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Full-Text Articles in Physical Sciences and Mathematics
Estuarine Microbiomes And Biogeochemistry: Impacts Of Spatiotemporal Variation, Algal Blooms, And Microplastics, Samantha Grace Fortin
Estuarine Microbiomes And Biogeochemistry: Impacts Of Spatiotemporal Variation, Algal Blooms, And Microplastics, Samantha Grace Fortin
Dissertations, Theses, and Masters Projects
Estuaries are biogeochemical hotspots connecting terrestrial and coastal ecosystems. Anthropogenic disturbances, including increased nitrogen loading and plastic pollution, may have significant impacts on estuarine carbon and nitrogen cycling by altering microbiome structure and functions. The overarching goal of this dissertation was to examine how microbiomes and their associated biogeochemical processes are influenced by natural variation and anthropogenic disturbances in the York River Estuary (YRE). In chapter 2, spatial and temporal variation in benthic microbiomes and the rates of denitrification, anaerobic ammonium oxidation (anammox), and dissimilatory nitrate reduction to ammonium (DNRA) were examined to determine biotic and abiotic drivers of nitrogen …
Recruitment And Post-Settlement Mortality Of The Soft-Shell Clam, Mya Arenaria, Shantelle Landry
Recruitment And Post-Settlement Mortality Of The Soft-Shell Clam, Mya Arenaria, Shantelle Landry
Dissertations, Theses, and Masters Projects
The soft-shell clam, Mya arenaria, is a benthic, filter-feeding, infaunal clam typically found in intertidal and shallow subtidal waters. Chesapeake Bay stocks of M. arenaria have been depleted since the 1960s due to various factors including predation, temperature, low recruitment, habitat loss, disease mortalities, and commercial harvest. As an important prey item for many commercial species, low abundances of these clams are mostly the result of the voracious appetite of the blue crab, Callinectes sapidus. In addition to predation, summer water temperatures in the Chesapeake Bay are likely driving the low abundances of M. arenaria, as water temperatures commonly surpass …
Quantifying The Increased Resiliency Of Chesapeake Bay Hypoxia To Environmental Conditions: A Benefit Of Nutrient Reductions, Luke Thomas Frankel
Quantifying The Increased Resiliency Of Chesapeake Bay Hypoxia To Environmental Conditions: A Benefit Of Nutrient Reductions, Luke Thomas Frankel
Dissertations, Theses, and Masters Projects
Seasonal hypoxia is a characteristic feature of the Chesapeake Bay as a result of anthropogenic eutrophication from agriculture and urban development throughout the watershed. Although in recent years coordinated management efforts have successfully reduced the flux of nutrients into the Bay, the overall goal of sufficient oxygen concentrations below the pycnocline for living resources remains unfulfilled. This was particularly apparent in 2018 and 2019 when the volume of hypoxic water exceeded the long-term (35-year) average due to anomalously high riverine discharge. To quantify the impact of watershed nutrient reductions, conventional statistical methods were employed in concert with a 3-D numerical …
Dealing With Many Species: Improving Methodology For Forming And Assessing Species Complexes, Kristen Omori
Dealing With Many Species: Improving Methodology For Forming And Assessing Species Complexes, Kristen Omori
Dissertations, Theses, and Masters Projects
In the United States, the Magnuson-Stevens Reauthorization Act mandates that all federally fished species must have catch limits, which can be challenging for data-limited species. One approach is to assess and manage a group of species with similar life history characteristics, vulnerability to the fishery, and overlapping geographic distributions in a single management unit, or a complex (i.e., stock or species complex). Using the Gulf of Alaska (GOA) Other Rockfish complex as a case study, the main goals of this dissertation are five-fold: 1) review species complexes in the United States; 2) compare multivariate techniques for assigning species to complexes; …
Improving Observation, Assessment, And Management Of Atlantic Coastal Sharks, Cassidy Dawn Peterson
Improving Observation, Assessment, And Management Of Atlantic Coastal Sharks, Cassidy Dawn Peterson
Dissertations, Theses, and Masters Projects
Coastal sharks represent a group of stocks for which observation, assessment, and management are particularly challenging. Large distributional ranges, complex migratory behavior, low economic value, and relatively few observations in fishery independent surveys hinder relative abundance estimation. Assessing stock status of coastal sharks is encumbered by limited data availability, data quality, and knowledge of life history strategy. Further, coastal sharks are challenging to manage due to their slow intrinsic population growth rates, competing stakeholder interests, history of overexploitation, and in some cases, subjection to international exploitation. This dissertation aimed to improve the capacity to observe relative abundance of coastal sharks. …