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Full-Text Articles in Physical Sciences and Mathematics
Fecal Pellet Production By North Atlantic Zooplankton, Michael Gibson
Fecal Pellet Production By North Atlantic Zooplankton, Michael Gibson
Undergraduate Honors Theses
Fecal pellet carbon (FPC) production by zooplankton is a significant component of the ocean’s biological carbon pump: the suite of biological processes that mediate export of carbon to the deep ocean, ultimately leading to the sequestration of atmospheric carbon dioxide in the ocean. In this study, mesozooplankton (zooplankton 0.2 mm to ~2 cm) were collected from the epipelagic zone in the temperate North Atlantic Ocean during day and night in May 2021. Zooplankton were live separated into five size fractions and incubated on board ship in natural surface seawater to measure fecal pellet production rate of the mixed mesozooplankton community. …
Analysis Of Edna To Assess Effects Of Water Quality On Freshwater Fungal Diversity In A Virginia Coastal Watershed, Lauren French
Analysis Of Edna To Assess Effects Of Water Quality On Freshwater Fungal Diversity In A Virginia Coastal Watershed, Lauren French
Undergraduate Honors Theses
Freshwater fungi comprise a phylogenetically and functionally diverse group which contributes to wide-ranging ecosystem processes in aquatic systems. Saprotrophic fungi convert detritus into nutrient-rich food sources for fish and invertebrates, whereas pathogenic and parasitic fungi can cause disease and population declines of other aquatic organisms. With their diverse and important roles, changes in freshwater fungal community structure may have far-reaching impacts on ecosystems. To understand how natural and anthropogenic stressors to freshwater systems impact fungal-mediated ecosystem processes, a greater understanding of the taxonomic and functional composition of freshwater fungal communities is needed. We assessed relationships among freshwater habitat types, water …
Three Centuries Of Vegetation Change In The William & Mary College Woods Reconstructed Using Phytoliths, Timothy Terlizzi
Three Centuries Of Vegetation Change In The William & Mary College Woods Reconstructed Using Phytoliths, Timothy Terlizzi
Undergraduate Honors Theses
The College Woods, west of William & Mary’s campus, consists of ~900 acres of protected southern mixed hardwood forest. The woods surround Lake Matoaka, a former millpond established in ~1700. Despite the rich history of the area, little is known about how the dominant vegetative landcover has shifted over the last 300 years. This study set out to quantify the modern vegetation within the College Woods via the phytolith assemblages within the soil and identify shifts in the assemblages since the creation of Lake Matoaka and whether these changes are distinct from the vegetation that existed in the area before …
Applying The Concept Of Thresholds In Ecotoxicology With Focus On The Joint Effects Of Habitat Fragmentation And Contamination, Marcos Krull
Applying The Concept Of Thresholds In Ecotoxicology With Focus On The Joint Effects Of Habitat Fragmentation And Contamination, Marcos Krull
Dissertations, Theses, and Masters Projects
A threshold can be defined as the point where small changes in an environmental driver produce an abrupt change within a biological system. These changes can occur at different levels of organization, from organisms to ecosystems. Although thresholds seem to be receiving more attention by ecotoxicologist, not much is known about how contaminants cause or affect thresholds at the landscape level, such as habitat fragmentation thresholds. Habitat fragmentation thresholds can occur due to rapid changes in the landscape structure after a certain amount of habitat is lost, which can cause abrupt effects on the movement of organisms, population abundance and …
Ecosystem Services Of Restored Oyster Reefs In A Chesapeake Bay Tributary: Abundance And Foraging Of Estuarine Fishes, Bruce William Pfirrmann
Ecosystem Services Of Restored Oyster Reefs In A Chesapeake Bay Tributary: Abundance And Foraging Of Estuarine Fishes, Bruce William Pfirrmann
Dissertations, Theses, and Masters Projects
Oyster reef restoration may enhance the production of ecologically or economically important fish species, an ecosystem service, by providing refuge and foraging habitat. Predicting the effects of oyster habitat restoration on fisheries production in Chesapeake Bay requires a better understanding of fish habitat use, trophic dynamics, and the processes leading to production on a habitat-scale. The objective of this thesis was to evaluate the influence of restored subtidal oyster reefs on the abundance and foraging patterns of mobile estuarine fishes. Specifically, I compared the 1) abundance, 2) stomach fullness, 3) diet composition, and 4) daily consumption rate of fishes collected …
Modeling Phytoplankton Community Response To Nutrient Loading And Climate Change In A Shallow Temperate Estuary, Sara Aimee Blachman
Modeling Phytoplankton Community Response To Nutrient Loading And Climate Change In A Shallow Temperate Estuary, Sara Aimee Blachman
Dissertations, Theses, and Masters Projects
Phytoplankton account for at least half of all primary production in estuarine waters and are at the center of biogeochemical cycles and material budgets. Environmental managers use water column chlorophyll-a (chl-a) concentrations as a basic water quality indictor, as the problems of eutrophication and hypoxia are intrinsically linked to excessive phytoplankton growth. Evidence suggests that the distribution and frequency of harmful algal blooms may be increasing worldwide. For the most part, phytoplankton communities follow a standard seasonal pattern, with specific groups dominating the assemblage during the time of year when environmental conditions correspond to their requisites for growth. However, climate …
Zooplankton Community Composition And Grazing In The Amazon River Plume And Western Tropical North Atlantic Ocean, Brandon J. Conroy
Zooplankton Community Composition And Grazing In The Amazon River Plume And Western Tropical North Atlantic Ocean, Brandon J. Conroy
Dissertations, Theses, and Masters Projects
Large river plumes and frontal zones are important physical features influencing plankton distribution in the marine environment. In the western tropical North Atlantic Ocean (WTNA) the Amazon River plume may extend over an area reaching 1.5 x 106 km2. The freshwater plume creates a low-density lens in the surface 25m and supplies silicon and phosphorus to the WTNA. These physical and chemical gradients create an ideal environment for large-scale blooms of diatom diazotroph associations (DDAs), a symbiotic relationship between nitrogen-fixing cyanobacteria and chain-forming diatoms. While the physical and chemical properties of the plume with regard to influences on phytoplankton have …
Influence Of Structural Complexity And Location On The Habitat Value Of Restored Oyster Reefs, Melissa Ann Karp
Influence Of Structural Complexity And Location On The Habitat Value Of Restored Oyster Reefs, Melissa Ann Karp
Dissertations, Theses, and Masters Projects
In the Chesapeake Bay, < 1% of the historic oyster population remains, and efforts have been increasing to restore oysters and the services they provide. Building reefs that successfully provide ecosystem services–especially habitat and foraging grounds–may require different restoration techniques than those previously used, and success may depend on reef morphology (complexity), location, and environmental conditions. Salinity and habitat complexity are two important factors that may interact to effect benthic communities and predator-prey interactions on restored reefs. The goals of this project were: (1) Characterize the benthic communities on restored oyster reefs in lower Chesapeake Bay, and (2) examine the effects of structural complexity and salinity on benthic communities and predator-prey interactions. A two-year field survey of restored reefs was carried out in four rivers in lower Chesapeake Bay to characterize faunal communities on restored reefs and to quantify the effect of reef complexity on faunal communities. A laboratory mesocosm experiment was conducted to examine the effect of reef complexity on predator foraging. In total, 61 macrofaunal species were identified among all samples, and restored reefs supported on average, 6,169 org/m2 and 67.88 g-AFDW/m2. There were significant differences in the community composition and diversity among the rivers, and salinity was the environmental factor that best explained the observed differences in species composition across the rivers. Salinity and rugosity (i.e., structural complexity) both positively affected diversity, while salinity negatively affected macrofaunal abundance and biomass. Oyster density and rugosity positively affected macrofaunal biomass, and oyster density positively affected mud crab, polychaete, and mussel densities. In the mesocosm experiment, predator foraging, measured by proportion and number of prey consumed, was significantly reduced in the presence of oyster shell structure. However, predators were able to consume more prey when prey density was increased, even in the presence of oyster shell structure. These results combine to enhance our understanding of the benefits of increased habitat complexity for both prey and predators on restored oyster reefs. Increasing complexity worked to increase the abundance, biomass, and diversity of organisms inhabiting restored reefs, and even though predator consumption was reduced in the presence of structure compared to non-structured habitat, predators were able to consume more prey individuals when prey density was increased. Therefore, increasing the structure of oyster reef habitat may benefit prey species by providing refuge habitat, and benefit predators by providing an increased abundance of available prey items.
Fishes In Seagrass Habitats: Species Composition, Trophic Interactions, And Production, Kathryn L. Sobocinski
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. …
Impact Of Mercury Exposure On Birds And The Effect Of Molt On Mercury Depuration In Songbirds, Margaret Crossley Whitney
Impact Of Mercury Exposure On Birds And The Effect Of Molt On Mercury Depuration In Songbirds, Margaret Crossley Whitney
Dissertations, Theses, and Masters Projects
No abstract provided.
Ecologically-Framed Mercury Database, Exposure Modeling And Risk/Benefit Communication To Lower Chesapeake Bay Fish Consumers, Xiaoyu Xu
Dissertations, Theses, and Masters Projects
Mercury concentrations and determinants of mercury accumulation were examined for ten finfish species from the lower Chesapeake Bay and its tributaries. None of the sampled fish had total mercury concentrations approaching the U.S. EPA human health screening value. Mercury concentrations in different fish species generally increased with increasing delta 15N, but not delta 13C, suggesting that trophic position, but not dietary carbon source was a dominant determinant. A methylmercury biomagnification model was built to estimate a food web magnification factor of approximately 10-fold increase per trophic level in Chesapeake Bay. Based on otolith strontium-calcium ratios, Atlantic croaker inhabiting less saline …
Habitat And Fish Population Dynamics: Advancing Stock Assessments Of Highly Migratory Species, Patrick D. Lynch
Habitat And Fish Population Dynamics: Advancing Stock Assessments Of Highly Migratory Species, Patrick D. Lynch
Dissertations, Theses, and Masters Projects
Fisheries sustainability is inherently linked to an understanding of the population-level effects of fishing. With an accurate characterization of historical fish and fishery dynamics, management agencies are more equipped to create regulations that sustain fishery resources over the long term. The overarching goal of this dissertation is to contribute to the advancement of fisheries stock assessment and promote resource sustainability. My research focused on highly migratory species (HMS), particularly fishes that reside in the open ocean. These species constitute some of the highest valued global fisheries; however, numerous factors compromise HMS stock assessment and management. These challenges are fully described …
Foraging Ecology And Habitat Use Of The Northern Diamondback Terrapin (Malaclemys Terrapin Terrapin) In Southern Chesapeake Bay, Diane C. Tulipani
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 …
Modeling The Formation Of Periodic Hypoxia In Partially Mixed Estuaries And Its Response To Oligotrophication And Climate Change, Samuel J. Lake
Modeling The Formation Of Periodic Hypoxia In Partially Mixed Estuaries And Its Response To Oligotrophication And Climate Change, Samuel J. Lake
Dissertations, Theses, and Masters Projects
The development of hypoxia represents one of the most common and ecologically detrimental effects of anthropogenic nutrient enrichment in coastal marine ecosystems. Due to the physiological importance of oxygen as a key component of metabolic processes, the development and persistence of hypoxia can reduce the distribution of important species, modify food webs, decrease diversity and richness, and sub-lethally affect growth and reproductive rates. While many recent studies have focused on the global increase in hypoxia and highlighted the need for nutrient reduction strategies, some key processes associated with hypoxia remain understudied. of particular importance is the resolution of the major …
Movements, Growth, And Mortality Of Chesapeake Bay Summer Flounder Based On Multiple Tagging Technologies, Mark J. Henderson
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 …
Evaluating Persistent Organic Pollutants (Pops) And Mercury In The West Antarctic Peninsula (Wap) Food Web, With A Focus On Antarctic Fur Seals (Arctocephalus Gazella), Emily K. Brault
Dissertations, Theses, and Masters Projects
No abstract provided.
The Effects Of Hypoxia On Macrobenthic Production And Function In The Lower Rappahannock River, Chesapeake Bay, Usa, S. Kersey Sturdivant
The Effects Of Hypoxia On Macrobenthic Production And Function In The Lower Rappahannock River, Chesapeake Bay, Usa, S. Kersey Sturdivant
Dissertations, Theses, and Masters Projects
Human development has eroded Chesapeake Bay's health, resulting in an increase in the extent and severity of hypoxia (≤2 mg O2 l-1). The Bay's hypoxic zones have an adverse affect on community function and secondary production of macrobenthos. The production of macrobenthos is important as these fauna link energy transfer from primary consumers to epibenthic predators and demersal fish, and serve as the foremost pathway that carbon is recycled out of the sediment. Additionally, bioturbation, an essential macrobenthic function that causes the displacement and mixing of sediment particles, increases the quality of marine sediments. In the marine environment bioturbation is …
Net Microbial Activity, Vegetation Dynamics, And Ecosystem Function In Created And Natural Palustrine Forested Wetlands In Southeastern Virginia, Usa, Christian A. Hauser
Net Microbial Activity, Vegetation Dynamics, And Ecosystem Function In Created And Natural Palustrine Forested Wetlands In Southeastern Virginia, Usa, Christian A. Hauser
Dissertations, Theses, and Masters Projects
No abstract provided.
Copepod Carcasses, Mortality And Population Dynamics In The Tributaries Of The Lower Chesapeake Bay, David Thomas. Elliott
Copepod Carcasses, Mortality And Population Dynamics In The Tributaries Of The Lower Chesapeake Bay, David Thomas. Elliott
Dissertations, Theses, and Masters Projects
Several studies have documented the occurrence of substantial numbers of zooplankton carcasses in marine field samples. However, the potential effect of carcasses on conclusions resting on zooplankton abundance estimates, and the reasons for carcass occurrence have been largely disregarded. Many field studies do not account for the presence of carcasses in their sampling methodology. Zooplankton carcasses in situ are significant for several reasons. as concentrated particles of organic matter in the water column, zooplankton carcasses can be important vehicles for organic matter transport and hotspots of microbial abundance and activity. If dead animals are treated alive, carcasses could bias the …
Habitat Complexity And Habitat Function Of Native (Crassostrea Virginica) And Non-Native (C. Ariakensis) Oysters In The Chesapeake Bay Region, Heather D. Harwell
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 …
Bioavailability Of Biosolids- And Consumer Product-Associated Polybrominated Diphenyl Ether (Pbde) Flame Retardants To Terrestrial Invertebrates, Michael O. Gaylor
Bioavailability Of Biosolids- And Consumer Product-Associated Polybrominated Diphenyl Ether (Pbde) Flame Retardants To Terrestrial Invertebrates, Michael O. Gaylor
Dissertations, Theses, and Masters Projects
The primary objectives of this research were therefore to evaluate polybrominated diphenyl ether (PBDE) bioavailability to ecologically distinct soil invertebrates exposed to Penta-BDE-treated consumer polyurethane foam (PUF) products and biosolid products with incurred PBDEs. In laboratory bioassays, earthworms (Eisenia fetida) bioaccumulated SigmaPBDEs (47+99+100+183) up to 11,000 mug/kg lipid after 28 days from a mixture of artificial soil and anaerobically-digested sludge biosolid (ADB). Earthworms also bioaccumulated SigmaPBDEs (47+99+100+153+154+183) up to 13,500 and 838,000 mug/kg lipid after 28 d from a mixture of artificial soil and composted sludge biosolid (CB) and Penta-BDE-spiked artificial soil (SAS), respectively. No previous lab studies on bioaccumulation …
Persistent Organic Pollutants(Pops) As Tracers Of Environmental Change And Antarctic Seabird Ecology, Heidi N. C. Geisz
Persistent Organic Pollutants(Pops) As Tracers Of Environmental Change And Antarctic Seabird Ecology, Heidi N. C. Geisz
Dissertations, Theses, and Masters Projects
Antarctic seabirds including Adelie penguins (Pygoscelis adeliae), south polar skuas (Catharacta maccormicki), southern giant petrels (Macronectes gigantus) are high trophic level predators that accumulate persistent organic pollutants (POPs) present in the food webs in which they forage. Little is known about the levels of POPs in some Antarctic organisms (e.g. southern giant petrels), as well as the long-term trends of POPs in the Antarctic ecosystem. Samples from all three seabird species were collected post mortem, including eggs, from the Western Antarctic Peninsula (WAP) and in the Ross Sea throughout the austral summer breeding seasons of 2004--2006. The samples were analyzed …
Assessing The Functional Status Of Created Wetlands In Eastern Virginia Via A Soil And Vegetative Developmental Trajectory, Sara Elizabeth Kreisel
Assessing The Functional Status Of Created Wetlands In Eastern Virginia Via A Soil And Vegetative Developmental Trajectory, Sara Elizabeth Kreisel
Dissertations, Theses, and Masters Projects
No abstract provided.
Effects Of Habitat Quality On Secondary Production In Shallow Estuarine Waters And The Consequences For The Benthic-Pelagic Food Web, David James Gillett
Effects Of Habitat Quality On Secondary Production In Shallow Estuarine Waters And The Consequences For The Benthic-Pelagic Food Web, David James Gillett
Dissertations, Theses, and Masters Projects
Anthropogenic degradation of coastal and estuarine habitats is an ongoing problem facing scientists, natural resource mangers, and the general public. Decreases in habitat quality produce relatively predictable changes in the structure and composition of macrobenthic communities and it has traditionally been assumed that the ecosystem functions of the community change as well. In Chesapeake Bay, the most pervasive cause for the degradation of benthic habitats is the excessive inputs of nutrients that lead to eutrophication and the accumulation of organic matter in the system. Working within this framework, a study was conducted investigating changes in macrobenthic (i.e., secondary) production along …
Acoustics Of Anthropogenic Habitats: The Impact Of Noise Pollution On Eastern Bluebirds, Caitlin Rebecca Kight
Acoustics Of Anthropogenic Habitats: The Impact Of Noise Pollution On Eastern Bluebirds, Caitlin Rebecca Kight
Dissertations, Theses, and Masters Projects
An increasing number of habitats are affected by anthropogenic noise pollution, which is often louder, has a different frequency emphasis, and may occur over a different temporal scale, than natural noise. An increasing number of studies indicate that acoustically-communicating animals in such areas can modify their vocalizations in order to make themselves heard over the noise, but many questions still remain, including: How taxonomically widespread is vocal flexibility in response to anthropogenic noise, and do all vocally flexible species employ the same mechanisms to escape acoustic masking? Are there fitness repercussions for living, communicating, and breeding in noisy habitats? and, …
Effects Of Urban Development On Breeding Bird Diversity: The Role Of Diet And Migration, Elise Anne Larsen
Effects Of Urban Development On Breeding Bird Diversity: The Role Of Diet And Migration, Elise Anne Larsen
Dissertations, Theses, and Masters Projects
No abstract provided.
Community Dynamics In Submersed Aquatic Vegetation: Intermediate Consumers As Mediators Of Environmental Change, James G. Douglass
Community Dynamics In Submersed Aquatic Vegetation: Intermediate Consumers As Mediators Of Environmental Change, James G. Douglass
Dissertations, Theses, and Masters Projects
Natural ecosystems are strongly affected by changes in resource supply (bottom-up forces) and by changes in upper trophic levels (top-down forces). The extent to which these processes impact a system depends largely on the responses of organisms at middle trophic levels. In seagrass beds, a group of mid-level consumers known as mesograzers form a critical link in the chain of impact, connecting seagrass and epiphytic algae with predatory fishes and crustaceans. I observed dramatic seasonal and interannual changes in mesograzer abundance and species composition in eelgrass (Zostera marina) beds of lower Chesapeake Bay, Virginia, and endeavored to explain the top-down …
Status, Distribution And Reproductive Rates Of American Oystercatchers In Virginia, Alexandra Lee Wilke
Status, Distribution And Reproductive Rates Of American Oystercatchers In Virginia, Alexandra Lee Wilke
Dissertations, Theses, and Masters Projects
No abstract provided.
The Influence Of Predation On The Nesting Ecology Of Diamondback Terrapins (Malaclemys Terrapin) In The Lower Chesapeake Bay, Victoria Ann Ruzicka
The Influence Of Predation On The Nesting Ecology Of Diamondback Terrapins (Malaclemys Terrapin) In The Lower Chesapeake Bay, Victoria Ann Ruzicka
Dissertations, Theses, and Masters Projects
No abstract provided.
Developing A Stock Assessment For The Barndoor Skate (Dipturus Laevis) In The Northeast United States, Todd Gedamke
Developing A Stock Assessment For The Barndoor Skate (Dipturus Laevis) In The Northeast United States, Todd Gedamke
Dissertations, Theses, and Masters Projects
The barndoor skate Dipturus laevis is one of seven species in the United States Northwest Atlantic skate complex. The species received little attention until a recent article published in Science reported that the barndoor skate might be on the brink of extinction. In this study, we address not only the virtual lack of information on the life history of the species, but also develop methodologies to assist in the assessment of the barndoor skate population. to investigate the life history of the species, data were collected from 2,310 specimens caught during commercial sea scallop dredging in the southern section of …