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Marine Biology

Old Dominion University

1999

Articles 1 - 17 of 17

Full-Text Articles in Life Sciences

Pfiesteria Piscicida And Dinoflagellates Similar To Pfiesteria, Harold G. Marshall Oct 1999

Pfiesteria Piscicida And Dinoflagellates Similar To Pfiesteria, Harold G. Marshall

Virginia Journal of Science

Pfiesteria pisiccida is a microscopic, unicellular organism that is classified as both a mixotrophic and heterotrophic dinoflagellate, which has been associated with both fish deaths and a cause of human illness (Burkholder et al., 1992; Glasgow et al., 1995; Burkholder and Glasgow, 1997). This species possesses a complex life cycle that includes motile forms (e.g. zoospores, gametes, amoebae) and a cyst stage that may remain dormant in the sediment (Burkholder et al., 1995b). Pfiesteria piscicida is known to have toxin and non-toxin producing populations, where cyst transformation into the toxic motile zoospores may be initiated by the presence of certain …

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A Study Of The Seasonal Composition And Abundance Of Phytoplankton And Autotrophic Picoplankton In A Brackish Water Lake In Portsmouth Virginia, Jennifer Leigh Wolny Oct 1999

A Study Of The Seasonal Composition And Abundance Of Phytoplankton And Autotrophic Picoplankton In A Brackish Water Lake In Portsmouth Virginia, Jennifer Leigh Wolny

Biological Sciences Theses & Dissertations

The phytoplankton and autotrophic picoplankton populations of Hoffler Lake, a brackish-water lake in Portsmouth, Virginia, were monitored from May 1997 through May 1998, Analyses of the phytoplankton community using the Utennohl method showed a dominance of Chlorophytes (61-88% of the total abundance) throughout the year, including a winter bloom of Chlamydomonas snowii (maximum concentration of 2.5 x 101 cells/L). Subdominants were Cyanobacteria (10-33% of the total abundance) whose composition included several species of Anabaena, Lyngbya, and a fall bloom of Microcoleus sp. Diatoms, dinoflagellates, and cryptophytes played a secondary role in the phytoplankton community of Hoffler Lake. …

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The Impact Of Resident And Transient Predators On The Popultation Dynamics Of Juvenile Caribbean Spiny Lobster (Panulirus Argus) In Florida Bay, Florida, Jason Edward Schratwieser Oct 1999

The Impact Of Resident And Transient Predators On The Popultation Dynamics Of Juvenile Caribbean Spiny Lobster (Panulirus Argus) In Florida Bay, Florida, Jason Edward Schratwieser

Biological Sciences Theses & Dissertations

There has been a considerable amount of research devoted to exploring the relationship between predators and prey, but many of these studies fail to address how predation can vary over spatial and temporal scales. The tendency of ecologists to model predation as a static entity often masks its capacity for creating distinctive effects in prey populations and communities. Most predation studies also focus on the effect of a single species of predator on a prey population, an unrealistic situation in nature. In the Florida Keys, juvenile spiny lobsters are subjected to two general classes of predators: i) "resident" predators such …

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Use Of Extractable Lipofuscin For Age Determination Of Blue Crab Callinectes Sapidus, Se-Jong Ju, David H. Secor, H. Rodger Harvey Aug 1999

Use Of Extractable Lipofuscin For Age Determination Of Blue Crab Callinectes Sapidus, Se-Jong Ju, David H. Secor, H. Rodger Harvey

OES Faculty Publications

The blue crab Callinectes sapidus is an economically and ecologically important species in many temperate estuaries, yet stock assessments have been limited to length-based methods for demographic analyses. We evaluated the potential of age pigments (lipofuscins) sequestered in neural tissue of eye-stalks and brains to estimate the age of blue crabs collected from Chesapeake Bay and Chincoteague Bay. The rate of lipofuscin accumulation was determined using crabs of known age reared in the laboratory. Age pigments were extracted from neural tissues (eye-stalk or brain), quantified, and normalized to protein content to allow comparisons across tissue types and crab sizes. Field-collected …

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Encystment, Excystment And Photosynthetic Activity In The Temporary Cysts Of Amphidinium Carterae, Steven R. Kibler Jul 1999

Encystment, Excystment And Photosynthetic Activity In The Temporary Cysts Of Amphidinium Carterae, Steven R. Kibler

OES Theses and Dissertations

Although the formation of temporary cysts has been documented in several papers, the physiology of these stages has remained obscure. Research dealing with dinoflagellate resting stages has primarily targeted sexual cysts. Accordingly, formation, germination and photosynthetic activity in the temporary cysts of Amphidinium carterae have been investigated in the present study. The effect of light intensity upon cyst germination was tested by incubating temporary cysts at three different light intensities. In order to assess the potential for photosynthesis in cysts, cellular chlorophyll-a concentrations and cellular fluorescence were quantified during encystment. Photosynthetic carbon uptake of H14CO3- was …

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Adaptive Strategies That Reduce Predation On Caribbean Spiny Lobster Postlarvae During Onshore Transport, Charles A. Acosta, Mark J. Butler Iv May 1999

Adaptive Strategies That Reduce Predation On Caribbean Spiny Lobster Postlarvae During Onshore Transport, Charles A. Acosta, Mark J. Butler Iv

Biological Sciences Faculty Publications

Like many marine species with meroplanktonic larvae, the Caribbean spiny lobster (Panulirus argus) has a postlarval stage that moves from the oceanic plankton to inshore nurseries only under specific environmental conditions (i.e., at night, in the surface water layer, on the flood tide, and during new moon), presumably to avoid predation or to enhance onshore transport. Using held and mesocosm experiments, we compared predation on planktonic postlarvae swimming at night near the surface and bottom over coastal habitats along typical offshore-inshore transport paths and determined whether predation rates differed between lunar periods (new moon vs, full moon) and with prey …

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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 …

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Modeling The Msx Parasite In Eastern Oyster (Crassostrea Virginica) Populations. I. Model Development, Implementation, And Verification, Susan Ford, Eric Powell, John Klinck, Eileen Hofmann Jan 1999

Modeling The Msx Parasite In Eastern Oyster (Crassostrea Virginica) Populations. I. Model Development, Implementation, And Verification, Susan Ford, Eric Powell, John Klinck, Eileen Hofmann

CCPO Publications

A mathematical model simulating the host-parasite-environmental interactions of eastern oysters (Crassostrea virginica) and the pathogen, Haplosporidium nelsoni, which causes MSX disease, has been developed. The model has 2 components. One replicates the infection process within the oyster and the other simulates transmission. The infection-development component relies on basic physiological processes of both host and parasite, modified by the environment, to reproduce the observed annual prevalence cycle of H. nelsoni. Equations describing these rates were constructed using data from long-term field observations, and field and laboratory experiments. In the model, salinity and temperature have direct effects upon …

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Modeling The Msx Parasite In Eastern Oyster (Crassostrea Virginica) Populations. Iii. Regional Application And The Problem Of Transmission, Eric N. Powell, John M. Klinck, Susan E. Ford, Eileen E. Hofmann, Stephen J. Jordon Jan 1999

Modeling The Msx Parasite In Eastern Oyster (Crassostrea Virginica) Populations. Iii. Regional Application And The Problem Of Transmission, Eric N. Powell, John M. Klinck, Susan E. Ford, Eileen E. Hofmann, Stephen J. Jordon

CCPO Publications

A model of transmission for Haplosporidium nelsoni, the disease agent for MSX disease, is developed and applied to sites in Delaware Bay and Chesapeake Bay. The environmental factors that force the oyster population- H. nelsoni model are salinity, temperature, food, and total suspended solids. The simulated development of MSX disease was verified using 3 time series of disease prevalence and intensity: 1960 to 1970 and 1980 to 1990 for Delaware Bay, and 1980 to 1994 for Chesapeake Bay, and for a series of sites covering the salinity gradient in each bay. Additional simulations consider the implications of assumptions made …

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Comparative Study Of Selenium Requirements Of Three Phytoplankton Species: Gymnodinium Catenatum, Alexandrium Minutum (Dinophyta) And Chaetoceros Cf. Tenuissimus (Bacillariophyta, Martina A. Doblin, Susan I. Blackburn, Gustaaf M. Hallegraeff Jan 1999

Comparative Study Of Selenium Requirements Of Three Phytoplankton Species: Gymnodinium Catenatum, Alexandrium Minutum (Dinophyta) And Chaetoceros Cf. Tenuissimus (Bacillariophyta, Martina A. Doblin, Susan I. Blackburn, Gustaaf M. Hallegraeff

OES Faculty Publications

This study investigated the selenium (Se) requirements of three phytoplankton species which commonly bloom in southern Australian estuaries. The present study showed that the toxic dinoflagellate Gymnodinium catenatum Graham had an obligate requirement for Se (IV) in culture. After two transfers (~ 4 weeks ≈ 7 generations) in Se-deficient seawater medium, this phytoplankton species exhibited a decline in growth rate (25%) and biomass yield (90%), while complete cessation of cell division occurred under prolonged (8 weeks ≈ 12 generations) Se starvation. Addition of 10-9-10-7 M H2SeO3 to nutrient-enriched seawater medium resulted in increased G.catenatum …

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Growth And Feeding Studies On The Algal Feeding Stage Of A Pfiesteria-Like Dinoflagellate, David W. Seaborn, A. Michelle Seaborn, William M. Dunstan, Harold G. Marshall Jan 1999

Growth And Feeding Studies On The Algal Feeding Stage Of A Pfiesteria-Like Dinoflagellate, David W. Seaborn, A. Michelle Seaborn, William M. Dunstan, Harold G. Marshall

Virginia Journal of Science

The dinoflagellate Cryptoperidiniopsis sp. was isolated from sediment samples taken from Virginia estuaries, and established in culture for subsequent growth and feeding studies. The maximum abundance, or yield, of Cryptoperidiniopsis is exponentially related to the concentration of algal prey and is saturated at about 4.00 X 105 mL-1. Salinity from 10-20 ppt and temperature between 15-25 C have no effect on the yield of this form of Cryptoperidiniopsis. Light intensity has a secondary effect in that the algal prey reproduces more quickly in higher light as they are being grazed. Growth rates of Cryptoperidiniopsis were …

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Water Quality Relationships To Concentrations Of Pfiesteria-Like Organisms In Virginia Estuaries For 1998, Everett P. Weber, Harold G. Marshall Jan 1999

Water Quality Relationships To Concentrations Of Pfiesteria-Like Organisms In Virginia Estuaries For 1998, Everett P. Weber, Harold G. Marshall

Virginia Journal of Science

A series of statistical analyses were performed to identify the relationship between abundance of dinoflagellates grouped as Pfiesteria-like organisms and a set of 25 water quality variables from May through October of 1998 at 41 estuarine locations. Although regions were identified in relation to seasonal density of cells present, there were no strong relationships to specific water quality variables. Factors that may have influenced these results included: a) several species were included in the group analyzed and this composite did not respond as a unit to changing environmental conditions; b) cell concentrations were low and there were a large …

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Modeling The Effects Of Doliolids On The Plankton Community Structure Of The Southeastern Us Continental Shelf, A. G. Edward Haskell, Eileen E. Hofmann, Gustav-Adolf Paffenhofer, Peter G. Verity Jan 1999

Modeling The Effects Of Doliolids On The Plankton Community Structure Of The Southeastern Us Continental Shelf, A. G. Edward Haskell, Eileen E. Hofmann, Gustav-Adolf Paffenhofer, Peter G. Verity

CCPO Publications

A model of the lower trophic levels that consists of a system of coupled ordinary differential equations was developed to investigate the time-dependent behavior of doliolid populations associated with upwelling features on the outer southeastern US continental shelf. Model equations describe the interactions of doliolids with two phytoplankton size fractions, five copepod developmental stages and a detrital pool. Additional equations describe nitrate and ammonia. Model dynamics are based primarily upon data obtained from field and laboratory experiments for southeastern US continental shelf plankton populations. Variations on a reference simulation, which represents average upwelling conditions without doliolids, were carried out to …

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Resource Allocation And Sucrose Mobilization In Light Limited Eelgrass Zostera Marina, Teresa Alcoverro, Richard C. Zimmerman, Donald G. Kohrs, Randall S. Alberte Jan 1999

Resource Allocation And Sucrose Mobilization In Light Limited Eelgrass Zostera Marina, Teresa Alcoverro, Richard C. Zimmerman, Donald G. Kohrs, Randall S. Alberte

OES Faculty Publications

This study evaluated the ability of Zostera marina L. (eelgrass) to balance the daily photosynthetic deficit by mobilization of carbon reserves stored in below-ground tissues during a period of extreme winter light limitation. A quantitative understanding of the mobilization process and its limitations is essential to the development of robust models predicting minimum light levels required to maintain healthy seagrass populations. Plants were grown in running seawater tanks under 2 light regimes. One treatment was provided with 2 h irradiance-saturated photosynthesis (Hsat) to produce severe Light Limitation, while control plants were grown under 7 h Hsat, …

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Growth And Feeding Studies On The Algal Feeding Stage Of A Pfiesteria-Like Dinoflagellate, David W. Seaborn, A. Michelle Seaborn, William M. Dunstan, Harold G. Marshall Jan 1999

Growth And Feeding Studies On The Algal Feeding Stage Of A Pfiesteria-Like Dinoflagellate, David W. Seaborn, A. Michelle Seaborn, William M. Dunstan, Harold G. Marshall

Biological Sciences Faculty Publications

The dinoflagellate Cryptoperidiniopsis sp. was isolated from sediment samples taken from Virginia estuaries, and established in culture for subsequent growth and feeding studies. The maximum abundance, or yield, of Cryptoperidiniopsis is exponentially related to the concentration of algal prey and is saturated at about 4.00 X 105 mL-1. Salinity from 10-20 ppt and temperature between 15-25 C have no effect on the yield of this form of Cryptoperidiniopsis. Light intensity has a secondary effect in that the algal prey reproduces more quickly in higher light as they are being grazed. Growth rates of Cryptoperidiniopsis were …

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The Cause And Consequence Of Ontogenetic Changes In Social Aggregation In New Zealand Spiny Lobsters, Mark J. Butler Iv, Alistair B. Macdiarmid, John D. Booth Jan 1999

The Cause And Consequence Of Ontogenetic Changes In Social Aggregation In New Zealand Spiny Lobsters, Mark J. Butler Iv, Alistair B. Macdiarmid, John D. Booth

Biological Sciences Faculty Publications

Ontogenetic changes in the behavior, spatial distribution, or habitat use of a species are presumably adaptations to ecological forces that differ in their effect on various life stages. The New Zealand rock lobster Jasus edwardsii is one of several species of spiny lobster that exhibits dramatic ontogenetic shifts in sociality and spatial distribution, and we tested whether such changes are adaptive. We first surveyed several natural populations of J. edwardsii to document size-specific differences in aggregation. To determine if chemical cues discharged by conspecifics promote aggregation of certain ontogenetic stages, we tested the responsiveness of lobsters of 3 ontogenetic stages …

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Water Quality Relationships To Concentrations Of Pfiesteria-Like Organisms In Virginia Estuaries For 1998., Everett P. Weber, Harold G. Marshall Jan 1999

Water Quality Relationships To Concentrations Of Pfiesteria-Like Organisms In Virginia Estuaries For 1998., Everett P. Weber, Harold G. Marshall

Biological Sciences Faculty Publications

A series of statistical analyses were performed to identify the relationship between abundance of dinoflagellates grouped as Pfiesteria-like organisms and a set of 25 water quality variables from May through October of 1998 at 41 estuarine locations. Although regions were identified in relation to seasonal density of cells present, there were no strong relationships to specific water quality variables. Factors that may have influenced these results included: a) several species were included in the group analyzed and this composite did not respond as a unit to changing environmental conditions; b) cell concentrations were low and there were a large …

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