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Microbial Community And Vibrio Parahaemolyticus Population Dynamics In Relayed Oysters, Michael Anthony Taylor
Microbial Community And Vibrio Parahaemolyticus Population Dynamics In Relayed Oysters, Michael Anthony Taylor
Doctoral Dissertations
The CDC estimates that 45,000 people are sickened each year by foodborne Vibrio parahaemolyticus in the United States. Filter-feeding bivalve shellfish, such as oysters, are routinely inhabited by human pathogenic V. parahaemolyticus and there currently is not a contaminant management process that effectively reduces concentrations of V. parahaemolyticus in oysters. The transplanting of V. parahaemolyticus -laden oysters to an area with low concentrations or no V. parahaemolyticus, called oyster relay, is one reduction strategy that holds promise for treating live oysters. A key consideration for effective strategies to reduce Vibrio spp. in shellfish is the influence of microbiota in natural …
Effects Of Agricultural Practices On Soil Communities And Their Associated Ecosystem Services, Lesley W. Atwood
Effects Of Agricultural Practices On Soil Communities And Their Associated Ecosystem Services, Lesley W. Atwood
Doctoral Dissertations
To maximize crop yields, commodity crop production systems typically rely on inputs of fertilizers, pesticides, and irrigation; simplification of crop rotations (e.g., monocultures); and strategic use of soil disturbance (e.g., tillage, cultivation, etc.). While these practices are intended to optimize the soil conditions for crop development and reduce spatial and temporal variability in crop yield, they also impact soil biological diversity and the important agroecosystem services soil communities provide. Identification of management practices that are less prone to causing undesirable changes in the soil food web community are central to improving the sustainability of our agricultural systems. In this dissertation, …
Patterns And Drivers Of Carbon Fluxes In Temperate Forests, Andrew Ouimette
Patterns And Drivers Of Carbon Fluxes In Temperate Forests, Andrew Ouimette
Doctoral Dissertations
Despite decades of carbon cycling research in terrestrial ecosystems, a complex suite of biotic and abiotic interactions make a complete understanding of the natural carbon cycle elusive. This thesis aims to advance our understanding of the carbon cycle, and stems from several ongoing projects aimed at quantifying carbon dynamics in forest ecosystems across a range of scales, with a specific effort to include both above and belowground components of forest ecosystems. I begin with a project using detailed chemical measurements on specific segments of root systems from two different tree species, in order to help refine methods that quantify the …
Nitrogen Dynamics And Retention In The River Network Of A Tropical Forest, Luquillo Mountains, Puerto Rico, Richard Brereton
Nitrogen Dynamics And Retention In The River Network Of A Tropical Forest, Luquillo Mountains, Puerto Rico, Richard Brereton
Doctoral Dissertations
This dissertation identifies gaps in the scientific understanding of nutrient cycling, particularly nitrogen (N) cycling, in streams and riparian zones of tropical montane forests, and addresses several of those gaps with original field-based research using study watersheds in the Luquillo Mountains of Puerto Rico as the model system. The Luquillo Mountains have features typical of mature montane tropical forests, such as high background N concentrations in streams and groundwater relative to streams in other biomes. As a USDA Forest Service Experimental Forest, the Luquillo Mountains are accessible to researchers and have abundant monitoring and experimental datasets from which to build …
Moose Density, Habitat, And Winter Tick Epizootics In A Changing Climate, Kyle Ball
Moose Density, Habitat, And Winter Tick Epizootics In A Changing Climate, Kyle Ball
Master's Theses and Capstones
Unregulated hunting and habitat loss led to a near extirpation of moose (Alces alces) in New Hampshire in the 1800s. After state protection in 1901, the estimated population increased slowly to ~500 moose in 1977, then increased rapidly in the next 2 decades to ~7500 following an increase in browse habitat created by spruce budworm (Choristoneura fumiferana) and related timber salvage operations, and then halved from 1998-2016 despite highly available optimal habitat. The declining population was partially related to the specific management objective to reduce moose-vehicle collisions, and a possible change in deer hunter and moose behavior that influence population …
Manganese Limitation As A Mechanism For Reduced Decomposition In Soils Under Long-Term Atmospheric Nitrogen Deposition, Emily D. Whalen
Manganese Limitation As A Mechanism For Reduced Decomposition In Soils Under Long-Term Atmospheric Nitrogen Deposition, Emily D. Whalen
Master's Theses and Capstones
Long-term atmospheric nitrogen (N) deposition has been shown to reduce leaf litter and lignin decomposition in forest soils, leading to an accumulation of soil carbon. Reduced decomposition has been accompanied by altered structure and function of fungal communities, the primary decomposers in forest ecosystems; however, a mechanistic understanding of fungal responses to chronic N enrichment is lacking. A reduction in soil and litter manganese (Mn) concentrations under N enrichment (i.e., Mn limitation) may explain these observations, because Mn is a cofactor and regulator of lignin-decay enzymes produced by fungi. We conducted a 6-month incubation study to evaluate the effect of …
Land Use Change In The Northeast United States: Retaining Forest Structure And Its Soil Hydraulic Properties Through Silvopasture, Anthony John Stewart
Land Use Change In The Northeast United States: Retaining Forest Structure And Its Soil Hydraulic Properties Through Silvopasture, Anthony John Stewart
Master's Theses and Capstones
Growing demand for locally produced agriculture in the Northeast US could result in significant land use change from forests to open pasture and other agricultural uses. This conversion may reduce the soil hydrologic flow due to tree removal and increased soil compaction, leading to increasing surface runoff and erosion. Silvopasture—an agroforestry system that integrates trees with livestock—offers a potentially more sustainable alternative to conversion to open pasture, and has recently gained interest with local land owners and farmers in the region. The retention of trees within pastures may help maintain critical hydrologic functions of forest soils by promoting higher infiltration …
Discerning Differences Between Zooplankton Communities Based On Lake Trophic Status, Jonathan Dufresne
Discerning Differences Between Zooplankton Communities Based On Lake Trophic Status, Jonathan Dufresne
Master's Theses and Capstones
In 2007 the United States Environmental Protect Agency sampled 1157 lakes to determine the state of the nation’s lakes. The data they collected provided a unique opportunity to study the effects of eutrophication on zooplankton community structure across a range of lakes from a large geographical area. Using this data set two main questions were assessed: 1) what level of taxonomic identification is necessary to detect differences in zooplankton community composition as it relates to patterns in water quality and 2) in a dataset that has extensive spatial and temporal variability, how does one account for regional differences in zooplankton …
Phylogenetic And Phylogeographic Analyses Reveal A Species Complex In The Estuarine Nudibranch Tenellia Adspersa, Amanda Sobel
Phylogenetic And Phylogeographic Analyses Reveal A Species Complex In The Estuarine Nudibranch Tenellia Adspersa, Amanda Sobel
Master's Theses and Capstones
Until recently, the nudibranch genus Tenellia (Nudibranchia: Fionidae) was thought to include a single or group of species restricted to temperate estuarine waters. Given the addition of numerous other species from recent studies, the genus now encompasses species from polar, temperate, and tropical oceans from oceanic to estuarine salinities. One such fionid, Tenellia adspersa, is found in temperate estuarine waters globally and its presence is ecologically important as its congeners are capable of decimating colonies of their hydroid prey within a single generation (approx. 20-60 days). The literature is historically vague and conflicted on the morphology, taxonomy, and geographic distribution …