Showing papers on "Oyster published in 1984"
TL;DR: Oyster reefs are dense concentrations of filter-feeding animals in estuarine ecosystems and a flow-through plastic tunnel is a feasible method of determining significant changes in material concentrations in tidal waters passing over an oyster reef.
222 citations
TL;DR: Analysis of the oyster fatty acids showed that oysters were able to incorporate some of the dietary14C label into long-chain fatty acids not supplied in the diet, e.g., C20 and C22 mono- and polyunsaturated fatty acids, and particularly 20∶5ω3.
Abstract: Tetraselmis suecica andDunaliella tertiolecta were grown for 24 hr in the presence of14C sodium bicarbonate and then fed separately to batches of juvenile oysters,Crassostrea gigas, for 3 days.D. tertiolecta contained fatty acids no longer than C18; 22∶6ω3 was absent inT. suecica. Analysis of the oyster fatty acids by radio gas chromatography (GC) showed that oysters were able to incorporate some of the dietary14C label into long-chain fatty acids not supplied in the diet, e.g., C20 and C22 mono- and polyunsaturated fatty acids, and particularly 20∶5ω3. However, the low14C incorporation into fatty acids longer or more unsaturated than those supplied in the diet suggests that elongation and desaturation activity in young oysters is not sufficient to sustain optimum growth.
158 citations
TL;DR: Sediment preferences of blue crabs, Callinectes sapidus Rathbun, and predation rates on various size classes of the hard clam, Mercenaria mercenaria (Linne), in a variety of sediment types were studied in the laboratory.
121 citations
TL;DR: Hatchery techniques were developed for introduced species of edible bivalves, Saccostrea echinata and Perna viridis, and cultivation methods were developed in specially fitted-up areas to supply the pearl-oyster farming industry, and to address the problems of depleted natural stock.
93 citations
TL;DR: The results are supported by the determination of the trace metal levels in the dissolved state and in the suspended material in the ambient sea water of the bivalves.
Abstract: Trace metal concentrations (Zn, Cd, Pb and Cu) were studied in two different bivalve species of the same age, the mussel Mytilus galloprovincialis, Lmk., and the oyster Ostrea edulis, Linnaeus, which had been grown in the water of Lim Fjord, North West Yugoslavia (Peninsula Istria), i.e. under the same physicochemical conditions. The study offers a realistic view on the metal accumulation ability of oysters and mussels. The distribution of trace metals over the different organs and the edible parts of the mussels and oysters, collected in June 1979, was determined and is discussed in detail. The results are supported by the determination of the trace metal levels in the dissolved state and in the suspended material in the ambient sea water of the bivalves. Concentration factors for zinc, cadmium, lead and copper in the mussels of: 95 000, 9 100, 1 500 and 4 000; and in the oysters of: 95 500, 30 400, 3 400 and 64 500 were found, respectively. The values were evaluated comparing the metal concentration in the bivalve soft part and the dissolved trace metal levels in the adjacent water.
92 citations
TL;DR: The structure of the benthic community of the Oyster Ground was investigated by studying 107 box cores and 97 incubation bottles, which defined the area as a rich Amphiura community, with spatangids, Chaetopterus, callianassids, Arctica and amphiuroids as most dominant taxa.
67 citations
TL;DR: Food costs of culturing juvenile oysters could be reduced by 56% using a 50% algal ration supplemented with yeast, rice starch and kaolinite instead of using a 100% ration of algae alone.
66 citations
TL;DR: The results indicate that small numbers of potentially pathogenic vibrios are frequently a part of the microflora of purified oysters, and usually at lower levels in purified than in unpurified oysters.
60 citations
57 citations
TL;DR: The main obstacle to its further development is the insidious build up of pollutants in vital areas, such as Hiroshima Bay and the Seto inland sea in general, and the seeming reluctance of the cooperatives to accept maximum production thresholds with the dire consequences of ignoring such advice.
Abstract: Publisher Summary The actual culture of oysters probably dates back to the beginning of the seventeenth century (early Tokugawa period), when it is recorded that oyster spat settling on stones and bamboo poles of fish traps were replanted in the intertidal zone surrounded by bamboo fences to keep predators out, which in turn acted as the collectors of oyster spat All records indicate that oyster culture began in Hiroshima Prefecture where Hiroshima Bay provided ideal sheltered conditions with a wide mud free shoreline exposed by an average 25 m tide, and near the ready market of the city of Japan's new thriving merchant class, Osaka Nowadays in Japan the culture of oysters is based on intensive off-the-bottom methods of three types (1) Rack culture (2) Raft culture and (3) Long-line culture The present industry in its steady production state, averaging over 200,000 tonnes in shell weight and 34,000 tonnes of meat per year from 1962, is an example of efficient utilization of a natural resource The main obstacle to its further development is the insidious build up of pollutants (organic/inorganic) in vital areas, such as Hiroshima Bay and the Seto inland sea in general, and the seeming reluctance of the cooperatives to accept maximum production thresholds with the dire consequences of ignoring such advice
54 citations
TL;DR: Results of laboratory feeding experiments suggest that oyster (Crassostrea virginica) larvae select small phytoplanktonic organisms (<10 μm) over larger-celled forms from natural estuarine assemblages, but that little selection occurs within the small phytochemical fraction.
Abstract: Results of laboratory feeding experiments suggest that oyster (Crassostrea virginica) larvae select small phytoplanktonic organisms (<10 μm) over larger-celled forms from natural estuarine assemblages, but that little selection occurs within the small phytoplankton fraction. Laboratory-reared larvae grazed each of five small-celled phytoplankton groups enumerated (coccoids, centrate diatoms, pennate diatoms, dinoflagellates, and flagellates) at rates proportional to phytoplankton group densities in controls (no larvae added). Larval grazing rates (number of cells removed per larva per hour) were inversely proportional to both larval density and experimental duration.
TL;DR: The gamotogenic cycle of the Suminoe oyster was compared with that of two groups of Pacific oysters on an intertidal oyster bed in Oakland Bay, Washington, and C. rivularis did not spawn but, rather, initiated phagocytosis of gametes by leucocytes.
TL;DR: On determine en laboratoire les taux de filtration, ingestion, assimilation, excretion and respiration d'O.c. en vue d'etablir le budget energetique en fonction of the taille and of de two concentrations of l'aliment (algue).
Abstract: On determine en laboratoire les taux de filtration, ingestion, assimilation, excretion et respiration d'O.c. en vue d'etablir le budget energetique en fonction de la taille et de deux concentrations de l'aliment (algue)
01 Jan 1984
TL;DR: Experimental evidence suggested that reduced variation in oyster growth was due to an indirect effect of the antibiotics on the qualitative composition of bacterial populations present in the oyster cultures.
TL;DR: Tissues of oysters and clams showed a significant increase in buffering capacity when tissues were isolated from animals held under anoxic conditions compared with control aerobic animals; however, no consistent effect of environmental anoxia was found, nor wasbuffering capacity related to the tissue levels of succinate accumulated during anaerobiosis.
Abstract: Buffering capacities (β) (measured in slykes = micromoles of base required to titrate the pH of 1 g wet weight of tissue by one pH unit between pH 6 and pH 7) due to nonbicarbonate buffers were measured for the tissues of three marine molluscs, the oyster, Crassostrea virginica, the cherrystone clam, Mercenaria mercenaria, and the channeled whelk, Busycotypus canaliculatum. In general β was higher in muscle tissues (adductors, foot, heart, radular retractor) than in the gill and mantle, but hepatopancreas of the whelk had a β two- to threefold higher than that of any other whelk tissue. Selected tissues (gill of oyster, catch adductor of clam, heart and hepatopancreas of whelk) showed a significant increase in buffering capacity when tissues were isolated from animals held under anoxic conditions compared with control aerobic animals; however, no consistent effect of environmental anoxia was found, nor was buffering capacity related to the tissue levels of succinate accumulated during anaerobiosis. Tissue...
TL;DR: Experiments confirmed the absence of food selectivity in P. margaritifera and found that Coscinodiscus sp.
Abstract: Plankton samples and gut contents of P. margaritifera were analysed monthly from April 1972 to March 1973. Coscinodiscus sp. was the most ingested food by pearl oysters of all ages. However, food variety increased as the oyster grew older. Experiments confirmed the absence of food selectivity in P. margaritifera. Unlike the young ones, the adult showed reduced growth during summer (July–September), which coincides with its spawning season.
TL;DR: The reduction in growth rate of parasitized oysters, the snaiľs propensity towards parasitizing small oysters and the snail's tendency to be contagiously distributed suggests that B. impressa potentially exerts a significant influence on the population structure and health of oyster populations.
Abstract: . Boonea (= Odostomia) impressa is a common ectoparasite of oysters. In the laboratory, small oysters (Crassostrea virginica) parasitized by natural densities of B. impressa produced 75 % less new shell than unparasitized oysters. Shell deposition rates of previously parasitized oysters increased significantly after all B. impressa were removed. Thus, the decrease in growth rate, although significant, apparently was not permanent. B. impressa preferentially parasitized small, living oysters (≤2.5cm) in the field, even though a higher percentage of large, living oysters (>2.5cm) was available. The snails maintained an aggregated distribution on the oyster reef. The number of B. impressa per oyster clump was positively correlated with the number of living oysters per clump, however some clumps with few or no living oysters had many B. impressa. Thus, food availability only partially explained the pattern of distribution. B. impressa was very mobile. About 50 % of the population moved in one week. Reproduction occurred throughout the year with a peak period in May. Recruitment was greatest in July, however new recruits were observed throughout the year. The reduction in growth rate of parasitized oysters, the snaiľs propensity towards parasitizing small oysters and the snail's tendency to be contagiously distributed suggests that B. impressa potentially exerts a significant influence on the population structure and health of oyster populations.
TL;DR: There was very little difference between the retention by mice that ingested organic (oyster bound) Cd and those fed inorganic Cd (CdCl2), but when the Cd retained in the intestine was excluded, retention of organic Cd was significantly greater than that of in Organic Cd.
TL;DR: The metal levels were sufficiently low that the molluscs could be consumed without any danger to health and the salinity of the water appeared to influence the uptake as higher levels of metals were found during the flood season when salinity was lower.
Abstract: This investigation was carried out as part of Thailand's participation in the global ‘Mussel Watch’ program. The levels of Cd, Cr, Cu, Pb, and Zn in the green mussel, Perna viridis, oyster, Crassostrea commercialis, and the cockle, Anadara granosa, were studied from July 1982 to November 1982. Comparison was made with the previous study in August 1981 which also included the short necked clam, Paphia undulata and moon scallop, Amusium pleuronectes. It was found that the metal levels were sufficiently low that the molluscs could be consumed without any danger to health. The salinity of the water appeared to influence the uptake as higher levels of metals were found during the flood season when salinity was lower.
TL;DR: Bth filtrate of a Vibrio species, isolated from spontaneously occurring epizootics among cultured oyster larvae, Crassostrea virginica (Gmelin), was shown to contain an exotoxin, which was heat-labile and exposure to heat-produced toxoid had a beneficial effect on oyster embryonic development.
Abstract: . Broth filtrate of a Vibrio species, isolated from spontaneously occurring epizootics among cultured oyster larvae, Crassostrea virginica (Gmelin), was shown to contain an exotoxin. Bioassays demonstrated that LC50 value was less than 46.6 μg of toxin/l culture of oyster embryos. This quantity was produced by 2.9 × 109 colony-forming units. Purified toxin showed neither proteolytic nor amylase activity; it did, however, demonstrate bacteriostatic capability. Studies showed that the toxin was heat-labile and that exposure to heat-produced toxoid had a beneficial effect on oyster embryonic development. Data revealed that although toxin was inactivated by heating, the bacteriostatic capability of the metabolite was not lost. Molecular weight of the toxin was estimated to be 68000.
01 Oct 1984
TL;DR: In the Kakinada Bay several species of bivalves and gastropods are regularly fished and the annual production has been estimated to be about 6,000 t.
Abstract: In the Kakinada Bay several species of bivalves and gastropods are regularly fished and the annual production has been estimated to be about 6,000 t. Among them the window-pane oyster Placenta placenta (Linnaeus) and the blood-clam Anadara granosa (Linnaeus) are of particular interest. With these objectives a survey of the Kakinada Bay was conducted in March- April 1983. Environmental data which may have bearing on the distribution and abundance of the molluscs were also collected. In the present study A. granosa and P. placenta were generally abundant in areas where more than 50% of the sediment particles were 0.125 mm). The present study indicates considerably wider area and also overlapping in the distribution of these two species.
TL;DR: The effects of physiological and nutritional factors and of temperature on the uptake of L-methionine by Saccostrea commercialis were investigated on cultured rock oysters from Port Stephens, New South Wales, Australia, in 1983.
Abstract: The effects of physiological and nutritional factors and of temperature on the uptake of L-methionine by Saccostrea commercialis were investigated on cultured rock oysters from Port Stephens, New South Wales, Australia, in 1983. Optimum conditions for L-methionine accumulation were 30°C, 18 h exposure and concentrations of other amino acids less than that of L-methionine. The uptake of L-glycine was inhibited by L-methionine in a reciprocal manner. There was no effect of salinity on the accumulation of L-methionine by acclimated oysters. During the latter investigations the range of osmoconformity was found to be 15 to 45‰ S. Oysters take 2 d to conform to new media osmolarities after salinity changes of 15‰. Amino acid supplements in oyster diets should be kept within the same order of magnitude to reduce inhibition of uptake.
TL;DR: Brood stock of the large tropical intertidal oysters S. c.
Abstract: Brood stock of the large tropical intertidal oysters S. c. tuberculata and C. echinata introduced to Guam in 1978 and 1979, respectively, were kept in 1-m2 cages in Sasa Bay and their growth and reproductive condition monitored. Weight of tagged S. c. tuberculata increased by 25.4% in 255 days; weight of tagged C. echinata at an inner bay site increased by 137.7% in 660 days and at a site near the mouth of the bay by 50.6% in 453 days. Based on a mean wet flesh weight of 6.5% of total weight, optimum growth rates for adult C. echinata at a density of 50 oysters per square metre, and a ratio of oyster-tray area to water area of 2/3, an estimated potential yield of 2445-3260 kg flesh weight ha-' year-l could be produced in Sasa Bay. Fouling by the smaller indigenous oyster S. cucullata was considerable (mean number of S. cucullata per C. echinata shell, 34), but growth was highest in areas where fouling was highest. Therefore, it appeared that competition for food was not a problem. Histological examination revealed one complete (plus partial second) gametogenic cycle during 1980. The major peak in spawning activity was in March and the development of another was evident in late November. Environmental parameters (exogenous factors) that were monitored did not act as cues for spawning.
TL;DR: A deterministic model of the growth in the sea of Ostrea edulis and Crassostrea gigas has been developed from published information in which oyster size and seawater temperature are treated as determinants of instantaneous growth rate.
TL;DR: The Mexican Pacific coastline is 7,165 km long and has 932,365 ha (2.3 million acres) of coastal logoons and estuaries which support many populations of commercially important molluscs, but only 29 of the 67 identified species are intensively exploited along their whole distribution range.
TL;DR: In a comparison of fattening procedures, oysters held in a fertilised pond and those fed a second artificial diet fattened in 4 and 6 weeks respectively, whereas those held in an estuary did not fatten at all.
TL;DR: The variety of serotypes isolated, coupled with consistent recoveries throughout the year, suggests that salmonellae may represent a portion of the natural background flora in these seafoods rather than recent single source contamination.
TL;DR: Four polymorphic loci in seven natural oyster populations of the Chesapeake Bay were analyzed by protein-gel electrophoresis for genetic variation and frequency of one genotype was significantly correlated with mean temperature over the water monitoring period (1972–1977).
Abstract: Four polymorphic loci in seven natural oyster (Crassostrea virginica Gmelin) populations of the Chesapeake Bay were analyzed by protein-gel electrophoresis for genetic variation. Samples of about 100 each were taken in 1977 along environmental gradients from stations in the James and Potomac rivers. The distribution of genotypes at four loci for each of the stations was nog significantly different from Hardy-Weinberg expectations. At two loci (Pgi andLap-2), a pool of all seven stations was also in equilibrium. Significant genetic differentiation between rivers was detected for two other loci (Pgm-1 andLap-1), and frequency of one genotype (Lap-1 95/95) was significantly correlated with mean temperature over the water monitoring period (1972–1977).
TL;DR: The economic impact of paralytic shellfish poisoning is reviewed, the factors that increase the impact beyond the normal response, and requirements necessary to lessen the impact on the oyster industry are reviewed.