Showing papers on "Oyster published in 1985"

Bacteria in bivalve shellfish with special reference to the oyster.

Abstract: Kueh, C.S.W. & Chan, K-Y. 1985. Bacteria in bivalve shellfish with special reference to the oyster. Journal of Applied Bacteriology, 59, 41–47. The bacterial flora of the Pacific oyster Crassostrea gigas, the sea mussel Perna viridis and the arkshell clam Scapharca cornea differed considerably from that of seawater in both numbers and generic composition. The numbers of heterotrophic bacteria in the bivalve shellfish, including the anaerobes and spore-forming bacteria, were greater than that in the surrounding water. Pseudomonas spp. were the dominant organisms, comprising over one third of the 321 strains characterized after isolation from the bivalves and seawater. Other bacteria isolated from the shellfish included Vibrio, Acinetobacter, and Aeromonas spp., whereas the seawater flora consisted mainly of coliform organisms, coryneform bacteria and Flavobacterium/ Cytophaga spp. Bacteria associated with the deposit-feeding clams were higher in density and more distinct in generic composition as compared with those in the suspension-feeding oysters and mussels. Over 90% of the coliform and heterotrophic bacteria in oysters were found in organs associated with the digestive tract. Coliforms were mainly found in the stomach while heterotrophs were present in both stomach and the lower intestine. The results suggest that the stomach flora of oysters are mainly derived from the external environment and, through a process of selection and multiplication, that it may be gradually replaced by a more indigenous population which dominates the lower digestive tract.

Characterization of a Marine Bacterium Associated with Crassostrea virginica (the Eastern Oyster)

Abstract: A gram-negative bacterium found to be closely associated with oysters has been isolated and characterized. The organism, designated LST, has a generation time of 106 min in Marine broth under optimal growth conditions at 25 degrees C. During the decline phase of growth, it exhibits a morphological transition from a motile rod (ca. 1 mum in length) to an elongated, 3- to 40-mum, nonmotile, tightly coiled helix. LST synthesizes and releases a pigment in the stationary and decline phases of growth. Identified as melanin on the basis of chemical properties and UV absorbance maxima, the pigment comprises polymers of heterogeneous molecular weights, ranging from 12,000 to 120,000. The guanosine-plus-cytosine content of the LST DNA is 46%, and results of phenetic analysis and DNA-DNA hybridization indicate that this bacterium represents a new species. LST adheres to a variety of surfaces, including glass, plastics, and oyster shell, and has been shown to promote the settlement of oyster larvae.

Use of RNA:DNA ratios as an indicator of nutritional stress in the American oyster Crassostrea virginica

Abstract: Hatchery spawned oysters approximately 1% yr old were subjected to starvation stress by exposing them to 1 wm filtered seawater over an 8 wk period. Control (fed) oysters were exposed to unfiltered flowing seawater. RNA:DNA ratios in mantle tissue from fed and starved oysters were monitored throughout, together with shell length, width, height, whole specimen displacement and shell displacement. Wet welght was estimated from whole weight determinations made before and at the end of the experiment. From Day -4 (before the start of the experiment) to Day 52, there was a 32 % increase in mean weight of fed animals and a 12.6 % loss in wet weight of starved animals. Rate of wet weight growth was significantly less in starved oysters than in fed oysters after Day 3. Shell height increased in fed oysters, but remained more constant in starved specimens. Shell lengths were significantly different from Day 42. Condition index, defined as ratio of wet tissue weight to cavity volume, decreased rapidly in starved oysters and became significantly less than in fed oysters. Two sample t-tests between treatments showed that there was a significant difference in RNA:DNA ratio between treatments on all sampling days except Day 0. By Day 55, starved oysters had 36.5 % lower ratios than fed oysters. Over the 55 day experimental period the RNA:DNA ratio correlated highly with cond~tion index, but was lower in response to starvation than in reported studies on vertebrates.

Uptake and clearance of Vibrio vulnificus from Gulf coast oysters (Crassostrea virginica).

Abstract: Oysters collected in late winter, when they were free of Vibrio vulnificus, were exposed in the organism in the laboratory. The oysters effectively concentrated the bacteria from seawater, but when the inoculum was removed, the bacteria were rapidly cleared from the oyster tissues. These results suggest that V. vulnificus may be found in oysters as a result of filtration of the bacteria from seawater rather than active multiplication of the bacteria in the oysters.

Setting of the American oyster Crassostrea virginica in the James River, Virginia, USA: temporal and spatial distribution *

Abstract: Setting of larvae of the oyster Crassostrea virginica was monitored in the James River, Virginia, USA from 1963 to 1980. Setting patterns were similar in two ways to those described prior to 1960 (before the onset of the oyster pathogen Haplosporidium nelsoni (MSX) in Chesapeake Bay): (1) setting intensity (average number of spat per shell) was greater at stations in the lower than upper estuary, and (2) on the average, 60 to 80% of the total annual set at each station occurred during a 6-week period from mid-August through September. However, annual setting intensity from 1963–1980 was lower than previously recorded, and annual sets occurred as a series of discrete pulses rather than continuously throughout the season. Pulses were each approximately 1 to 2 weeks in duration and separated by a period of diminished or no setting. Cross-correlation analysis of annual setting patterns among stations revealed three zones in the James River: the upper estuary and entire southwest side, the lower estuary, and a mid-estuary transition zone. Setting pulses tended to be synchronous at stations within each zone, but occurred 1 to 2 weeks later at stations in downriver than in upriver zones. The location of zones is related to known aspects of water circulation in the James River estuary. Moreover, pulse setting itself may be related to the absence of strong vertical salinity gradients accompanying the fortnightly stratification-destratification process.

Feeding By Oyster Larvae: The Functional Response, Energy Budget and A Comparison With Mussel Larvae

Abstract: Whereas there is a wealth of literature on the feeding of herbivorous holo-plankton, notably copepods, feeding by herbivorous larvae of benthic animals has been somewhat neglected. This paper considers the functional feeding response of veliger larvae of Ostrea edulis L., Crassostrea gigas (Thunberg) and Mytilus edulis L. fed on several micro-algal species. It also provides some data on the influence of temperature on feeding, and assesses the energy needs of the larvae in relation to their potential ingestion rate and to the availability in the sea of micro-organisms on which they feed.

Synoptic Review of the Literature on the Southern Oyster Drill Thais haemastoma floridana

Abstract: This literature search identifies a majority of the publications in the period 1880-1980 concerned with the marine gastropod, Thais haemastomafloridmul (Conrad). The southern oyster drill is an economically important oyster predator in the western Atlantic and Gulf of Mexico littoral. Major contributions of each paper to our knowledge of the drill's biology are briefly categorized. Hitherto unpublished research by the author on the snail's biology is documented. (PDF file contains 15 pages.)

The Benthic Macrofauna Associated with the Oyster Reefs of the James River Estuary, Virginia, U.S.A.†‡

Abstract: Productive, natural oyster reefs within the James River estuary, were quantitatively sampled for associated macrofauna for a year. The 192 samples yielded 142 taxa. Mean faunal density on these reefs ranged from 5,757 to 57,857 m−2. Over 770/0 of the individuals collected belonged to 11 taxa. The number of species and informational diversity (H') decreased up the estuarine gradient. The quality of available shell surface was deemed important in determining density. The spatial heterogeneity provided by the shell surface allowed development of a densely populated, diverse faunal assemblage which differs from soft-bottom assemblages principally in quantitative aspects. The assemblage is not spatially or temporally homogeneous and undergoes significant changes in community structure both seasonally and along the estuarine gradient.

Variation in tissue burdens of polycyclic aromatic hydrocarbons in indigenous and relocated oysters

Abstract: Levels of polycyclic aromatic hydrocarbons (PAHs) were determined by gas chromatography in indigenous oysters (Crassostrea virginica) from three rivers in the southern Chesapeake Bay. Accumulation and depuration rates of PAHs in oysters were measured in situ by relocation experiments between industrially impacted and nomimpacted sites. Elizabeth River oysters at Norfolk, Virginia, contained the highest PAH tissue burdens among oysters from the rivers sampled; the sum of six PAHs identified was 3 9 ppm dry weight. PAH levels in James River oysters ranged from 0 to 2 3 ppm at Wreck Shoals near Newport News, Virginia No PAHs were detected in oysters from the Piankatank River In accumulation experiments, PAH levels increased from 0 to as much as 11 7 ppm dry weight within 3 d of exposure in the Elizabeth River, they then stabilized Depuration or transformation of PAHs in Elizabeth River oysters to undetectable levels occurred within 4 d of relocation to the Ware River Differences in oyster PAH levels generally corresponded with the degree of industrial and urban development and shipping traffic in the habitats.

Polynuclear aromatic hydrocarbons in oyster tissue around three coastal marinas.

Abstract: Marinas present the potential for introduction of various pollutants into the surrounding waters such as coliform bacteria, primary pathogens, heavy metals, and petroleum hydrocarbons. Little data have been presented specifically addressing the effects of recreational marinas on petroleum hydrocarbon levels or, for that matter, other constituent levels in oysters near those marinas. In order to obtain such data, a comprehensive assessment of water and oyster quality around three coastal marinas was conducted by the South Carolina Department of Health and Environmental control (SCDHEC) during 1983. Polynuclear aromatic hydrocarbons (PAH) were selected as the petroleum hydrocarbon fraction of interest since they are mainly of pyrogenic origin; have been shown to be the most toxic/carcinogenic fraction of oil; have been shown to affect the respiration and heart rates of mussels; and have been shown to be linked to neoplasia in clams and proliferative disorders in mussels. C. virginica was chosen as the mollusc of interest because of its widespread distribution in the estuaries of South Carolina, its importance as an economic and recreational resource, and its suitability as a sentinel organism for monitoring coastal pollution.

Survival of Vibrio cholerae During Cold Storage in Artificially Contaminated Seafoods

Abstract: Homogenates of sterilized crab, shrimp, and oyster meats were inoculated with log phase cells of V. cholerae 01 (Louisiana strain 5875) and placed in frozen and refrigerated storage. The number of V. cholerae cells decreased over time, but surviving cells persisted in refrigerated and frozen samples for longer than three weeks. Survival differences were observed among seafoods and between refrigerated and frozen storage conditions.

Comparison of Some Single Cell Proteins in the Diet of the Sydney Rock Oyster (Saccostrea commercialis)

Abstract: Growth, composition and condition of meats were examined for Sydney rock oysters (Saccostrea commercialis) fed diets containing four different types of single cell protein. Significant increases in glycogen content and condition index were obtained with the bacterial protein Pruteen (methylophilus methylotrophus) and the food yeast (Candida utilis). Therefore both these ingredients are suitable for use in oyster fattening diets but for commercial application, artificial diets should be encapsulated.

The Effects of Hydraulic Dredging to Control Oyster Drills on Benthic Macrofauna of Oyster Grounds in Delaware Bay, New Jersey

Abstract: This study describes the extent and nature of the effects of hydraulic dredging to control oyster drills (Urosalpinx cinerea and Eupleura caudata, Family Muricidae, Order Neogastropoda) on benthic macrofauna and sediments of the oyster grounds in Delaware Bay, New Jersey. The immediate effects of hydraulic dredging were reductions in numbers of species as well as in total numbers of animals on the three oyster grounds selected. However, oyster drills were most affected. Benthic populations have recovered three to ten months after dredging. The sediments of the dredged grounds can be described as muddy sands. Immediately after dredging, additional mud was brought up from subsurface layers which reduced the median grain size on Ground 154 test plot. On Ground 515 test plot, however, there was a slight loss in the mud which increased the median grain size.

The potential food poisoning hazard of Vibrio parahaemolyticus in New Zealand Pacific oysters

Abstract: The level of Vibrio parahaemolyticus was generally very low in Pacific oysters sampled from 4 New Zealand oyster farms between November 1982 and May 1983. Of the 149 samples collected, only one was found to contain greater than the 1000 organisms g‐1regarded as the maximum allowable by international standards (International Commission on Microbiological Specifications for Foods 1982: Micro‐organisms in Foods, Vol. 2. Academic Press, New York). V. parahaemolyticus was detected in 57% of the oyster samples, but 95% of these contained less than 10 organisms g‐1. Maximum levels appeared to coincide with high water temperatures at the farm sites. Chilling, freezing, and depuration reduced V. parahaemolyticus numbers in oysters after harvest. However, holding at ambient temperatures (19–25°C) resulted in up to a 35‐fold increase in organism numbers with a maximum after one day. The food poisoning hazard from V. parahaemolyticus in New Zealand‐grown Pacific oysters thus appears to be minimal. Recommenda...

Simultaneous accumulations of naphthalene, a PCB mixture, and benzo(a)pyrene, by the oyster,Crassostrea virginica

Abstract: The objective of the present investigation was to assess accumulations or ogranic contaminants when the oyster Crassostrea virginica was simultaneously exposed to several contaminants. Polychlorinated biphenyls (PCBs), naphthalene, and benzo(a)pyrene were selected for study due to their toxicity and ubiquitous distribution in the marine environment. The objective included considering the possible significance of contaminant accumulations to humans by using a commercially important organism, and possible antagonistic-synergistic effects of multiple contaminants. The bioavailability of contaminants presented as dissolved versus particulate matter was also investigated.

Determination and distribution of trace elements in marine invertebrates

Abstract: Inductively coupled plasma atomic fluorescence spectrometry (ICP-AFS) was applied to the determination of trace elements in edible parts of marine invertebrates. Element contents (except aluminium and lead) in the NBS standard reference material 1566: oyster tissue measured by ICP-AFS were in agreement with certified values. Furthermore, analytical results indicated that ICP-AFS is one of the effective multielement analyses, because of a simultaneous determination capability, large dynamic ranges, small interelement interferences, and a satisfactory precision.From the investigation of the elemental distribution in marine invertebrates, the highest concentrations of transition elements were found in the kidney of the scallop. It was found that the liver of the lobster contained high levels of copper and cadmium. Especially, the cadmium concentration in the liver was about two thousand times higher than that of the abdominal muscle.Gel filtration profiles (Sephadex G-75) of iron, copper, zinc and cadmium in livers of marine organisms varied according to species. Moreover, a significant difference in the chromatogram of copper was observed among the oyster samples collected from five sampling sites. The ratio of the third peak area indicating the lowest molecular weight (below 5, 000) to the whole was related to the total amount of copper in the liver of the oyster.The result by analytical electron microscopy indicated that iron, copper and sulphur were localized in granules of epithelial cells of the oyster gills. In contrast, these elements were not detected in other analytical points such as nuclei or cytoplasm.

Survey of clam and oyster resources of some karnataka estuaries

Abstract: Of an estimated standing stock of about 6700 tonnes of clams and oysters in the estuaries on the southwest coast of India between Mangalore and Honavar 80% were clams and 20% were oysters. Among clams Meretrix casta was the chief species, followed by Villorita cyprinoides, Paphia malabarica, Meretrix meretrix and Katelysia opiina. The important oyster was Crassostrea madrasensis. Mulky, Udyavara and Coondapur were the more productive estuaries, among which Mulky topped with a production rate of 18 t/ha of clams and oysters.

Determination of polyaromatic hydrocarbons in scallops (Pecten maximus) by UV fluorescence and HPLC combined with UV and fluorescence detectors.

Abstract: During the last few years, the northern coasts of Brittany (France) were heavily polluted with several oil spills. This area of considerable economic importance for its oyster and scallop production is heavily dependent on the quality of its coastline and inshore waters. After the Amoco Cadiz oil spill, studies have been conducted on oysters from defined areas to determine the fate and effects of the hydrocarbons. No work was done on scallop samples. The purpose of this paper is to provide information on the level of hydrocarbon pollution in areas concerned with scallop breeding. It is an attempt to use these organisms as biomonitors.

Length-Weight relationship of giant oyster, Crassostrea gryphoides (Schlotheim)

Abstract: Relationship between shell length and total weight, shell weight and meat weight of giant oyster, Crassostrea gryphoides revealed that the growth of these parameters is very fast and significant. It indicates the suitability of the species concerned for intensive culture, where the attainment of marketable size, in minimum time is advantageous