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Impacts And Uncertainties Of Climate Change On The Chesapeake Bay, Kyle E. Hinson

Dissertations, Theses, and Masters Projects

Climate change impacts in the Chesapeake Bay will limit the efficacy of nutrient reduction efforts and decrease dissolved oxygen, but uncertainties associated with the magnitude of these effects remain. An understanding of underlying mechanisms that have driven recent warming trends will narrow uncertainties for future pathways of temperature change. Additionally, future simulations of climate impacts in the estuary are dependent on multiple different sources of uncertainty, many of which have not yet been fully evaluated. This dissertation used a three- dimensional coupled hydrodynamic-biogeochemical model to investigate recent warming trends as well as underlying uncertainties likely to influence regional projections of …

Is Diversity Dammed? Analysis Of Fish Diversity In Dammed And Undammed Estuary Streams Within The Virginia Peninsula Using Environmental Dna (Edna), Melinda Ann Spence

Dissertations, Theses, and Masters Projects

Anthropogenic activities are the leading cause to biodiversity decline worldwide. It has been well documented that large dams disrupt dispersal and alter local habitat often leading to less diverse aquatic systems. Yet, it is not well known how much more numerous smaller dams impact fish communities in estuary systems where dispersal is a critical part of the ecosystem, or how dams affect variation in species composition across sites (beta diversity). Coastal waterways of Virginia are impounded by hundreds of small dams. Here we used eDNA (environmental DNA) to assess the alpha, beta, and gamma diversity of fish species within the …

Succession Of The Late Summer Phytoplankton Blooms In The York River Estuary, Va, Heather Kathleen Corson

Dissertations, Theses, and Masters Projects

The influence of bottom-up and top-down controls on the formation and persistence of phytoplankton blooms has been well studied. However, the relative importance of these bottom-up and top-down controls vary spatially and temporally. In the tidal tributaries and mainstem of Chesapeake Bay, the summer dinoflagellate population follows a succession of bloom-producing species. The dinoflagellate species Margalefidinium polykrikoides and Alexandrium monilatum are currently considered the end of this succession. These species form near-annual blooms in the lower half of Chesapeake Bay and are considered harmful algal bloom (HAB) species due to their negative ecological impacts. However, analysis of long-term monitoring data …

Effects Of Environmental Stress From A Changing Climate On Populations Of Commercially Important Bivalves Along The Eastern Coast Of The United States, Anthony Robert Himes

Dissertations, Theses, and Masters Projects

This dissertation evaluates population-level variability in physiological tolerances to environmental stressors in the eastern oyster, Crassostrea virginica, and the hard clam, Mercenaria mercenaria, two ecologically and economically important bivalve species that inhabit the eastern coast of the United States. In Chapter 2, an assessment of the acidification tolerance of larval eastern oysters spawned from two reefs in Chesapeake Bay revealed physiological differences under control and acidified conditions. Differences observed at control conditions indicate potential variations in basal metabolic processes, while the variations in acidification tolerance illustrate the potential for some oyster populations to possess greater resilience to ongoing acidification. More …

Comparing Low Salinity Transcriptomic Profiles Among Hard Clam, Mercenaria Mercenaria, Lines, Leslie Speight Youtsey

Dissertations, Theses, and Masters Projects

The hard clam is an important ecological and economic resource along the U.S. Eastern Seaboard. In Virginia alone, farm gate sales were estimated at $38.8 million in 2018 and $57.8 million in 2021, making Virginia the largest producer of hard clams in the U.S. This industry is primarily limited to higher salinity habitats on the seaside of the Eastern Shore of Virginia and lower Chesapeake Bay. Although the hard clam can be found in lower salinity habitats, they do not grow or survive at rates that are practical for productive aquaculture. Even in areas of higher salinity, hard clams are …

Ecology Of Larval Fishes Along The Western Antarctic Peninsula: Climate-Change Impact, Taxonomy, Phenology, And Thermal Tolerance, Andrew Derik Corso

Dissertations, Theses, and Masters Projects

The Antarctic fish fauna is unique, with approximately 88% of the ~375 known species endemic to the Southern Ocean. One group, the perciform suborder Notothenioidei, dominates fish richness and biomass. These fishes possess several traits that allow existence in frigid conditions, but also limit their ability to cope with temperature increases due to climate change. In the western Antarctic Peninsula (WAP) region, a combination of anthropogenic impacts, including climate change and fishing pressure, threaten these fishes. The WAP is one of the most rapidly warming regions globally (3.4 °C per century) and has the highest fishing pressure for Antarctic krill …

From Field To Shore: Policy Improvements To Better Protect Ecosystem And Human Health From Poultry Wastes In Virginia, Rachael A. King

Dissertations, Theses, and Masters Projects

Commercial poultry production is a large industry with economic importance in Virginia. However, mismanagement of manures and wastes generated from the poultry industry can be a serious threat to ecosystem and human health. Primarily, there is a concern about nutrient pollution related to runoff and infiltration of poultry wastes. High nutrient loading can cause groundwater contamination, eutrophication, and harmful algal blooms (HABs). Additional concerns include metals, antibiotics, and pesticides that can be found in poultry wastes. To determine existing threats to ecosystem and human health from the poultry industry, Virginia policies regulating the industry are reviewed and their strengths and …

Impacts Of Minuca Pugnax On Ecosystem Functioning In Its Historical And Expanded Range, Kayla Shanice Martinez-Soto

Dissertations, Theses, and Masters Projects

Animals across Earth are shifting or expanding their ranges because of climate change. These are climate migrants. Although climate migrants are well-documented, their impacts on recipient ecosystems are not. Climate migrants that are also ecosystem engineers (species that modify or create habitats) will likely have profound effects on ecosystem functioning. The Atlantic marsh fiddler crab, Minuca pugnax, is a burrowing crab that recently expanded its range into the northeast United States. The historical range of M. pugnax was between southern Cape Cod, Massachusetts and Daytona Beach, Florida (Grimes et al., 1989). In 2014, Johnson (2014) found that M. pugnax was …

Impact Of Substrate Type On Eastern Oyster (Crassostrea Virginica) Recruitment And Benthic Community Structure And Productivity In The York River, Jainita Patel

Dissertations, Theses, and Masters Projects

Restoration of eastern oyster (Crassostrea virginica) reefs in the Chesapeake Bay and its tributaries is important, as oyster reefs provide habitat for temperate estuarine communities and shoreline protection. Oysters that settle in crevices, such as those found on natural shell substrates, suffer low mortality, but natural shell is becoming a limited resource in the Chesapeake Bay. Finding an alternative settlement substrate that is complex like natural shell and mimics the benefits of shell substrates with less expense could be the best way to encourage oyster recruitment and survival. The two main goals of this experiment were to (1) understand which …

Ecological Restoration Of The Native Oyster, Crassostrea Virginica, To Chesapeake Bay, David Martin Schulte

Dissertations, Theses, and Masters Projects

Native oyster populations have largely collapsed worldwide, with extensive losses of habitat and ecological function. Efforts to restore oysters have been initiated in Europe, Australia, China and North America. In 2004, the first large-scale oyster restoration project was constructed in Chesapeake Bay, employing novel methods including increasing reef height to mimic pre-exploitation reefs, enlarged reef area to address spatial scale, and augmenting recruitment. High-relief reefs (HRR) were built from 25-40 cm in height to better mimic pre-exploitation reefs, while low-relief reefs (LRR) were built at 6-8 cm off existing bottom, mimicking repletion methods by state fishery management agencies used for …

Hybridization As A Tool For Rapid Adaptation To Novel Environments In Virginia Asclepias, Casey Hensen

Dissertations, Theses, and Masters Projects

Plants, unlike animals, lack the ability to quickly move to desirable locations, which poses a challenge when faced with climate change. Here, we use anthropogenic forest canopy loss in the eastern United States as a model for understanding the effects of climate change. Removal of the forest canopy significantly alters the abiotic habitat, as does climate change, by increasing the variability of moisture, light, and temperature. One powerful mechanism plants can use to cope with environmental change is hybridization, as it provides novel genetic variation. Hybridization, followed by introgression, makes it possible to pass along adaptive traits between species, which …

Disentangling Directed Dispersal: Seed Traits, Shade Tolerance, And Squirrel Caching Decisions, Patrick Lynch

Dissertations, Theses, and Masters Projects

Animal-mediated dispersal of seeds is a crucial step for many trees to relocate propagules to favorable locations for establishment. Scatter-hoarding rodents, such as the Eastern grey squirrel (Sciurus carolinensis), choose cache locations in such a way as to balance the value of the seed and effort taken to cache it against the risk of pilferage from conspecifics. Pilferage avoidance strategies observed in squirrels and other rodents have been described by the optimal density model and the habitat structure hypothesis. These mutually non-exclusive models suggest, respectively, that rodents increase the dispersion of seeds proportional to the value of the seeds and …

Investigating Behavioral Responses To Lead (Pb) Exposure In A Cosmopolitan, Urban Songbird, Joseph Francis Di Liberto

Dissertations, Theses, and Masters Projects

Globally, the contamination of anthropogenically-disturbed environments with lead (Pb) pollution constitutes a major threat for exposed organisms. While Pb is widely known to be toxic at high levels of exposure, recent literature has shown that sublethal levels of this toxin can cause a suite of deleterious effects on individual organismal systems. However, there remain considerable holes in our understanding of how multi-systematic and sensitive responses like behavior are impacted by this form of pollution. Moreover, recent work has suggested that the high selective pressure caused by chronic Pb exposure may drive the resistance and local adaptation of terrestrial organisms. However, …

Empirical Valuation Of Primary And Alternative Nursery Habitats For The Blue Crab Callinectes Sapidus In Chesapeake Bay, Alexander C. Hyman

Dissertations, Theses, and Masters Projects

The blue crab (Callinectes sapidus) is a commercially and ecologically importantspecies found along the Atlantic coast of North and South America. These crustaceans play a critical role in coastal ecosystems, serving as both predators and prey in the food web. The blue crab supports a major fishery in Chesapeake Bay, where the species is a cultural icon. Juvenile blue crabs, the smallest and most vulnerable size classes of individuals, are reliant upon structurally complex habitats. Population dynamics of this species are therefore influenced by spatiotemporally fluctuating environmental variables, such as habitat availability. Understanding blue crab ecology is essential for managing …

Tracing Atlantic Sea Scallops Using Radio Frequency Identification (Rfid) Technology, Will Shoup

Dissertations, Theses, and Masters Projects

Traceable seafood can be linked back to its origin and method of catch. Improving the traceability of marine organisms involves establishing a transparent Chain of Custody (CoC) by collecting data at checkpoints throughout the supply chain, from ship to shore to store. This report explores the feasibility of integrating Radio Frequency Identification (RFID) technology into the United States Atlantic sea scallop (Placopecten magellanicus) fishery in order to improve traceability. This report serves as a forward-looking evaluation of RFID technology that is intended to inform interested stakeholders of its functionality and capabilities. It is not intended to serve as a management …

Place-Based Estuary Science Education At Machicomoco State Park, Anna Caputo

Dissertations, Theses, and Masters Projects

Project description:

This experiential estuary science field trip program was initially created as a master's capstone project by Anna Caputo in partnership with Machicomoco State Park, the Virginia Institute of Marine Science (VIMS), and the Chesapeake Bay National Estuarine Research Reserve (CBNERR). The ultimate goal of the project is to strengthen community estuarine literacy in the local area by teaching students who will be future marine scientists, community leaders, watermen, and environmentally conscious citizens. The program is designed to highlight the coastal habitats at the state park, the issues those habitats are facing, and how science and monitoring efforts done …

Biotic And Abiotic Factors Associated With Temporal And Spatial Variability Of Constitutive Mixotroph Abundance And Proportion, Marcella Dobbertin Da Costa

Dissertations, Theses, and Masters Projects

Mixotrophic protists, which combine the use of photosynthesis and prey ingestion to obtain nutrients for growth, comprise a substantial portion of the plankton community. However, there is a major gap in our understanding of how mixotroph prevalence varies spatially and temporally and under what conditions they dominate. I utilized a recently developed molecular technique to experimentally identify active mixotrophs (taxa identified to be grazing when samples were collected) and combined this with microscopy data to estimate active mixotroph abundance and proportion at two locations in a temperate estuary over a year. Active mixotroph abundance was compared to potential mixotroph (taxa …