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Articles 1 - 22 of 22

Full-Text Articles in Life Sciences

A Dynamical Perspective On Enzymatic Catalysis, Shiying Shang Jan 2002

A Dynamical Perspective On Enzymatic Catalysis, Shiying Shang

Dissertations, Theses, and Masters Projects

No abstract provided.


Distribution, Fluxes, And Bacterial Utilization Of Different Molecular Weight Fractions Of Dissolved Organic Matter In The York River Estuary, Carol J. Pollard Jan 2002

Distribution, Fluxes, And Bacterial Utilization Of Different Molecular Weight Fractions Of Dissolved Organic Matter In The York River Estuary, Carol J. Pollard

Dissertations, Theses, and Masters Projects

No abstract provided.


Chromosome Set Instability In 1--2 Year Old Triploid Crassostrea Ariakensis In Multiple Environments, Mingfang Zhou Jan 2002

Chromosome Set Instability In 1--2 Year Old Triploid Crassostrea Ariakensis In Multiple Environments, Mingfang Zhou

Dissertations, Theses, and Masters Projects

No abstract provided.


Aspects Of Age, Growth, Demographics And Thermal Biology Of Two Lamniform Shark Species, Kenneth J. Goldman Jan 2002

Aspects Of Age, Growth, Demographics And Thermal Biology Of Two Lamniform Shark Species, Kenneth J. Goldman

Dissertations, Theses, and Masters Projects

Age and growth rates for salmon sharks (Lamna ditropis) in the eastern North Pacific (ENP) were estimated from seasonally formed bands in the vertebrae, and compared to previously published life history parameters for this species from the western North Pacific (WNP). Results of this study show that salmon sharks in the ENP achieve their maximum length at a faster rate, reach sexual maturity at an earlier age and achieve a greater weight-at-length than those in the WNP. Additionally, this dissertation shows that adult salmon sharks maintain a specific body temperature independent of changes in ambient temperature through a combination of ...


Effects Of Urbanization And Land Use On Pah Accumulation In Wetland Sediments, Kimani L. Kimbrough Jan 2002

Effects Of Urbanization And Land Use On Pah Accumulation In Wetland Sediments, Kimani L. Kimbrough

Dissertations, Theses, and Masters Projects

The relationship between wetland polycyclic aromatic hydrocarbon (PAH) concentrations and adjacent land use was assessed using surface sediments, sediment cores and global information systems (GIS) in the Elizabeth River, Virginia, an urbanized subestuary of the Chesapeake Bay. Wetlands adjacent to parking lots and petroleum industrial sites exhibited the highest PAH concentrations of all land uses in surfaces sediment and historically. Automobile and coal are the dominant sources of PAHs in wetland sediments historically as determined by relative concentration, fingerprinting and source specific compounds. An analysis of variance (ANOVA) test used to compare sixteen surface sediment sites based on land use ...


Genetic Stock Structure Of The Sailfish, Istiophorus Platypterus, Based On Nuclear And Mitochondrial Dna, Jan Renee Mcdowell Jan 2002

Genetic Stock Structure Of The Sailfish, Istiophorus Platypterus, Based On Nuclear And Mitochondrial Dna, Jan Renee Mcdowell

Dissertations, Theses, and Masters Projects

The results of life history studies involving the sailfish, Istiophorus platypterus, from the Atlantic, Pacific, and Indian oceans were reviewed. Results of studies agree on several aspects of sailfish biology; sailfish exhibit opportunistic feeding behavior, follow the 28??C isotherm, spawn in summer mature at approximately age 3, and are the least migratory of the billfishes. However, results are in conflict concerning sex ratio and whether sailfish are single or multiple spawners. Although many researchers have reported that sailfish are sexually dimorphic, their fragile otoliths make them difficult to age, aging studies have not been validated, and sexual dimorphism has ...


Predicting Metal Interactions With A Novel Quantitative Ion Character -Activity Relationship (Qicar) Approach, David R. Ownby Jan 2002

Predicting Metal Interactions With A Novel Quantitative Ion Character -Activity Relationship (Qicar) Approach, David R. Ownby

Dissertations, Theses, and Masters Projects

Environmental toxicologists adopted QSARs from pharmacology fairly early on to predict organic contaminant toxicity. In contrast, models relating metal ion characteristics to their bioactivity remain poorly explored and underutillized. Quantitative Ion Character-Activity Relationships (QICARs) have recently been developed to predict metal toxicity. The QICAR approach based on metal-ligand binding tendencies has been applied to a wide range of effects, species, and media on a single metal basis. In previous single metal studies, a softness parameter and the ; log of KOH ; were the ion qualities with the highest predictive value for toxicity. Here, QICAR modeling was brought a step further to ...


Microevolutionary Processes In Chesapeake Bay (Virginia, Usa) Eelgrass, Zostera Marina L, Jennifer Michelle Rhode Jan 2002

Microevolutionary Processes In Chesapeake Bay (Virginia, Usa) Eelgrass, Zostera Marina L, Jennifer Michelle Rhode

Dissertations, Theses, and Masters Projects

Eelgrass (Zostera marina L.) is the northern hemisphere's dominant marine angiosperm, a species with both ecological and economic importance. Initial allozyme surveys of eelgrass populations in Chesapeake Bay (Virginia, USA) revealed substantial amounts of geographically-partitioned genetic variation, which could be the result of nonselective demographic processes, including founder events and drift. However, strong spatial variation in the environment and in eelgrass morphology suggests that differential adaptation of isolated beds to local environmental conditions could also produce these patterns. This dissertation used three sets of studies to investigate microevolutionary processes might produce the observed variation among Chesapeake eelgrass beds: (1 ...


Fate Of Organic Compounds Associated With Extractable And Bound Phases Of Estuarine Sediments Deposited Under Varying Depositional Regimes, Krisa Murray Arzayus Jan 2002

Fate Of Organic Compounds Associated With Extractable And Bound Phases Of Estuarine Sediments Deposited Under Varying Depositional Regimes, Krisa Murray Arzayus

Dissertations, Theses, and Masters Projects

Surficial sediments and sediment cores were collected from two distinct depositional regimes of the York River subestuary of Chesapeake Bay to document seasonal inputs, spatial variability, and longer-term (>40 years) fate of total organic carbon (TOC), lipid biomarker compounds and polycyclic aromatic hydrocarbons (PAHs). These regimes included biological mixing in the lower York and episodic mixing at the mid river site. Compounds were selected to represent a range of chemical reactivities, biological and anthropogenic sources, and modes of entry to the environment. The depositional environments were characterized with a suite of analytical tools: x-radiographs, Eh, 210Pb and 137Cs, total organic ...


Development Of A Watershed And Stream-Reach Spawning Habitat Model For River Herring Alosa Pseudoharengus And Alosa Aestivalis, Rebecca A. Boger Jan 2002

Development Of A Watershed And Stream-Reach Spawning Habitat Model For River Herring Alosa Pseudoharengus And Alosa Aestivalis, Rebecca A. Boger

Dissertations, Theses, and Masters Projects

This research develops a model to identify indicators of potential suitable spawning habitat for river herring, Alosa pseudoharengus and A. aestivalis, using watershed and stream-reach metrics. The results of icthyoplankton samples collected from thirty-four streams feeding into the Rappahannock River below the Embree Dam at Fredericksburg indicate where river herring spawning occurred. Watershed and stream-reach metrics were either measured in the field or derived from digital data in a GIS. Benthic macroinvertebrate analysis was used to compare habitat quality among sites. Streams were classified as either absence or presence of herring eggs or larvae based on the results of the ...


Comparison Of The Fate Of Dissolved Organic Matter In Two Coastal Systems: Hog Island Bay, Va (Usa) And Plum Island Sound, Ma (Usa), Tami L. Lunsford Jan 2002

Comparison Of The Fate Of Dissolved Organic Matter In Two Coastal Systems: Hog Island Bay, Va (Usa) And Plum Island Sound, Ma (Usa), Tami L. Lunsford

Dissertations, Theses, and Masters Projects

No abstract provided.


Nekton Utilization Of Intertidal Fringing Salt Marsh And Revetment Hardened Shorelines, Robert A. Carroll Jan 2002

Nekton Utilization Of Intertidal Fringing Salt Marsh And Revetment Hardened Shorelines, Robert A. Carroll

Dissertations, Theses, and Masters Projects

No abstract provided.


Diet Composition Of Young-Of-The-Year Bluefish, Pomatomus Saltatrix, In The Lower Chesapeake Bay And Virginia's Coastal Ocean, James Gartland Jan 2002

Diet Composition Of Young-Of-The-Year Bluefish, Pomatomus Saltatrix, In The Lower Chesapeake Bay And Virginia's Coastal Ocean, James Gartland

Dissertations, Theses, and Masters Projects

No abstract provided.


Organism -Sediment Interactions: The Role Of Seabed Dynamics In Structuring The Mesohaline York River Macrobenthic Community, Elizabeth K. Hinchey Jan 2002

Organism -Sediment Interactions: The Role Of Seabed Dynamics In Structuring The Mesohaline York River Macrobenthic Community, Elizabeth K. Hinchey

Dissertations, Theses, and Masters Projects

Estuaries are dynamic physical environments. The stability of the sediment-water interface is influenced by sources and rates of sediment delivery and physical reworking of sediments by currents, tides, waves and biology, but effects of disruption of this interface on benthic biology are poorly resolved. For this study, I investigated effects of prevalent gradients in seabed disturbance processes and associated seabed characteristics on estuarine benthic community structure and function in the mesohaline York River, a tributary of Chesapeake Bay, USA. I used a variety of approaches to characterize the seabed, including sediment grain size, sediment water content, maximum depth of 7Be ...


Molecular And Morphological Evolution Of The Amphipod Radiation Of Lake Baikal, Kenneth S. Macdonald Iii Jan 2002

Molecular And Morphological Evolution Of The Amphipod Radiation Of Lake Baikal, Kenneth S. Macdonald Iii

Dissertations, Theses, and Masters Projects

The amphipods of Lake Baikal, Russia, are a taxonomically and morphologically diverse group, and have been cited as a classic example of adaptive radiation. An unfortunate consequence of this diversity has been an instability of Baikal amphipod classification, with frequent revisions spurred by differing opinions about the phylogenetic utility of different characters. Classifications have never been based on a rigorous phylogenetic analysis of morphological data and only recently has the phylogeny of Lake Baikal's amphipods been examined using molecular tools. Unfortunately, most of these studies have led to a limited expansion of our understanding of Baikal amphipod systematics. Phylogenetic ...


Organic Matter Cycling In The York River Estuary, Virginia: An Analysis Of Potential Sources And Sinks, Leigh Mccallister Jan 2002

Organic Matter Cycling In The York River Estuary, Virginia: An Analysis Of Potential Sources And Sinks, Leigh Mccallister

Dissertations, Theses, and Masters Projects

A study of the organic matter (OM) sources and biogeochemical and physicochemical sinks was undertaken in the York River estuary, Virginia. The reactivity of dissolved organic carbon (DOC) was enhanced from ∼25--68% by the combined effects of exposure to natural sunlight and bacterial decomposition. In contrast, sunlight exposure decreased the bioreactivity of DOC in the higher salinity lower York by a factor of five. The combined effects of photochemical and bacterial processing were found to modify both the bioavailability and metabolic fate of OM (e.g. respiration vs. biomass). Stable isotopic (delta13C, delta15N) and radiocarbon (Delta14C) values of bacterial nucleic ...


Comparisons Of Community Structure Between Seep And Vent Mussel-Beds, Mary Parker Turnipseed Jan 2002

Comparisons Of Community Structure Between Seep And Vent Mussel-Beds, Mary Parker Turnipseed

Dissertations, Theses, and Masters Projects

No abstract provided.


Patch Use Of Winter Resident And Migrant American Kestrels (Falco Sparverius) In The Coastal Plain Of Virginia, Rhonda Lynn Hardesty Sipe Jan 2002

Patch Use Of Winter Resident And Migrant American Kestrels (Falco Sparverius) In The Coastal Plain Of Virginia, Rhonda Lynn Hardesty Sipe

Dissertations, Theses, and Masters Projects

No abstract provided.


The Effects Of Prostaglandin E2 On The Neurons Of The Ventromedial Preoptic Area Of The Hypothalamus: A Mechanism Of Fever, Heather J. Ranels Jan 2002

The Effects Of Prostaglandin E2 On The Neurons Of The Ventromedial Preoptic Area Of The Hypothalamus: A Mechanism Of Fever, Heather J. Ranels

Dissertations, Theses, and Masters Projects

No abstract provided.


Coastal Zone Landscape Classification Using Remote Sensing And Model Development, Kevin R. Slocum Jan 2002

Coastal Zone Landscape Classification Using Remote Sensing And Model Development, Kevin R. Slocum

Dissertations, Theses, and Masters Projects

Coastal zone landscape characterization and empirical model development were evaluated using multi-spectral airborne imagery. Collectively, four projects are described that address monitoring and classification issues common to the resource management community. Chapter 1 discusses opportunities for remote sensing. Chapter 2 examines spectral and spatial image resolution requirements, as well as training sample selection methods required for accurate landscape classification. Classification accuracy derived from 25nm imagery with 4m pixel sizes outperformed 70nm imagery with 1m pixel sizes. Eight natural and five cultural landscape features were tested for classification accuracy. Chapter 3 investigated the ability to characterize 1m multispectral imagery into rank-ordered ...


Effects Of Habitat Fragmentation On The Utilization Of Eelgrass (Zostera Marina) By Mobile Epifauna And Macrofauna, Scott R. Marion Jan 2002

Effects Of Habitat Fragmentation On The Utilization Of Eelgrass (Zostera Marina) By Mobile Epifauna And Macrofauna, Scott R. Marion

Dissertations, Theses, and Masters Projects

The threat to biodiversity posed by increasing rates of anthropogenic habitat fragmentation necessitates an understanding of the consequences of spatial pattern for natural communities. Reduction of patch size, loss of habitat, changes in the quantity and proportion of habitat edge, and reduced connectivity among habitats can all shape ecological processes and faunal behavior. Seagrass habitats provide a natural model system for examining spatial inf1uences on marine fauna, but separating the effects of habitat structure, environmental conditions, and spatial pattern is difficult because shoot density, percent cover, and hydrodynamic regime often co-vary with patch size. This study used experimentally manipulated seagrass ...


Temporal And Spatial Variation In Reproductive Output Of The Veined Rapa Whelk (Rapana Venosa) In The Chesapeake Bay, Catherine C. Ware Jan 2002

Temporal And Spatial Variation In Reproductive Output Of The Veined Rapa Whelk (Rapana Venosa) In The Chesapeake Bay, Catherine C. Ware

Dissertations, Theses, and Masters Projects

No abstract provided.