Life Sciences Commons^™

From Rain Drops To Rivers: Unraveling Aridification's Influence On Coastal Stream Ecosystem Dynamics, Sean Kelly Kinard

Dissertations, Theses, and Masters Projects

This dissertation addresses the escalating threat of aridification to global freshwater ecosystems due to anthropogenic climate change, focusing on South-Central Texas, USA, using a space-for-time approach along a precipitation gradient from semi-arid to sub-humid. Over the 2017-2020 survey period, I integrated community, stable isotope, climate, and hydrologic data.In Chapter 2, my initial assessment of fish and invertebrate communities along the precipitation gradient unveiled compositional shifts and other nuanced responses. Positive correlations between fish diversity and rainfall, coupled with unexpected invertebrate diversity patterns, underscored the role of water quality in shaping fish assemblages. Drier conditions imposed abiotic filters, reducing diversity and …

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 …

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 …

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 …

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 …

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 …

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 …

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 …

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 …

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 …

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 …

Spartina Alterniflora Defense Against Herbivory, Serina Sebilian Wittyngham

Dissertations, Theses, and Masters Projects

Plants can alter their chemical, structural (‘resistance strategy’), or morphological traits (‘tolerance strategy’) to deter or mitigate herbivore damage. Developed in terrestrial ecosystems, plant defense theory provides a testable framework for evaluating drivers of plant trait variation and defense strategy selection. Yet, it has rarely been tested in coastal vegetated ecosystems, where intense grazing can denude large spatial areas and disrupt ecosystem services and functioning. Through the lens of plant defense theory, this dissertation examines abiotic and biotic control on traits and defense in the tidal marsh plant, Spartina alterniflora, and assesses their influence on further grazing and herbivore distribution. …

Invertebrates In A Migrating Salt Marsh, Emily Marie Goetz

Dissertations, Theses, and Masters Projects

As sea-level rise converts coastal forest to salt marsh, marsh invertebrates may migrate inland; however, the resulting changes in forest and marsh invertebrate communities, including the stage of forest retreat that first supports saltmarsh species, remain unknown. Additionally, the ghost forest that forms in the wake of rapid forest retreat offers unknown quality of habitat to marsh invertebrates. In a migrating marsh on the Eastern Shore of Virginia, USA, ground-dwelling arthropod communities were assessed across the forest-to-marsh gradient, and the ecological equivalency of ghost forest and high marsh habitats was evaluated to determine if marsh invertebrates utilized expanded marsh in …

Environmental Ecology And Life History Variation Of Perkinsus Marinus, Lydia M. Bienlien

Dissertations, Theses, and Masters Projects

Marine resources provide a growing world population with the opportunity to increase food security, particularly through aquaculture. Oysters are prominent aquacultured species, but marine diseases are a threat to the growth and sustainability of oyster culture. Perkinsus marinus is the most important oyster pathogen of the Atlantic and Gulf coasts of the U.S., where it causes substantial mortality. Despite being one of the most well-studied protozoan parasites of bivalve molluscs, much is still unknown about P. marinus. This research investigated multiple characteristics of P. marinus.In Chapter Two, the environmental ecology of P. marinus was explored through tidal sampling and year-long …

The Role Of Zooplankton Community Composition In Fecal Pellet Carbon Production In The York River Estuary, Chesapeake Bay, Kristen Nicole Sharpe

Dissertations, Theses, and Masters Projects

The biological pump is a critical component of carbon transformation in aquatic ecosystems, but the role that zooplankton play in carbon production and vertical export is rarely studied in estuaries. Zooplankton produce carbon-rich fecal pellets which sink to depth and can fuel benthic community metabolism. The body size and taxonomic structure of the zooplankton community varies on interannual, seasonal, and diel time scales, and can lead to varying carbon production and export rates. We quantified fecal pellet carbon (FPC) production by the whole mesozooplankton community (> 200 µm) in the York River, a sub-estuary of Chesapeake Bay. Biomass and taxonomic …

Ecosystem Enriching And Efficient Solar Energy: Exploring The Effects Of Pollinator-Friendly Solar Facilities On Ecosystem Function And Solar Panel Efficiency, Jordan Martin

Dissertations, Theses, and Masters Projects

As the solar energy industry grows, many hundreds of thousands of acres of land will be transformed into solar panel facilities. With this large change in land use, there is the opportunity to promote biodiversity and support pollinators by using pollinator-friendly management practices at the solar facilities. This paper explores the ecological and economic effects of a pollinator-friendly solar facility compared to a turfgrass solar facility.

I hypothesized that a pollinator-friendly solar facility would be functionally equivalent in pollinator support and overall insect diversity to a pollinator-friendly non-solar field and that both sites would have far greater pollinator support and …

A Retrospective Analysis Of Atlantic Surfclam (Spisula Solidissima) Growth And Distribution In The Context Of A Changing Ocean, Alexis Hunter Hollander

Dissertations, Theses, and Masters Projects

Climate change is one of the greatest challenges the natural world currently faces, particularly in marine ecosystems, as many marine organisms are sensitive to warming water temperatures and other aspects of climate change. The Mid Atlantic Bight region is warming rapidly in comparison to the rest of the world’s oceans. In the face of climate change, organisms must either adapt to altered environmental conditions or shift their distribution to avoid extinction. One such example of the latter is the Atlantic Surfclam (Spisula solidissima), whose range has exhibited a shift over the past 4 decades, recorded in both stock assessments and …

Diel, Seasonal, And Interannual Changes In Coastal Antarctic Zooplankton Community Composition And Trophic Ecology, John A. Conroy

Dissertations, Theses, and Masters Projects

Throughout the ocean, zooplankton transfer energy from primary producers to higher predators and transport carbon from surface waters to depth. The efficiency of these processes depends in part upon the taxonomic composition and trophic ecology of the zooplankton community. Zooplankton species abundance and distribution shifted over recent decades along the West Antarctic Peninsula during a period of rapid regional warming and sea-ice decline. Although conducted within the context of long-term change, this dissertation research focuses on zooplankton dynamics at finer temporal scales that have received less attention. I analyzed depth-stratified net samples to investigate zooplankton diel vertical migration during Antarctic …

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 …

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. …

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 …

A Quantitative Genetic Analysis Of Commercial Traits In Polyploid Crassostrea Virginica, With An Evaluation Of Strategies For Genetic Improvement Of Triploids, Joseph L. Matt

Dissertations, Theses, and Masters Projects

Triploids are a popular product in commercial oyster aquaculture and make up most of the hatchery-produced Crassostrea virginica farmed in the Chesapeake Bay. Despite their importance to commercial aquaculture, the potential of genetically improving triploid C. virginica from selective breeding and breeding strategies for their improvement had not been evaluated. In this dissertation, the prospect of improving triploid C. virginica through selective breeding was assessed with a quantitative genetic analysis from a field test, and breeding strategies for genetically improving triploids were compared by computer simulation. Heritability and genetic correlations involving commercial traits in triploids, including mass mortality associated with …

Bird-Window Collisions And Reflection As A Daytime Risk Factor, Lauren Celeste Emerson

Dissertations, Theses, and Masters Projects

Bird-window collisions account for millions of bird deaths annually in the United States. Despite many correlative studies citing the potential influence of reflective glass on daytime collision risk, few studies have explicitly tested this hypothesis. We aimed to determine whether reflection from a window influences daytime collision risk by manipulating the lighting conditions on exterior and interior window surfaces. We conducted this research within a flight tunnel in which domesticated zebra finches (Taeniopygia guttata) flew towards a window structure with two windows situated behind a mist-net. We assessed collision risk and flight velocity through 3D videography. We predicted that risk …

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 …

Evaluating The Use Of Acoustic Warning Signals To Reduce Avian Collision Risk, Robin Grace Thady

Dissertations, Theses, and Masters Projects

Collisions with human-made structures are responsible for billions of bird deaths each year, resulting in ecological damage as well as regulatory and financial burdens to many industries. Acoustic warning signals can alert birds to obstacles in their flight paths in order to mitigate collisions, but these signals should be tailored to the sensory ecology of birds in flight. The effectiveness of various acoustic warning signals likely depends on the influence of background noise and the relative ability of various sound types to propagate within a landscape. I evaluated the ability of four sound signals to elicit collision-avoidant flight behaviors from …

Co-Occurring Hab Species And Phycotoxins: Interactions With Oysters, Sarah Krystal Desautels Pease

Dissertations, Theses, and Masters Projects

Harmful algal bloom (HAB) events are generally marked by the over-abundance of one particular HAB species. Co-occurrence of multiple HAB species or HAB toxins, especially at low cell or toxin concentrations, is common. While much research has been dedicated to understanding the detrimental effects of individual HAB species and toxins on human health and the environment, implications of HAB co-occurrence for seafood safety and shellfish health are poorly understood.Oysters support economically-valuable fisheries and aquaculture worldwide, however, oysters encounter co-occurring HAB species and toxins in their environment. Some HAB species and toxins are harmful to oyster health, harming the immune system, …

Endangered Species Act: Quantifying Threats Impacting Listing, Delaney Costante

Dissertations, Theses, and Masters Projects

With species increasingly becoming imperiled due to anthropogenic activities, conservation practitioners are tasked with determining conservation priorities in order to make the best use of limited resources. The United States’ Endangered Species Act (ESA) has two listing statuses into which imperiled species are placed to receive protections: Threatened or Endangered. In the first chapter, our objective was to identify differences between Threatened and Endangered species beyond what is outlined in their ESA definitions. To our knowledge, this is the first study to compare listing status for species protected by the ESA on the basis of types and number of threats …

Stock Composition Of Striped Marlin (Kajikia Audax) In The Central North Pacific Ocean Inferred By Analyses Of Genome-Wide Molecular Markers, Jackson Martinez

Dissertations, Theses, and Masters Projects

Relative to many highly migratory fishes, Striped Marlin, Kajikia audax, exhibit considerable stock structure. At least four genetically distinct stocks of Striped Marlin have been delineated in the Pacific and Indian oceans, although stock composition in the central North Pacific (CNP) remains unclear and the presence of an additional stock in the North Pacific has been suggested in two recent studies. The goals of this research were to clarify the number of Striped Marlin stocks in the North Pacific and utilize temporal sampling to better understand the stock dynamics of Striped Marlin exploited by the Hawaii-based pelagic longline fishery (HBPLLF). …

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; …

Evaluating The Impacts Of Land Use And Climate Change On The Hydrology Of Headwater Wetlands In The Coastal Plain Of Virginia, Pamela Braff

Dissertations, Theses, and Masters Projects

Located at the interface between uplands and surface water networks, headwater wetlands act as a natural filter to improve downstream water quality and play a critical role in maintaining the ecological integrity of downstream aquatic ecosystems. Vulnerable to development pressure, as well as indirect impacts from land use and climate change, the loss and alteration of headwater wetlands has been linked to the loss of biodiversity and regional water quality declines worldwide. The overall goal of this dissertation is to address some of the challenges associated with the management and conservation of headwater wetlands in the coastal plain of Virginia …