Showing papers on "Oyster published in 1975"
TL;DR: In this article, complementary techniques of midden analysis have been applied to large oyster mounds on the Richmond River, New South Wales, in order to quantify the dietary contribution of the molluscs.
128 citations
TL;DR: During October and November 1973, outbreaks of hepatitis A associated with consumption of raw oysters occurred in Houston and in Calhoun, Ga.
Abstract: During October and November 1973, outbreaks of hepatitis A associated with consumption of raw oysters occurred in Houston and in Calhoun, Ga. The oysters implicated in both outbreaks had been harvested in two Louisiana bays. Although the bays had been contaminated with polluted Mississippi River water two months before the oysters were harvested, at the time of harvesting the bays met national sanitation standards for shellfish growing and were certified for oyster fishing. These epidemics raise serious questions about the adequacy of shellfish sanitation monitoring systems currently in use. ( JAMA 233:1065-1068, 1975)
121 citations
TL;DR: The 96-h lethal tolerance limits of the hard clam Mercenaria mercenaria (Linné) and the oyster Crassostrea virginica (Gmelin) to ammonia, nitrite ion, nitrate ion, and orthophosphate were defined.
Abstract: The 96-h lethal tolerance limits of the hard clam Mercenaria mercenaria (Linne) and the oyster Crassostrea virginica (Gmelin) to ammonia, nitrite ion, nitrate ion, and orthophosphate were defined. Sublethal effects of the chemicals upon the rates at which the shellfish removed algal cells from suspension were also studied. In comparison with other marine and aquatic species which have been studied, hard clams and oysters are extremely tolerant.
102 citations
TL;DR: Adult oysters, Crassostrea virginica (Gmelin) were held in seawater containing 10 or 100 ppb mercury in the form of mercuric acetate for 45 days, and smaller oysters consistently accumulated more mercury per gram wet weight than larger oysters in populations exposed to 10 and 100ppb mercury.
Abstract: Adult oysters, Crassostrea virginica (Gmelin) were held in seawater containing 10 or 100 ppb mercury in the form of mercuric acetate for 45 days. Mercury concentration in tissues was determined by analysis of individually homogenized oyster meats using wet digestion and flameless absorption spectrophotometry. After 45 days, average mercury tissue concentration was 91,600 and 12,100 ppb in the 100 and 10 ppb mercury groups, respectively. A slight decline in mercury residues in the 100 ppb group during the accumulation period was attributed to spawning. Clearance of mercury from tissues was studied in a constant temperature regime (25°C±2Co) for 25 days and in a declining temperature regime (25° to 5°C) for 80 days by exposing treated adults to estuarine water with no mercury added. The biological half-life of mercuric acetate was 16.8 and 9.3 days in the 25°C temperature regime, and 35.4 and 19.9 days in the declining temperature regime, for the 10 and 100 ppb groups, respectively. Smaller oysters (0 to 7 g) consistently accumulated more mercury per gram wet weight than larger oysters (7 to 20 g) in populations exposed to 10 and 100 ppb mercury.
75 citations
TL;DR: Exposure to Cd and/or109Cd has shown that the element was efficiently accumulated in oysters and soybeans as well as in rats.
Abstract: Exposure to Cd and/or109Cd has shown that the element was efficiently accumulated in oysters and soybeans as well as in rats. Differential centrifugation of oyster, soybean, rat liver, and rat kidney homogenates followed by analysis showed that Cd was associated primarily with proteins in the 105,000×g supernatants. Separation of these proteins by Sephadex chromatography and subsequent analysis by atomic absorption spectroscopy or by radioactivity measurements revealed that Cd in oysters and rat organs was principally bound to proteins of 9,200 to 13,800 molecular weight. A significant amount of Cd in oysters was also associated with fractions of > 50,000 and 50,000 molecular weight.
73 citations
TL;DR: In this article, the trace metal content of bottom sediments and waters of five estuaries and their catchment drainage, representing both contaminated and relatively uncontaminated environments, were investigated.
64 citations
TL;DR: In this article, Histological estimates of the numbers of oyster granular basophilic blood cells, or basophils, per oyster were found to differ significantly for various populations of Pacific and American oysters.
59 citations
TL;DR: Although the initial pattern of accumulation was identical for both mercury compounds within each exposure group, the fate of the accumulated mercury was very different after 45-days depuration.
Abstract: Oysters (Crassostrea virginica) were exposed for 3 days to mercury-203 labeled HgCl2 or CH3HgCl added directly to artificial seawater or added preconcentrated on the marine diatom Phaeodactylum tricornutum. The concentration of mercury in 5 tissues was measured for 45 days after mercury was removed from the ambient water. At the beginning of the depuration period, the highest concentrations of mercury in tissues were attained in: gill>digestive system>mantle>gonad>muscle in oysters exposed to water containing mercury; and in digestive system>gill>mantle> gonad>muscle in oysters fed labeled algae. This same distribution pattern is seen for both chemical forms of mercury. Although the initial pattern of accumulation was identical for both mercury compounds within each exposure group, the fate of the accumulated mercury was very different after 45-days depuration. In oysters accumulating mercury directly from seawater, inorganic mercury residues rapidly declined in gill and digestive tissue, but were slowly reduced in mantle, gonadal, and muscle tissue. This pattern was duplicated by oysters exposed to methyl mercuric chloride in seawater except that gonadal and muscle residues greatly increased during depuration. In oysters ingesting labeled P. tricornutum cells, mercuric chloride and methyl mercuric chloride residues rapidly declined in gill and digestive tissue, remained constant in the mantle, but sharply increased in gonadal and muscle tissue during depuration.
54 citations
TL;DR: The American oyster,Crassostrea virginica, was found to contain structurally homologous nonmethylene-interrupted dienoic (NMID) fatty acids and a combination of analytical procedures was required for conclusive structure determination.
Abstract: The American oyster, Crassostrea virginica, was found to contain structurally homologous nonmethylene-interrupted dienoic (NMID) fatty acids. The major C20 and C22 nonmethylene-interrupted dienoic fatty acid isomers were shown to occur as two pairs of homologues 5,13-20:2 with 7,15-22:2 and 5,11-20:2 with 7,13-22:2. A combination of analytical procedures was required for conclusive structure determination.
53 citations
TL;DR: Bacteriological and virological examinations of Louisiana and Texas Gulf Coast oysters were done over a 12-month period, and virus was present in one of 17 samples in which V. parahaemolyticus was not detected.
Abstract: Bacteriological and virological examinations of Louisiana and Texas Gulf Coast oysters were done over a 12-month period. Oysters taken from approved waters sometimes contained detectable enteroviruses: echovirus 4 and poliovirus 1 were in one each of 17 samples from Texas, and poliovirus 3 was in one of 24 samples from Louisiana. Neither the coliform MPN for the water from the shellfish beds nor the coliform MPN, Escherichia coli MPN, or aerobic plate counts for the shellfish meats was clearly indicative of the presence of virus. Two of the 24 oyster meat samples which contatined Vibrio parahaemolyticus also yielded virus; however, virus was present in one of 17 samples in which V. parahaemolyticus was not detected. Poliovirus 1 was also found in frozen, shucked oysters imported from Japan.
46 citations
TL;DR: The eggs of two groups of oysters containing significantly different levels of copper and cadmium were collected, the eggs were collected and trace metal contents measured, and no conclusion could be made about the transfer of these three metals from adults to eggs of oyster.
TL;DR: Epizootiologic differences noted between native oysters (adult and juvenile) and the introduced juvenile populations were also evident from the stages of the disease, and may indicate genetic resistance developed by natural selection and manifested by an increased ability to survive and overcome infection.
Abstract: SYNOPSIS. Minchinia nelsoni disease in oysters (Crassostrea virginica) from Marumsco Bar, Pocomoke Sound, Maryland (an estuarine tributary of Chesapeake Bay) was studied for 8 years (1961–68) to determine epizootiologic relationships concerning life cycle of the parasite, pathologic effects on the host, and effects of physical factors on population density and recruitment of the host and parasite. The study period covered pre-epizootic, epizootic, and post-epizootic disease conditions. Data on the native oyster population as well as annual introductions of previously unexposed, susceptible populations of juvenile oysters from 1965–68 were included. Salinity, water temperature, mortality, prevalence, incidence, life cycle stages, gross pathology, and histopathologic relationships were observed.
Mortality was high (45–55% per year) during the first 3 years of the study; however, M. nelsoni prevalences were low (> 25%) and did not clearly imply a cause and effect relationship. Drought conditions that began in the summer of 1963 and continued through 1967 caused higher salinities, and apparently initiated epizootic disease in the native oyster population. The epizootic peaked in May 1965 with a diagnosed prevalence in native oysters of 70%. Enzootic levels of annual mortality (40% in 1966, 30% in 1967, and 2% in 1968) and fall prevalence (16%, 24%, and 4%) developed after that time. Introduced populations had a typical epizootiologic pattern in 1965 (55% annual mortality, 82% incidence) and 1966 (55% annual mortality, 66% incidence) which declined in 1967 (30% annual mortality, 44% incidence) followed by a disappearance of the disease in 1968.
Epizootiologic differences noted between native oysters (adult and juvenile) and the introduced juvenile populations were also evident from the stages of the disease. Infections in native animals tended to be less serious, and in many cases were delayed or attenuated, while infections in introduced oysters progressed to advanced or terminal phases. Occult manifestations (mantle recession thought to be due to M. nelsoni in oysters not showing histologic evidence of infection) were absent in introduced populations and common in the native population.
These differences are interpreted as evidence of resistance in surviving native oysters and their progeny, and may indicate genetic resistance developed by natural selection and manifested by an increased ability to survive and overcome infection.
Patent•
14 Jul 1975
TL;DR: In this paper, the authors described a system for the forced feeding of mollusks such as free oyster and clam seed employing a flume or a raft, having means holding the free oysters or clam seed.
Abstract: Systems are described for the forced feeding of mollusks such as free oyster and clam seed employing rafts or a flume, having means holding the free oyster or clam seed. Water containing nutrients is forced upwardly through the free oyster or clam seed to feed a dense population thereof by tide flow in a system operating below water level. The rafts are anchored to take advantage of the tide flow. Baffles graduated in length from the forward end to the rear are provided at spaced intervals, transverse to the direction of the incoming tide flow. These baffles extend downwardly at a forward inclined angle. The system includes trays having foraminous bottom walls in which the free oyster or clam seed rests. The upward flow of water through the oyster and/or clam population also continuously removes detritus generated.
TL;DR: The development of a simple method for concentrating enteroviruses from oysters is described, and viruses in homogenized oyster tissues are efficiently absorbed to oyster solids at pH 5.5 and low salt concentration.
Abstract: The development of a simple method for concentrating enteroviruses from oysters is described. In this method viruses in homogenized oyster tissues are efficiently adsorbed to oyster solids at pH 5.5 and low salt concentration. After low-speed centrifugation, the supernatant is discarded and viruses are eluted from the sedimented oyster solids by resuspending them in pH 3.5 glycine-buffered saline. The solids are then removed by low-speed centrifugation, and the virus-containing supernatant is filtered through a 0.2-μm porosity filter to remove bacteria and other small particulates without removing viruses. The virus-containing filtrate is then concentrated to a volume of a few milliliters by ultrafiltration, and the concentrate obtained is inoculated directly into cell cultures for virus assay. When tested with pools of oysters experimentally contaminated with small amounts of different enteroviruses, virus recovery efficiency averaged 63%.
TL;DR: Zinc at concentrations of 250 and 500 μg/l suppressed spat growth, but recovery was rapid upon subsequent on-growing in clean water conditions, and larvae subjected to zinc immediately prior to settlement showed evidence of slowing in behavioural development.
Abstract: The influence of zinc upon the pattern and success of settlement was examined in the oyster Crassostrea gigas. Late larvae were more tolerant of zinc than embryos. A delay in settlement was recorded in treatments containing zinc as low as 125 μg/l, and numbers of larvae settling was reduced in the presence of zinc. Larvae subjected to zinc immediately prior to settlement showed evidence of slowing in behavioural development. Those larvae which settled in the presence of zinc, however, when ongrown in clean water were as viable as controls. Zinc at concentrations of 250 and 500 μg/l suppressed spat growth, but recovery was rapid upon subsequent on-growing in clean water conditions.
TL;DR: In this paper, high Cd levels of up to 9 ppm wet wt. have been found in the dredge oyster, Ostrea lutaria (Hutton), from Foveaux Strait, New Zealand.
Abstract: High Cd levels of up to 9 ppm wet wt. have been found in the dredge oyster, Ostrea lutaria (Hutton), from Foveaux Strait, New Zealand. Average Cd levels in the oysters were determined at 24 stations in order to obtain a pattern of the geographic distribution of Cd. These data, in combination with a consideration of the prevailing currents, indicate that the source of the Cd must lie to the west of Foveaux Strait, possibly in Fiordland. These high Cd levels are naturally occurring since there is no industrial pollution in the area. Compared with other oyster species, O. lutaria may have a predilection for accumulating Cd.
TL;DR: An investigation of mercury-resistant bacteria was undertaken to determine their role in the accumulation of mercury in a simplified food chain and mercury accumulation in the oysters was significantly higher in the gill and visceral tissue than other tissue.
Abstract: An investigation of mercury-resistant bacteria was undertaken to determine their role in the accumulation of mercury in a simplified food chain. Oysters (Crassostrea virginica) were maintained in a closed system, sealed aquarium with stirred, aerated water containing 10 μg of 203HgCl2 per liter. Uptake of 203Hg by oysters held under control conditions was compared with that of 203Hg uptake by oysters under similar conditions except that mercury-accumulating and mercury-metabolizing species of Pseudomonas, isolated from Chesapeake Bay, were added to the experimental oysters. After incubation for 4 days, the major portion of the 203Hg in the water column was found to be associated with the microparticulate fraction, corresponding to a rise in total viable count. Mercury accumulation in the oysters was significantly higher in the gill and visceral tissue than other tissues. Mercury concentrations were 200 times greater in tissue fractions of oysters dosed with mercury-metabolizing bacteria compared with the oysters held under control conditions without mercury-metabolizing bacteria.
TL;DR: The American or Eastern oyster, Crassostrea virginica Gmelin (family Ostreidae), inhabits Atlantic and Gulf coastal waters where current patterns, salinity and temperature gradients, and turbidity are often altered by dredging, coastal construction, salt-water intrusions, and flooding.
Abstract: The American or Eastern oyster, Crassostrea virginica Gmelin (family Ostreidae), inhabits Atlantic and Gulf coastal waters where current patterns, salinity and temperature gradients, and turbidity are often altered by dredging, coastal construction, salt-water intrusions, and flooding (Galtsoff 1964; St. Amant 1973). The introduction of oil and other hazardous materials into coastal waters poses additional problems of survival for oysters and other shellfish resources. Increased study on the physiology of these estuarine animals points to the growing concern over both environmental alteration and release of potentially toxic materials into the environment. The importance of osmoregulation in estuarine bivalves was first discussed in detail by Krogh (1939). Later work by Hiscock (1953a, 1953b), Lange (1963), Potts and Parry (1963), and Potts (1968) better defined the relationships between molluscs and their respective environments. Pierce (1970) and Bedford and Anderson (1972) studied osmotic concentrations of vari-
TL;DR: The specific activities and subcellular distribution of eleven enzymes were determined in whole body homogenates of the American oyster, Crassostrea virginica, and the activities of lactic dehydrogenase, cytochrome oxidase, and acid phosphatase were inversely proportional to organism weight.
Abstract: 1. 1. The specific activities and subcellular distribution of eleven enzymes were determined in whole body homogenates of the American oyster, Crassostrea virginica . 2. 2. The activities of lactic dehydrogenase, cytochrome oxidase, and acid phosphatase were inversely proportional to organism weight. 3. 3. Seasonal fluctuations were observed for malic dehydrogenase, glutamic oxaloacetic transaminase, glutamic pyruvic transaminase, acetylcholinesterase, alkaline phosphatase and acid phosphatase.
TL;DR: Quantitative and qualitative bacteriological studies were conducted on sea water utilized in laboratory culture of American oyster larvae (Crassostrea virginica) andseudomonas was the dominant genus present in storedSea water, irradiated sea water, and sea water from oyster larval cultures.
Abstract: Quantitative and qualitative bacteriological studies were conducted on sea water utilized in laboratory culture of American oyster larvae (Crassostrea virginica).The generic diversity of bacteria isolated from a laboratory seawater storage tank did not change during a 15-day sampling period, although bacterial numbers increased substantially. The mean number of bacteria in ultraviolet light-irradiated sea water was less than that in nonirradiated sea water, although individual samples varied considerably. Over a 10-day sampling period during which oyster larval cultures were sampled repetitively, bacteria were more numerous at 24 h and 48 h than at 0 h.Pseudomonas was the dominant genus present in stored sea water, irradiated sea water, and sea water from oyster larval cultures.
TL;DR: A field sampling study was conducted in the Chesapeake and Delaware Canal and adjacent waters in order to describe the blue crab population inhabiting the region and also to assess the significance of the Canal as an avenue for recruitment from the Delaware Bay spawning grounds to the upper Chesapeake Bay as mentioned in this paper.
Abstract: In 1971 and 1972, a field sampling study was conducted in the Chesapeake and Delaware Canal and adjacent waters in order to describe the blue crab population inhabiting the region and also to assess the significance of the Canal as an avenue for recruitment from the Delaware Bay spawning grounds to the upper Chesapeake Bay. Field sampling consisted of simultaneous towing of a 25 ft. otter trawl, with tickler chain attached, and a 42 in. wide, lined oyster dredge. The catch of all sizes of crabs was seasonal: in winter and early spring the catch was close to zero; by mid-summer, crabs had re-inhabited the region. Catch densities were higher on the Chesapeake Bay side of the Canal than on the Delaware Bay side, Catch densities in the Canal region were much lower than in Tangier Sound, Md., even though the regions are equidistant from spawning grounds in the Delaware and Chesapeake Bays respectively. The population inhabiting the Canal region during the summer consists mostly of juvenile crabs and is predominated by males. The Canal seems of little significance as an avenue for recruitment of blue crabs to the upper Chesapeake Bay.
01 Mar 1975
TL;DR: Waste motor oil concentrations of 20 ppm and higher induced lesions in the vascular systems of Atlantic silversides and oyster and were associated with the pseudobranch, the hea...
Abstract: Waste motor oil concentrations of 20 ppm and higher induced lesions in the vascular systems of Atlantic silversides and oyster. These lesions were associated with the pseudobranch, the heart, and the arterial system of the Atlantic silversides, and the branchial efferent vein of the oyster. Lesions occurred in the gastro-intestinal tract of oyster, the gill and kidney of scallop, and the mantle of both species. Based on these preliminary exposures, the scallop, of the three species tested, demonstrated the highest sensitivity to the toxic effects of 20 ppm waste motor oil, or higher, for periods up to 60 days. The LC-50 (96 hr) value for waste motor oil and adult Atlantic silversides was 1,7000 ppm. Acute toxicity values were not determined for the oyster or scallop.
TL;DR: The warm temperatures in the discharge canal during this period permitted the oysters to feed during the very large spring phytoplankton bloom, while the control oysters in the ambient temperature remained relatively inactive.
Abstract: 1. 1. The oysters in the heated effluent averaged 56 per cent higher in protein concentration, 109 per cent higher in carbohydrate concentration and 22 per cent higher in condition index than the control oysters during the winter and spring months. The warm temperatures in the discharge canal during this period (14–19°C) permitted the oysters to feed during the very large spring phytoplankton bloom, while the control oysters in the ambient temperature (2–7°C) remained relatively inactive. 2. 2. During the summer months, the control oysters attained levels of protein, carbohydrate and condition index that were similar to those of the warm-water grown oysters. 3. 3. The development of the gonads of the oysters in the heated effluent occurred 4 months earlier than in the controls, but spawning took place only 1 month earlier. 4. 4. The warm-water grown oysters produced thicker shells than the control oysters.
TL;DR: Calculation of the mass action ratio from the amounts of glycolytic intermediates determined suggests that there are at least three limiting enzymes in the gly colytic system in unfertilized and fertilized eggs of each species examined, and phosphorylase, phosphofructokinase, and pyruvate kinase may be rate-limiting enzymes for the Glycolysis system in Urechis eggs as well as in oyster eggs.
TL;DR: Oysters are faecally contaminated, particularly in the summer months when the rain-bearing south-east monsoon flushes out the rivers, streams and watercourses (drains) into the oyster producing areas as discussed by the authors.
01 Mar 1975
TL;DR: In this paper, ultraviolet spectrophotometric and gas chromatographic analyses of tissues revealed significant amounts of oil-derived petroleum hydrocarbons from oysters collected at Morgan's Point Reef at the lower end of the Houston Ship Channel.
Abstract: Field and laboratory studies of petroleum hydrocarbons in the tissues of the American oyster, Crassostrea virginica, a primary shellfish resource in the Galveston Bay system, were conducted from 1971–1974. Initial ultraviolet spectrophotometric and gas chromatographic analyses of tissues revealed significant amounts of oil-derived petroleum hydrocarbons from oysters collected at Morgan's Point Reef at the lower end of the Houston Ship Channel. Lower values, when detectable, were found in oyster meats collected at natural and artificial reefs scattered throughout the lower bay system. Laboratory and field studies were conducted to determine uptake and depuration of petroleum hydrocarbons by oysters. Rapid depuration of petroleum hydrocarbons accumulated in field and experimental exposures was found. In oil-free seawater, oysters released saturated chains and most aromatic fractions rapidly with depuration to below detectable levels (0.1 ppm) taking place within 52 days. Transfer of oysters for dep...
TL;DR: A new gnathostomatid nematode, Echinocephalus crassostreai sp.
TL;DR: The technique developed can be used to study oyster metabolism in the laboratory and indicate that inorganic orthophosphate and radioactive studies indicate that these substrates are metabolized by oysters.
TL;DR: The total reducing substance test for oyster quality was found to give highly reproducible results, and the results returned for pH were also reproducible, but to a lesser degree than was total reducing substances concentration.
Abstract: A new test for oyster quality has been developed. The test procedure measures the group of compounds designated as total reducing substances (TRS). The analysis for TRS is simple and utilizes the quantitative determination of both volatile and non-volatile substances in oysters which are capable of reducing an alkaline solution of potassium permanganate. By virtue of comparisons v?ith other indices of quality, the total reducing substance test appears to offer the most rapid and reliable means of ascertaining oyster quality. The applicability of the total reducing substance test was determined by comparison with existing chemical.indices of quality, namely pH, trimethylamine-nitrogen, total vol atile bases, and indole. Microbiological studies on meso philic and psychrophilic plate counts and organoleptic evaluations were performed in conjunction with the chemical tests during a 15 day iced-storage period. Where applicable determinations were made on both oyster meat and oyster liquor. Statistical analyses were performed on the data from each chemical, microbiological, and organoleptic test to determine if significant changes occurred during the stor age period and to evaluate the reliability of each test procedure. Correlation coefficients were then determined between the various tests, using organoleptic quality as a basis for comparison. The results showed that there were highly significant differences (P<0.01) in total reducing substances, pH, trimethylamine-nitrogen, total volatile bases, psychrophili plate counts, and organoleptic evaluations. In addition, significant changes (P < 0.05) were found to occur in meso philic plate counts. No significant changes were found in the indole content. The total reducing substance test for oyster quality was found to give highly reproducible results. The results returned for pH were also reproducible, but to a lesser degree than was total reducing substance concentration. Trimethylamine-nitrogen, total volatile bases, indole, mesophilic plate counts and psychrophilic plate counts were not found to be reproducible, and their reliability as quality indices for oysters is therefore questionable. Highly significant, positive correlations (P