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Oceanography

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Articles 31 - 60 of 347

Full-Text Articles in Fresh Water Studies

Fishes In Seagrass Habitats: Species Composition, Trophic Interactions, And Production, Kathryn L. Sobocinski Jan 2014

Fishes In Seagrass Habitats: Species Composition, Trophic Interactions, And Production, Kathryn L. Sobocinski

Dissertations, Theses, and Masters Projects

The value of habitats in terms of biological production is of interest to ecologists and resource managers. Seagrasses are a commonly occurring habitat type in shallow marine waters and have been shown to support high abundances of fish and invertebrates. In lower Chesapeake Bay, seagrasses grow in a shallow fringe in the subtidal zone. Although, ample evidence exists for the value of these habitats as foraging and rearing areas for a variety of organisms, the connectivity among species and the benefits derived from these habitats in terms of production have not been well described, especially for small, seasonally occurring finfishes. …


Factors Influencing Year-Class Strength And Growth Of Young-Of-The-Year Summer Flounder (Paralichthyidae: Paralichthys Dentatus), Lauren N. Nys Jan 2014

Factors Influencing Year-Class Strength And Growth Of Young-Of-The-Year Summer Flounder (Paralichthyidae: Paralichthys Dentatus), Lauren N. Nys

Dissertations, Theses, and Masters Projects

No abstract provided.


Quantification Of Nursery Habitats For Blue Crabs In Chesapeake Bay, Gina M. Ralph Jan 2014

Quantification Of Nursery Habitats For Blue Crabs In Chesapeake Bay, Gina M. Ralph

Dissertations, Theses, and Masters Projects

The blue crab is an iconic species in Chesapeake Bay, supporting important commercial and recreational fisheries and functioning as a critical link in the food web. Structurally complex habitats are often cited as nurseries for the blue crab, and other commercially important fish and crustacean species, by providing enhanced growth and survival for juveniles. I quantified the value of shallow habitats as nurseries for blue crabs through field studies and a demographic model. In Chapter 2, I utilized a two-year juvenile survey in vegetated habitats of the lower Bay to examine the effect of habitat complexity on the density of …


Post-Release Mortality Of School-Size Atlantic Bluefin Tuna (Thunnus Thynnus) In The U.S Recreational Troll Fishery, Benjamin Jon Marcek Jan 2013

Post-Release Mortality Of School-Size Atlantic Bluefin Tuna (Thunnus Thynnus) In The U.S Recreational Troll Fishery, Benjamin Jon Marcek

Dissertations, Theses, and Masters Projects

Atlantic bluefin tuna Thunnus thynnus (ABFT) support commercial and recreational fisheries throughout the North Atlantic Ocean. Due to heavy fishing pressure over the course of several decades, the eastern and western stocks of ABFT were overfished and the current biomass of the western stock is estimated to be approximately 19% of the biomass necessary for maximum sustainable yield. Despite a variety of management measures, including the implementation of minimum sizes and reductions of the total allowable catch (TAC) and country-specific quotas, little change was observed in the status of the western stock. The U.S. commercial and recreational ABFT fisheries are …


Seasonal Nitrogen Uptake And Regeneration In The Water Column And Sea-Ice Of The Western Coastal Arctic, Steven E. Baer Jan 2013

Seasonal Nitrogen Uptake And Regeneration In The Water Column And Sea-Ice Of The Western Coastal Arctic, Steven E. Baer

Dissertations, Theses, and Masters Projects

The logistical difficulties of research in extremely low temperatures and lack of access to the Arctic have meant that there is a historic dearth of knowledge of coastal Arctic biogeochemistry, especially during winter when sea ice is present. Recent observations, however, indicate that the Arctic is changing rapidly. Changes include increased temperatures, decreased extent and volume of sea ice, and increased freshwater inputs. How these changes influence biogeochemical cycles is an open question, especially in the highly productive coastal regions of the Chukchi Sea. Here I present nitrogen (N) uptake and regeneration rates for phytoplankton and bacteria measured in the …


Foraging Ecology And Habitat Use Of The Northern Diamondback Terrapin (Malaclemys Terrapin Terrapin) In Southern Chesapeake Bay, Diane C. Tulipani Jan 2013

Foraging Ecology And Habitat Use Of The Northern Diamondback Terrapin (Malaclemys Terrapin Terrapin) In Southern Chesapeake Bay, Diane C. Tulipani

Dissertations, Theses, and Masters Projects

The northern diamondback terrapin (Malaclemys terrapin ) is the only estuarine turtle residing along western Atlantic and Gulf of Mexico coasts of North America. Through predation, terrapins may be a key species in coastal marine habitats by exerting top-down control on marsh invertebrates, and thereby help to maintain healthy marshes. Despite the terrapin's ecological importance, there has not been a thorough study of terrapin foraging ecology and movements in lower Chesapeake Bay. In this dissertation, the research focused on the foraging habits of diamondback terrapins and their effects within salt marsh and seagrass habitats of lower Chesapeake Bay. I provided …


Food Availability And Utilization For Cultured Hard Clams, Richard Garrik Secrist Jan 2013

Food Availability And Utilization For Cultured Hard Clams, Richard Garrik Secrist

Dissertations, Theses, and Masters Projects

Aquaculture of the hard clam Mercenaria mercenaria is a valuable industry on the east coast. At high planting densities, cultured bivalves can become limited by food availability, resulting in reduced growth. Centric diatoms are considered the dominant food source to cultured bivalves. Alternative sources may also be important, including resuspended benthic microalgae (pennate diatoms) and detritus from macroalgae growing on predator exclusion nets. This study measured (1) the availability of different food sources in clam beds at Cherrystone Inlet in Chesapeake Bay, including the effects of macroalgae on food availability, and (2) the clearance rates and absorption efficiencies by cultured …


Improvements In Triploid Crassostrea Virginica Production: Characterizing The Diploid Parent, Brian R. Callam Jan 2013

Improvements In Triploid Crassostrea Virginica Production: Characterizing The Diploid Parent, Brian R. Callam

Dissertations, Theses, and Masters Projects

The effect of triploidy to effect faster growth and increased survival compared to diploid oysters is called the ‘triploid advantage’ and this advantage in the Chesapeake Bay for Crassostrea virginica is the principal reason for the value of triploid C. virginica in the Chesapeake Bay, USA. The triploid advantage is hypothesized to be the result of genetic effects, physiological changes, or a combination of both. The causative genetic mechanisms at play may include additive genetic effects and heterosis while the physiological changes obtain from triploid sterility. The triploid advantage was examined by comparing 13 diploid and 13 triploid crosses across …


Interannual And Regional Differences In Krill And Fish Prey Quality Along The Western Antarctic Peninsula, Kate E. Ruck Jan 2012

Interannual And Regional Differences In Krill And Fish Prey Quality Along The Western Antarctic Peninsula, Kate E. Ruck

Dissertations, Theses, and Masters Projects

Polar zooplankton and fish safeguard against the seasonality of food availability by using the summer months to build large reserves of lipids, which in turn are utilized to meet the metabolic demands of apex predators such as penguins, seals, and whales. A warming trend in the northern part of the western Antarctic Peninsula (WAP) has led to a decrease in perennial and summer sea ice, an increase in heat content over the shelf, and lower phytoplankton biomass, which could affect prey quality. We compared prey quality, including elemental (C, N) content and ratios, total, neutral, and polar lipid content, and …


Movements, Growth, And Mortality Of Chesapeake Bay Summer Flounder Based On Multiple Tagging Technologies, Mark J. Henderson Jan 2012

Movements, Growth, And Mortality Of Chesapeake Bay Summer Flounder Based On Multiple Tagging Technologies, Mark J. Henderson

Dissertations, Theses, and Masters Projects

The research projects presented in this dissertation used multiple tagging technologies to examine the movements, growth, and mortality rates of summer flounder tagged and released in Chesapeake Bay. In the first two chapters, I used acoustic, archival, and conventional tags to examine the behavior of summer flounder on different spatial scales. Investigating the movement behavior of individuals on different scales is an important step towards understanding how large-scale distributions of a population are established. Based on the observed behaviors of summer flounder, I hypothesize that the movements of these fish are primarily related to foraging behavior while they are resident …


Patterns Of Population Structure And Historical Dispersal In Squaloid Sharks: A Species-Level Approach Using Molecular Markers, Ana Christina Pimenta Verissimo Jan 2012

Patterns Of Population Structure And Historical Dispersal In Squaloid Sharks: A Species-Level Approach Using Molecular Markers, Ana Christina Pimenta Verissimo

Dissertations, Theses, and Masters Projects

Squaloids (Order Squaliformes) are a highle diverse group of mostly deepwater habitats (> 200 m). Many species are regularly caught in commercial fisheries worldwide but their low productivity and correspondingly low intrinsic rebound potentials make them particularly vulnerable to population depletion and overexploitation. of special concern to fisheries management and conservation efforts are the spiny dogfish Squalus acanthias, the leafscale gulper shark Centrophorus squamosus and the Portuguese dogfish Centroscymnus coelolepis. These taxa have recently been declared overfished in several parts of each species' distribution but management efforts have been made to recover the "stocks" without a good understanding of the …


Rogue Fishermen: Codfish, Atlantic Items, And The Isles Of Shoals, Megan Victor Jan 2012

Rogue Fishermen: Codfish, Atlantic Items, And The Isles Of Shoals, Megan Victor

Dissertations, Theses, and Masters Projects

No abstract provided.


Habitat Utilization And Trophic Interactions By Fauna In A Shallow Estuary: Comparisons Between Clam Aquaculture And Natural Sites, Lara Gates Kling Jan 2012

Habitat Utilization And Trophic Interactions By Fauna In A Shallow Estuary: Comparisons Between Clam Aquaculture And Natural Sites, Lara Gates Kling

Dissertations, Theses, and Masters Projects

Aquaculture of the hard clam, Mercenaria mercenaria, has steadily increased in the United States over the past 25 years. In some areas, including along Virginia’s coast, this industry has grown to such a scale that aquaculture systems now exist as agroecosystems within coastal waters. Several features of these aquaculture systems, such as high clam densities and protective mesh netting, may modify the availability of habitat, food, and nutrients and may be expected to affect benthic and nektonic community structure. Few studies, however, have evaluated these effects. We conducted seasonal (May – September) sampling in a tidal tributary of Chesapeake Bay …


Evaluating The Impact Of Stock Structure Uncertainty In Stock Assessments Of Sailfish In The Atlantic Ocean, Catarina Wor Lima Jan 2012

Evaluating The Impact Of Stock Structure Uncertainty In Stock Assessments Of Sailfish In The Atlantic Ocean, Catarina Wor Lima

Dissertations, Theses, and Masters Projects

No abstract provided.


Effects Of Life History And Physical Variables On Winter Distribution Of Blue Crabs In Chesapeake Bay, Gabrielle G. Saluta Jan 2012

Effects Of Life History And Physical Variables On Winter Distribution Of Blue Crabs In Chesapeake Bay, Gabrielle G. Saluta

Dissertations, Theses, and Masters Projects

No abstract provided.


Evaluating The Use Of Flow-Through Larval Culture For The Eastern Oyster, Crassostrea Virginica, Stephanie L. Reiner Jan 2011

Evaluating The Use Of Flow-Through Larval Culture For The Eastern Oyster, Crassostrea Virginica, Stephanie L. Reiner

Dissertations, Theses, and Masters Projects

One system used for bivalve mollusc culture is flowthrough larval culture, which provides a continuous flow of food and seawater to the tank. Flowthrough culture enables larvae to be reared at stocking densities up to 100 larvae/mL, a characteristic that should recommend it as the culture system of choice for the East coast; however, Eastern oyster larvae have never been tested in flowthrough culture, discouraging implementation of the system. The thesis objectives are designed to address questions regarding the survival, growth, competent period, cell consumption, growth efficiency, and cell selection of oyster larvae reared in flowthrough culture. The objectives are: …


Molecular Marker Development For The Discrimination Of Atlantic And Pacific Blue Marlin (Makaira Nigricans), Laurie Sorenson Jan 2011

Molecular Marker Development For The Discrimination Of Atlantic And Pacific Blue Marlin (Makaira Nigricans), Laurie Sorenson

Dissertations, Theses, and Masters Projects

No abstract provided.


Accounting For Undesirable Outputs In Productivity Measurements: Application To The California-Oregon Drift Gillnet Fishery, Tara L. Scott Jan 2010

Accounting For Undesirable Outputs In Productivity Measurements: Application To The California-Oregon Drift Gillnet Fishery, Tara L. Scott

Dissertations, Theses, and Masters Projects

Many production activities typically produce undesirable outputs, e.g., the production of the pollutant sulfur dioxide in the generation of electricity. Traditional economic metrics may overstate the efficiency and productivity of these production activities by failing to account for the undesirable outputs. These omissions can lead to conclusions that are biased against resource conservation and protection. Many fisheries capture their target species concomitantly with undesirable outputs such as bycatch of juvenile fish, marine mammals, sea birds, and sea turtles. One such fishery is the California-Oregon (CA/OR) drift gillnet fishery (DGNF), which incidentally takes protected species, such as sea turtles and marine …


Incorporating Industry Based Dredge Surveys Into The Assessment Of Sea Scallops, Placopecten Magellanicus, David B. Rudders Jan 2010

Incorporating Industry Based Dredge Surveys Into The Assessment Of Sea Scallops, Placopecten Magellanicus, David B. Rudders

Dissertations, Theses, and Masters Projects

Cooperative research utilizing industry vessels represents a viable approach to acquire the data necessary to meet the increasing needs associated with the modern management of marine resources. This dissertation addresses a variety of topics associated with the integration of commercial vessels into the stock assessment of the sea scallop, Placopecten magellanicus. In this study we evaluate the efficacy of utilizing industry vessels with respect to topics that range from rotational closed area survey design, sampling gear evaluation as well as an experiment that broadens the scale of the traditional use of industry vessels in this fishery and provides data to …


"You Have No Boss Here To Work For": Women And Labor In Chesapeake Bay Fishing Communities, Elizabeth Marie O'Grady Jan 2010

"You Have No Boss Here To Work For": Women And Labor In Chesapeake Bay Fishing Communities, Elizabeth Marie O'Grady

Dissertations, Theses, and Masters Projects

No abstract provided.


The Life History Of Longnose Gar, Lepisosteus Osseus, An Apex Predator In The Tidal Waters Of Virginia, Patrick E. Mcgrath Jan 2010

The Life History Of Longnose Gar, Lepisosteus Osseus, An Apex Predator In The Tidal Waters Of Virginia, Patrick E. Mcgrath

Dissertations, Theses, and Masters Projects

Longnose gar (Lepisosteus osseus) inhabit all of the major tributaries of Chesapeake Bay in Virginia, extending from fresh to estuarine waters. Literature concerning longnose gar from tidal environments is limited and this is study concerns important aspects of the life history (e.g., growth, reproduction, dimorphism, movements, and diet). Age, growth, and reproduction are important life history aspects for understanding the biology of fishes and may be affected by the environment in which an individual lives. This study found no differences in the age, growth, and fecundity parameters between longnose gar from tidal portions of Chesapeake Bay tributaries and previous studies …


Estimating Detection Probabilities In Beach Seine Surveys For Estuarine Fishes, Branson D. Williams Jan 2010

Estimating Detection Probabilities In Beach Seine Surveys For Estuarine Fishes, Branson D. Williams

Dissertations, Theses, and Masters Projects

Detectability, the probability that a species is encountered if it inhabits a site, is often overlooked in fisheries research despite its potential to obscure habitat use inferences. Detectability can be estimated using models that also provide an estimate of occupancy (Ψ), the probability that a species inhabits a site. I used these models to estimate both probabilities, and to examine factors affecting detectability and occupancy for three fishes in Chesapeake Bay tributaries: young-of-the-year striped bass (Morone saxatilis), yearling Atlantic croaker (Micropogonias undulatus), and spottail shiner (Notropis hudsonius). Occupancy models were fitted to data from a seine survey conducted during summer, …


The Effect Of Salinity On Experimental Hematodinium Sp Infections In The Blue Crab, Callinectes Sapidus, Anna Huntley Coffey Jan 2010

The Effect Of Salinity On Experimental Hematodinium Sp Infections In The Blue Crab, Callinectes Sapidus, Anna Huntley Coffey

Dissertations, Theses, and Masters Projects

No abstract provided.


Exploring The Potential For Bay Scallop Restoration In The Lynnhaven River Sub-Estuary Of Chesapeake Bay, Ana Liza Hernandez Cordero Jan 2010

Exploring The Potential For Bay Scallop Restoration In The Lynnhaven River Sub-Estuary Of Chesapeake Bay, Ana Liza Hernandez Cordero

Dissertations, Theses, and Masters Projects

No abstract provided.


Partial Year Tagging Models: Accounting For Changing Tag Visibility And Delayed Mixing, Lynn Waterhouse Jan 2010

Partial Year Tagging Models: Accounting For Changing Tag Visibility And Delayed Mixing, Lynn Waterhouse

Dissertations, Theses, and Masters Projects

No abstract provided.


Habitat Complexity And Habitat Function Of Native (Crassostrea Virginica) And Non-Native (C. Ariakensis) Oysters In The Chesapeake Bay Region, Heather D. Harwell Jan 2010

Habitat Complexity And Habitat Function Of Native (Crassostrea Virginica) And Non-Native (C. Ariakensis) Oysters In The Chesapeake Bay Region, Heather D. Harwell

Dissertations, Theses, and Masters Projects

Complex oyster reefs created by the Eastern oyster, Crassostrea virginica, though once prominent features of the Chesapeake Bay region, have become relatively scarce in comparison to historic descriptions. This decline, caused by a combination of overfishing, disease, habitat destruction and pollution, this decline continues despite substantial restoration efforts that have spanned decades. In response to this decline, the states of Virginia and Maryland considered the intentional introduction of the non-native Suminoe oyster, C. ariakensis. Previous studies questioned the reef-building capability of this Crassostrea species, which may affect its habitat function. Through a combination of field and mesocosm studies, I examined …


Variability In Juvenile Growth, Mortality, Maturity, And Abundance Of American Shad And Blueback Herring In Virginia, Troy D. Tuckey Jan 2009

Variability In Juvenile Growth, Mortality, Maturity, And Abundance Of American Shad And Blueback Herring In Virginia, Troy D. Tuckey

Dissertations, Theses, and Masters Projects

Young-of-year (YOY) population dynamics of American shad and blueback herring in Virginia's rivers were examined with an emphasis on variability in growth and mortality rates. In addition, an analysis was conducted to relate juvenile abundance indices of American shad to adult indices to establish a stock-recruitment relationship. to accomplish the stock recruitment relationship, an additional study that examined maturation schedules and inter-annual variability in maturation schedules among stocks was performed. Results of population dynamics studies found that growth and mortality rates of American shad and blueback herring varied by river and year and that conspecific abundance was an important factor …


Mortality Of Diamondback Terrapins In Blue Crab Traps: Population Changes And Conservation In Southeastern Virginia, Megan Ann Rook Jan 2009

Mortality Of Diamondback Terrapins In Blue Crab Traps: Population Changes And Conservation In Southeastern Virginia, Megan Ann Rook

Dissertations, Theses, and Masters Projects

No abstract provided.


Assessing Genetic Variation Within And Among Native Populations And Hatchery Stocks Of Crassostrea Ariakensis Using Microsatellite Markers, Jie Xiao Jan 2009

Assessing Genetic Variation Within And Among Native Populations And Hatchery Stocks Of Crassostrea Ariakensis Using Microsatellite Markers, Jie Xiao

Dissertations, Theses, and Masters Projects

Assessing genetic variation within and among native populations and hatchery stocks of Crassostrea ariakensis using microsatellite markers In response to the dramatic decline of eastern oyster (Crassostrea virginica) populations in the Chesapeake Bay, introduction of the non-native Asian oyster Crassostrea ariakensis has been proposed. Currently several hatchery stocks of C. ariakensis, derived from a few wild populations along the coast of Japan and China, are being maintained in U.S. hatcheries in the Pacific northwest and on the east coast. In recent years, as the risks of the proposed introduction are being assessed, these hatchery animals have been widely used for …


Nutrient Loading And System Response In The Coastal Lagoons Of The Delmarva, Juliette Christina Poleto Giordano Jan 2009

Nutrient Loading And System Response In The Coastal Lagoons Of The Delmarva, Juliette Christina Poleto Giordano

Dissertations, Theses, and Masters Projects

No abstract provided.