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Showing papers on "Oyster published in 1982"


Journal ArticleDOI
TL;DR: Oyster condition measures should be standardized through use of Hopkins' formula: Condition Index = (dry meat weight in g) (100)/(internal cavity volume in cm3).
Abstract: Oyster condition measures should be standardized through use of Hopkins’ formula: Condition Index = (dry meat weight in g) (100)/(internal cavity volume in cm3). Cavity volumes, previously measured chiefly as capacity by a water displacement method, may be determined by subtracting the weight in air of the oyster’s valves from the weight in air of the intact oyster (both in g). This method is valid because the effective density of cavity contents is close to 1g per cm3. The technique is simple and time-efficient and could promote more widespread use of oyster condition studies.

192 citations


01 Jan 1982
TL;DR: In the lower bay of Delaware Bay, a previously unknown sporozoan parasite, now designated as Haplosporidium nelsoni (known as MSX), killed 90-95% of the oysters in lower Delaware Bay as discussed by the authors.
Abstract: Abstract Between 1957 and 1959, a previously unknown sporozoan parasite, now designated as Haplosporidium nelsoni (formerly Minchinia nelsoni ), or MSX, killed 90–95% of the oysters in lower Delaware Bay. Native oysters have been studied for more than 20 years since then to determine long-term disease and mortality patterns resulting from this host-parasite association. Development of resistance to MSX-kill in native oysters has reduced disease mortality to about half the original level, even though the pathogen continues to be very active in the bay. Since the initial epizootic, MSX levels have fluctuated in a cyclic pattern with peaks every 6 to 8 years. Periods of low disease pressure follow very cold winters, while average or above average winter temperatures correlate with high MSX activity. During peak years, every oyster in the lower bay may become infected. Although the parasite is salinity limited, salinities in the lower bay, the area from which oysters are marketed, are nearly always favorable for MSX, and fluctuations in river flow have almost no effect on MSX in this region. Infection periods recur each summer. Some oysters die soon after becoming infected; others survive through winter, but die in spring as the pathogen compounds normal overwinter stresses. Many survivors are able to suppress or rid themselves of infections when temperatures approach 20°C in late spring. Resistance to MSX-kill in native oysters is not correlated with an ability to prevent infection, but with restriction of parasites to localized, nonlethal lesions. The persistence of “hot spots” for infection in areas where oysters are sparse, the lack of spores in infected oysters, and failure to transmit the disease experimentally lead to the hypothesis that an alternate or reservoir host produces infective stages of MSX.

135 citations


Journal ArticleDOI
TL;DR: Resistance to MSX-kill in native oysters is not correlated with an ability to prevent infection, but with restriction of parasites to localized, nonlethal lesions, which leads to the hypothesis that an alternate or reservoir host produces infective stages of MSX.

119 citations


Book ChapterDOI
01 Jan 1982
TL;DR: Circulation processes can explain the observational evidence of estuarine larval retention, but knowledge of water motion is required on the small spatial and temporal scales appropriate to larval transport.
Abstract: Circulation processes can explain the observational evidence of estuarine larval retention, but knowledge of water motion is required on the small spatial and temporal scales appropriate to larval transport. Two cases are presented - the oyster Crassostrea uirginica and the blue crab Callinectes sapidus - in which the operative mechanism is recruitment or return rather than retention in the strict sense. In the case of the oyster, marked differences in spat settlement success between two adjacent tributaries in the lower Choptank River (Chesapeake Bay) are explained by subtle differences in the exchange mechanisms between the tributaries and the lower Choptank proper. In the case of the blue crab, the return of later stage larvae to Chesapeake Bay from the continental shelf can be provided by the northward flowing inner shelf band which is driven by the wind against the prevailing southward flow.

91 citations


Journal ArticleDOI
TL;DR: In this article, the authors investigated the relationship of salinity to the distribution and effect of Haplosporidium nelsoni infection in native oysters in the estuary.

84 citations



Journal ArticleDOI
TL;DR: The FAA pool's response was unique for each stress studied suggesting that the FAA pool may prove to be a useful diagnostic tool for determining a posteriori the causative agent responsible for a given stress response.

60 citations


Journal ArticleDOI
TL;DR: The objective of this research was to evaluate the effect of temperature on cadmium accumulations in the tissue of the American oyster, Crassostrea virginica, under controlled laboratory conditions.
Abstract: Estuarine and coastal waters have increasingly become repositories for the effluents frc~both industrial and agricultural activities. Cadmit~nconcentration in coastal_marine organisms reflect increased concentrations of cadmiumin seawater (MCINTYRE & M/LLS 1975; PHILLIPS 1977; ZAROOGIAN 1976). Although several authors have documented cadmium accululation in oyster (BROOKS & RUMSKY 1967; PRINf~ et al. 1968; SCRUDATO & ESTES 1976; FRAZIER 1976), many questions remain concerning the effects of specific environmental parameters on uptake of cadmium in oyster tissues. The objective of this research was to evaluate the effect of temperature on cadmium accumulations in the tissue of the American oyster, Crassostrea virginica, under controlled laboratory conditions. Oysters have been reported to acc~aalate cadmit~n from seawater containing added cadmium chloride. However, the chemical form of cadmium in seawater has not been defined. This may profoundly influence the mechanism of uptake. Therefore, the present report is also concerned with the effect of chelating agents on the uptake of cadmium. bIATERIALSAND~-THODS Oyster Collection- Single source, adult oysters of similar size (about 3-4 year old) collected from corsrercial fisherman in Deal Island area of Maryland were kept in clean seawater for two days to allow defecation and then brought back to the laboratory. During the two-day period, several gentle cleanings and a final sorting were performed to insure a vigorous group of animals for the experiments. After two weeks of acclimation to the controlled environmental conditions, oysters were used in exposure experiments. Design for Exposure System- Cadmit~n exposure tests were conducted in the laboratory aquaria containing about 50 gal of synthetic seawater which were continuously aerated. The aquaria were equipped with efficient biological filters containing calcite and dolcrnite. Flow rate in each chamber was well controlled. The pH was monitored daily and maintained at 8.1. Toxicant concentrations for cadmium were selected in the range of 40 to 60 ppb. The photoperiod regimen was set according to natural sunlight. The effects of temperature de~ondence on cadmium uptake were^conducted in the range of 5 to 20 C. Salinity was fixed at 15 U/O0.

57 citations



Journal ArticleDOI
TL;DR: The transport proposed can explain the 30 yr record of consistently higher spat set success in one tributary, Broad Creek, relative to an adjoining tributARY, the Tred Avon River, which may be a general mechanism whereby oysters maintain reproductive success and emigrate to seed bed regions in the Chesapeake Bay.
Abstract: Vertical and horizontal distributions of 3 larval stages of the oyster Crassostrea virginica were measured concurrently with phytoplankton species compositions, phytoplankton size distributions and physical hydrographic parameters in tributaries of the Chesapeake Bay (USA) during the oyster spawning seasons of 1980 and 1981. The superposition of the biological distributions upon the physical hydrographic data provide instantaneous distributions of the entire system which are consistent with the upstream transport of oyster larvae. Oyster larvae distributions in the Choptank River and its Broad Creek and Tred Avon River tributaries can be described in terms of three contiguous regions: (1) a common spawning region, (2) an intermediate, upstream transport region and (3) a seed bed region where major spat set occurs. The phytoplankton species compositions and abundances in the size fraction less than 10 μm in the tributary system during the transport were sufficient to supply optimum growth requirements of developing larvae. The transport proposed can explain the 30 yr record of consistently higher spat set success in one tributary, Broad Creek, relative to an adjoining tributary, the Tred Avon River. This may be a general mechanism whereby oysters maintain reproductive success and emigrate to seed bed regions in the Chesapeake Bay.

55 citations


Journal ArticleDOI
TL;DR: A disease of cultured juvenile European oyster, Ostrea edulis, and American oysters, Crassostrea virginica, was characterized by infection of conchiolinous ligament and periostracum by surface-coating Vibrio spp.
Abstract: . A disease of cultured juvenile European oyster, Ostrea edulis, and American oysters, Crassostrea virginica, was characterized by infection of conchiolinous ligament and periostracum by surface-coating Vibrio spp. bacteria. A similar bacterium was isolated from diseased cultured hard clams, Mercenaria mercenaria, held in a facility about 300 km distance from the oyster hatcheries. The oysters demonstrated fragile, undercalcified peripheral shell and apparently excessive chalky deposits. Histological and scanning electron microscopical examination revealed that the oysters' eroded ligaments and perforated peripheral periostracum were infected with uniform rod-shaped bacteria. The infection appeared to interfere with normal proteinaceous and calcareous shell deposition and possibly with normal ligament function. Histological examination of the digestive system organs suggested that normal digestive processes were also interrupted. Two predominant bacteria were isolated from oyster samples and one predominant bacterium was isolated from clam samples. One of the isolates from oyster culture facilities was found almost exclusively associated with oyster shell surfaces and culture tank surfaces, this isolate was similar to the one taken from clam shell surfaces. The other predominant bacterium was found in water column samples in oyster culture facilities at levels from about 105 to 107 per ml. This isolate had a DNA base ratio (moles % G + C) of 43.6; the two surface-associated isolates had base ratios of 43.6 and 44.5%. These Gram-negative, oxidase positive, fermentive rods have been identified as a Vibrio spp. group. Specific antibody was produced which differentiated these bacteria from each other and from other similar isolates. Practical procedures for controlling the bacteria in shellfish culture systems are described.


Journal ArticleDOI
TL;DR: A selective breeding program with the European Oyster Ostrea edulis L. has been in progress at Dalhousie University since 1977, and selection has been for growth rate only.
Abstract: A selective breeding program with the European Oyster Ostrea edulis L. has been in progress at Dalhousie University since 1977. First generation selected lines were produced in 1977 and 1978. The selected parents came from the 1975 hatchery year class which were offspring of the original imports to Nova Scotia, considered here as the parental oysters. In both years, the parental oysters were respawned as control lines. Oysters from all lines, individually labelled within a few months of spawning, were stocked in lantern nets and grown in the field. Up to this time selection has been for growth rate only. The analysis of these lines will show the progress made in the early stages of this selective breeding program.

Journal ArticleDOI
TL;DR: A survey acrried out from the spring to summer of 1979 at 31 stations in Tohoku and nearby areas revealed that shellfishes were infested in varied degrees by paralytic shellfish poison at almost all stations, with Protogonyaulax tamarensis identified as the causative organism.
Abstract: A survey acrried out from the spring to summer of 1979 at 31 stations in Tohoku and nearby areas revealed that shellfishes were infested in varied degrees by paralytic shellfish poison at almost all stations. The rates of accumulation of toxin differed markedly from species to species and the toxicity levels decreased in the following order: scallop Patinopecten yessoensis, scallop Chlamys nipponensis akazara, mussel Mytilus edulis, and oyster Crassostrea gigas. The edible tunicate Holocynthia roretzi also accumulated the toxin at a fairly high level. In the absence of the causative plankton M. edulis eliminated the toxin rapidly but P. yessoensis retained it for a long period at a high level. Protogonyaulax tamarensis was identified as the causative organism occurring during the investigation period. It caused mussels to become highly toxic even at a low population density of several cells per mililiter.

Journal ArticleDOI
TL;DR: There was a general deficiency of heterozygotes in the three age groups and this deficiency decreased with age (reflecting reduction in heterozygote deficiency), which suggests genotype-specific mortality during ontogeny.
Abstract: Following our earlier reports on one-year-old oyster populations of Prince Edward Island (Singh and Zouros, 1978, 1981; Zouros et al., 1980), cohorts of three-year classes were studied from Cape Br...

Journal ArticleDOI
TL;DR: Potential biological monitors for the South African marine environment have been discussed in general terms on the basis of the reported use of related species, but few data on the accumulator ability, or on their tolerance to metals are available.
Abstract: Potential biological monitors for the South African marine ~nvironment have been discussed in general terms on the basis of the reported use of related species (DAP~KACOTT and WATLING 197~). Metal concentrations in a number of these molluscs are being determined in several laboratories as part of the National Marine Pollution Monitoring Programme (CLOETE and WATLiNG 1981). However, few data on the accumulator ability of these species, or on their tolerance to metals are available.

Journal ArticleDOI
TL;DR: Because of their ability to concentrate pollutants from their environment, the clam, Rangia cuneata and the oyster were analyzed to compare metal uptake and to see whether their microphageous behavior is reflected in the relationship of body weight burden of trace metal to levels in the sediments and water column.
Abstract: Because of their ability to concentrate pollutants of various kinds from their environment, the clam, Rangia cuneata and the oyster, Crassostrea virginica were analyzed to compare metal uptake and to see whether their microphageous behavior is reflected in the relationship of body weight burden of trace metal to levels in the sediments and water column. The metals chosen for analysis were arsenic, antimony, beryllium, cadmium, chromium, cobalt, copper, iron, lead, mercury, molybdenum, nickel, selenium, strontium, titanium, vanadium and zinc. (JMT)

Journal ArticleDOI
TL;DR: In this article, the condition of oysters was analyzed and compared in two South Carolina estuaries, one of which was considered polluted by coliform bacteria standards, and the results showed that oysters from the unpolluted habitat showed a consistently and significantly higher condition index.
Abstract: The Condition Index [(dry meat weight)(100)/(internal cavity volume)] has been analyzed and compared in the American oyster,Crassostrea virginica, from two South Carolina estuaries, one of which was considered polluted by coliform bacteria standards. During the warmer months, oysters from the unpolluted habitat showed a consistently and significantly higher Condition Index. Best fit and power function regressions of Condition Index on total coliform bacteria levels conform with previously cited effects of pollutants on oysters. Condition Index droped markedly as the incidence of total coliforms increased toward levels of 100 per 100 ml of water. Our results and the known sensitivity of oysters to a spectrum of pollutants suggest that their condition could be used to monitor waterborne pollution in coastal zone areas.

Journal ArticleDOI
TL;DR: Both methods provide effective protection, but continuous spraying appears to be preferable while hot, potentially lethal, temperatures prevail, and there was no temperature difference between clean and muddy oysters.

Journal ArticleDOI
TL;DR: Analysis of variance and response surface methodology indicated that there was a significant interaction between salinity and metal concentration in increasing embryotoxicity in the Pacific oyster, where a dramatic decrease in percent normal embryonic development occurred at the lowest concentrations of copper and silver.
Abstract: Embryonic development of the Pacific oyster was monitored under various combinations of copper × salinity and silver × salinity. Oyster embryos were exposed to salinities between 14.5 and 33 %, copper concentrations between 0 to 10 ppb and silver concentrations between 0 to 18 ppb. Exposure to salinities between 22.7 and 33 % had no significant effect on normal embryonic development, but salinities below 22.7 % were highly deleterious. Analysis of variance and response surface methodology indicated that there was a significant interaction between salinity and metal concentration in increasing embryotoxicity. This interactive effect was manifested at low salinities where a dramatic decrease in percent normal embryonic development occurred at the lowest concentrations of copper and silver. The direction of the response surface isopleths indicated a shift from a salinity effect to a more pronounced concentration effect as copper concentration was increased, whereas a salinity effect was evident throughout the entire concentration range in the silver experiments. Optimum development of oyster embryos is predicted at salinities between 23 and 33 %, at silver concentration below 15 ppb and copper concentrations below 2 ppb. Low levels of copper and silver, when combined with low salinities, may represent a significant threat to the normal recruitment of oyster embryos.

Journal ArticleDOI
TL;DR: In some areas, chemical pollution, disease, and predators have eliminated some species of shellfish, whereas organic pollution has enhanced the growth of other species in the United States as discussed by the authors.
Abstract: Historically, shellfish made a significant contribution to the American diet. Early inhabitants found abundant supplies of bivalve mollusks that could easily be harvested year-round. Shellfish, along with an ample supply of fish, provided high quality protein with little effort or cost to the consumer. Even today fish and shellfish proteins are highly competitive with other animal proteins, especially in areas along the extensive US coastline. The value of the shellfish grounds to the early settlers was demonstrated in 1659 when the Dutch Council of New Amsterdam passed an ordinance limiting shellfish harvesting in the East River. Similar legislative actions pertaining to conservation of the shellfish resources were passed in New York (1715), New Jersey (1730), and Rhode Island (1734) (Houser 1965). Records on the quantity of shellfish harvested in the United States were not reported until the late 1800s. In 1890 more than 15 million pounds of oyster shellstock were harvested from the San Francisco Bay. Because of pollution, shellfishing has been prohibited in the Bay since 1930 (Jarvis 1980). In 1897 more than 40,000 bushels of soft-shell clams were harvested from the Boston Harbor. This shellfish area was closed in 1907 (Field 1909). The Raritan Bay, which borders on the shores of New York and New Jersey, was a yearly source of thousands of bushels of hardand soft-shell clams and oysters. On the New York portion of the shore alone more than 20,000 acres of the estuary were used in 1900 for oyster production, with a yearly income of $2-4 million. The oysters were extirpated in 1916 because of pollution. By 1960 pollution had caused the closing of all but 10% of the original Raritan Bay shellfish harvesting grounds. Since 1961, shellfishing in the bay has been prohibited because of outbreaks of hepatitis A that were shown to be associated with raw clam consumption (Campbell 1965). A similar situation occurred in the Narragansett Bay area, which also lost its oyster resource to pollution. Older residents of the Chesapeake Bay area remember that oyster shucking plants were in operation in the early 1900s that employed more than 100 shuckers and processed close to 1 million oysters/day. During the peak of the oyster-producing period in the small town of Oxford, MD, one could walk around the village by crossing from boat to boat when the oyster fleet landed to unload its catch in the late afternoon. On one dock there were five shucking houses. Today, there are none. Natural phenomena, overfishing, and pollution have reduced shellfish resources. In some areas, chemical pollution, disease, and predators have eliminated some species of shellfish, whereas organic pollution has enhanced the growth of other species of shellfish. Water microbiological standards prohibit harvesting from polluted areas, but regulatory agencies allow shellfish to be transferred out of polluted areas. Transfer from nonapproved to approved areas is called "relaying," whereas transfer to seawater tanks is referred to as "depuration." Relaying and small depuration units are used to recover oysters from organically polluted waters in a number of areas in the United States. For more than 50 years soft-shell clams recovered from moderately polluted waters have been depurated in Massachusetts. Shellfish harvested from approved areas may be conditioned in seawater tanks for direct marketing if proper controls are maintained. This process is used for sand removal and for short-term natural storage of the product.

Journal ArticleDOI
TL;DR: Electron microscopy revealed that oyster spermatozoa underwent acrosome reaction on the sea urchin vitelline coat, and their acrosomal membrane fused with the egg plasma membrane after the appearance of an intricate membranous structure in the boundary between the acrosomic process and the egg cytoplasm.
Abstract: Interphylum crossing was examined between sea urchin eggs (Temnopleurus hardwicki) and oyster sperm (Crassostrea gigas). The eggs could receive the spermatozoa with or without cortical change. The fertilized eggs that elevated the fertilization envelope began their embryogenesis. Electron microscopy revealed that oyster spermatozoa underwent acrosome reaction on the sea urchin vitelline coat, and their acrosomal membrane fused with the egg plasma membrane after the appearance of an intricate membranous structure in the boundary between the acrosomal process and the egg cytoplasm. Oyster spermatozoa penetrated sometimes into sea urchin eggs without stimulating cortical granule discharge and consequently without fertilization envelope formation. The organelles derived from oyster spermatozoa seemed to be functionally inactive in the eggs whose cortex remained unchanged.

Journal ArticleDOI
01 Nov 1982-Lipids
TL;DR: Oysters (Crassostrea gigas) contain at least 8 predominant sterols as determined by gas liquid chromatography and a modified Liebermann-Burchard reaction and the possible sources of these sterols are discussed.
Abstract: Oysters (Crassostrea gigas) contain at least 8 predominant sterols as determined by gas liquid chromatography and a modified Liebermann-Burchard reaction. These sterols and the average amount found in mg/100 are: C26-sterol (22-trans-24-norcholesta-5, 22-diene-3 beta-ol), 19.1; 22-dehydrocholesterol, 15.1; cholesterol, 46.8; brassicasterol, 27.2; delta 5,7-sterols (i.e., 7-dehydrocholesterol) 22.5; 24-methylenecholesterol 29.1; 24-ethylcholesta-5,22-diene-3 beta-ol, 1.2; and 24-ethylcholesta-5-en-3 beta-ol, 12.7. The distribution of these sterols appears uniform (r2 = 0.938) between 5 major organs of the oyster. The percent body mass vs percent total sterols in these 5 organs are: mantle 44.1--41.4; visceral mass 30.3--36.7; gills 13.2--11.7; adductor muscle 8.3--3.7; and labial palps 4.2--6.5. The possible sources of these sterols are discussed.


Journal ArticleDOI
TL;DR: A procedure is discussed for the extraction of poliovirus from oyster meats by modification of several enterovirus extraction techniques, which uses meat extract and Cat-Floc, a polycationic electrolyte, for virus extraction and concentration.



Journal ArticleDOI
R. D. Braley1
TL;DR: The population of Saccostrea cucullata (Born) in Sasa Bay had low level continuous reproduction with three main peaks throughout the year, in November–December, March–April, and late June, indicating the length of the planktonic larval period.
Abstract: The population of Saccostrea cucullata (Born) in Sasa Bay had low level continuous reproduction with three main peaks throughout the year, in November–December, March–April, and late June. Gametogenic cycles were 3–4 months in length. The periods of gonadal development and regression were similar for both sexes. Partial spawning with resorption of unspawned gametes generally occurred. Changes in water temperature, salinity, turbidity and climatological parameters were not correlated with spawning. Peaks in spat collection followed peaks in gonad ripeness by 3 wk to 1 month, indicating the length of the planktonic larval period. There were significant differences in the abundance of spatfall between sites but not between collector types. Metamorphosing larvae preferred concave over convex surfaces. Oyster larvae were a major component of bivalve larvae taken in zooplankton tows.

Journal ArticleDOI
TL;DR: The effects of ozone-produced oxidants (OPO) on three developmental stages of the American oyster, Crassostrea virginica, were evaluated in this article, where Mortality was used as the response parameter.

Journal ArticleDOI
TL;DR: The results suggest that the gill may be the critical organ during a challenge with cadmium-at both lethal and sublethal concentrations, and that the accumulation of Cadmium in S. commercialis is non-linear at some water concentrations of cadMium.
Abstract: The Sydney rock oyster (S. commercialis) was exposed to a control and four concentrations of cadmium (nominally 0, 10,25,50 and 150µg I-1) in a flowing seawater system in the laboratory. Oysters from the 10 and 50 µg 1-1 groups were briefly exposed to 109Cd, then frozen in liquid CO2 and sectioned. The thin sections of whole oyster were apposed to X-ray film. The resulting images showed that 109Cd accumulated mainly in the gut, kidney and gill, with little in the gonad and glycogen storage areas of the visceral mass. Oysters from all water concentrations of cadmium were removed after 1,4,8 and 16 weeks of treatment with cadmium. The visceral mass, gill, mantle, muscle and heart-kidney were analysed for total cadmium. All groups of oysters rapidly accumulated cadmium. The heart-kidney attained the highest concentration and the muscle invariably displayed the lowest concentration. The visceral mass contained the greatest amount of cadmium in all oysters. The gill changed its position in the ranking of the organ concentrations of cadmium, increasing with increasing water concentrations of cadmium. The results suggest that the gill may be the critical organ during a challenge with cadmium-at both lethal and sublethal concentrations. The long-term nature of this experiment reveals that the accumulation of cadmium in S. commercialis is non-linear at some water concentrations of cadmium.