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Crassostrea virginica

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Articles 31 - 52 of 52

Full-Text Articles in Life Sciences

Native And Invasive Competitors Of The Eastern Oyster Crassostrea Virginica In Mosquito Lagoon, Florida, Michelle Boudreaux Jan 2005

Native And Invasive Competitors Of The Eastern Oyster Crassostrea Virginica In Mosquito Lagoon, Florida, Michelle Boudreaux

Electronic Theses and Dissertations, 2004-2019

Populations of Crassostrea virginica within Mosquito Lagoon, Florida have recently undergone significant die-offs, which are a subject of major concern. Restoration efforts within Mosquito Lagoon are focusing on reconstructing the three-dimensional reef habitats. Before effective protocols can be established, however, important questions about the sources of juvenile and adult oyster mortality must be answered. Potential causes of Crassostrea virginica mortality in the Indian River Lagoon system include sediment loads, competition, predation, and disease. My research focused on the interactions between oysters and the competitors that may affect the settlement, growth, and survival of Crassostrea virginica. The four objectives of my ...


The Effect On Habitat Selection By Pinfish, Lagodon Rhomboides, In The Presence Of A Predator, The Lesser Blue Crab, Callinectes Similis, Janet Mcnaughton Jan 2003

The Effect On Habitat Selection By Pinfish, Lagodon Rhomboides, In The Presence Of A Predator, The Lesser Blue Crab, Callinectes Similis, Janet Mcnaughton

All Volumes (2001-2008)

This study was performed to observe the effect of the blue crab, Callinectes similis, on the habitat preference of its prey, pinfish, Lagodon rhomboides. It was hypothesized that the pinfish would prefer the most structurally complex habitat, the live oyster clumps, but in the absence of a predator, may not show a strong association with the live oyster. It was also thought that the addition of a predator would strengthen the association with the live oyster. The experiment consisted of placing pinfish in a pool containing four distinct habitat types. The habitats were sand bottom (the least complex), oyster shell ...


Modeling The Msx Parasite In Eastern Oyster (Crassostrea Virginica) Populations. Ii. Salinity Effects, Michelle C. Paraso, Susan E. Ford, Eric N. Powell, Eileen E. Hofmann, John M. Klinck Jan 1999

Modeling The Msx Parasite In Eastern Oyster (Crassostrea Virginica) Populations. Ii. Salinity Effects, Michelle C. Paraso, Susan E. Ford, Eric N. Powell, Eileen E. Hofmann, John M. Klinck

CCPO Publications

An oyster population model coupled with a model for Haplosporidium nelsoni, the causative agent of the oyster disease MSX, was used with salinity time-series constructed from Delaware River flow measurements to study environmentally-induced variations in the annual cycle of this disease in Delaware Bay oyster populations. Model simulations for the lower Bay (high salinity) sire reproduced the annual cycle observed in lower Delaware Bay. Simulations at both upper Bay (low salinity) and lower Bay sites produced prevalences and intensities that were consistent with field observations. At all sites, low freshwater discharge resulted in increased disease levels, whereas high freshwater discharge ...


Understanding The Success And Failure Of Oyster Populations: The Importance Of Sampled Variables And Sample Timing, Thomas M. Soniat, Eric N. Powell, Eileen E. Hofmann, John M. Klinck Jan 1998

Understanding The Success And Failure Of Oyster Populations: The Importance Of Sampled Variables And Sample Timing, Thomas M. Soniat, Eric N. Powell, Eileen E. Hofmann, John M. Klinck

CCPO Publications

One of the primary obstacles to understanding why some oyster populations are successful and others are not is the complex interaction of environmental variables with oyster physiology and with such population variables as the rates of recruitment and juvenile mortality. A numerical model is useful in investigating how population structure originates out of this complexity. We have monitored a suite of environmental conditions over an environmental gradient to document the importance of short time-scale variations in such variables as food supply, turbidity, and salinity. Then, using a coupled oyster disease population dynamics model, we examine the need for short rime-scale ...


A Modeling Study Of The Effects Of Size- And Depth-Dependent Predation On Larval Survival, Margaret M. Dekshenieks, Eileen E. Hofmann, John M. Klinck, Eric N. Powell Jan 1997

A Modeling Study Of The Effects Of Size- And Depth-Dependent Predation On Larval Survival, Margaret M. Dekshenieks, Eileen E. Hofmann, John M. Klinck, Eric N. Powell

CCPO Publications

The form of the predation pressure experienced by larval stages of marine invertebrates is largely unknown. However, it is believed that the type, timing and rate of larval predation are critical in determining recruitment to adult populations. In this study, a time and depth-dependent model of the growth and behavior of larvae of the Eastern oyster, Crassostrea virginica, was used to investigate the effects of different forms of size-and depth-dependent predation on larval survivorship. The simulated larval survival for a cohort experiencing size-dependent predation showed that the greatest percent of the cohort survived to competent settlement size when the predation ...


Butyltins In Crassostrea Virginica From Nine Reefs In Mississippi Sound, Thomas F. Lytle, Julia S. Lytle Jan 1997

Butyltins In Crassostrea Virginica From Nine Reefs In Mississippi Sound, Thomas F. Lytle, Julia S. Lytle

Gulf and Caribbean Research

Tributyltin (TBT), a very effective anti-foulant, has been banned from most marine paint uses since 1988 because of its reputed toxicity to nontarget organisms. Crassostrea virginica were collected from nine reefs in the Mississippi Sound in 1993 and analyzed for concentrations of butyltins: TBT, dibutyltin (DBT) and monobutyltin (MBT). TBT concentrations ranged from <2 to >20 ng(Sn)/g wet wt. Highest concentrations of butyltins were found at eastern Sound reefs near intense shipping and ship building activities with lowest concentrations found in the western Sound.


Modeling Diseased Oyster Populations. Ii. Triggering Mechanisms For Perkinsus Marinus Epizootics, Eric N. Powell, John M. Klinck, Eileen E. Hofmann Jan 1996

Modeling Diseased Oyster Populations. Ii. Triggering Mechanisms For Perkinsus Marinus Epizootics, Eric N. Powell, John M. Klinck, Eileen E. Hofmann

CCPO Publications

Densities of Crassostrea virginica remain high enough to support substantial fisheries throughout the Gulf of Mexico despite high mortality rates produced by the endoparasite Perkinsus marinus. The infrequency of epizootics in these populations suggests that controls exist on the disease intensification process. The progression of epizootics in oyster populations, the factors that trigger epizootics, and the factors that terminate epizootics once started were investigated with a coupled oyster population—P. marinus model.

The time development of a simulated epizootic was triggered by environmental conditions that occurred and disappeared as much as t8 months prior to the onset of mortality in ...


Modeling The Vertical Distribution Of Oyster Larvae In Response To Environmental Conditions, Margaret M. Dekshenieks, Eileen E. Hofmann, John M. Klinck, Eric N. Powell Jan 1996

Modeling The Vertical Distribution Of Oyster Larvae In Response To Environmental Conditions, Margaret M. Dekshenieks, Eileen E. Hofmann, John M. Klinck, Eric N. Powell

CCPO Publications

A size-structured, time and vertically-dependent model was used to investigate the effects of water column structure on the distribution of larvae of the oyster Crassostrea virginica. Formulations used to model larval growth and behavior are based upon laboratory studies. Simulated vertical larval distributions obtained for conditions representative of a well-mixed, partially stratified and strongly stratified water column illustrate the effect that salinity and temperature gradients have on moderating larval swimming and hence on larvae vertical location. For well-mixed conditions, smaller larvae are dispersed throughout most of the water column. For strongly stratified conditions, the smaller-sized larvae cluster within the region ...


Shell Disease In The Gold Lip Pearl Oyster, Pinctada Maxima And The Eastern Oyster, Crassostrea Virginica, Frank O. Perkins Jan 1996

Shell Disease In The Gold Lip Pearl Oyster, Pinctada Maxima And The Eastern Oyster, Crassostrea Virginica, Frank O. Perkins

VIMS Articles

A description is provided of the anomalous conchiolin deposits which are formed by Pinctada maxima and which are associated with unusual morta]jties. Comparisons are made with brown ring disease found in Ruditapes philippinarum and juvenile Crassostrea virg inica. In P. maxima, the deposits are not organized into a ring but rather a.re broad-based and result in retraction of the mantle with the deposits lying outside the edge of the mantle. Vibrio sp. have been implicated in causing the di seases of P. max ima and R. philippinarum whereas the etiological agent of the disease in C. virginica is ...


A Survey Of Disease In The Oyster Crassostrea Virginica (Gmelin, 1791) In Rhode Island Coastal Estuaries, Retno Andamari, Michael A. Rice, Paul P. Yevich Dec 1995

A Survey Of Disease In The Oyster Crassostrea Virginica (Gmelin, 1791) In Rhode Island Coastal Estuaries, Retno Andamari, Michael A. Rice, Paul P. Yevich

Michael A Rice

The presence of potential pathogens and lesions in American oysters, Crassostrea virginica (Gmelin, 1791), from coastal estuaries in Rhode Island was studied. Oysters were collected by hand or tongs from three stations in the Pawcatuck River, two stations in Narrow River, three stations in Charlestown Pond, and three stations in Green Hill Pond, during July/August 1991, November 1991, March 1992, and May 1992. Oysters were processed for histologic examination and determination of condition index. MSX, Haplosporidium nelsoni (Haskin, Stauber et Mackin, 1966), was detected in four of 480 oysters (0.8%); Sphenophyra sp., 15 of 480 (3.1%); Bucephalus ...


Modeling Oyster Populations Ii. Adult Size And Reproductive Effort, E. E. Hofmann, J. M. Klinck, E. N. Powell, S. Boyles, M. Ellis Jan 1994

Modeling Oyster Populations Ii. Adult Size And Reproductive Effort, E. E. Hofmann, J. M. Klinck, E. N. Powell, S. Boyles, M. Ellis

CCPO Publications

A time-dependent model of energy flow in post-settlement oyster populations is used to examine the factors that influence adult size and reproductive effort in a particular habitat, Galveston Bay, Texas, and in habitats that extend from Laguna Madre, Texas to Chesapeake Bay. The simulated populations show that adult size and reproductive effort are determined by the allocation of net production to somatic or reproductive tissue development and the rate of food acquisition, both of which are temperature dependent. For similar food conditions, increased temperature reduces the allocation of net production to somatic tissue and increases the rate of food acquisition ...


Modeling Oyster Populations. Iv. Rates Of Mortality, Population Crashes, And Management, E. N. Powell, J. M. Klinck, E. E. Hofmann, S. M. Ray Jan 1994

Modeling Oyster Populations. Iv. Rates Of Mortality, Population Crashes, And Management, E. N. Powell, J. M. Klinck, E. E. Hofmann, S. M. Ray

CCPO Publications

A time-dependent energy-flow model was used to examine how mortality affects oyster populations over the latitudinal gradient from Galveston Bay, Texas, to Chesapeake Bay, Virginia. Simulations using different mortality rates showed that mortality is required for market-site oysters to be a component of the population's size-frequency distribution; otherwise a population of stunted individuals results. As mortality extends into the juvenile sizes, the population's size frequency shifts toward the larger sizes. In many cases adults increase despite a decrease in overall population abundance. Simulations, in which the timing of mortality varied, showed that oyster populations are more susceptible to ...


Effect Of Neutral Red Stain On Settlement Ability Of Oyster Pediveligers, Crassostrea Virginica, Patrick Baker Jan 1991

Effect Of Neutral Red Stain On Settlement Ability Of Oyster Pediveligers, Crassostrea Virginica, Patrick Baker

VIMS Articles

The effect of neutral red stain on the settlement of oyster Crassostrea virginica (Gmelin) pediveligers was examined. Larvae were offered two types of substrate: oyster shell and acetate sheets. Settlement was measured as the proportion of pediveligers settled after 24 hours and analyzed with two-factor ANOV A. Staining did not significantly affect settlement, although settlement onto acetate was much lower than onto oyster shell.


Effect Of Decreasing Oxygen Tension Of Swimming Rate Of Crassostrea Virginica (Gmelin, 1791) Larvae, Roger L. Mann, Julia S. Rainer Jan 1990

Effect Of Decreasing Oxygen Tension Of Swimming Rate Of Crassostrea Virginica (Gmelin, 1791) Larvae, Roger L. Mann, Julia S. Rainer

VIMS Articles

Four sizes of Crassostrea virginica Gmelin larvae (mean lengths 76.8, 118.1, 139.7 and 290.2 [Lm) were exposed to ·stepwise decreases in oxygen concentration from I 00% saturation (5 .38 mill at 22°C and 22 ppt salinity) to as low as 10% saturation and their swimming rates (net vertical movement per unit time) were recorded at each oxygen concentration. No cessation of swimming was observed and in only two conditions, that of 76.8 [Lm larvae at 10% saturation and 290.2 j.Lm larvae at 21% saturation, was swimming rate significantly lower than that of ...


Recruitment And Growth Of Oysters On Shell Planted At Four Monthly Intervals In The Lower Potomac River, Maryland, Reinaldo Morales-Alamo, Roger L. Mann Jan 1990

Recruitment And Growth Of Oysters On Shell Planted At Four Monthly Intervals In The Lower Potomac River, Maryland, Reinaldo Morales-Alamo, Roger L. Mann

VIMS Articles

Oyster shells were planted on four successive months (May to August 1986) in contiguous plots at Jones Shore Bar in the Potomac River, Maryland, to study the effect of differences in time of cultch planting on settlement and survival of oyster spat. The plots were usually sampled at two-week intervals from time of planting through November, 1986, and once in June, 1987. A massive concentration of the tunicate Molgula manhattensis covered the bottom in all plots within four to six or eight weeks following shell planting. A commercially acceptable number of spat per shell, between 1.8 and 2.2 ...


Settlement Patterns Of Crassostrea Virginica (Gmelin, 1791) Larvae In Relation To Tidal Zonation, G. Curtis Roegner, Roger L. Mann Jan 1990

Settlement Patterns Of Crassostrea Virginica (Gmelin, 1791) Larvae In Relation To Tidal Zonation, G. Curtis Roegner, Roger L. Mann

VIMS Articles

Experiments were conducted to determine the settlement distribution of the oyster Crassostrea virginica (Gmelin) in relation to tidal zonation in an area where adult populations are largely confined to the intertidal zone. Hatchery-reared pediveliger larvae were interned in PVC tubes positioned at known tidal heights. The influence of non-tidal factors was limited: mesh covering the ends of the tubes prevented loss of larvae to dispersal or predation, the settling substrate was not colonized by competitors, and the effects of light and horizontal currents were minimized. Settlement was found to occur throughout the intertidal zone but predominated at the bottom of ...


Effects Of Inter-Specific Density And Food Supply On Survivorship And Growth Of Newly Settled Benthos, Roman Zajac, Robert B. Whitlatch, Richard W. Osman Aug 1989

Effects Of Inter-Specific Density And Food Supply On Survivorship And Growth Of Newly Settled Benthos, Roman Zajac, Robert B. Whitlatch, Richard W. Osman

Biology and Environmental Science Faculty Publications

Using a laboratory model system comprised of newly settled oysters Crassostrea virginica and established fouling species (Botrylloides sp. initially, and others including Styela clava and Ciona intestinalis as the experiment progressed), we tested how differences in food supply and competitor density may affect post-settlement surivorship and growth of sessile marine invertebrates over a 44 d period. After 15 d, results were mixed but indicated that both food and density conditions affected growth and survivorship significantly, with some suggestion of high food levels ameliorating high density effects However, 44 d after settlement, oysters had reduced survivorship and growth when competitors were ...


Effects Of Resident Species On Recruitment Into A Community: Larval Settlement Versus Post-Settlement Mortality In The Oyster Crassostrea Virginica, Roman Zajac, Richard W. Osman, Robert B. Whitlatch Jun 1989

Effects Of Resident Species On Recruitment Into A Community: Larval Settlement Versus Post-Settlement Mortality In The Oyster Crassostrea Virginica, Roman Zajac, Richard W. Osman, Robert B. Whitlatch

Biology and Environmental Science Faculty Publications

Laboratory and field experiments revealed that a variety of species of common, sessile invertebrates, including barnacles, ascidians, and bryozoans, affected the settlement and post-settlement abundance of the oyster Crassostrea virginica (Gmelin). While the nature of the effects varied, most species both reduced oyster settlement by covering and removing substrate available for attachment, and increased settlement on adjacent surfaces. The solitary ascidians Ciona intestinalis (L.) and Styela clava (Herdman), were found to be predators of oyster larvae. Post-settlement survivorship and growth were also strongly affected by the presence of sessile species. In most cases the effects were negative and correlated with ...


Anatomical Features In Histological Sections Of Crassostrea Virginica (Gmelin, 1791) As An Aid In Management Of Gonad Area For Reproductive Assessment, Reinaldo Morales-Alamo, Roger L. Mann Jan 1989

Anatomical Features In Histological Sections Of Crassostrea Virginica (Gmelin, 1791) As An Aid In Management Of Gonad Area For Reproductive Assessment, Reinaldo Morales-Alamo, Roger L. Mann

VIMS Articles

The relationship between gonad area in transverse histological sections of the American oyster Crassostrea virginica (Gmelin 1790) and body location from which the section was cut was studied in specimens collected from four stations in the James River, Virginia in 1984 and 1986. Gonad area, expressed as percentage of total body area, increases in an antero-posterior direction; this requires use of sections from the same body location in comparisons between oysters. Approximate body locations, identified according to the anatomy and arrangement of the internal organs in the sections, were grouped into five types with similar gonad area percentages. One of ...


The Growth Of Cultchless Crassostrea Virginica Spat At Biloxi Bay, Mississippi Using Different Methods Of Culture, John T. Ogle Jan 1989

The Growth Of Cultchless Crassostrea Virginica Spat At Biloxi Bay, Mississippi Using Different Methods Of Culture, John T. Ogle

Gulf and Caribbean Research

Oyster spat produced from the experimental hatchery of the Gulf Coast Research Laboratory at Point Cadet, Biloxi, Mississippi, were grown under a variety of conditions. Recovery of spat planted on adjacent bay bottom was negligible, despite the use of either whole oyster valves, crushed oyster shell or clam shell as a substrate. Negligible growth occurred for spat held in vertical and horizontal water tanks. Growth of spat in horizontal tanks was affected by the density of stocking, with lower densities producing faster growth. Growth in all studies was slower than anticipated and a comparison on growth for spat from a ...


Predation On Single Spat Oysters Crassostrea Virginica (Gmelin) By Blue Crabs Callinectes Sapidus Rathbun And Mud Crabs Panopeus Herbstii Milne-Edwards, Robert Bisker, Michael Castagna Jan 1987

Predation On Single Spat Oysters Crassostrea Virginica (Gmelin) By Blue Crabs Callinectes Sapidus Rathbun And Mud Crabs Panopeus Herbstii Milne-Edwards, Robert Bisker, Michael Castagna

VIMS Articles

Single spat oysters Crassostrea virginica of four size classes (3.4-24.6 mm mean shell heights [SH]) were offered to six size classes of blue crabs Ca/linectes sapidus (9.3-85.5 mm mean carapace width [CW]) and five size classes of mud crabs Panopeus herbstii (7.1-34.4 mm mean CW) for 48 hr. Predation rate, recorded as the number of dead oyster spat/crab/day, was directly proportional to crab size and inversely proportional to oyster size. Mud crabs of 34.4 mm CW and blue crabs of 85 .5 mm CW had predation rates of 22.5 ...


Survival Of The Oyster Crassostrea Virginica (Gmelin) In The Laboratory Under The Effects Of Oil Drilling Fluids Spilled In The Laguna De Tamiahua, Mexico, Jorge Cabrera Jan 1971

Survival Of The Oyster Crassostrea Virginica (Gmelin) In The Laboratory Under The Effects Of Oil Drilling Fluids Spilled In The Laguna De Tamiahua, Mexico, Jorge Cabrera

Gulf and Caribbean Research

In 1965, 970.12 m3 of oil drilling fluid were spilled in the Laguna de Tamiahua, Mexico. Laboratory experiments were carried out to determine possible effects of this upon the oyster Crassostrea virginica. It was found that drilling fluid reduced the survival of oysters to a significant degree in concentrations above 200 ppm. At turbidities between 200 and 500 ppm, there was 50% survival on the seventh day. Tanino in concentrations between 90 and 170 ppm had a drastic effect upon survival which was 50% between the fourth and fifth days. Bentonita in 110 to 190 ppm resulted in ...