Showing papers on "Oyster published in 1980"

Effect of particle concentration on filtration efficiency of the bay scallop Argopecten irradians and the oyster Crassostrea virginica

Abstract: Filtration efficiency of the bay scallop Argo Pecten irradians and the oyster Crassostrea virginica was examined in the laboratory using dilute algal suspensions, over a range of concentrations from 0.88 to 10.89 mg wet algal weight. 1-1. Efficiency of retention was measured in flowing seawater for each of 8 size classes of particles (1.73 to 9.97 μm diameter) by comparing number of particles in both inhalent and exhalent water. Algal suspensions were composed of isogravimetric amounts of Dunaliella tertiolecta, lsochrysis galbana, Platymonas suecica, and Thalassiosira pseudonana. In low algal concentrations, A. irradians and C. virginica showed no change in filtration efficiency for particles larger than 7 and 3 μm in diameter, respectively. As algal concentration increased, A. irradians became more efficient in retaining small (2 to 4 μm) particles, due to increased mucus (pseudofecal) production. Conversely, as algal concentration increased, C. virginica periodically became less efficient in r...

Behavior of pathogenic bacteria in the oyster, Crassostrea commercialis, during depuration, re-laying, and storage.

Abstract: Oysters (Crassostrea commercials) harvested from major cultivation areas within the state of New South Wales, Australia, were commonly contaminated with low levels of the food-poisoning organisms Bacillus cereus, Clostridium perfringens, and Vibrio parahaemolyticus. Salmonella was found in oysters on only one occasion. These bacteria were cleansed from oysters during oyster purification by re-laying in a non-polluted waterway. Oysters were laboratory contaminated to levels in excess 1,000 cells per g with either B. cereus, C. perfringens, V. parahaemolyticus, Salmonella typhimurium, or S. senftenberg. These species were cleansed from such oysters during purification in a laboratory depuration unit that used ultraviolet light for sterilizing the depuration water. Escherichia coli was also cleansed from oysters under the same re-laying or depuration conditions so that its measurement alone could be used to indicate the cleansing of the above pathogenic species. The levels of these bacteria were also measured during the storage of oysters under conditions that occur during marketing. While B. cereus counts remained relatively stable during storage, the Salmonella spp. gradually decreased in numbers and C. perfringens rapidly died off. V. parahaemolyticus counts increased slightly during the first 4 days of storage, after which decreases occurred.

The fatty acid composition of three unicellular algal species used as food sources for larvae of the American oyster (Crassostrea virginica)

Abstract: The total lipid and fatty acid content of 3 algal species,Pyramimonas virginica, Pseudoisochrysis paradoxa andChlorella sp., which have been successful as food sources for rearing larvae of the American oyster,Crassostrea virginica, was determined. Of the fatty acids of ω6 and ω3 families which have been shown to be essential fatty acids for normal growth in many animals, only the ω6 fatty acids were found to be higher in these 3 species of algae than in the traditional oyster larvae diet which consists of the algaeMonochrysis lutheri andIsochrysis galbana. The major fatty acid constituents of the total lipids of the 3 species were the C12, C14, C16 and C18 saturated fatty acids and the C16 and C18 mono- and polyunsaturated acids. These components constituted 70–93% of the total lipid in cultures of all ages. There were modest amounts of C20 and C22 polyunsaturated acids; some of these existed only in trace amounts. InP. virginica andChlorella sp., hexadecanoic acid was dominant (23–39%). The presence of large quantities of tetradecanoic acid (22–26%) and oleic acid (17–21%) was characteristic ofP. paradoxa. Chlorella sp. had the highest proportion of octadecatrienoic acid (18∶3ω3) which accounted for up to 17% of the total lipids. γ-Linolenic acid (18∶3ω6) was found only inChlorella sp., but in the 5th-day culture only. The lowest proportion of total polyethylenic acid was inP. paradoxa; however, lipid analyses showed this alga had the most lipid/individual cell. Some variations were observed in the fatty acid composition with age of the culture.

Comparative descriptions of some oyster larvae from New Zealand and Chile, and a description of a new genus of oyster, Tiostrea

Abstract: Detailed comparisons of the larvae of four species of New Zealand oyster (Saccostrea glomer‐ata, Crassostrea gigas, Ostrea lutaria, and a new species of Ostrea) and one Chilean oyster (Ostrea chilensis) showed that larvae of species other than O. lutaria and O. chilensis share certain features. One conspicuous feature is a distinct tract, termed here the posterior dorsal sulcus, which runs from the posterior margin of prodissoconch I to the valve margin of prodissoconch II; other characteristic features are an umbonate, inequivalve shell and a provinculum bearing distinct teeth. The larvae of O. lutaria and O. chilensis, in contrast, lack the posterior dorsal sulcus, are nonumbonate, and have nearly equal valves with an edentulous provinculum. These distinctive features, together with other adult features, suggest that the two species are more appropriately included in a separate genus. The name Tiostrea is proposed for the new genus. Certain supraspecific groupings within the Ostreinae need to be re‐exam...

Sterols of the oyster, Crassostrea virginica.

Abstract: A commericial sample of the oyster,Crassostrea virginica, obtained from Maryland waters of the Chesapeake Bay, contained 31 desmethylesterols and at least eight 4-monomethylsterols. The combined gas liquid chromatography-mass spectra of the minor components showed the presence of 6 unusual sterols, 24-ethylcholest-22-en-3β ol, 4α-methyl-24-ethylcholestan-3β-ol, occelasterol, (24E)-24-propylidene-cholest-5-en-3β-ol, (24ZO-24-propylidene-cholest-5-en-3β-ol, and 24-methylene-cholestanol. The C-24 configuration of 24-ethylcholest-5-enol, 24-methyl-cholesta-5,22-dienol, and 24-ethylcholesta-5,22 dienol were elucidated by 220 MHz nuclear magnetic resonance spectrometry.

Distribution of neutral lipids in the tissues of the oysterCrassostrea virginica

Abstract: The content of neutral lipids was determined in the tissues of oysters (Crassostrea virginica Gmelin) collected in June, July and March. The lipid content of starved March oysters was also determined. Oyster tissue from the June harvest contained the highest quantities of triglyceride; starved and July (late spawning) oysters had decreased levels of triglycerides in all tissues except the digestive diverticula/gonad. Free sterol content of all the tissues averaged 1.21 mg equivalent cholesterol/g wet weight tissue, and the steryl ester concentration averaged about 10% of this value. Findings of this investigation indicate that the triglyceride content of oyster tissue fluctuates seasonally and is there-fore keyed to the physiological state of the animal. Furthermore, triglycerides may be an important energy reserve for reproductive tissue.

Experimental pathogenicity of reovirus 13p2 for juvenile American oysters Crassostrea virginica (Gmelin) and bluegill fingerlings Lepomis macrochirus (Rafinesque)

Abstract: . A viral agent (13p2), isolated from clinically normal juvenile American oysters (Crassostrea virginica) and characterized as a new serotype of reovirus, was tested to determine if it could replicate and produce disease in experimental juvenile oysters. Because the virus replicated well in the bluegill fry (BF-2) fish cell line, fingerling bluegills Lepomis macrochirus were included in the pathogenicity experiments. Exposure of oysters to the 13p2 virus in ambient seawater resulted in no significant mortality and no increased virus titres or histological lesions. Virus particles were not observed in tissues of exposed oysters when examined with transmission electron microscopy (TEM). Intraperitoneal inoculation of the 13p2 virus into bluegills resulted in 44% mortality associated with a focal necrotic hepatitis. Evidence of virus replication, when evaluated histological or by virus titration, was observed in 94% of 32 inoculated fish. Samples of infected livers examined with TEM revealed typical cytoplasmic arrays of 13p2 virus particles in affected hepatocytes. Rising virus titres and hepatic lesions also occurred in bluegills exposed to water containing the 13p2 virus. These results indicated the natural host of the 13p2 virus was not the American oyster, but that it was a significant pathogen for at least one fish species.

Range extensions of teredinids (shipworms) and polychaetes in the vicinity of a temperate-zone nuclear generating station

Abstract: A study of marine boring and fouling organisms in the vicinity of the thermal effluent from the Oyster Creek Nuclear Generating Station, Barnegat Bay, New Jersey, USA has been conducted since 1971. Two subtropical species of shipworms have been found in significant numbers in the effluent. These are Teredo bartschi Clapp and Teredo furcifera von Martens. The shipworm Lyrodus sp. and the flatworm Taenioplana teredini Hyman, which is predatory on teredinids, were also found, but on only one occasion. The polychaete Ficopomatus enigmaticus (Fauvel) has been found for the first time on the Atlantic Coast of North America. Three other polychaetes, Potamilla (Potamethus) spathiferus (Ehlers), Loimia medusa (Savigny), and Sphaerosyllis sp., have been newly identified from Barnegat Bay, but probably are not recent range extensions. Only T. bartschi, T. furcifera, and F. enigmaticus have established breeding populations. Their distributions and abundances are probably related to the thermal effluent; this is most clear in the case of T. bartschi and least clear in the case of F. enigmaticus. T. bartschi was confined at first to the heated effluent in Oyster Creek, but has spread to Forked River. It has become a major faunal element in Oyster Creek. The impact of the other exotic species has been negligible. The primary mechanism of the range extensions is by boat transport.

Studies on paralytic shellfish poison from the oyster cultured in Senzaki Bay, Yamaguchi prefecture.

Abstract: Attempts were made to search the cause of food poisoning in which 16 persons developed numbness in the mouth by ingestion the oyster Crassostrea gigas from Senzaki Bay, Yamaguchi Prefecture. The midgut glands of the oyster collected from Senzaki Bay, soon after the poisoning (mid-Jan., 1979) were extracted with acidified 80% ethanol. The extract was defatted three times with chloroform, treated with activated charcoal, and then purified by chromatography on Bio-Gel P-2 and Bio-Rex 70. The toxic fractions obtained were analyzed by cellulose acetate strip electrophoresis and thin layer chromatography on silica gel . The results showed that the fractions contained gonyautoxins-1, 2, 3, and 5, together with saxitoxin and neosaxitoxin. It was concluded from these results that the poisoning was caused by the paralytic shellfish poison which had accumulated in the oyster.

The Darwin outbreak of oyster-associated viral gastroenteritis.

Abstract: Approximately 60 persons attended a Christmas dinner, at a Darwin hotel, where oysters were served au natural as part of the menu. Twenty-five of the 28 persons who ate oysters developed symptoms of food poisoning--an attack rate of 89%. Of the 60 persons attending the dinner 44 were investigated. The incubation period and duration of illness were about 36 hours. Diarrhoea occurred in 100% of patients, with colic and nausea in 88% and 80% respectively. Half the patients complained of vomiting and headache. The storage temperature at which the oysters were kept was satisfactory and no bacterial pathogens were grown from the oyster and stool specimens. Electron microscopy revealed two distinct parvovirus-like particles in stool specimens, one of which was identified as Norwalk virus. Serological studies by immune electron microscopy showed the development of antibodies to the Norwalk-like particle by seven out of 10 patients. Confirmatory studies by radioimmunoassay showed a significant rise in antibody titre to Norwalk virus in seven patients.

Some ecological aspects of the edible oyster Crassostrea cucullata (born) occurring in association with mangroves in negombo lagoon, Sri Lanka

Abstract: Ecology of an oyster population (Crassostrea cucullata (Born)), associated with the roots of Rhizophora micronata Link, on an islet in the Negombo lagoon on the west coast of Sri Lanka, was studied. The associated fauna was described.

Functional morphology of the coelomocytes of the larval oysters (Crassostrea virginica and Crassostrea gigas)

Abstract: The functional morphology of the coelomocytes of larval oysters, Crassostrea virginica and C. gigas, based on observations of live animals and histological and ultrastructural examination of tissues, is presented. Two predominant types of coelomocytes were found in the larval oysters. One, the SER cell, not found in the adult oyster, is large with a spheroidal nucleus, and exhibits basophilic cytoplasm which consists of abundant smooth endoplastic reticulum. This cell appears to participate in metabolic conversion processes. The other predominant cell type, the phagocyte, appears identical to the phagocyte observed in the adult oyster. Both differential cell types were observed from one day post fertilization to metamorphosis, the oldest stage studied.

Determination of benzo(a)pyrene, hexachlorobenzene and pentachlorophenol in oysters from Galveston Bay, Texas.

Abstract: Intensive development of industrial plants located along the Houston Ship Channel is a major potential source of refractory organic contaminants to the Galveston Bay estuarine system. Petroleum production and shipping also contribute extensively to the pollutant load of the Bay. For example, previous workers have reported that oyster samples collected at the lower end of the Houston Ship Channel, particularly Morgan's Point, consistently revealed high levels (130 to 240 ppM) of petroleum hydrocarbons. As bivalves have been suggested as potentially valuable sentinel organisms for indicating levels of pollutants in coastal marine waters, this study was undertaken to analyze oysters from Galveston Bay for selected pollutants. Three compounds, each representing a particular class of organic pollutant, were selected for determination in oysters (Crassostrea virginica) collected near Morgan's Point. These were benzo(a)pyrene (polycyclic aromatic hydrocarbon), hexachlorobenzene (polycholoroaromatic hydrocarbon), and pentachlorophenol (chlorinated phenol). These compounds were selected because of their large annual production, patterns of use and disposal which favor their entry into the oceans, high toxicity, and persistence in the environment.

Distribution and Seasonality of Macroalgae on Oyster Communities of Central Chesapeake Bay

Abstract: Abstract Field studies of the benthic macroalgae of fifteen selected Chesapeake Bay oyster communities were conducted over a period of a year (March 1977 to February 1978). Algal distribu tion and seasonal occurrence were studied in relation to changes in the physical environment. Salinity, temperature, and light availability were important factors in the spatial and temporal distributions of algae in these subtidal habitats. Seventeen species of Chlorophyta, Phaeophyta, and Rhodophyta were recorded from the fifteen study sites distributed over 130 kilometers within the Maryland portion of Chesapeake Bay. Species of Chlorophyta were associated with oyster communities throughout the year of study with maximum numbers of species and maximum biomass occurring in spring. Only once was a member of the Phaeophyta encountered; a single filamentous species, Ectocarpus, was collected during winter. Species of Rhodophyta were present throughout the year at the study sites. Most of the algae collected reproduced asexually by spores and/or vegetative fragments. Sexual reproduction occurred in some of the red algal species. The presence of tetrasporic and cystocarpic plants of Dasya baillouviana and Polysiphonia harveyi var. olneyi may indicate that the usual triphasic Florideophycean life history occurs in this estuary.

Effects of Chlorine-Produced Oxidants on Survival of Larvae of the Oyster Crossostrea virginica

Abstract: Effects of chlorination on two larval stages of the oyster Crassostrea virginica (Gmelin, 1790), were studied in flowing estuarine water. Straight-hinge veliger larvae were exposed to concentrations of 0.01, 0.05, 0.1 and 0.2 ppm chlorineproduced oxidants (CPO) for 6, 12,24 and 36 h, and to 0.05, 0.1,0.2 and 0.3 ppm CPO for 8, 24, 48,72 and 96 h. Setting pediveliger larvae were exposed to 0.05, 0.1,0.2 and 0.3 ppm CPO for 6, 24, 48, 72 and 96 h in two experimental trials. Mortality of straighthinge and pediveliger larvae was directly related to increased concentrations of CPO and extended exposure tlme. Pediveliger larvae were generally more resistant to CPO than straight-hinge larvae, especially with longer exposure time. Equations for predicting mortality under different conditions of time and CPO concentration were developed using these data.