produced high variability in disease prevalence; in the lower Bay, they produced a much lesser effect. Changes in salinity within the 10-20 ppt range produced the greatest changes in disease levels and patterns. Simulated shifts in timing of the spring runoff from March to either February or May affected the mid-Bay (13-19 ppt) only. A February runoff reduced the spring prevalence peak and caused a complete loss of systemic infections. In contrast, a May discharge occurred too late to affect parasite proliferation in the spring so that the spring peak was higher than average. Almost 100% of the infections were systemic by June, which resulted in high oyster mortality during July at this site. Model results indicate thar parasite infection intensity under changing salinity is more complex than a simple function of salinity as it affects parasite proliferation and death rates within the oyster, and that the rate of infection is most likely reduced at low salinity. The simulated results demonstrate the ability of the model to reproduce field measurements and its usefulness in elucidating the association between the magnitude and timing of Delaware River discharge, its associated salinity variations, and the H. nelsoni annual cycle Pascual, M. A. and Kareiva, P. 1996. Predicting the outcome of competition using experimental data: maximum likelihood and bayesian approahes. Ecology 77: 337-349. Ref ID: 17 Abstract: Lotka-Volterra (LV) equations have been used extensively to explore the possible dynamic outcomes of interspecific competition. But while there have been hundreds of papers on the mathematical properties of Lotka-Volterra models, there have been only a handful of papers that explore techniques for fitting these models to actual data, and no papers that explore the interface of experimental design and statistical inference when fitting LV equations to census data. In this paper we present a statistical analysis of Gause's experimental cultures of Paramecium aurelia and P. caudatum, using analytical methods based on maximum likelihood and Bayesian statistics. We compare the effectiveness of these two approaches in addressing several questions about competition from experimental data: Are the mutual effects of competing populations substantial? Are these competitive effects symmetrical? Are two populations expected to coexist or to eliminate each other by competition? We show that even a laboratory-derived data set with minimal variability can entail significant levels of uncertainty about the nature of the competitive interaction. We assess the errors involved in estimating the strength and symmetry of competition, and find that one's conclusions depend critically on assumptions about sources of variability in the data. We also estimate the probabilities of alternative dynamic behaviors for competing species. We use simulations to evaluate how particular experimental designs might improve our power to characterize the dynamic; outcome of competition. We show that much more information is gained by running competition experiments at different starring conditions than by replicating the same experiment for a particular starting condition. Paynter, K. T. and Dimichele, L. 1990. Growth of tray cultured oysters (Crassostrea virginica Gmelin) in Chesapeake Bay. Aquaculture 87: 289-297. Ref ID: 414 Paynter, K. T. and Burreson, E. M. 1991. Effects of Perkinsus marinus infection in the eastern oyster, Crassostrea virginica: II. Disease development and impact on growth rate at different salinities. Journal of Shellfish Research 10: 425-431. Ref ID: 198 Paynter, K. T., Pierce, S. K., and Burreson, E. M. 1995. Levels of intracellular free amino acids used for salinity tolerance by oysters (Crassostrea virginica) are altered by protozoan (Perkinsus marinus) parasitism. Marine Biology 122: 67-72. Ref ID: 195 Paynter, K. T. 1996. The effects of Perkinsus marinus infection on physiological processes in the eastern oyster, Crassostrea virginica. Journal of Shellfish Research 15: 119-125. Ref ID: 197 Abstract: Although Perkinsus marinus infections have been associated with high mortalities in populations of the eastern oyster Crassostrea virginica for several decades, the pathological mechanism(s) by which death is induced is unclear. Physiological changes in the oyster associated with P. marinus infection are not well studied. Infections typically cause significant reductions in growth rare and several studies have shown reductions in condition index as well. The reduction in condition index may be the result of a perturbation in free amino acid metabolism caused by infection. Further, the effects on free amino acid metabolism may be associated with parasite-induced changes in mitochondrial function. A significant acidosis has also been shown to occur in the hemolymph of infected oysters which may affect general tissue functions. However, changes in oxygen consumption and clearance and assimilation rates of whole oysters have not been correlated with increasing infection. Finally, reproductive capacity may be reduced by P. marinus infection. Paynter, K. T. 1999. Managing around oyster diseases in Maryland and Maryland oyster roundtable strategies.M. W. Luckenbach, R. Mann, and J. A. Wesson, editors. Oyster Reef Habitat Restoration: A Synopis and Synthesis of Approaches. Virginia Institute of Marine Science Press, Glouchester Point, VA. Ref ID: 100 Pearson, T. N. and Hopley, C. W. 1999. A practical approach for assessing ecological risks associated with fish stocking programs. Fisheries 24: 16-23. Ref ID: 111 Abstract: As wild fish populations continue to decline, fisheries managers are increasingly concerned about how hatchery operations might be contributing to declines of highly valued wild populations. Ecological risk assessments can provide decision makers with critical information about potential effects of stocking. In this paper we describe a practical approach for assessing ecological risks to select nontarget taxa (NTT) associated with fish stocking programs. This approach requires the completion of five tasks: (1) Determine acceptable impacts to NTT (e.g., impact of 10% to a species distribution, abundance, or size structure); (2) determine potential spatial-temporal overlap of NTT life stages with target taxon; (3) determine potential strong ecological interactions; (4) determine ecological risk; and (5) determine scientific uncertainty of ecological risk assessment. These tasks are accomplished by analyzing information gathered from scientists, managers, and policy makers. The result of the assessment is a listing of the ecological risks and associated uncertainties of failing to meet a stated objective for a variety of NTT. We also describe a decision matrix that prescribes various levels of uncertainty resolution, risk minimization strategies, risk containment monitoring, and stocking proposal implementation. Prescriptions reflect the amount of ecological risk and scientific uncertainty. Application of ecological risk assessment concepts to hatchery stocking decisions allows for a balanced approach when evaluating the benefits of hatchery stocking relative to ecological costs to nontarget populations and the economic costs of risk management. Pebbles, E. B., Hall, J. R., and Tolley, S. G. 1996. Egg production by the bay anchovy Anchoa mitchilli in relation to adult and larval prey fields. Marine Ecology-Progress Series 131: 61-73. Ref ID: 629 Perdue, J. A. and Erickson, G. 1984. A comparison of the gametogenic cycle between the Pacific oyster Crassostrea gigas and the Suminoe oyster Crassostrea rivularis in Washington state. Aquaculture 37: 231-237. Ref ID: 48 Pernell-Lewis, V. and Peters, D. S. 1994. Diet of juvenile and adult Atlantic menhaden in estuarine and coastal habitats. Transactions of the American Fisheries Society 123: 803-810. Ref ID: 604 Peterson, C. H. and Heck, K. L. 1999. The potential for suspension feeding bivalves to increase seagrass productivit. Journal of Experimental Marine Biology and Ecology 240: 37-52. Ref ID: 661 Abstract: Suspension feeding bivalves are commonly associated with seagrass habitats in the Gulf of Mexico and Caribbean Sea. Biodeposits of some suspension feeding bivalves have been shown to be high in nitrogen and phosphorus. Consequently, filter feeding bivalves may act as a benthopelagic couple bringing planktonic production to the benthos, thereby elevating submerged aquatic vegetation growth by increasing the nutrients available to the rhizosphere. Laboratory feeding experiments were used to calculate the filtration rate of a typical suspension feeding bivalve Modiolus americanus. Filtration rates were estimated to be 2.87+/-0.821 h(-1) g tissue dry weight(-1) Consumption rates were estimated to be 9.41+/-2.62 mu g Chi a h(-1) g tissue dry weight(-1). In addition, field experiments were used to calculate mean biodeposition rates. Biodeposition rates were estimated to be 2.25+/-0.36 g dry wt material g tissue dry weight day(-1). Therefore, at mean field densities M. americanus are capable of depositing 218 kg dry weight material m(-2) annually. These deposits will contain 215 g N and 7.1 g P. A flower pot experiment demonstrated that the biodeposits of M. americanus were capable of increasing the pore water nutrient content and a mussel density manipulation in the field revealed that the presence of mussels significantly reduced leaf tissue C:N and C:P ratios. Pore water ammonium and phosphate concentrations were four times greater in the highest mussel density than in the control treatments and the lower leaf tissue C:N and C:P ratios in the presence of mussels established that this increased pore water nutrient was available to the seagrass, Thalassia testudinum. Collectively, these experiments suggest that suspension feeding bivalves may be important resource conduits converting inaccessible PON and POP in the water column to elevated sediment nutrient levels within the rhizosphere available for absorption by submerged aquatic vegetation. (C) 1999 Elsevier Science B.V. All rights reserved. Peterson, C. H., Summerson, H. C., Thomson, E., Lenihan, H. S., Grabowski, J., Manning, L., Micheli, F., and Johnson, G. 2000. Synthesis of linkages between benthic and fish communities as a key to protecting essential fish habitat. Bulletin of Marine Science 66: 759-774. Ref ID: 432 Abstract: Several essential fish habitats lack the protections necessary to prevent degradation because of failure to integrate the scientific disciplines required to understand the causes of the degradation and failure to integrate the fragmented state and federal management authorities that each hold only a piece of the solution. Improved protection of essential habitat for demersal fishes requires much better synthesis of benthic ecology, fisheries oceanography, and traditional fisheries biology. Three examples of degraded habitat for demersal fishes and shellfishes are high-energy intertidal beaches, subtidal oyster reefs, and estuarine soft bottoms. In each case, both scientific understanding of and management response to the problem require a holistic approach. Intertidal beach habitat for surf fishes could be protected by constraints on the character of sediments used in beach nourishment acid restriction of nourishment activity to biologically inactive seasons. Subtidal oyster-reef habitat for numerous crabs, shrimps, and finfishes could be protected and restored by reduction of nitrogen loading to the estuary and elimination of dredge damage to reefs. Estuarine soft-bottom habitat for demersal fin- and shellfishes could also be protected by reduction of the nutrient loading of the estuary, which could prevent associated problems of nuisance blooms and low dissolved oxygen. Although a broad general understanding of the nature of habitat degradation exists for each of these three examples, the interdisciplinary science needed to sort out the separate and interactive contributions of all major contributing factors is incomplete. Adopting the holistic approach embodied in the principles of ecosystem management sets a course for addressing both the scientific inadequacies and the management inaction Peterson, C. H., Grabowski, J., and Powers, S. P. 2003. Estimated enhancement of fish production resulting from restoring oyster reef habitat: quantitative valuation. Marine Ecology-Progress Series 264: 249-264. Ref ID: 584 Abstract: We reviewed studies providing quantitative measurements of abundance of fishes and large mobile crustaceans on oyster reefs and on nearby sedimentary habitat in the southeast United States. For each species, we compared density by size (age) class on oyster reefs and sedimentary bottom as a means of estimating the degree to which restoration of oyster reef on sedimentary bottom could augment abundances. By applying published information on growth rates of each species and a combination of empirical data and published information on age-specific survivorship, we calculated the per-unit-area enhancement of production of fishes and large mobile crustaceans expected from the addition of oyster reef habitat. For this calculation, we gave the reef habitat full credit for the expected lifetime production of species whose recruitment was judged to be limited by the area of oyster reefs based on nearly exclusive association of recruits to reefs. For species that were only modestly enhanced in abundance by oyster reefs, we gave the reef credit for the fraction of production that is derived from consumption of reef-associated prey, using a combination of gut content data and natural history information. This combination of analyses and calculations revealed that 10 m(2) Of restored oyster reef in the southeast United States is expected to yield an additional 2.6 kg yr(-1) of production of fish and large mobile crustaceans for the functional lifetime of the reef. Because the reef is biogenic and self-sustaining, the lifetime of a reef protected from bottom-disturbing fishing gear is limited by intense storms or sedimentation. A reef lasting 20 to 30 yr would be expected to augment fish and large mobile crustacean production by a cumulative amount of 38 to 50 kg 10 m(-2), discounted to present-day value. This set of calculations assumes that oyster reef habitat now limits production of reef-associated fish and crustaceans in the southeast United States. This assumption seems reasonable based on the tight associations of so many fishes with reef-dependent prey, and the depletion of reef habitat over the past century. Petrik, R., Levin, P. S., Stunz, G. W., and Malone, J. 1999. Recruitment of Atlantic croaker, Micropogonias undulatus: Do postsettlement processes disrupt or reinforce initial patterns of settlement? Fishery Bulletin 97: 954-961. Ref ID: 662 Abstract: Understanding the relative importance of pre- and postsettlement processes is critical to understanding the population dynamics of marine fishes. Our goals in this study were 1) to examine habitat preference and habitat use of newly settled Atlantic croaker, Micropogonias undulatus, and 2) to determine if postsettlement growth or predation Varied with habitat type. Field surveys showed no difference in croaker abundance among three estuarine habitats: marsh edge, seagrass, and sand. Behavioral experiments in laboratory mesocosms suggested that the pattern of similar use of habitats in the field results from a lack of preference among habitats. In a field experiment, croaker recruitment was greater to artificial seagrass than to sand habitats, but there was no difference in fish density in habitats with or without food supplementation. Moreover, growth rates were similar in both sand and artificial seagrass habitats and in habitats with or without food supplementation. In a second experiment, we were unable to detect a difference in the density of newly settled croaker between sand and artificial seagrass habitats, or between habitats with predator access limited by cages and cage controls. Our results demonstrate that newly settled croaker use different estuarine habitats similarly, and there does not appear to be a fitness consequence of using many habitats. We suggest that for habitat generalists, such as the Atlantic croaker, variability in larval supply will be a stronger predictor of population dynamics than will variability of habitat attributes. Petrocci, C. 2002. Hope on the half shell: new oyster species for the Chesapeake Bay. Aquaculture Magazine 28: 8-11. Ref ID: 549 Pietros, J. M. and Rice, M. A. 2003. The impacts of aquacultured oysters, Crassostrea virginica (Gmelin, 1791) on water column nitrogen and sedimentation: results of a mesocosm study. Aquaculture 220: 407-422. Ref ID: 331 Abstract: To determine effects of aquacultured oysters Crassostrea virginica (Gmelin, 1791) on the overlying water column, a mesocosm study was performed at the Marine Ecosystem Research Laboratory (MERL) from June to October, 2000. The MERL facility is located adjacent to Narragansett Bay and consists of fourteen 13,000-l mesocosm tanks designed to simulate the Bay environmental conditions. Two hundred oysters ( approximate to 35 mm valve height; nominally filtering about 55 l/day/individual) were placed into three mesocosms, and three mesocosms were maintained without oysters as controls. Experiments were run with varying rates of water exchange in the tanks ranging from 0% to 100% per day (13,000 l/day). Parameters that were measured and compared between the two treatments included chlorophyll-a, particulate organic and inorganic matter, sedimentation, nitrate, ammonia, selected phytoplankton species and oyster growth rates. Oysters affected phytoplankton species composition and increased rates of sedimentation. Large diatoms were net sampled, and Nitzchia striata was predominant in mesocosms with oysters, while Skeletonema costatum dominated the control tanks. Ammonia excretion rates were determined for C. virginica using the salicylate-hypochlorite method. Ammonia excretion can be described by the allometric equation E = 50.65w(0.699) when E is the ammonia excretion rate in mug/h, and w is the soft tissue dry weight in grams. Based on rates of ammonia excretion by oysters and observed steady states of ammonia and other forms of inorganic nitrogen in mesocosm tanks, it can be hypothesized that ammonia generated by oysters is taken up by rapidly regenerating phytoplankton in the water column. (C) 2003 Elsevier Science B.V. All rights reserved Placyk, J. S. and Harrington, B. A. 2004. Prey abundance and habitat use by migratory shorebirds at coastal stopover sites in Connecticut. Journal of Field Ornithology 75: 223-231. Ref ID: 630 Abstract: Stopover areas are vital for the successful migration of many species of shorebirds, as they, in part, allow individuals to deposit large quantities of Fat needed to fuel their northward and southward journeys. While much research has focused on bird migration, few studies closely examine the environmental characteristics of specific stopover areas. For our study, we conducted prey availability surveys and documented shorebird habitat use during northward summer migration for three historically important stopover areas along the Connecticut Long Island Sound coastline in 2000. Coastal Connecticut provides important habitat not only for shorebirds migrating from northern Canada to South America, but also for resident breeding shorebirds (e.g., oystercatcliers, plovers, and sandpipers). Our prey availability surveys indicate that all three stopover sites were characterized by some combination of polychaete worms, crustaceans, and mollusks. Polychaete worms of the family Neredidae were the most common prey item at two of the three sites. In addition, the site frequented by the greatest densities of shorebirds also had the greatest density of nereid worms and the greatest diversity of invertebrates. In terms of habitat use, our results indicate that foraging densities tended to be highest on intertidal habitats that were sheltered from coastal wave action and where densities of benthic (burrowing) and epifaunal (surface-dwelling) prey tended to be high. However, some shorebird species, including one breeding resident, the American Oystercatcher (Haematopus palliatus) and one migrant, the Ruddy Turnstone (Arenaria interpres), both of special management concern, favored foraging on beach-front habitats. In contrast to foraging habitat preferences, shorebirds roosting at high tidal phases showed strong preferences for beach habitats fronting the Long Island Sound. The use of beach-front habitats for both foraging and roosting poses a challenging situation for beach managers Plotkin, P. T., Wicksten, M. K., and Amos, A. F. 1993. Feeding ecology of the loggerhead sea turtle Caretta caretta in the northwestern Gulf of Mexico. Marine Biology 115: 1-5. Ref ID: 637 Abstract: Digestive tract contents collected from carcasses of 82 loggerhead sea turtles (Caretta caretta) found on the south Texas coast from 1986 through 1988 were examined. Benthic invertebrates were the predominant prey. Sea pens (Virgularia presbytes), crabs, and mollusks accounted for 94 % of the dry weight of the digestive tract samples. Temporal changes in the percent occurrence and percent dry weight of sea pens, crabs, and mollusks in the digestive tract samples were significant. Loggerheads fed primarily on sea pens during spring, then primarily on crabs during summer and fall. The increase of crabs in the loggerhead diet paralleled the annual increase in the abundance of crabs in the Gulf of Mexico. Sea pens were located nearshore at depths of 6 to 12 m and had a disjunct distribution. Porter, E. T., Cornwell, J. C., and Sanford, L. P. 2004. Effect of oysters Crassostrea virginica and bottom shear velocity on benthic-pelagic coupling and estuarine water quality. Marine Ecology-Progress Series 271: 61-75. Ref ID: 583 Abstract: Increasing the biomass of bivalve suspensions feeders has been proposed as a means to improve water quality in eutrophic estuaries such as the Chesapeake Bay. However, water quality impacts are likely to be determined by the balance of bivalve feeding and the deposition and sediment regeneration of nutrients from particulate organic matter. In shallow-water environments, benthic and pelagic processes are closely coupled and water flow can regulate the supply of seston to the bivalves. In addition, such flow may regulate benthic-pelagic nutrient fluxes through mass transfer limitation and resuspension. We studied the interacting effects of juvenile oysters Crassostrea virginica and bottom shear velocity on phytoplankton biomass and on nutrient regeneration in a series of three 4 wk long comparative experimental ecosystem experiments. All mesocosms had a 1000 l water volume, a 1 m(2) sediment surface area, and a 1 m water-column depth, and the same realistic water-column mixing (turbulence intensity 1 cm s(-1)). The systems included a multi-component mesocosm with moderate bottom shear velocity (0.6 cm s(-1)) and 2 standard cylindrical tanks with an unrealistically low bottom shear velocity (0.1 cm s(-1)). Oysters shifted processes to the sediments by decreasing phytoplankton biomass without stimulating additional blooms and by increasing light penetration to the bottom. Through complex and indirect relationships, the interaction of oysters and enhanced shear velocity significantly affected microphytobenthos biomass. Light, as enhanced by the oyster feeding on phytoplankton, increased microphytobenthos biomass; a moderate bottom-shear velocity eroded the biomass. Microphytobenthos biomass decreased nutrient regeneration from the sediments to the water column and may have implications for water quality in low-energy parts of shallow-water estuaries such as Chesapeake Bay. Enhanced bottom shear in more energetic parts of shallow estuaries negatively affects microphytobenthos biomass and may increase nutrient regeneration from the sediments. Pouvreau, S., Bacher, C., and Heral, M. 2000. Ecophysiological model of growth and reproduction of the black pearl oyster, Pinctada margaritifera: potential applications for pearl farming in French Polynesia. Aquaculture 186: 117-144. Ref ID: 4 Abstract: A model of bioenergetics of the black pearl oyster (Pinctada margaritifera) was built to simulate growth, reproduction and spawning in suspended culture at field sites in Takapoto lagoon (French Polynesia). This model was based on allometric scaling of physiological functions and scope for growth (SFG) calculations. The input functions were clearance rate (CR, 1 day(-1)), retention efficiency (RE, %) for each kind of particle encountered in suspended matter, pseudofaeces and faeces productions (PF and F, mg C day(-1)), excretion and respiration rate (U and R, mg C day(-1)). The assimilated carbon (i.e., SFG, mg C day(-1)) was partitioned to the three internal state variables (somatic tissue, shell and gonad) according to the asymptotic increase of the reproductive effort (ER, %) with the age. Given organic and mineral particulate matter in suspension in lagoon water (POM and PIM, mg L-1) and assuming that the taxonomic composition of POM was fairly constant throughout the year, the model predicted annual evolution of total tissue weight (W-Tissue, g dry weight), shell weight (W-Shell, g DW) and gonad weight (W-Gonad, g DW) of pearl oysters at various ages. Data on tissue and shell growth, but also on gonad development of cultivated pearl oysters, acquired in 1997-1998 in Takapoto lagoon, were used to validate the model outputs. Results of the simulations indicated that the P. margaritifera growth model provided realistic growth trajectories for shell, somatic tissue and gonad, for pearl oysters aged from 1 to 4 years. Powell, E. N., Gauthier, J. D., Wilson, E. A., Nelson, A., Fay, R. R., and Brooks, J. M. 1992. Oyster disease and climate change - Are yearly changes in Perkinsus marinus parasitism in oysters (Crassostrea virginica) controlled by climatic cycles in the Gulf of Mexico. Marine Ecology 13: 243-270. Ref ID: 245 Abstract: The protozoan Perkinsus (= Dermocystidium) marinus is the most important pathogen of eastern oysters (Crassostrea virginica) in the Gulf of Mexico. Prevalence of P. marinus has been related to salinity and temperature, with low temperatures and salinities usually limiting infection. In 1986, a yearly monitoring program was begun to describe the regional distribution and yearly trends in P. marinus prevalence and infection intensity in the Gulf of Mexico in connection with NOAA's Mussel Watch program. Between 1986 and 1989, prevalence and infection intensity dropped in the southeastern and southwestern Gulf, infection intensity most strongly, and rose in the Florida panhandle, prevalence most strongly. Infection intensity fell but prevalence rose on both sides of the Mississippi delta; central/north Texas remained essentially unchanged. The regional and temporal distribution of P. marinus in the Gulf of Mexico can be considered a product of two spatio-temporal phenomena. (1) A relatively stable spatial pattern exists each year with centers of infection on the order of 300 km. (2) A concordance.in yearly shifts in prevalence and infection intensity occurs among sites on a scale of much greater than 1,000 km. The spatial scale of concordant yearly changes is much larger than the scale of centers of infection, and probably originates in broad shifts in weather patterns as they affect temperature and salinity (via rainfall and river runoff). Long-term climatic changes are most likely responsible for these spatio-temporal shifts and, as such, P. marinus prevalence and infection intensity may eventually be predictable from climatic models. Our data demonstrate the importance of multi-year cycles, not just seasonal cycles and occasional heavy rains, in determining P. marinus prevalence and implicate salinity as the primary mediating factor Powell, E. N., Klinck, J. M., Hofmann, E. E., and Ray, S. M. 1994. Modeling oyster populations. IV: Rates of mortality, population crashes, and management. Fishery Bulletin 92: 347-373. Ref ID: 1 Abstract: A time-dependent energy-flow model was used to examine how mortality affects oyster populations over the latitudinal gradient from Galveston Bay, Texas, to Chesapeake Bay, Virginia. Simulations using different mortality rates showed that mortality is required for market-site oysters to be a component of the population's size-frequency distribution; otherwise a population of stunted individuals results. As mortality extends into the juvenile sizes, the population's size frequency shifts toward the larger sizes. In many cases adults increase despite a decrease in overall population abundance. Simulations, in which the timing of mortality varied, showed that oyster populations are more susceptible to population declines when mortality is restricted to the summer months. Much higher rates of winter mortality can be sustained. Comparison of simulations of Galveston Bay and Chesapeake Bay showed that oyster populations are more susceptible to intense population declines at higher latitudes. The association of population declines with disease agents causing summer mortality and the increased frequency of long-term declines at high latitudes result from the basic physiology of the oyster and its population dynamics cycle. Accordingly, management decisions on size limits, seasons and densities triggering early closure must differ across the latitudinal gradient and in populations experiencing different degrees of summer and winter mortality relative to their recruitment rate. More flexible size limits might be an important management tool. When fishing is the primary cause of mortality, populations should be managed more conservatively in the summer. The latitudinal gradient in resistance to mortality requires more conservative management at higher latitudes and different management philosophies from those used in the Gulf of Mexico. Powell, E. N., Klinck, J. M., Hofmann, E. E., Wilson-Ormond, E. A., and Ellis M.S. 1995. Modeling oyster populations. V. Declining phytoplankton stocks and the population dynamics of American oyster (Crassostrea virginica) populations. Fisheries Research 24: 199-222. Ref ID: 8 Abstract: Phytoplankton standing stocks have shown a steady decline in Galveston Bay, Texas over the last 20 years. Phytoplankton provides the primary food resource for oyster populations in Galveston Bay. We used a time-dependent population dynamics model of oyster populations to examine the impact of a decline in phytoplankton stocks on oyster populations. Simulations were run with two different types of mortality: winter mortality, assuming that the oyster fishery is the primary source of mortality; and summer mortality, assuming that predators and disease are the primary source of mortality, All simulations showed the same qualitative trends. Market-size adults disappear from the population in about 4 years, with an approximate 15% decline in food supply. Submarket-size adults maintained an increasing or steady population density for 10-14 years, after which the populations crashed to near extinction in 2-4 years. The proximate cause was a cessation in reproductive activity when food supply ceased to be sufficient to generate a fall spawn, an approximate 60% drop in food from current levels in Galveston Bay. The temporal sequence of mortality affected the outcome very little, The simulations suggest that populations decline rapidly in response to declining food supplies because a minimum food level is required to support a market-size population and a minimal reproductive activity. The simulations suggest that a reduction in market-size individuals is the primary early-warning signal of decreased food supply within the affected population and that this warning signal might easily be mistaken for overfishing. Proper management requires the monitoring of food supply and the use of a mathematical model to assess the importance of observed declines in population abundance. Unfortunately, once the fishery is affected, little time may remain before the termination of spawning and population extinction. Powell, E. N., Klinck, J. M., and Hofmann, E. E. 1996. Modeling diseased oyster populations. II. Triggering mechanisms for Perkinsus marinus epizootics. Journal of Shellfish Research 15: 141-165. Ref ID: 2 Abstract: Densities of Crassostrea virginica remain high enough to support substantial fisheries throughout the Gulf of Mexico despite high mortality rates produced by the endoparasite Perkinsus marinus. The infrequency of epizootics in these populations suggests that controls exist on the disease intensification process. The progression of epizootics in oyster populations, the factors that trigger epizootics, and the factors that terminate epizootics once started were investigated with a coupled oyster population-P. marinus model. The time development of a simulated epizootic was triggered by environmental conditions that occurred and disappeared as much as 18 months prior to the onset of mortality in the oyster population. Initiation of epizootic conditions was detected as an increase in infection intensity in the submarket-size adult and juvenile portions of the oyster population. Infection intensity of the marker-size adults is maintained at a relatively stable level by the death of heavily infected individuals and the slow rate of P. marinus division at high infection intensities. Once started, most of the simulated epizootics resulted in population extinction in 2 to 4 years. Stopping an epizootic required reducing the infection intensity in the submarket-size adults and juveniles. The infection intensity of market-size adults does not need to be reduced to stop an epizootic nor must it be raised to start one. The simulated oyster populations show that a reduction in ingestion rate (by reduced food supply or increased turbidity) can trigger an epizootic, especially if the reduction occurs during the summer. Increasing food supply or decreasing turbidity in the following year does not necessarily prevent the occurrence of an epizootic. Rather, the onset of the event is simply delayed. Additional simulations show that the relative combination of variations in salinity and temperature is important in determining the occurrence of an epizootic. A dry (high-salinity) summer followed by a warm winter produces conditions that favor the development of an epizootic. Conversely, a warm dry pear followed by a cool wet year fails to produce an epizootic. Simulations that consider variations in the biological characteristics of oyster populations, such as changes in recruitment rate or disease resistance, show that these are important in regulating the occurrence of an epizootic as well as in terminating the event. In particular, increased recruitment rate dilutes the infected population sufficiently to terminate an epizootic. One primary conclusion that can be obtained from these simulations is that epizootics of P. marinus in oyster populations are difficult to generate simply with changes in either temperature or salinity. Rather, the epizootics are triggered by some other factor, such as reduced food supply or reduced recruitment rate, that occurs prior to or coincident with high salinity or temperature conditions. Powell, E. N., Klinck, J. M., Hofmann, E. E., and Ford, S. 1997. Varying the timing of oyster transplant: implications for management from simulation studies. Fisheries Oceanography 6: 213-237. Ref ID: 552 Abstract: The transplanting of oysters from one ground to another is a common practice in the oyster industry. In Delaware Bay, for instance, oysters are typically transplanted from upper-bay low-salinity seed beds onto lower-bay leased grounds for growth and conditioning before market. The higher salinity on the leased grounds, however, also favours higher losses to predation and disease. A coupled oyster-Perkinsus marinus-predator model was used to investigate how varying the timing of transplant affects the ultimate yield of Eastern oysters, Crassostrea virginica, in Delaware Bay. Simulations were run in which oysters were moved from seed beds to leased grounds in November, January, March, April and May. The number of market-size (greater than or equal to 76 mm) adults available for harvest in the following July to November was compared for populations undergoing mortality from predation (crabs, oyster drills) and/or disease (Perkinsus marinus). In all simulations, the abundance of market-size oysters declined between July and November. However, transplanting oysters in November resulted in the largest yield of market-size oysters for all harvest times; transplanting in May resulted in the smallest yield. The autumn transplant allows oysters to benefit from the larger spring phytoplankton bloom over the leased grounds in the lower estuary. The effect of varying the season of transplant was most noticeable if oysters were harvested early (July or August). In all simulations, transplanting resulted in a higher abundance of market-size oysters than direct harvest from the seed beds. Direct harvest would rarely be advantageous if the cost of transplant were insignificant and the relative rates of mortality were as stipulated. However, a May transplant is only moderately better than a direct harvest and the economic benefits of either option are likely to be determined by the cost of transplanting and the mortality associated with the process. In the same vein, the decision as to when to harvest relies on balancing the increased price obtained for oysters in the autumn with the increased loss owing to predation and disease. Awaiting an autumn harvest is clearly much riskier if the principal source of mortality is disease rather than predation, because disease mortality is concentrated on the market-size oysters and is greatest in the autumn Powell, E. N., Barber, R. D., Kennicutt, M. C., and Ford, S. E. 1999. Influence of parasitism in controlling the health, reproduction and PAH body burden of petroleum seep mussels. Deep-Sea Research Part I-Oceanographic Research Papers 46: 2053-2078. Ref ID: 511 Abstract: Petroleum seep mussels are often exposed to high hydrocarbon concentrations in their natural habitat and, thus, offer the opportunity to examine the relationship between parasitism, disease and contaminant exposure under natural conditions. This is the first report on the histopathology of cold-seep mussels. Seep mussels were collected by submersible from four primary sites in the Gulf of Mexico, lease blocks Green Canyon (GC) 184, GC-234, GC-233, and Garden Banks 425 in 550-650 m water depth. Five types of parasites were identified in section: (1) gill "rosettes" of unknown affinity associated with the gill bacteriocytes, (2) gill "inclusions" similar to chlamydia/rickettsia inclusions, (3) extracellular gill ciliates, (4) body "inclusions" that also resemble chlamydial/rickettsial inclusions, and (5) Bucephalus-like trematodes. Comparison to shallow-water mytilids demonstrates that: (1) both have similar parasite faunas; (2) seep mytilids are relatively heavily parasitized; and (3) infection intensities are extremely high in comparison to shallow-water mytilids for Bucephalus and chlamydia/rickettsia. In this study, the lowest prevalence for chlamydia/ricketttsa was 67%. Prevalences of 100% were recorded from three populations. Bucephalus prevalence was greater than or equal to 70% in three of 10 populations. The parasite fauna was highly variable between populations. Some important parasites were not observed in some primary sites. Even within primary sites, some important parasites were not observed in some populations. Bucephalus may exert a significant influence on seep mussel population dynamics. Forty percent of the populations in this study are severely reproductively compromised by Bucephalus infection. Only a fraction of petroleum seep mussel populations are maintaining the entire beta-level population structure of this species. Variation in two parasites, gill ciliates and Bucephalus, explained most of the variation in PAH body burden between mussel populations. PAHs are known to be sequestered preferentially in gametic tissue. Bucephalus would be expected to reduce overall body burden, at high infection intensities, by replacing gametic tissue. PAH concentrations exceeded 1 ppm in 4 of 9 populations, a ratio significantly higher than the 8 of 30 mussel locales in the NOAA Mussel Watch Program. Only five Mussel Watch locales exceeded the highest value for a petroleum seep population. Digestive gland and gill tissue atrophy were not significantly correlated with PAH body burden, even though some populations were characterized by body burdens exceeding I ppm, suggesting that seep mussels may not be as sensitive to PAH exposure as are some shallow-water mytilid populations. (C) 1999 Elsevier Science Ltd. All rights reserved Powell, E. N., Klinck, J. M., Ford, S. E., Hofmann, E. E., and Jordan, S. J. 1999. Modeling the MSX parasite in eastern oyster (Crassostrea virginica) populations. III. Regional application and the problem of transmission. Journal of Shellfish Research 18: 517-537. Ref ID: 520 Abstract: A model of transmission for Haplosporidium nelsoni, the disease agent for MSX disease, is developed and applied to sites in Delaware Bay and Chesapeake Bay. The environmental factors that force the oyster population-ii. nelsoni model are salinity, temperature, food, and total suspended solids. The simulated development of MSX disease was verified using 3 time series of disease prevalence and intensity: 1960 to 1970 and 1980 to 1990 for Delaware Bay, and 1980 to 1994 for Chesapeake Bay, and for a series of sites covering the salinity gradient in each bay. Additional simulations consider the implications of assumptions made in development of the model for constraining the mode of transmission of H. nelsoni disease in oyster populations.Transmission of H. nelsoni includes non-local factors that exert a paramount influence on the transmission process. Key environmental forcing factors of season, salinity, and winter temperature exert a direct control on the transmission process, either by controlling the availability of infective particles in the water column or by controlling the population dynamics of an alternate host. Salinity's role is a dual one. Salinity acts on the local host population by varying the infectivity of infective particles as they impinge the oyster gill during the filtration process. In addition, salinity exerts a regional influence on the transmission process by controlling, in part and on a bay-wide scale, the concentration of infective particles in the water column (or perhaps the abundance of an alternate host). In addition to the effect of salinity, infective particle concentration also decreases for 1 to 2 years after a cold winter and returns to high levels faster after a warm winter. It is the presence in the H. nelsoni transmission model of these bay-wide influences of environmental change that make this model different: from most other transmission models. Simulations suggest that epizootic cycles are principally the product of enhanced transmission rather than enhanced intensification. These influences of transmission on the course of infection, in many cases, have multiyear implications for prevalence and infection intensity, and the root of much of this multiyear behavior is in the processes that control the concentration of infective particles in the water column Powell, E. N., Ashton-Alcox, K. A., Banta, S. E., and Bonner, A. J. 2001. Impact of repeated dredging on a Delaware Bay oyster reef. Journal of Shellfish Research 20: 961-975. Ref ID: 507 Abstract: The impact of commercial dredging on an oyster reef was evaluated at four sites chosen on New Beds, one of the most important commercial oyster beds in Delaware Bay. Dredging occur-red on two of these sites in late October 1999, early and late November 1999, April 2000, and July 2000. Dredging was conducted according to standard industry procedures. Each day, dredging was continuous during approximately an 8-h period. Both one-dredge and two-dredge boats were used. Market-size oysters were culled and sacked in the standard manner. Total dredge coverage for the study was about 240,000 m(2) on each experimental site. The most heavily dredged areas were completely covered by the dredge 4 to 6 times during the study. Two 8-h dredging events within a 10-day period produced barely detectable changes in the oyster population. Minor chipping and abrasion of the shell increased in frequency, but no other discernible impacts were found. Over the 10-mo study that included five dredging events, many of the taphonomic indicators of dredge damage showed time-dependent trends that differed between control and experimental sites. However, these effects were limited mostly to minor chipping and indications of abrasive wear, rather than the more serious aspects of shell damage defined as major chipping, breakage, cracking, and shell perforation. A variety of population health indicators were assayed during the study, including the ratio of live oysters to boxes, condition index, Perkinsus marinus infection intensity, and oyster size-frequency distribution, These indicators should have monitored growth, disease pressure, and mortality. Essentially no significant effects could be discerned for any of these measures. Over a very long time, dredging may significantly influence oyster bed physiography and community structure. However, once the bed has become a fished bed, this study suggests that moderate dredging that results in a yearly swept area of no more than four times the area of the bed is unlikely to result in significant further impact on the oyster populations living there Powell, E. N., Ashton-Alcox, K. A., Dobarro, J. A., Cummings, M., and Banta, S. E. 2002. The inherent efficiency of oyster dredges in survey mode. Journal of Shellfish Research 21: 691-695. Ref ID: 335 Abstract: To develop a quantitative stock assessment for the New Jersey oyster (Crassostrea virginica) seed beds, oyster dredge efficiency was measured on 10 different oyster beds in the Delaware Bay. Depending on size class and location, mean dredge efficiency for market-size oysters varied from 7.8 to >85%. The sampled beds could be allocated into two groups, one characterized by low dredge efficiency and the other characterized by high dredge efficiency. The low-efficiency group, Group 1, had mean dredge efficiencies for market-size oysters that ranged from 10.9 to 19.5%. The high-efficiency group, Group 2, had mean dredge efficiencies for market-size oysters that always exceeded 45%. A strong tendency existed for market-size oysters to be captured with higher efficiency than smaller oysters. In addition, live oysters tended to be captured with higher efficiency than boxes (articulated valves). Although a conclusion cannot be reached unequivocally, the differential in dredge efficiency observed between Group I and Group 2 beds may represent the difference between dredge efficiencies on beds routinely fished and those not routinely fished. An effect of salinity regime cannot be excluded as a possible explanation, however. The differential in dredge efficiency between the two bed groups, about a factor of 4.5 for market-size oysters indicates that variations in bed consolidation may have a large influence on dredge efficiency and may significantly bias estimates of abundance if not taken into account in stock assessments Powell, E. N., Klinck, J. M., Hofmann, E. E., and McManus, M. A. 2003. Influence of water allocation and freshwater inflow on oyster production: A hydrodynamic-oyster population model for Galveston Bay, Texas, USA. Environmental Management 31: 100-121. Ref ID: 513 Abstract: A hydrodynamic-oyster population model was developed to assess the effect of changes in freshwater inflow on oyster populations in Galveston Bay, Texas, USA. The population model includes the effects of environmental conditions, predators, and the oyster parasite, Parkinsus marinus, on oyster populations. The hydrodynamic model includes the effects of wind stress, river runoff, tides, and oceanic exchange on the circulation of the bay. Simulations were run for low, mean, and high freshwater inflow conditions under the present (1993) hydrology and predicted hydrologies for 202, and 2049 that include both changes in total freshwater inflow and diversions of freshwater from one primary drainage basin to another.Freshwater diversion to supply the Houston metropolitan area is predicted to negatively impact oyster production in Galveston Bay. Fecundity and larval survivorship both decline. Mortality from Perkinsus marinus increases, but to a lesser extent. A larger negative impact in 2049 relative to 2024 originates from the larger drop in fecundity under that hydrology. Changes in recruitment and mortality, resulting in lowered oyster abundance, occur because the bay volume available for mixing freshwater input from the San Jacinto and Buffalo Bayou drainage basins that drain metropolitan Houston is small in comparison to the volume of Trinity Bay that presently receives the bulk of the bay's freshwater inflow. A smaller volume for mixing results in salinities that decline more rapidly and to a greater extent under conditions of high freshwater discharge.Thus, the decline in oyster abundance results from a disequilibrium between geography and salinity brought about by freshwater diversion. Although the bay hydrology shifts, available hard substrate does not. The simulations stress the fact that it is not just the well-appreciated reduction in freshwater inflow that can result in decreased oyster production. Changing the location of freshwater inflow can also significantly impact the bay environment, even if the total amount of freshwater inflow does not change Purcell, J. E., Cresswell, F. P., Cargo, D. G., and Kennedy, V. S. 1991. Differential ingestion and digestion of bivalve larvae by the Scyphozoan Chrysaora quinquecirrha and the Ctenophore Mnemiopsis leidyi. Biological Bulletin 180: 103-111. Ref ID: 505 Abstract: We investigated predation on bivalve veligers by the scyphozoan Chrysaora quinquecirha and the ctenophore Mnemiopsis leidyi. We found that the medusa stage of C. quinquecirrha captures, but does not digest, veliger larvae: 99% of oyster veligers (Crassostrea virginica) caught by medusae were egested alive within 7 h of capture, and 98% survived for 24 h after egestion; 98% of oyster, mussel (Mytilus edulis), and clam (Mulinia lateralis) veligers placed on the oral arms of medusae were rejected; all bivalve veligers in field-collected medusae were closed and full of tissue. Our laboratory evidence suggests that the shell of larval bivalves probably offers protection from medusae: 23% of dead, open veligers were ingested by medusae compared with 0.7% of live, closed veligers; open veligers were retained longer than closed veligers; and tissue excised from recently settled oyster larvae was ingested and digested. Freeswimming C. quinquecirrha ephyrae ingested but did not digest veligers. By contrast, the benthic scyphistoma stage ingested 69% of veligers that contacted their tentacles and digested 48% of those ingested. Each scyphistoma consumed an average of 1 veliger/day at densities of 0.3 veligers ml-1. However, larval settlement was not reduced on oyster shells bearing scyphistomae. By contrast to the results on C. quinquecirrha, ctenophores egested only 4% of veligers alive, and 25% of the veligers in their gut contents were digested. Predation on veligers by ctenophores was estimated to be 0.2 to 1.7%/day in Chesapeake Bay. We conclude that C. quinquecirrha medusae are not important predators of bivalve veligers, but rather may reduce their mortality by consuming ctenophores, which do eat veligers Qiqian, Z. 1992. Research on marine bivalves in the People's Republic of China. American Malacological Bulletin 9: 207-215. Ref ID: 51 Que, H. and Allen, S. K. Jr. 2002. Hybridization of tetraploid and diploid Crassostrea gigas (Thunberg) with diploid C. ariakensis (Fujita). Journal of Shellfish Research 27: 137-143. Ref ID: 145 Abstract: Three replicates of hybrid crosses of tetraploid and diploid C gigas (Thunberg) with diploid C ariakensis (Fujita) were produced with controls. Larval survival and growth were documented. Cytological events were also monitored in oocytes from hybrid crosses following insemination. Among the four types of hybrid crosses, diploid C. gigas (female) x diploid C. ariakensis (male) (GA) was the most successful. Survival of GA was about the same as that of controls in two of three replications, although its growth rate was 25-30% lower. Crosses of tetraploid C. gigas (female) and diploid C. ariakensis (male) (GGA) had poor yield at day 2 post-fertilization (0.05%), but grew nearly as well as controls subsequently. The other two types of hybrids (i.e., diploid C. ariakensis [female] and tetraploid C. gigas [male] [AGG], diploid C ariakensis [female] and diploid C. gigos [male] [AG]) suffered very low yield at day 2 (0.01% and 0.003%) and grew very slowly. Spat were obtained from all replicates of GA crosses and one of three replicates of GGA, and proved to be hybrids by polymerase chain reaction/restriction fragment length polymorphism (PCR/RFLP) diagnosis. GGA hybrids were confirmed to be triploid by flow cytometry. No larvae survived to eyed stage in AGG or AG crosses. Cytological examination revealed that the vast majority (>99%) of oocytes from hybrid crosses had a prolonged meiotic prophase I or metaphase I at least through 180 min post-insemination. Ragone Calvo, L. M. and Burreson, E. M. 1994. Characterization of overwintering infections of Perkinsus marinus (Apicomplexa) in Chesapeake Bay Oysters. Journal of Shellfish Research 13: 123-130. Ref ID: 402 Abstract: To determine the nature and abundance of over-wintering P. marinus infections, infected oysters (Crassostrea virginica) collected from the upper James River, VA, were placed in a tray and suspended from a pier in the lower York River, VA in November 1991. Every six weeks through May 1992 oysters (n = 25) were removed from the tray, examined for P. marinus by hemolymph culture in fluid thioglycollate medium (FTM), gradually warmed in individual containers to 25-degrees-C and held for one month. After the incubation period, which permitted the development of very light and/or cryptic parasite stages to detectable levels, the oysters were reanalyzed for P. marinus by both hemolymph and tissue cultures in FTM. A second group of 25 oysters from the tray was sacrificed at the initiation of each incubation, diagnosed using FTM cultures of hemolymph and tissue, and examined for cryptic stages using immunoassays. On the basis of FTM assays, prevalence of P. marinus gradually declined from 100% in November 1991 to 32% in May 1992. Incubation of oysters at 25-degrees-C always resulted in an increase of P. marinus prevalence and intensity, suggesting that the parasite was more abundant than initial FTM cultures indicated. Immunoassay diagnosis revealed infections in many of the oysters diagnosed as negative by FTM cultures. Most infections detected by immunoassay were comprised of individual P. marinus meronts within hemocytes in the midgut epithelial lining. Previously unidentified cryptic stages were not observed. Perkinsus marinus appears to overwinter at very low intensities in a high proportion of oysters. Comparison of P. marinus prevalence and intensity in transplanted oysters maintained in the York River to that in oysters monitored at the original James River collection site suggests that salinity may greatly influence overwintering infections. Infection intensity and prevalence declined earlier and to a greater extent at the James River site (4-12 ppt) than at the York River location (19-23 ppt). It appears that the synergistic effect of low temperature and low salinity may be more important in regulating P. marinus epizootics than either factor acting alone Ragone Calvo, L. M., Wetzel, R. L., and Burreson, E. M. 2001. Development and verification of a model for the population dynamics of the protistan parasite, Perkinsus marinus, within its host, the eastern oyster, Crassostrea virginica, in Chesapeake Bay. Journal of Shellfish Research 20: 231-241. Ref ID: 562 Abstract: A simulation model was developed to investigate the population dynamics of the protistan parasite, Perkinsus marinus, within its host, the eastern oyster, Crassostrea virginica. The main objective was to evaluate the relationship between P. marinus population dynamics and environmental conditions in order to predict the onset and termination of P. marinus epizootics in Chesapeake Bay oyster populations. Information derived from laboratory experiments and from direct field observations of P. marinus dynamics in the James River for the years 1990 to 1993 was utilized for model development. The individual-based model, which is driven by temperature and salinity, tracks the average within-host parasite density at a daily time step. The model was verified against monthly field observations of parasite abundance for the years 1994 to 1999 at three oyster bars located along a 0-20-ppt salinity gradient in the James River, Virginia. Simulated populations exhibited a distinct seasonal periodicity with annual density maximums and minimums occurring in October and May, respectively. Parasite abundance decreased in an upriver direction with decreasing salinity along the salinity gradient. Predicted parasite densities significantly correlated with actual observed densities at all three locations; however, the strength of the association decreased from bar to bar in an upriver direction. Predicted parasite abundance exhibited a dynamic steady state for all three oyster bars during the 6-year time series. Simulations run without the input of a midsummer transmission event resulted in a destabilization and extinction of the parasite from the oyster population located farthest upriver. but the parasite remained enzootic during the six year simulation at the two lower river stations. This suggests that a single transmission event may be sufficient for P. marinus to become enzootic in specific year classes of oyster populations located in moderate to high salinity areas, while periodic transmission events are required for the parasite to persist in low salinity areas. Simulation results suggest that fairly accurate quantitative predictions of P. marinus abundance can be made using in situ temperature and salinity data and a relatively simple model Ragone Calvo, L. M., Calvo, G. W., and Burreson, E. M. 2003. Dual disease resistance in a selectively bred eastern oyster, Crassostrea virginica, strain tested in Chesapeake Bay. Aquaculture 220: 69-87. Ref ID: 38 Abstract: Selective breeding efforts have yielded oyster strains, Crassostrea virginica, with improved survival and resistance against Haplosporidium nelsoni (MSX); however, because of susceptibility to the oyster pathogen Perkinsus marinus (Dermo), their utility has been limited in areas where the two parasites co-occur. Dual resistance to H. nelsoni and P marinus was achieved through four generations of artificial selection of wild Delaware Bay oyster progeny at a site in the lower York River, Virginia, USA where both diseases are enzootic. During 1993-1995, survival, growth, and disease susceptibility of third generation Delaware Bay (F-3-DEBY) oysters were evaluated at the York River site in comparison to that of similarly selected third generation James River, Virginia oysters (F-3-JR), and first generation Louisiana oysters (F-1-LA), whose parents were naturally selected in the wild for resistance to P marinus. During 1997-1999, the performance of F-4-DEBY was evaluated at three sites in Virginia in comparison to two groups of first generation oysters whose parents originated from Mobjack Bay and Tangier Sound, Virginia where both R. marinus and H. nelsoni are enzootic. In the presence of high infection pressure from both H. nelsoni and P. marinus, the F-3-DEBY stock showed significantly higher survival and growth than either the F-3-JR or F-1-LA strain. After 15 months of deployment, 79% of F-3-DEBY, 11% of F-3-JR and 17% of F-1-LA oysters were market size (greater than or equal to76.2 mm) and cumulative mortality was only 16% in F3-DEBY as compared to 42% in FOR and F-1-LA. At the termination of the study, F-3-DEBY oysters exhibited 22% lower mortality than the F-1-LA stock, which outperformed the F-3-JR stock. Relative performance in respect to disease varied considerably with sample date; however, average H. nelsoni weighted prevalence varied such that F-3-DEBY25% aerial exposure) during high temperature periods. Only in autumn did recruitment occur in the intertidal area occupied by natural oyster populations. In contrast, low intertidal and subtidal populations persisted through the month long experiments where adult oysters were rare. Growth (shell area) of intertidal oysters exposed >25% was reduced relative to more immersed oysters. Density-dependent growth was not observed. While the natural oyster population appeared to be relegated to the suboptimum intertidal, successful recruitment to this zone was limited on a seasonal basis by lethal air temperatures >30 degrees C. The mortality agents which structure the intertidal population affect recently settled and juvenile oysters. Rosenberg, A. A. and Restrepo, V. R. 1994. Uncertainty and risk evaluation in stock assessment for U.S. marine fisheries. Canadian Journal of Fisheries and Aquatic Science 51: 2715-2720. Ref ID: 176 Abstract: This paper describes some of the ways that the uncertainty in fisheries scientific advice has been communicated to managers for different fisheries in the United States in the past several years. Describing the uncertainty can be important in allowing managers to weigh the benefits and losses of different management strategies and to allay concerns about the effects of process, measurement, and model errors on the scientific advice, even if a formal decision theoretic risk analysis has not been carried out. The four general steps in analyzing uncertainty and assessing risk are estimation of the uncertainty in the assessment of current stock status due to measurement error, evaluation of the impacts of potential model errors on the assessment, stochastic projections incorporating estimation error and process errors to investigate the impacts of different management options, and assessment of risk using simple utility functions. At least one of these steps has been included in assessment analyses of about 20 major U.S. fisheries. All of these steps have been incorporated in the scientific advice on a few fisheries to date and should be attempted whenever possible to improve the information available to fishery managers. Ross, S. W. 2003. The relative value of different estuarine nursery areas in North Carolina for transient juvenile marine fishes. Fishery Bulletin 101: 384-404. Ref ID: 664 Abstract: Offshore winter-spawned fishes dominate the nekton of southeastern United States estuaries. Their juveniles reside for several months in shallow, soft bottom estuarine creeks and bays called primary nursery areas. Despite similarity in many nursery characteristics, there is, between and within species, variability in the occupation of these habitats. Whether all occupied habitats are equally valuable to individuals of the same species or whether most recruiting juveniles end up in the best habitats is not known. If nursery quality varies, then factors controlling variation in pre-settlement fish distribution are important to year-class success. If nursery areas have similar values, interannual variation in distribution across nursery creeks should have less effect on population sizes or production. I used early nursery period age-specific growth and mortality rates of spot (Leiostomus xanthurus) and Atlantic croaker (Micropogonias undulatus)-two dominant estuarine fishes-to assess relative habitat quality across a wide variety of nursery conditions, assuming that fish growth and mortality rates were direct reflections of overall physical and biological conditions in the nurseries. I tested the hypothesis that habitat quality varies for these fishes by comparing growth and mortality rates and distribution patterns across a wide range of typical nursery habitats at extreme ends of two systems. Juvenile spot and Atlantic croaker were collected from 10 creeks in the Cape Fear River estuary and from 18 creeks in the Pamlico Sound system, North Carolina, during the 1987 recruitment season (mid-March-mid-June). Sampled creeks were similar in size, depth, and substrates but varied in salinities, tidal regimes, and distances from inlets. Spot was widely distributed among all the estuarine creeks, but was least abundant in the creeks in middle reaches of both systems. Atlantic croaker occurred in the greatest abundance in oligohaline creeks of both systems. Instantaneous growth rates derived from daily otolith ages were generally similar for all creeks and for both species, except that spot exhibited a short-term growth depression in the upriver Pamlico system creeks-perhaps the result of the long migration distance of this species to this area. Spot and Atlantic croaker from upriver oligohaline creeks exhibited lower mortality rates than fish from downstream polyhaline creeks. These results indicated that even though growth was similar at the ends of the estuaries, the upstream habitats provided conditions that may optimize fitness through improved survival. Rothschild, B. J., Ault, J. S., Goulletquer, P., and Heral, M. 1994. Decline of the Chesapeake Bay Oyster population: a century of habitat destruction and overfishing. Marine Ecology Progress Series 111: 29-39. Ref ID: 165 Abstract: The oyster population in the Maryland portion of Chesapeake Bay, USA, has declined by more than 50-fold since the early part of this century. The paper presents evidence that the mechanical destruction of habitat and stock overfishing have been important factors in the decline, even though it is commonly thought that 'water quality' and, more recently, oyster diseases are critical. Quantitative analyses show that the long-term decline of oysters largely results from habitat loss associated with intense fishing pressure early in this century, and stock overfishing from early in the century through recent times. Furthermore, the major ecological effects on Chesapeake Bay occurred well before World War II, before industrialization and the reported prevalence of disease. To effect the recovery of the ailing Chesapeake Bay oyster stock, a 4-point management strategy is proposed. Ruesink, J. L., Parker, I. M., Groom, M. J., and Kareiva, P. M. 1995. Reducing the risks of nonindigenous species introductions. BioScience 45: 465-477. Ref ID: 110 Ruiz, G. M., Fofonoff, P., Hines, A. H., and Grosholz, E. D. 1999. Non-indigenous species as stressors in estuarine and marine communities: Assessing invasion impacts and interactions. Limnology and Oceanography 44: 950-972. Ref ID: 283 Abstract: Invasions by non-indigenous species (NIS) are recognized as important stressors of many communities throughout the world. Here, we evaluated available data on the role of MS in marine and estuarine communities and their interactions with other anthropogenic stressors, using an intensive analysis of the Chesapeake Bay region as a case study. First, we reviewed the reported ecological impacts of 196 species that occur in tidal waters of the bay, including species that are known invaders as well as some that are cryptogenic (i.e., of uncertain origin). Second, we compared the impacts reported in and out of the bay region for the same 54 species of plants and fish from this group that regularly occur in the region's tidal waters. Third, we assessed the evidence for interaction in the distribution or performance of these 54 plant and fish species within the bay and other stressors. Of the 196 known and possible NIS, 39 (20%) were thought to have some significant impact on a resident population, community, habitat, or process within the bay region. However, quantitative data on impacts were found for only 12 of the 39, representing 31% of this group and 6% of all 196 species surveyed. The patterns of reported impacts in the bay for plants and fish were nearly identical: 29% were reported to have significant impacts, but quantitative impact data existed for only 7% (4/54) of these species. In contrast, 74% of the same species were reported to have significant impacts outside of the bay, and some quantitative impact data were found for 44% (24/54) of them. Although it appears that 20% of the plant and fish species in our analysis may have significant impacts in the bay region based upon impacts measured elsewhere, we suggest that studies outside the region cannot reliably predict such impacts. We surmise that quantitative impact measures for individual bays or estuaries generally exist for <5% of the NIS present, and many of these measures are not particularly informative. Despite the increasing knowledge of marine invasions at many sites, it is evident that we understand little about the full extent and variety of the impacts they create-singly and cumulatively. Given the multiple anthropogenic stressors that overlap with NIS in estuaries, we predict NIS-stressor interactions play an important role in the pattern and impact of invasions Santopietro, G. D. and Shabman, L. A. 1992. Property rights to the Chesapeake Bay oyster fishery: history and implications. Society & Natural Resources 5: 165-178. Ref ID: 462 Abstract: This paper presents a history of the evolution of the property rights structure to the Chesapeake Bay oyster grounds, which includes both common and private property, and explains the reasons for the creation and persistence of this mixed system during the past 100 years. Implications for future management follow from this history Saoud, I. G., Rouse, D. B., Wallace, R. K., Supan, J. E., and Rikard, S. 2000. An in situ study on the survival and growth of Crassostrea virginica juveniles in Bon Secour Bay, Alabama. Journal of Shellfish Research 19: 809-814. Ref ID: 533 Abstract: Experimental plots were established at a relic oyster reef on the eastern side of Mobile Bay, Alabama between July 1998 and November 1999 to determine whether elevated beds might improve oyster survival and growth. Oysters (Crassostrea virginica) were spawned in a hatchery and the spat were allowed to settle on small oyster shell fragments and on whole oyster shell. Two-month-old juveniles (15-18 mm) were deployed in polyethylene oyster bags on bottom and on underwater shell pads 20 cm and 40 cm above bottom. Oysters on whole shells were deployed outside bags in order to evaluate predation. Remote sensing data loggers were deployed near bottom and 40 cm above bottom to measure temperature, salinity, and oxygen concentration. Growth (increase in height), survival, and condition of oysters in bags at the three experimental depths were compared. Temperature and salinity varied between 11.8 degreesC-32.8 degreesC and 4.4 pot-29.7 ppt, respectively. Periodic anoxic events, which lasted from a few hours to 6 days, were documented. Oysters at the three experimental levels grew to approximately 55 mm during the first year. Total mortality was observed at all three levels during the second summer when oxygen levels dropped to 0 mg L-1 for five consecutive days while water temperature was 28 degreesC. If the 17 months monitored during this study are typical, restoration of Fish River Reef will be difficult due to periodic anoxic events Scarpa, J. and Allen, S. K. Jr. 1992. Comparative kinetics of meiosis in hybrid crosses of Pacific oyster Crassostrea gigas and Suminoe oyster C. rivularis with the American oyster C. virginica. The Journal of Experimental Zoology 263: 316-322. Ref ID: 130 Abstract: Interspecific hybridization of bivalve molluscs within the genera Crassostrea and Pinctada have yielded progeny of one parental type, leading to speculation of gynogenetic or androgenetic development. Therefore, meiotic and early mitotic events of oocytes from the oysters Crassostrea gigas and C. rivularis fertilized with C. virginica sperm, as well as the reciprocal and control crosses, were critically observed in samples taken up to 90 minutes post-insemination. Chromosomal material in oocytes was visualized with the DNA-specific fluorochrome DAPI and epifluorescence microscopy. All crosses produced fertilized oocytes which were observed to proceed through meiosis and early mitosis. Fertilization was approximately 20% less successful in hybrid than straight crosses of C. gigas and C. virginica (P = 0.022) but no difference in fertilization was evident in C. rivularis and C. virginica crosses (P = 0.169). The time interval between meiotic and mitotic landmarks was not significantly different among all crosses within each full reciprocal cross. There was no cytological evidence of parthenogenetic, gynogenetic, or androgenetic development. In previous reports, non-hybrid progeny found in hybrid groups were probably contaminants. Schmid, J. R. 1998. Marine turtle populations on the west-central coast of Florida: Results of tagging studies at the Cedar Keys, Florida, 1986-1995. Fishery Bulletin 96: 589-602. Ref ID: 646 Abstract: Large-mesh tangle nets were used to collect marine turtles in Waccasassa Bay, near the Cedar Keys, Florida, from June 1986 to October 1995. Tagging records were analyzed to determine the species composition, population structure, and seasonal occurrence of Kemp's ridley, Lepidochelys kempii, loggerhead, Caretta caretta, and green, Chelonia mydas, turtles. Additional information on local movements, morphometrics, growth, population estimation, and diet was provided for Kemp's ridley turtles. Subadult green turtles dominated the catch on the seagrass shoals of Waccasassa Reefs. Subadult Kemp's ridley turtles and, to a lesser degree, subadult and adult loggerhead turtles were primarily captured near the oyster bars of Corrigan Reef. Marine turtles were caught in these nearshore waters from April to November. Recaptures indicate that some Kemp's ridley turtles remain in the vicinity of Corrigan Reef during their seasonal occurrence and return to this foraging area annually. Seasonal and annual size distributions of Kemp's ridley turtles were investigated and regression equations were developed for carapace morphometrics. Carapace growth averaged 4-5 cm/yr for Kemp's ridley turtles, but growth analyses were confounded by the extrapolation of annual estimates from short-term recaptures. Population estimates for the Kemp's ridley mark-recapture data indicated a mean annual population size of 159 turtles at Corrigan Reef with presumably high rates of immigration and emigration by larger subadult turtles. Examination of fecal samples indicated that crabs were the primary food items of Kemp's ridley turtles captured near oyster bars. Sea Grant. 2003. Oyster Research and Restoration in U.S. Coastal Waters., NOAA National Sea Grant, Maryland and Virgina Sea Grant Ref ID: 98 Sharov, A. F., Volstad, J. H., Davis, G. R., Davis, B. K., Lipcius, R. N., and Montane, M. M. 2003. Abundance and exploitation rate of the blue crab (Callinectes sapidus) in Chesapeake Bay. Bulletin of Marine Science 72: 543-535. Ref ID: 653 Abstract: We estimated absolute abundance of the blue crab stock in Chesapeake Bay during winter from stratified random surveys conducted baywide from 1990 to 1999, using the swept-area method. We estimated catching efficiency of the survey gear from multiple depletion experiments to correct for temporal and vessel/area differences in catchability. The survey was conducted during the winter, when crabs are dormant and "buried" in the bottom. Analysis of crab carapace width (CW) frequency distributions revealed two size modes: CW less or equal 60 mm and CW greater than 60 mm, corresponding to age-0 (recruits) and age-1+ (one year and older), respectively. Absolute density of blue crab recruits varied from 10 to 55 crabs per 1,000 m(2) across years (95 million to 540 million baywide), with no significant trends over time. Abundance of age-1 + crabs declined significantly from 35 to 38 crabs per I 000 m(2) in 1990-1991 (342 million to 371 million crabs baywide) to 8.3 in 1999 (92 million crabs baywide). A stronger decline in the number of males indicates that males were exploited more intensively than females. A three-year moving average of spawning stock abundance (age- 1+ females) declined twofold from the early to the late 1990s. The absolute abundance of the blue crab population in Chesapeake Bay varied from 241 million to 867 million. Over-wintering mortality was usually less than 2%, but substantially higher mortality occurred in 1994 (7.3%) and 1996 (11.9%). High correlation between January water temperature and the percentage of dead crabs provides strong evidence of the adverse effect of cold winter on survival of crabs. Large crabs were affected most by cold winter temperatures. We estimated exploitation rates for the commercial fishery by comparing abundance with total landings. The estimated exploitation rates varied from 40% to 52% from 1990 to 1998 and increased to a record high of 70% in 1999. Fishing mortality rates varied from 0.6 to 0.9 year(-1) ill most years and were above the level providing maximum yield per recruit (F-max = 0.64 year(-1)) in nearly all years. The record fishing mortality in 1999 (F-1999, = 1.6 year(-1)) exceeded the overfishing threshold (F-10% = 1.0 year(-1)). Despite evidence of growth overfishing, the blue crab population supported large harvests throughout the 1990s. Increase of fishing mortality above the F-10% in 1999, indicates that the population was overfished and is at risk of recruitment overfishing if fishing mortality remains at this level. Shaw, W. N. 1969. Oyster setting in two adjacent tributaries of Chesapeake Bay. Transactions of the American Fisheries Society 98: 309-314. Ref ID: 480 Sheridan, A. K. 1997. Genetic improvement of oyster porduction - a critique. Aquaculture 153: 165-179. Ref ID: 124 Abstract: Although heritability estimates for oyster production traits were extremely variable, it is encouraging that all of the oyster selection experiments were successful in altering the selected trait in the direction of selection. The selected traits included increased growth rate and improved resistance to specific diseases, With the exception of one study, outbred stocks were at least equivalent to inbred stocks for larval and oyster growth rate and survival. The non-conforming study used inbred female parents, thus possibly biasing the comparison due to a possible interaction between a poor maternal environment provided by the egg and the faster growth rate associated with the outbred larvae. There is considerable experimental evidence that the growth rate of oysters is sensitive to apparently small environmental differences. Depending upon the stocking density, oyster growth rate can also be influenced by competition from adjacent oysters. It is recommended that the market oyster be a cross between non-inbred selection lines that have been evaluated under standardised environmental conditions at a stocking density that precludes competition between neighbouring oysters. The performance of both reciprocal crosses should be evaluated. Consideration should also be given to the possible importance of genotype by environment interactions. Shoubai, R., Shumei, S., Qirong, M., Shaoqiong, L., Ze, L., Xiuzhu, Z., Wangdong, T., Shouwu, L., and Yimin, L. 1994. Tetraploid induced by physical and chemical methods in Jin jiang oyster (Crassostrea rivularis). Acta Oceanologica Sinica 13: 275-283. Ref ID: 185 Smith, G. F. and Greenhawk, K. N. 1998. Shellfish benthic habitat assessment in the Chesapeake Bay: Progress toward integrated technologies for mapping and analysis. Journal of Shellfish Research 17: 1433-1437. Ref ID: 438 Abstract: Combinations of mechanical and remotely sensed technologies were applied to the task of developing techniques to assess and chart the physical condition of oyster habitat in the mesohaline Maryland Chesapeake Bay. Acoustic sub-bottom profiling equipment, side-scan sonar, underwater video, sediment analysis, and seafloor classification systems were tested for their capability in characterizing important components or conditions of the benthic environment, as well as their ability to integrate and display this information via linked Global Positioning System (GPS) and Geographical Information System format (GIS). Acoustic seafloor classification fully integrated with shipboard and land-based GIS, linked to bottom validation techniques, seems to offer the most effective solution to oyster habitat assessment at virtually any scale of interest Smith, G. F., Greenhawk, K. N., Bruce, D. G., Roach, E. B., and Jordan, S. J. 2001. A digital presentation of the maryland oyster habitat and associated bottom types in the Chesapeake Bay (1974-1983). Journal of Shellfish Research 20: 197-206. Ref ID: 149 Abstract: Between 1975 and 1983, the Maryland Department of Natural Resources conducted a survey of Maryland's portion of the Chesapeake Bay to reassess the extent and condition of oyster bottom (bars) that were initially surveyed in 1912. A variety of methods were employed to assess bottom condition, including bottom grabs, sounding poles, and dragged microphones. The survey used six categories to describe substrate type. Three of these represented oyster bottom: cultch (exposed oyster shell), cultch with sand, and cultch with mud. The other three categories were non-oyster bottom: sand, mud, and consolidated hard sediment. Bottom characterizations were drawn on 37 transparent Mylar sheets. Although the resulting charts were used to generate new legal oyster bar boundaries, the original bottom characterizations were never published. We present here the digitized Mylars in a Geographic Information System (GIS) polygon format, which is now available as a digital file. A comparison of results with more recent habitat assessments indicate the survey was a generally valid representation of the true bottom condition. The digitized survey results, however, could be misapplied if used as an exact description of current bottom conditions, because in many areas, cultch categories are actually shell covered by varying depths of sediment. This work provides a demonstration of how GIS-based analysis can be employed to interpret historical surveys of oyster habitats and provide a useful management product to resource managers. Smith, G. F., Roach, E. B., and Bruce, D. G. 2003. The location, composition, and origin of oyster bars in mesohaline Chesapeake Bay. Estuarine Coastal and Shelf Science 56: 391-409. Ref ID: 422 Abstract: Sub-bottom profiling sonar surveys in the mesohaline Chesapeake Bay located pre-Holocene, hard terrace structures surrounded by or buried by softer sediments. The descending scarps of these hard terraces frequently correspond to the boundaries of charted oyster bars. The terraces are composed of a base of coarse Tertiary or Pleistocene sediments and may be covered by a layer of oyster shell, shell grit or mud. The presence of soft, methane gas-charged sediments adjacent to descending terrace scarps indicates that terrace/oyster bar configuration is due to the segmentation of the larger regional terrace structure by paleochannel drainage. These sediment filled channels, relicts of the last glacial period, extend into the estuary far beyond the current terrestrial shores and demarcate the oyster bar boundaries. Continual filling of the paleochannels segregating oyster bars, both by fluvial transport as well as in situ production of sediment, has lead to a decrease in relief in the terrace scarp profile. At some locations sediments are burying or have buried oyster bar terraces. Although widespread reduction of oyster bar relief in the Chesapeake Bay has been attributed to harvest activity, statistical analysis of bathymetry does not clearly support this premise. Our findings suggest that oyster habitat restoration should take place only on the clearly identified, hard terraces away from encroaching bottom sediments. (C) 2003 Elsevier Science B.V. All rights reserved Soniat, T. M. and Brody, M. S. 1988. Field validation of a habitat suitabiliy index model for the American oyster. Estuaries 11: 87-95. Ref ID: 12 Soniat, T. M. and Kortright, E. V. 1998. Estimating time to critical levels of Perkinsus marinus in eastern oysters, Crassostrea virginica. Journal of Shellfish Research 17: 1071-1080. Ref ID: 33 Abstract: A Visual-Basic program was developed as part of an Excel spreadsheet to estimate the time to a critical level (t(Crit)) Of Perkinsus marinus, in eastern oysters Crassostrea virginica. The estimate is accomplished by assuming that a weighted incidence (WI) of disease of 1.5 is critical, converting measured WI values and the critical WI to parasite number, calculating a rate of change (r) of the parasite population using measured values of water temperature (T) and salinity (S), and solving for t(Crit) by simulation. The model produces estimates of t(Crit) and r using a long-term data set of T, S, and WI from the Terrebonne estuary of Louisiana. The model does not predict future values of WI since it cannot predict future trends in T and S; however, regularly determining T and S, considering their interaction in a model, measuring WI at reasonable intervals, and iteratively estimating t(Crit) should be useful to oyster management. Estimates of t(Crit) would support decisions concerning transplanting infected oysters to lower salinity areas, harvesting heavily infected populations early, and diverting freshwater into high-salinity estuaries. Soniat, T. M., Powell, E. N., Hofmann, E. E., and Klinck, J. M. 1998. Understanding the success and failure of oyster populations: The importance of sampled variables and sample timing. Journal of Shellfish Research 17: 1149-1165. Ref ID: 536 Abstract: One of the primary obstacles to understanding why some oyster populations are successful and others are not is the complex interaction of environmental variables with oyster physiology and with such population variables as the rates of recruitment and juvenile mortality. A numerical model is useful in investigating how population structure originates out of this complexity. We have monitored a suite of environmental conditions over an environmental gradient to document the importance of short time-scale variations in such variables as food supply, turbidity, and salinity. Then, using a coupled oyster disease population dynamics model, we examine the need for short rime-scale monitoring. We evaluate the usefulness of several measures of food supply by comparing field observations and model simulations. Finally, we evaluate the ability of a model to reproduce field observations that derive from a complex interplay of environmental variables and address the problem of the time-history of populations. Our results stress the need to evaluate the complex interactions of environmental variables with a numerical model and, conversely, the need to evaluate the success of modeling against field observations of the results of complex processes. Model simulations of oyster populations only approached field observations when the environmental variables were measured weekly, rather than monthly. Oyster food supply was estimated from measures of total particulate organic matter, phytoplankton biomass estimated from chlorophyll a, and total labile organic matter estimated from a regression between chlorophyll a and total labile carbohydrate, lipid, and protein. Only the third measure provided simulations comparable to field observations. Model simulations also only approached field observations when a multiyear time series was used. The simulations show that the most recent year exerts the strongest influence on oyster population attributes, but that the longer time-history modulates the effect. The results emphasize that year-to-pear changes in environment contribute substantially to observed population attributes and that multiyear environmental time series are important in describing the time-history of relatively long-lived species Soniat, T. M., Finelli, C. M., and Ruiz, G. M. 2004. Vertical structure and predator refuge mediate oyster reef development and community dynamics. Journal of Experimental Marine Biology and Ecology 310: 163-182. Ref ID: 665 Abstract: In addition to their economic value, oysters supply a number of critical ecosystem services such as controlling eutrophication, recycling nutrients, and providing habitat for many invertebrates and fishes. Thus, the maintenance and restoration of oyster reefs is vital for properly functioning estuarine ecosystems. We hypothesized that spatially heterogeneous and refuge-rich reefs are superior habitats for oysters and associated invertebrates and fishes. If this is shown to be the case, then vertical structure and refuge should be included in the design of newly constructed oyster reefs and conserved in existing reefs. To test our hypothesis, models were built as concrete blocks into which shells were placed horizontally, vertically, and widely spaced, and vertically and closely spaced. Respectively, the units represent horizontal orientation with no refuge (HNR), vertical orientation with no refuge (VNR), and vertical orientation with refuge (VWR). Flume studies of velocity distributions over each model type showed distinctive differences that may contribute to differential settlement on the models in the absence of predators or sediment. A subsequent settlement study in the same flume showed significantly higher settlement densities to horizontal shells than to vertical shells regardless of refuge (HNR>VNR=VWR). This result indicates the primary importance of settlement surface orientation (horizontal vs. vertical) over predation refuge when predators are absent. In contrast, two field recruitment studies indicated that the importance of orientation relative to predation refuge might depend on sedimentation rates. When sedimentation was low, the number of oysters and barnacles (live, dead, and total) was significantly higher on no-refuge models than on refuge models (HNR=VNR>VWR). However, percent mortality was lower on the refuge models than on the no refuge models (HNR=VNR>VWR). This leads to a conclusion that although fewer oysters may settle on refuge shells, those that do have a higher rate of survival. In a year when sedimentation was high, recruitment and survival of oysters, barnacles, and bryozoans was higher on vertical models regardless of refuge. In aggregate, our results indicate that both vertical orientation and predation refuge are critical to the early development of the oyster reef community and should be included in restoration designs. (C) 2004 Elsevier B.V. All rights reserved. Southworth, M. and Mann, R. 1998. Oyster reef broodstock enhancement in the Great Wicomico River, Virginia. Journal of Shellfish Research 17: 1101-1114. Ref ID: 74 Abstract: The Great Wicomico River is a small, trap-type estuary on the western shore of the Chesapeake Bay that once supported substantial oyster populations. These populations were essentially eliminated by the combined effects of Tropical Storm Agnes in 1972, and subsequent disease mortalities related to Perkinsus marinus and Haplosporidium nelsoni. Oyster broodstock enhancement was initiated in June 1996 by the construction of a three-dimensional intertidal reef with oyster shell, followed by the "seeding," in December 1996, of that reef with high densities of large oysters from disease-challenged populations in Pocomoke and Tangier Sound. Calculations of estimated fecundity of the reef population suggest that oyster egg production from this source is within an order of magnitude of total egg production in the Great Wicomico River prior to Tropical Storm Agnes. Field studies in 1997 indicate spawning by reef oysters from July through September. P. marinus prevalence increased from 32% in June to 100% in July, whereas intensity increased from June to September; H. nelsoni was absent. Plankton rows recorded oyster larval concentrations as high of 37,362 +/- 4,380 m(-3) on June 23. Such values are orders of magnitude higher than those typically recorded in Virginia subestuaries of the Chesapeake Bay in the past three decades, and lend support to a premise that aggregating large oysters may increase fertilization efficiency. Drifter studies suggest strong local retention of larvae, a suggestion reinforced by marked increases in local oyster spatfall on both shellstring collectors and bottom substrate compared with years prior to 1997. In locations where local circulation promotes larval retention, the combination of reef construction with broodstock enhancement may provide an accelerated method for oyster population restoration. Southworth, M., Harding, J. A., and Mann, R. 2004. The Status of Virginia's Public Oyster Resource 2003., Molluscan Ecology Program, Virginia Institute of Marine Science, Gloucester Point, Virginia Ref ID: 565 Stanley, J. G., Hidu, H., and Allen, S. K. Jr. 1984. Growth of American oysters increased by polyploidy induced by blocking meiosis I but not meiosis II. Aquaculture 37: 147-155. Ref ID: 127 Steinberg, P. D. and Kennedy, V. S. 1979. Predation upon Crassostrea virginica (Gmelin) larvae by two invertebrate species common to Chesapeake Bay oyster bars. Veliger 22: 78-84. Ref ID: 417 Stewart, T. W., Miner, J. G., and Lowe, R. L. 2004. Quantifying mechanisms for zebra mussel effects on benthic macroinvertebrates: organic matter production and shell-generated habitat. Journal of the North American Benthological Society 17: 81-94. Ref ID: 619 Abstract: Quantitative descriptions of interactions between zebra mussels (Dreissena polymorpha) and other organisms are needed for an understanding of zebra mussel effects cn energy flow and community dynamics in North American freshwater ecosystems. We used a field experiment to quantify effects of 2 potential mechanisms for increasing benthic macroinvertebrate biomass and densities in the Great Lakes following the zebra mussel invasion: 1) habitat created by zebra mussel shells, and 2) habitat and food provided by increases in benthic organic matter. Macroinvertebrate biomass, macroinvertebrate densities, and organic matter mass thereafter termed organic matter) were measured on substrates (tiles without zebra mussels, with zebra mussel shells, and with live zebra mussels) that were held in western Lake Erie for 37 d. Organic matter was 3X-5X greater on tiles with live mussels than on plain tiles or tiles with shells, demonstrating that Titer-feeding zebra mussels increased organic matter on benthic substrates. Organic matter did not differ on tiles with shells and tiles without mussels. Similarly, total macroinvertebrate biomass was 2X-5X greater on tiles with live zebra mussels than on tiles with shells and tiles without mussels; however, macroinvertebrate biomass also was 3X greater on tiles with shells than on tiles without mussels. Habitat created by shells was the most important cause for zebra mussel-generated increases in total macroinvertebrate biomass and densities of Hydridae, Dugesia tigrina (Turbellaria), Physella sp. (Gastropoda), Gammarus fasciatus (Amphipoda), and Microtendipes pedellus (Chironomidae). However, organic matter produced by zebra mussels also caused increases in total macroinvertebrate biomass and densities of Physella and Microtendipes. Zebra mussels did not reduce densities of any macroinvertebrate taxon. Because benthic macroinvertebrates are important prey for crayfish and benthivorous fishes, increases in macroinvertebrate abundance may be important in channeling energy from zebra mussels to higher trophic levels in the Great Lakes. Stillman, R. A., West, A. D., Goss-Custard, J. D., Caldow, R. W. G., McGrorty, S., Durell, S. E. A. L., Yates, M. G., Atkinson, P. W., Clark, N. A., Bell, M. C., Dare, P. J., and Mander, M. 2003. An individual behaviour-based model can predict shorebird mortality using routinely collected shellfishery data. Journal of Applied Ecology 40: 1090-1101. Ref ID: 631 Abstract: 1. The debate over the interaction between shellfishing and shorebirds is long-running. Behaviour-based models predict how animal populations are influenced by environmental change from the behavioural responses of individual animals to this change. These models are a potential tool for addressing shellfishery problems, but to be of value they must produce reliable predictions using data that are readily available or can be collected relatively quickly. 2. We parameterized a behaviour-based model for the oystercatcher population of the Wash, UK, for 1990-99 using data from shellfishery (mussels and cockles), shorebird and climate monitoring schemes. During the 1990s the overwinter mortality rates of Wash oystercatchers varied widely. The model correctly identified the years in which the observed overwinter mortality was either low (1-2%) or high (10-26%) from annual variation in the food supply, oystercatcher population size and temperature. 3. Many oystercatchers were observed and predicted to die when only a fraction of the available food was consumed. Within the model at least, this was because interference competition excluded the least dominant birds from part of the food supply and the least efficient foragers died before the food supply was fully depleted. A simplified model, which excluded interference and individual variation, incorrectly predicted that all birds survived in all years. Models that exclude these two components of behaviour will tend to underestimate the effect of mussel and cockle food shortage on oystercatchers. Shellfishery management based on such predictions may cause high oystercatcher mortality rates even though enough food would appear to be reserved for the birds. 4. Synthesis and applications. This study shows how a behaviour-based model can be parameterized and predict annual variation in oystercatcher mortality using data routinely collected from the Wash. The principle on which the model is based, that animals behave in order to maximize their chances of survival and reproduction, applies to any system, and the shellfishery, bird and climate data used to parameterize the model are widely available. The model can be used to advise how to manage shellfisheries, by predicting the proportion of the stock that needs to remain unfished in order to maintain low oystercatcher mortality rates Stunz, G. W., Levin, P. S., and Minello, T. J. 2001. Selection of estuarine nursery habitats by wild-caught and hatchery-reared juvenile red drum in laboratory mesocosms. Environmental Biology of Fishes 61: 305-313. Ref ID: 267 Abstract: We examined patterns of habitat selection in wild-caught and hatchery-reared early juvenile red drum, Sciaenops ocellatus, using mesocosm experiments. Experiments were performed in the presence and absence of a pinfish, Lagodon rhomboides. We hypothesized that newly recruited red drum would have distinct patterns of habitat selection, and these patterns could be influenced by the presence of a pinfish predator. Red drum were introduced to replicate mesocosms containing all possible pair-wise comparisons of four different habitat types: marsh Spartina alterniflora, non-vegetated bottom/sand, oyster reef Crassostrea virginica, and seagrass Halodule wrightii. Wild-caught and hatchery-reared red drum showed distinctively different patterns of habitat selection. In general, wild-caught red drum selected structured habitats, while hatchery-reared fish did not show strong selection for any habitat type. When a predator was present, wild-caught red drum either changed habitat selection or showed significant selection for other structured habitats. This predator effect was similar albeit weaker for hatchery-reared red drum, but as in the trials without a predator, overall habitat selection was reduced compared to wild-caught red drum. Our results suggest that in the absence of seagrass, other habitat types such as marshes and oyster reefs may be important recruitment habitat for red drum. Additionally, hatchery-dependent behaviors may need to be assessed in designing stock enhancement programs Supan, J. E., Wilson, C. E., and Allen, S. K. Jr. 2000. The effect of cytochalasin B dosage on the survival and ploidy of Crassostrea virginica (Gmelin) larvae. Journal of Shellfish Research 19: 125-128. Ref ID: 537 Abstract: Survival and ploidy of D-stage oyster larvae (Crassostrea virginica) were determined following the rearing of embryos exposed to CB dosages of 0.5 mg/L, 0.25 mg/L, and 0.125 mg/L for 10 minutes, with 0.05% DMSO and ambient seawater as controls. The experiment was replicated three times on the same day with the same procedures and partially stripping the same male oysters; different females were used for each replicate. CB dosage treatments began when 50% of the eggs reached PBI (24-31 min). Embryos were reared for 48 h at ambient temperature and salinity. Resulting triploid percentages were 13% +/- 6.7% (0.125 mgCB/L), 61.8% +/- 6.2% (0.75 mgCB/L). and 68.2% +/- 14.1% (0.5 mgCB/L). No significant difference (P less than or equal to 0.05) in mean survival was found between the three CB treatments. Significant differences in mean survival between the three replicates implies variability because of different sources of eggs. Tarnowski, M. 2003. Maryland Oyster Population Status Report: 2002 Fall Survey., Maryland Department of Natural Resources, Shellfish Program and Sarbanes Cooperative Oxford Laboratory Ref ID: 97 Tchang, S. and Tze-Kong, L. 1956. A study on chinese oysters. Acta Zoological Sinica 8: 65-93. Ref ID: 56 Thiriot-Quievruex, C., Pogson, G. H., and Zouros, E. 1992. Genetics of growth rate variation in bivalves: aneuploidy and heterozygosity effects in a Crassostrea gigas family. Genome 35: 39-45. Ref ID: 141 Abstract: Enzyme homozygosity and somatic aneuploidy are both known to adversely affect juvenile growth rate in marine bivalves. We have examined the joint effects of these two factors by scoring genotypes at nine segregating allozyme loci and counting the numbers of chromosomes lost in 30 cells in each of 83 full sibs of the Pacific oyster. A highly significant negative correlation was observed between the number of chromosomes missing and shell length in full sibs of the same age. No relationship was seen, however, between allozyme heterozygosity and either shell length or chromosome loss, nor was there any difference in the distribution of aneuploidy among genotypes at any given enzyme locus. Thus, the effects of homozygosity and aneuploidy on growth rate appear to have different genetic bases. Even in the most aneuploid oysters, more than half the cells examined had a complete chromosome complement of 2n = 20. This eliminates somatic aneuploidy as an explanation for the excess of enzyme homozygosity frequently observed in populations of marine molluscs. Significant deviations from Mendelian expectations, favoring homozygotes at some loci and heterozygotes at others, were recorded at eight of the nine allozyme loci, but these occurred independently of the aneuploidy observed. Our results suggest that within families a much larger component of variation in growth rate is due to aneuploidy than to allozyme genotype, but this conclusion cannot, at present, be extended to natural populations. Thomas, M. H. 1997. A Protocol for the Release of Nonindigenous Aquatic Species., Florida Agricultural and Mechanical University, Tallahassee, FL Ref ID: 120 Thorson, G. 1966. Some factors influencing the recruitment and establishment of marine benthic communities. Netherlands Journal of Sea Research 3: 267-293. Ref ID: 168 Todd, C. D. and Keough, M. J. 1994. Larval settlement in hard substratum epifaunal assemblages: a manipulative field study of the effects of substratum filming and the presence of incumbents. Journal of Experimental Marine Biology and Ecology 181: 159-187. Ref ID: 508 Abstract: Natural larval settlement on black Perspex settlement panels was analysed for two experiments (1 and 2) conducted amongst epifaunal assemblages beneath pier pilings at Williamstown, Victoria and one experiment at Mornington, Victoria, in southeastern Australia. The overall objectives of this manipulative study were to distinguish experimentally the effects of ''filming'' of the substrata and the presence of previously settled incumbent invertebrates on subsequent larval settlement in the sublittoral. Filming of substrata, whilst largely excluding larval settlement, was permitted by the enclosure of settlement panels within tightly-fitting pouches of plankton gauze of 150 and 236 mu m mesh size. Williamstown 1 and Mornington included only fine-mesh treatments and Williamstown 2 included both coarse and fine mesh-sizes and also an additional treatment in which panels were initially filmed intertidally and then deployed sublittorally. Each experiment was conducted over periods of approximate to 2 wk. For Williamstown 1 filming generally enhanced larval settlement, with the exception of various ascidian species and the erect bryozoan Bugula neritina. Inhibitory effects of incumbents were found for Bugula dentata, the colonial ascidian Trididemnum spp. and Total Settlement: this effect was possibly attributable to Didemnids (excl. Trididemnum spp.). For the repeat of the first experiment (Williamstown 2), Bugula dentata and Serpulins all showed enhanced settlement in response to films developed on panels screened with both mesh sizes. Incumbents inhibited the settlement of Didemnids (excluding Trididemnum spp.) (cf. Williamstown 1) and Encrusting Bryozoans were facilitated. There was no significant difference in sublittoral settlement during the second week of the Williamstown 2 experiment between panels upon which the initial filming was developed either intertidally or sublittorally: settling larvae apparently responded simply to whether or not a substratum was filmed and not to the source of the film, although the possibility remains of rapid modification of the intertidal film to one typical of the sublittoral. At Mornington, Arborescent Bryozoans, Tricellaria occidentalis, Slime Sponges and Spirorbins all showed enhancement of their settlement by filming of the substrata, whereas incumbents significantly inhibited settlement of Didemnids, Microporella sp., Encrusting Bryozoans and Tricellaria occidentalis. The results show clearly the importance of repeating experimental analyses such as these at a given site and of undertaking experiments at different sites. One striking outcome was the marked inhibitory effect on other settlers of Didemnids (excluding Trididemnum spp.) at Williamstown 2. Those ascidians were themselves subject to high levels of post-settlement mortality and, although the cause of their mortality remains unknown, it is possible that the bacteria and ciliates attacking the ascidians were the source of the inhibitory effects on other settlers: these micro-organisms might therefore themselves provide adaptive biological cues indicative of otherwise unfavourable substrata to settling larvae Tojeiro, P. and Wheaton, F. 1991. Oyster orientation using computer vision. Transactions of the Asae 34: 689-693. Ref ID: 467 Abstract: Machines to automate shucking of oysters require the oysters to be properly oriented prior to entering the shucking machine. This article describes a computer vision system capable of automating orientation of oysters. The system developed uses one black and white video camera and a plane mirror to simultaneously collect both a top and side projected view of an oyster. Processing software developed determines the principal oyster axis and calculates two width to thickness ratios, one taken 1.5 cm from each end of the principal axis. A stepping motor attached to a rotary plate rotates the oyster to the desired position. The system was capable of correctly orienting (within +/- 0.13 rad) 98.2% of 233 oysters collected from four oyster beds in the Chesapeake Bay Torigoe, K. 1981. Oysters in Japan. Journal of Science Hiroshima University, Series B, Division 1 (Zoology) 29: 291-319. Ref ID: 167 Tucker, A. D., Yeomans, S. R., and Gibbons, J. W. 1997. Shell strength of mud snails (Ilyanassa obsoleta) may deter foraging by diamondback terrapins (Malaclemys terrapin). American Midland Naturalist 138: 224-229. Ref ID: 620 Abstract: Diamondback terrapins (Malaclemys terrapin) do not eat the common and abundant mud snail (ilyanassa obsoleta) even though terrapin diets are dominated by similarly sized gastropods. To resolve this paradox, we tested a structural defense hypothesis as the potential deterrent against predation. We compared resistance to compressive force of ilyanassa and three invertebrates (Littorina irrorata,) Uca spp, and Callinectes sapidus) that terrapins commonly eat. Ilyanassa shells were 2-3 times more resistant to crushing than the other prey. High processing costs for mud snails (in terms of structural resistance to crushing) may deter predation by terrapins despite the low search costs and equivalent energetic returns relative to alternative prey items. Tuckwell, J. and Nol, E. 1997. Foraging behaviour of American oystercatchers in response to declining prey densities. Canadian Journal of Zoology-Revue Canadienne de Zoologie 75: 170-181. Ref ID: 632 Abstract: American oystercatchers (Haematopus palliatus) responded to declines in the density of oysters (Crassostrea virginica) on a commercial oyster bed examined in 1979 and 1995 by increasing the number of species of prey eaten and search times, but not peck rates or handling times, Seasonal changes in foraging behaviour included oystercatchers choosing larger oysters with longer handling times in winter than in autumn, but with subsequently greater profitability and higher intake rates. Time budgets of foraging birds were similar in the two seasons. Oystercatchers ate fewer mussels in winter than in autumn, and fewer mussels than oysters at all times. Search and handling times for mussels were similar in autumn of the 2 years. After a commercial harvest of oysters at a second site, handling times for oysters did not decline: however, search times were significantly more variable, niche breadth was greater, and there was a trend towards longer search times post harvest. The recorded changes in foraging behaviour indicated a close match between search and handling times and prey density and size and behavioural flexibility of foraging birds in response to sometimes drastic changes in their prey base Tuckwell, J. and Nol, E. 1997. Intra- and inter-specific interactions of foraging American oystercatchers on an oyster bed. Canadian Journal of Zoology-Revue Canadienne de Zoologie 75: 182-187. Ref ID: 633 Abstract: We compared the rates of intraspecific and interspecific kleptoparasitism of foraging American oystercatchers (Haematopus palliatus) on a commercial oyster (Crassostrea virginica) bed during two seasons and between 1979 and 1995. In 1979 most conspecific kleptoparasites were immature oystercatchers and victims were adults. Both intra- and inter-specific parasitism were more common in 1979 than in 1994 or 1995. Kleptoparasitism by conspecifics was more common than by gulls (Larus argentatus, L. marinus) but was not density dependent, Gulls primarily kleptoparasitized oystercatchers foraging on mussels (Geukensia demissa), with their longer handling times. Kleptoparasitism by gulls increased as the number of gulls on the oyster bed increased, and the presence of gulls significantly depressed intake rates and sizes of mussels taken by oystercatchers during autumn. Oystercatchers ate smaller oysters in autumn than in winter in both the presence and absence of gulls. The presence of conspecific and gull kleptoparasites changed the oystercatchers' relative preference for oysters over mussels in their diet. The presence of gulls only partly explained the oystercatchers' lower rates of intake of oysters in autumn than in winter Turner, E. J., ZimmerFaust, R. K., Palmer, M. A., Luckenbach, M., and Pentcheff, N. D. 1994. Settlement of oyster (Crassostrea virginica) larvae - effects of water flow and a water soluble chemical cue. Limnology and Oceanography 39: 1579-1593. Ref ID: 310 Abstract: Although previous evidence indicates that larvae of benthic marine invertebrates can respond to waterborne cues in still water, the importance of waterborne cues in mediating natural settlement out of flowing water has been questioned. Here, we summarize the results of flume experiments demonstrating enhanced settlement of oyster larvae in small target wells (circles of 7-cm diam) with the release of a waterborne settlement cue compared to identical substrates without the cue. In concurrent still-water experiments, more oyster larvae settled in solutions of waterborne cue than in seawater controls. Velocity and electrochemical measurements of a conservative tracer verified that at low flow velocities (2 and 6 cm s(-1)) with U* values <0.25 cm s(-1), the waterborne cue was present above the targeted substrate to a height of less than or equal to 4 mm. Rapid vertical swimming or sinking in response to the waterborne cue can concentrate larvae in near-bottom waters and enhance larval settlement. Our investigation provides the first experimental evidence to demonstrate that dissolved chemical cues can mediate settlement by larvae under hydrodynamic conditions approaching those of natural benthic habitats Ulanowicz, R. E., Caplins, W. C., and Dunnington, E. A. 1980. The forecasting of oyster harvest in central Chesapeake Bay. Estuarine and Coastal Marine Science 11: 101-&. Ref ID: 478 Ulanowicz, R. E. and Tuttle, J. H. 1992. The trophic consequences of oyster stock rehabilitation in Chespeake Bay. Estuaries 15: 298-306. Ref ID: 193 Abstract: There is mounting speculation that overharvesting of oyster stocks (Crassostrea virginica) in Chesapeake Bay may be a factor contributing to the decline in water quality and shifts in the dominance of species inhabiting the estuary. The trophic consequences of increasing the oyster population may be addressed using a simple quasi-equilibrium, mass action model of the exchanges transpiring in the Chesapeake mesohaline ecosystem. According to output from the model, increasing oyster abundance would decrease phytoplankton productivity as well as stocks of pelagic microbes, ctenophores, medusae, and particulate organic carbon. Recently acquired field data on phytoplankton productivity, bacterioplankton, and labile organic carbon in the vicinity of rafted oyster aquaculture support model predictions. The model also indicates that more oysters should increase benthic primary production, fish stocks, and mesozooplankton densities. Hence, augmenting the oyster community by restoring beds or introducing raft culture represents a potentially significant adjunct to the goal of mitigating eutrophication through curtailment of nutrient inputs. Underwood, A. J. and Fairweather, P. G. 1989. Supply-side ecology and benthic marine assemblages. TREE 4: 16-20. Ref ID: 170 Urban, E. R. Jr., Pruder, G. D., and Landgon, C. J. 1983. Effects of ration of growth and growth efficieny of juveniles of Crassostrea virginica (Gmelin). Journal of Shellfish Research 3: 51-57. Ref ID: 157 US Altantic States Marine Fisheries Commission. 2002. Proceding of the Workshop on the Introduction of Asian Oysters (Crassostrea ariakensis) to the Chesapeake Bay. Special Report No. 74, United States Altantic States Marine Fisheries Commission, Washington, DC Ref ID: 162 US Fish and Wildlife Service. 1995. Proposed Release of Three Non-Indigeneous Insects Galerucella calnariensis, Galerucella pusilla, and Hylobius tansverovittatus for Biological Control of Purple Loosestrife (Lythrum salicaria). Ref ID: 641 van Montfrans, J., Ryer, C. H., and Orth, R. J. 2003. Substrate selection by blue crab Callinectes sapidus megalopae and first juvenile instars. Marine Ecology-Progress Series 260: 209-217. Ref ID: 254 Abstract: Various marine and estuarine species utilize chemical cues during settlement. We investigated responses by megalopae and first juvenile (J1) blue crabs to common Chesapeake Bay substrates in mesocosm and field experiments. Mesocosm trials examined responses of megalopae or J1 crabs to sand, marsh mud, live oysters Crassostrea virginica, sun-bleached oyster shell, eel grass Zostera marina and artificial seagrass in replicate 160 l tanks. Either 10 megalopae or J1 crabs isolated in each of 6 substrates were allowed total access after acclimation to test the null hypothesis of equal distribution among substrates after 13 h. Thirty-five percent of megalopae were recovered from Z. marina, with the remaining substrates containing fewer than half that many. In contrast, 30 % of J1 crabs (with only 17 % recovered from Z. marina) were found in live C. virginica. A field experiment quantified responses of ingressing megalopae to Z, marina, marsh mud, and C. virginica. Overnight settlement was significantly higher in Z. marina ((x) over bar = 3.3 ind.; 60 % of total) when compared to mud ((x) over bar = 0.9; 16 %) or C. virginica ((x) over bar = 1.3; 24 %). Likewise, J1 crabs were significantly more numerous in Z. marina ((x) over bar = 3.7 ind.; 55 % of total) than in C. virginica ((x) over bar = 1.8; 27 %) and mud ((x) over bar = 1.2; 18 %). J1 crab distribution in field plots likely reflected habitat selection by megalopae; laboratory results were equivocal and probably due to artifacts associated with density-dependent agonism. The initial non-random distribution of blue crabs in Chesapeake Bay may be deterministic and due to habitat-selection behavior by megalopae. Selection for seagrass assures the greatest likelihood of maximal survival and accelerated growth. Similar relationships may also exist in estuarine-dependent species with comparable habitat requirements and life-history characteristics Vesar, Inc. 1999. Risk Assessment of the Potential Effects of Stocking Triploid-Certified Grass Carp in the Potomac River Watershed on Submersed Aquatic Vegetation., Versar, Inc., Prepared for U.S. Environmental Protection Agency, Chesapeake Bay Program, Columbia, MD Ref ID: 108 Vincent, B., Joly, D., and Harvey, M. 1994. Spatial variation in growth of the bivalve Macoma balthica (L.) on a tidal flat: effect of environmental factors and intraspecific competition. Journal of Experimental Marine Biology and Ecology 181: 223-238. Ref ID: 63 Abstract: A descriptive field study was conducted on a tidal flat of the Lower St. Lawrence Estuary to examine spatial variations in shell growth of the infaunal bivalve Macoma balthica (L.) in relation to tidal level, sediment characteristics, and local density. This study was based on 83 0.3 x 0.3 m(2) sediment samples randomly located on a 1.6 km(2) tidal flat where maximal amplitude of tide was 4.8 m. Mean density of Macoma balthica for the whole sampling area was 1254 m(-2) (s (x) over bar = 87 m(-2)) and densities were higher and more variable near the mean water level. Variations in the effects of density and environmental factors along the tidal gradient were studied after a stratification of the stations by immersion time. Overall, shell growth rate increased with immersion time, the latter accounting for about 5 to 63% of the spatial variation of mean shell length for the six youngest generations. Fifty-two to 61% of the adjusted annual shell growth was explained by a linear relationship with tidal level. A significant but weaker linear relationship was obtained between growth and density, and between growth and sediment grain size. For the whole sampling area, a linear model with tidal level and density as independent variables explained 37 to 80% of the spatial variability of mean shell length for each generation and 59 to 77% of the spatial variability in adjusted annual growth rates. The effect of density was not significant in the lower part of the tidal flat, however, it became significant when immersion time was approximate to 50%, and had a maximum effect when immersion time was about 40%. About 65 to 85% of the spatial variability of the growth rate along the tidal gradient can be explained by stepwise multiple regressions involving density as the first independent variable. Overall, the results suggested that intraspecific competition played a major role in approximate to 67% of the population of Macoma balthica within the study area. Volety, A. K., Perkins, F. O., Mann, R., and Hershberg, P. R. 2000. Progression of diseases caused by the oyster parasites, Perkinsus marinus and Haplosporidium nelsoni, in Crassostrea virginica on constructed intertidal reefs. Journal of Shellfish Research 19: 341-347. Ref ID: 531 Abstract: The progression of diseases caused by the oyster parasites Perkinsus marinus and Haplosporidium nelsoni were evaluated by periodic sampling (May 1994-December 1995) of eastern oysters Crassostrea virginica on an artificial reef located in the Piankatank River, Virginia. The infections observed were recorded as a function of: (1) prevalence and intensity; (2) oyster size and age; and (3) depth below mean low water at which the host oyster was found on the reef. Only a very small number of oysters were infected with the two species of pathogens on the oyster reef during the first 11 months of Life. In the second year of oyster life. epizootiological patterns of disease development followed temperature and salinity trends. Oysters at residence depths less than or equal to 45 cm below mean low water exhibited significantly (P < 0.0001) lower prevalence and intensity of infections than oysters at depths greater than or equal to 90 cm. In contrast, oysters at residence depths greater than or equal to 90 cm had significantly higher growth rates (P < 0.05) than those at less than or equal to 45 cm. However, size differences were not significant (P > 0.05) at the end of the study. Results from this study may be used in managing oyster fisheries on natural or artificial reefs Wang, H., Guo, X., Zhang, G., and Zhang, F. 2004. Classification of jinjiang oysters Crassostrea rivularis (Gould, 1861) from China, based on morphology and phylogenetic analysis. Aquaculture 242: 137-155. Ref ID: 671 Abstract: The jinjiang oyster Crassostrea rivularis [Gould, 1861. Descriptions of Shells collected in the North Pacific Exploring Expedition under Captains Ringgold and Rodgers. Proc. Boston Soc. Nat. Hist. 8 (April) 33-40] is one of the most important and best-known oysters in China. Based on the color of its flesh, two forms of C rivularis are recognized and referred to as the "white meat" and 11 red meat" oysters. The classification of white and red forms of this species has been a subject of confusion and debate in China. To clarify the taxonomic status of the two forms of C. rivularis, we collected and analyzed oysters from five locations along China's coast using both morphological characters and DNA sequences from mitochondrial 16S rRNA and cytochrome oxidase 1, and the nuclear 28S rRNA genes. Oysters were classified as white or red forms according to their morphological characteristics and then subjected to DNA sequencing. Both morphological and DNA sequence data suggest that the red and white oysters are two separate species. Phylogenetic analysis of DNA sequences obtained in this study and existing sequences of reference species show that the red oyster is the same species as C. ariakensis Wakiya [1929. Japanese food oysters. Jpn. J. Zool. 2, 359-367.], albeit the red oysters from north and south China are genetically distinctive. The white oyster is the same species as a newly described species from Hong Kong, C. hongkongensis Lam and Morton [2003. Mitochondrial DNA and identification of a new species of Crassostrea (Bivalvia: Ostreidae) cultured for centuries in the Pearl River Delta, Hong Kong, China. Aqua. 228, 1-13]. Although the name C. rivularis has seniority over C. ariakensis and C. hongkongensis, the original description of Ostrea rivularis by Gould [1861] does not fit shell characteristics of either the red or the white oysters. We propose that the name of C. rivularis Gould [1861] should be suspended, the red oyster should take the name C. ariakensis, and the white oyster should take the name C. hongkongensis. Wang, Q. W., Golden, B., Wasil, E., and Bashyam, S. 1996. An operational analysis of shell planting strategies for improving the survival of oyster larvae in the Chesapeake Bay. Infor 34: 181-196. Ref ID: 448 Abstract: Maryland's oyster fishery has declined dramatically since 1930. Meanwhile, recent studies have shown that careful management of the shell planting process can lead to increased oyster yields. This is due to the fact that oyster larvae that attach to fossil shells at the bottom of the Chesapeake Bay have a greatly enhanced likelihood of survival. In this paper, we indicate how linear programming and a rule-based heuristic can be used in tandem to determine effective sites and schedules for shell planting. In particular, linear programming is used to address the macro problem of deciding where to plant the shells, subject to high-level constraints. The rule-based heuristic addresses the micro problem of scheduling tugboats, barges, and the planting crew, subject to more detailed constraints Wang, S. B. and Houde, E. D. 1995. Distribution, relative abundance, biomass, and production of bay anchovy Anchoa mitchilli in the Chesapeake Bay. Marine Ecology-Progress Series 121: 27-38. Ref ID: 677 Abstract: Seasonal distribution, relative abundance, biomass production, population consumption, and energy storage in bay anchovy Anchoa mitchilli were estimated from midwater trawl surveys in the upper and mid Chesapeake Bay from April 1990 to October 1991. Abundance and biomass both peaked in late summer and fall before declining significantly in winter, a result of southward migration to lower Bay areas that were not sampled. Production also peaked between summer and fall, a consequence of rapid growth and recruitment of larval and juvenile anchovies. Annual production of young-of-the-year (YOY) anchovy was 856.69 g 100 m(-3), 87.9% of which was produced in the first 3 mo of life. Production by YOY anchovy accounted for nearly all annual production (92.6%) in this short-lived species. Total annual production was estimated to be 233014 t wet wt in upper to mid-Bay regions. The production/biomass (P/($) over bar B) ratio for YOY anchovy was 8.07 when larval and early juvenile stages were included but only 0.97 without those stages. The estimated translocation of nitrogen biomass from the upper and mid Bay to the lower Bay via anchovy migration was 1027 t N during fall 1990, which is approximately 0.8% of the annual N input to Chesapeake Bay. Estimated population consumption (primarily zooplankton) by bay anchovy ranged from 5.29 to 12.81 g dry wt 100 m(-3) d(-1) in August and from 5.35 to 6.78 g dry wt 100 m(-3) d(-1) in October, suggesting that consumption by larvae and juveniles of this species could significantly impact populations of its plankton prey. Ward, R. D., English, L. J., McGoldrick, D. J., Maguire, G. B., Nell, J. A., and Thompson, P. A. 2000. Gentic improvement of the Pacific oyster Crassostrea gigas (Thunberg) in Australia. Aquaculture Research 31: 35-44. Ref ID: 142 Abstract: The Pacific oyster industry in Australia is derived from importations from Japan in the late 1940s and early 1950s to Tasmania and is almost completely hatchery based. This makes it a good target for developing and deploying genetically improved strains. An allozyme survey comparing hatchery stocks with self-recruiting Tasmanian stocks and with two collections from Japan found abundant variation and no significant evidence of allele loss. The subsequent selection programme (initiated in the summer of 1996/97) had several strands. We wanted to take advantage of the increased power that marker-assisted selection could bring and, therefore, needed to develop a linkage map and isolate flanking markers around quantitative trait loci (QTLs). Several types of markers (allozymes, microsatellites and AFLPs) were used, and single-pair crosses were set up; QTLs have been detected. Conventional selection programmes, one based on mass selection and one on family selection, have been established. Triploid Pacific oysters produced via chemical means have been available for several years, but rates of triploidy achieved by such means are usually less than 100%. In 1999, we will assess whether our tetraploid 2-year-old broodstock can be crossed with diploids to give 100% triploid offspring. West, A. D., Goss-Custard, J. D., McGrorty, S., Stillman, R. A., Durell, S. E. A. L., Stewart, B., Walker, P., Palmer, D. W., and Coates, P. J. 2003. The Burry shellfishery and oystercatchers: using a behaviour-based model to advise on shellfishery management policy. Marine Ecology-Progress Series 248: 279-292. Ref ID: 634 Abstract: The Burry inlet, South Wales, supports a licensed cockle Cerastoderma edule fishery and occasional mussel Mytilus edulis fishery. It is also an important overwintering ground for oystercatchers Haematopus ostralegus. In recent years mussels have settled over parts of some cockle beds, preventing cockle fishery there and leading to a request by shellfishers to remove this 'mussel crumble'. Conservation managers, however, were concerned that the mussel crumble might be providing a high-quality food source for the oystercatchers, making its removal detrimental to the birds. A behaviour-based model of oystercatcher feeding on cockles and mussels was parameterised for the inlet and its predictions tested against the distribution of birds across the shellfish beds and the amount of time they spent feeding. The model was then used to explore whether the birds were currently food-limited and what would be the effects on their mortality rate and body condition if the mussel crumble were to be removed, thereby re-exposing underlying cockle beds. The model predicted successfully the proportion of birds feeding on the different types of food and the number of hours birds spent feeding on neap tides. It was predicted that, at current bird population sizes, there would have to be a 50 % reduction in shellfish stocks and the areas of shellfish beds from 2000-01 levels to cause noticeable extra emigration or mortality. A given area of mussel bed was predicted to be able to support more birds than the same area of cockle bed, but the greater area of the cockle beds meant that they were more important than mussels in determining the number of birds supported by the inlet, The simulated removal of mussel crumble to expose underlying cockles had no effect on predicted bird mortality and body condition at 2000-01 shellfish stock levels. However, there were circumstances under which the mussel crumble was predicted to increase the inlet's capacity to support birds, particularly when the area of existing cockle and mussel beds was substantially reduced White, D. L., Bushek, D., Porter, D. E., and Edwards, D. 1998. Geographocal information systems (GIS) and kriging: analysis of the spatial and temporal distributions of the oyster pathogen Perkinsus marinus in a developed and an undeveloped estuary. Journal of Shellfish Research 17: 1473-1476. Ref ID: 32 Abstract: Infection and prevalence of Perkinsus marinus (Dermo), a common protozoan pathogen of the oyster (Crassostrea virginica), are commonly correlated with temperature and salinity. However, these factors do not account for all infection variability. Other factors such as watershed dynamics or anthropogenic disturbances may play a role. Geographic Information System (GIS) technology applying land use and anthropogenic activity was used to document Dermo infections in two South Carolina coastal estuaries. Kriging analysis was used to calculate disease prevalence from sample sites to the estuary as a whole. Results indicate that land use patterns may affect the distribution of the disease. Whitelaw, D. M. and Zajac, R. N. 2004. Assessment of prey availability for diamondback terrapins in a Connecticut salt marsh. Northeastern Naturalist 9: 407-418. Ref ID: 621 Abstract: Wheeler Marsh in Milford, Connecticut provides habitat for diamondback terrapins (Malaclemys terrapin), a unique estuarine turtle. To assess potential prey availability, the distribution and abundances of marsh snails (Melampus bidentatus), mud snails (Ilyanassa obsoleta), marsh mussels (Geukensia demissa), and fiddler crabs (Uca spp.) were studied in several subhabitats (marsh surface, marsh edge, creek bank, and mudflats) of five tidal creeks. Almost all terrapins have been found in one section of the marsh, Turtle Creek, where all four prey species were present in large numbers. However, high numbers of some prey were found in other sections of the marsh as well, suggesting that resource availability may not be the primary determinant of terrapin distribution. The physical structure, plant density, and tidal amplitudes of salt marsh creeks may also be important determinants of terrapin distribution via their influence on resource accessibility. Whitlatch, R. B. and Osman, R. W. 1994. A qualitative approach to managing shellfish populations: assessing the relative importance of trophic relationships between species. Journal of Shellfish Research 13: 229-242. Ref ID: 14 Abstract: Simple qualitative models are applied to investigate aspects of how ecological interactions between a variety of predators and competitors of shellfish can be used to assist with the development of resource management policies. The modeling approach illustrates how typically complex interspecific interactions which vary with species and shellfish life stage can influence shellfish populations. Model results show the importance of managing shellfish predators, as well as selected groups of fouling species that may function as larval predators or competitors or both with juvenile shellfish life stages. While the modeling approach is limited by the lack of estimating intensities of interspecific interaction, it allows first-order insight into the relative importance of different types of interactions on shellfish populations and which variables are likely to be the most important in affecting shellfish abundance. Coupled with rigorous experimental hypothesis testing, the qualitative modeling approach provides assistance regarding which life stages of a shellfish species or interacting species needs to be managed in order to maximize shellfish productivity. Examples using the eastern oyster (Crassostrea virginica) are given. Wilson, W. G. and Nisbet, R. M. 1997. Cooperation and competition along smooth environmental gradients. Ecology 78: 2004-2017. Ref ID: 25 Abstract: This paper explores the ecological consequences of competition and cooperation, and the resultant abrupt species zonation that could occur along smooth environmental stress gradients. We present one-and two-species models of sessile organisms incorporating competition for space and two forms of cooperation: habitat amelioration and positive recruitment. In these models, habitat amelioration reduces an organism's mortality rate when it is surrounded by other organisms (''safety-in-numbers''), and positive intraspecific recruitment enables juveniles to use the shelter of established individuals as settlement (or germination) sites. A single-species model incorporating both forms of cooperation may exhibit sharp discontinuities in population density along an environmental gradient. In a two-species model the same mechanisms may lead to sharp boundaries in species composition if, as empirical studies suggest, a trade-off exists between colonization and cooperation abilities (e.g., strong cooperators are poor colonizers). Positive interspecific recruitment obscures the interspecific boundaries. Wirth, E. F., Scott, G. I., Fulton, M. H., VanDolah, R. F., Maier, P. P., Hadley, N., Daugomah, J. W., and Key, P. B. 1996. In situ monitoring of dredged material spoil sites using the oyster Crassostrea virginica. Archives of Environmental Contamination and Toxicology 30: 340-348. Ref ID: 543 Abstract: In situ and laboratory bioassays using the eastern oyster, Crassostrea virginica, were undertaken in the Wright River Estuary, South Carolina, to determine the toxic potential of effluent and sediment from recently dredged sediments. Current standards (ASTM, USEPA, and USAGE) rely solely on laboratory-based bioassays to assess toxicity of dredge spoils prior to disposal. These bioassays do not necessarily replicate the natural physicochemical estuarine processes, limiting the environmental realism of this approach. In this study, oysters were collected from a site on Leadenwah Creek (SC) and deployed in plastic cages anchored above the sediment and within the intertidal zone for 90 days at four dredge spoil disposal areas (18 sites total, one bushel/site). Oysters were also deployed at a reference site (New River Estuary, SC) and the original collection site. Trace metals and polycyclic aromatic hydrocarbons (PAHs) in tissue, sediment, and effluent samples as well as the assessment of oyster health in adults (% mortality and % reduction in potential yield) and larvae; (larval development) were measured. Results indicated high arsenic concentrations in surface water samples (<10 to 147 mu g/L), some of which exceeded the USEPA chronic marine water quality criteria and sediment concentrations (<1.0-82.2 mg/kg), which also exceeded the ERM (70 mg/kg) and the ERL (8.2 mg/kg) for arsenic, and which may have contributed to the toxic response seen in deployed oysters. A positive relationship was also seen between the in situ percent reduction in potential yield and laboratory-derived data from larval oyster development bioassays. The advantage of the combined in situ/laboratory approach used in this study is the ability to resolve probable factors influencing the toxicity of these effluents to oysters With, K. A. 2004. Assessing the risk of invasive spread in fragmented landscapes. Risk Analysis 24: 803-815. Ref ID: 640 Wu, X. Z. and Pan, J. P. 2000. An intracellular prokaryotic microorganism associated with lesions in the oyster, Crassostrea ariakensis Gould. Journal of Fish Diseases 23: 409-419. Ref ID: 173 Zajac, R. N., Whitlatch, R. B., and Osman, R. W. 1989. Effects of inter-specific density and food supply on survivorship and growth of newly settled benthos. Marine Ecology Progress Series 56: 127-132. Ref ID: 27 Zhang, X. and Chen, L. 2000. The global dynamic behavior of the competition model of three species. Journal of Mathematical Analysis and Applications 245: 124-141. Ref ID: 21 Abstract: In this paper, we decompose the dynamic behavior of the competitive Lotka-Volterra (LV) model (x) over dot(i) = x(i)(1 - x(i) - alpha(i)x(i+1) - beta(i)x(i+2)), x(i)(0) > 0, alpha(i) > 0, beta(i) > 0, i = 1, 2, 3, with x(4) = x(1), x(5) - x(2), into the dynamic behavior of two two-dimensional manifolds, and completely analyse the global asymptotic behavior of the competitive LV model. We obtain the necessary and sufficient conditions for the equilibrium of the competitive LV model to be positive and globally asymptotically stable in Int R-+(3), the necessary and sufficient conditions for the model having a family of limit cycle solutions and a heteroclinic cycle, both of which are the omega-limit set of some other trajectories of the competitive LV model. Zhou, M. 2002. Chromosome set instability in 1-2 year old triploid Crassostrea ariakensis in multiple environments. College of William and Mary, Virginia Institute of Marine Science. Ref ID: 144 Zhou, M. and Allen, S. K. Jr. 2003. A review of published work on Crasostrea ariakensis. Journal of Shellfish Research 22: 1-20. Ref ID: 39