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From Rain Drops To Rivers: Unraveling Aridification's Influence On Coastal Stream Ecosystem Dynamics, Sean Kelly Kinard
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 …
Hybridization As A Tool For Rapid Adaptation To Novel Environments In Virginia Asclepias, Casey Hensen
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 …
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 …
Empirical Valuation Of Primary And Alternative Nursery Habitats For The Blue Crab Callinectes Sapidus In Chesapeake Bay, Alexander C. Hyman
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 …
Impacts Of Minuca Pugnax On Ecosystem Functioning In Its Historical And Expanded Range, Kayla Shanice Martinez-Soto
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 …
Invertebrates In A Migrating Salt Marsh, Emily Marie Goetz
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 …
A Retrospective Analysis Of Atlantic Surfclam (Spisula Solidissima) Growth And Distribution In The Context Of A Changing Ocean, Alexis Hunter Hollander
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 …
Spartina Alterniflora Defense Against Herbivory, Serina Sebilian Wittyngham
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. …
Co-Occurring Hab Species And Phycotoxins: Interactions With Oysters, Sarah Krystal Desautels Pease
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, …
Effects Of Acidification And Salinity On Callinectes Sapidus, Mercenaria Mercenaria, And Their Interactions, Katherine Sara Longmire
Effects Of Acidification And Salinity On Callinectes Sapidus, Mercenaria Mercenaria, And Their Interactions, Katherine Sara Longmire
Dissertations, Theses, and Masters Projects
Ocean acidification (OA) coupled with other stressors, will be detrimental at the species and ecosystem levels. Decreased carbonate ion concentrations negatively impact calcifying species, yet the combined effects of OA and other stressors are less well known, and many studies disregard species interactions. Multi-species studies involving OA and other stressors are crucial to comprehend the full threat of OA. Understanding how OA interacts with other stressors to affect species responses is necessary for future management of exploited species in an altered ecosystem. The objectives of my study were to assess: 1) the effects of long-term exposure to decreased pH and …
Predicting The Impacts Of Climate Change On The Sandbar Shark And Cobia, Daniel P. Crear
Predicting The Impacts Of Climate Change On The Sandbar Shark And Cobia, Daniel P. Crear
Dissertations, Theses, and Masters Projects
A changing climate has been identified as a major driver of changes in marine species’ distribution, phenology, and habitat selection in recent decades and is expected to continue to influence these traits. These changes are not only happening in our oceans, but within coastal habitats as well, where waters are susceptible to sudden changes in temperature and oxygen levels are influenced by nutrient inputs. These changes which will likely impact fish species that utilize these areas as nurseries, spawning habitat, or foraging grounds. In this dissertation I consider climate impacts on two important predators, the sandbar shark (Carcharhinus plumbeus) and …
A Comparison Of Shorebird Habitat Use Between Living Shorelines And Natural Fringing Marshes, Robert Michael Galvin
A Comparison Of Shorebird Habitat Use Between Living Shorelines And Natural Fringing Marshes, Robert Michael Galvin
Dissertations, Theses, and Masters Projects
We examined the use of fringing marshes by herons and shorebirds in the southern portion of Chesapeake Bay. From 13 pairs of natural fringing marshes and nearby, constructed living shoreline marshes, we completed analysis of videos recorded at discrete, 30-minute intervals (dawn, dusk, high tide, low tide) throughout the 2018 and 2019 field seasons (May through August). A total of 684 hours of recording yielded 91 individual observations of birds comprising six species. Spotted Sandpipers (Actitis macularius) were observed most frequently (25), but only at living shoreline marshes. Likewise, 15 of 16 observations of Green Herons (Butorides virescens) were at …
Speciation Dynamics Of Diverging Allopolyploid Monkeyflower (Mimulus), Caroline Victoria Schlutius
Speciation Dynamics Of Diverging Allopolyploid Monkeyflower (Mimulus), Caroline Victoria Schlutius
Dissertations, Theses, and Masters Projects
Our understanding of speciation has been greatly improved with advances in genomic technology, but most of our knowledge of speciation is still built on research of diploid systems. Polyploids, however, are found in many lineages across the tree of life and exhibit considerably different evolutionary dynamics than diploids. Here, we investigate patterns of population structure and divergence in a system of two allopolyploid species of Mimulus (monkeyflower) that occur sympatrically in Chile: M. luteus and M. cupreus. We find that while the two species have consistent phenotypic differences across the range, they are genetically clustered into a northern and southern …
The Epibiont-Host Interaction Between Zoothamnium Intermedium And Estuarine Copepods, Lucia S.L. Safi
The Epibiont-Host Interaction Between Zoothamnium Intermedium And Estuarine Copepods, Lucia S.L. Safi
Dissertations, Theses, and Masters Projects
Ciliates are basal eukaryotes from Phylum Ciliophora that were first described 400 years ago, but their origins date back 800 million years. Such early origins have allowed contemporary ciliates to be remarkably diverse in both their species numbers and ecological adaptations. Peritrichia, a subclass of ciliates, represents an ideal model to study ciliate diversity, as its members display complex phylogenetic relationships and can be epibionts colonizing the body surface of other organisms. Epibiotic relationships are ecologically and evolutionarily important due to the extensive adaptations in epibiont biology to the life cycles of hosts. These relationships are also important for host …
Within-Flight-Period Dynamics Driven By Phenology And Transect Quality, Not Patch Size Or Isolation, In A Specialist Butterfly, Panoquina Panoquin, Sam Mason
Dissertations, Theses, and Masters Projects
As sea levels rise, coastal salt marshes, and the organisms for which they provision, face existential threats. A first step in understanding how projected marsh loss and reconfiguration may impact obligate species is to define their contemporary distribution and temporal shifts in structure using dynamic occupancy models. While occupancy models have commonly been applied to multi-annual butterfly studies, few have investigated population dynamics within a single-season. Here, we used Bayesian dynamic use models to define within-flight-period trends in adult salt-marsh skipper (Panoquina panoquin) use and state change probability. In doing so, we developed and validated a fully-Bayesian test for closure, …
A Mechanistic Understanding Of Range Expansion Of Invasive Blue Catfish In The Chesapeake Bay Region, Vaskar Nepal
A Mechanistic Understanding Of Range Expansion Of Invasive Blue Catfish In The Chesapeake Bay Region, Vaskar Nepal
Dissertations, Theses, and Masters Projects
Blue catfish Ictalurus furcatus is an invasive species of great concern in coastal habitats throughout the eastern United States, inclulding the Chesapeake Bay and its tributaries. In this dissertation, I use field surveys, laboratory experiments and quantitative modeling to provide insights into several aspects of blue catfish biology at the individual level. In chapter 1, I characterize and compare patterns in growth and body condition in blue catfish populations in the James and York river subestuaries during two stages of invasion. Both the mean growth rate and mean body condition of blue catfish declined in the recent period in response …
Evaluating The Impacts Of Land Use And Climate Change On The Hydrology Of Headwater Wetlands In The Coastal Plain Of Virginia, Pamela Braff
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 …
Unexplored Aspects Of The Biotic Filter To Seedling Recruitment In Aquatic Environments, Andrew James Johnson
Unexplored Aspects Of The Biotic Filter To Seedling Recruitment In Aquatic Environments, Andrew James Johnson
Dissertations, Theses, and Masters Projects
Sexual reproduction provides submerged aquatic vegetation (SAV) populations unique opportunities for dispersal, genetic mixing, and resilience in the event of catastrophic population declines. Relative to asexual reproduction, sexual reproduction is a risky resource investment and can have a lower probability of success. A wide variety of abiotic and biotic interactions common in both terrestrial and aquatic environments can lead to significant mortality of seeds and seedlings. The goal of this dissertation is to explore the diversity of biological interactions that influence seed and seedling survival in SAV that drive the population dynamics and restoration success of SAV species. A combination …
Satellites, Seagrass, And Blue Crabs: Understanding Inter-Annual Fluctuations And Linkages In The York River, Kristen Bachand
Satellites, Seagrass, And Blue Crabs: Understanding Inter-Annual Fluctuations And Linkages In The York River, Kristen Bachand
Dissertations, Theses, and Masters Projects
To protect and manage ecosystems over large spatial scales, repeated mapping with remote sensing, such as aerial photography, is valuable, but several potential problems need to be overcome to generate accurate maps. For instance, to monitor submerged aquatic vegetation (SAV), such as seagrass, satellite imagery must often capture seasonal and interannual variation as well as disturbances. We used a model system, SAV and the blue crab Callinectes sapidus in the lower Chesapeake Bay, to examine (i) if Planet Lab (PL) satellite imagery can be used to accurately estimate SAV coverage by comparing PL images coincident with those of the VIMS …
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 …
Investigating The Spatiotemporal Distribution Of A Tick-Borne Pathogen, Ehrlichia Chaffeensis, Dylan Simpson
Investigating The Spatiotemporal Distribution Of A Tick-Borne Pathogen, Ehrlichia Chaffeensis, Dylan Simpson
Dissertations, Theses, and Masters Projects
The incidence of tick-borne diseases is on the rise in the US and around the world, due in part to emerging pathogens. However, the environmental drivers affecting these pathogens remain unclear. Most research on the topic in the US has focused on Borrelia burgdorferi, which causes Lyme, but it is unknown if the same conditions that affect B. burgdorferi also affect other pathogens, which may be carried by other ticks or reservoirs. The answer will help determine generalizable principles in tick-borne pathogen ecology, if they exist, as well as better manage for tick-borne pathogen risk in areas at risk from …
Shifting Patterns Of Ribbed Mussel Distribution And Ecosystem Services In Response To Sea Level Rise, Robert Earl Isdell
Shifting Patterns Of Ribbed Mussel Distribution And Ecosystem Services In Response To Sea Level Rise, Robert Earl Isdell
Dissertations, Theses, and Masters Projects
Throughout the salt marshes of the US Atlantic Coast, ribbed mussels (Geukensia demissa, Dillwyn, 1817) and smooth cordgrass (Spartina alterniflora Loisel) form an important mutualistic relationship. Spartina provides habitat and promotes settling of ribbed mussels, which, in turn, stabilize and fertilize the Spartina and sediment. This relationship, however, is at risk of interruption due to sea level rise, erosion, and coastal development. Among the most at-risk segments of the marsh, the front (waterward) edge of the marsh is also where ribbed mussels and their ecosystem services are concentrated. Despite their importance of ribbed mussels to the salt …
Effects Of Anthropogenic Noise On Songbird Social Networks, Carly Elizabeth Hawkins
Effects Of Anthropogenic Noise On Songbird Social Networks, Carly Elizabeth Hawkins
Dissertations, Theses, and Masters Projects
Anthropogenic noise, which is increasing globally, affects birds from gene expression up through alteration of community composition. as urbanization pushes further into undisturbed habitat, noise often disperses birds away from the point source. The impacts of this dispersal on surrounding quieter areas is not well understood. Therefore, in the first chapter, we sought to understand how noise-related dispersal affected the sociality of groups of songbirds as they moved away from the source of noise. as the displaced birds would likely be forced to occupy a smaller area that may already have resident individuals, we predicted that displaced birds would show …
The Role Of Ecological Interactions In Saltmarsh Geomorphic Processes, Bethany Lynn Williams
The Role Of Ecological Interactions In Saltmarsh Geomorphic Processes, Bethany Lynn Williams
Dissertations, Theses, and Masters Projects
Accelerated sea-level rise poses a significant threat to coastal habitats. Salt marshes are critical coastal ecosystems, providing a host of services such as storm protection, food production, and carbon storage. Persistence of salt marshes in the face of rising sea levels relies, in part, on vertical accretion. Current ecogeomorphic models and empirical studies emphasize the importance of the positive relationship between plant production and vertical accretion via sediment trapping by stems aboveground and belowground organic matter production. Thus, changes in plant production influence salt marsh persistence with sea-level rise. However, studies and models of marsh accretion do not consider the …
Carry-Over Effects In Complex Life Cycles: Linking Larval Food Supply With Juvenile Recruitment Success In Sea Stars, Emily Richardson
Carry-Over Effects In Complex Life Cycles: Linking Larval Food Supply With Juvenile Recruitment Success In Sea Stars, Emily Richardson
Dissertations, Theses, and Masters Projects
The supply of new individuals into a population is one of the most important factors impacting species distributions and ecological interactions within a community. For marine invertebrates with complex life cycles, the supply of new individuals into a population can be influenced by factors experienced throughout their life history—before, during, or after metamorphosis. In recent years, scientists have begun to take a more holistic approach to understanding marine population assemblages by considering links between early life stages. When experiences in the pre-metamorphic life stages impact post-metamorphic life stages, this is known as carry-over effects. Because carry-over effects impact fitness of …
Range-Wide Variation In Common Milkweed Traits And Its Effect On Larvae Of The Monarch Butterfly, David De La Mater
Range-Wide Variation In Common Milkweed Traits And Its Effect On Larvae Of The Monarch Butterfly, David De La Mater
Dissertations, Theses, and Masters Projects
Plants play an important role in structuring ecological communities from the bottom up through interactions with herbivores, and environmental variation can affect these interactions. We use the interaction between common milkweed (Asclepias syriaca) and the monarch butterfly (Danaus plexippus) to examine 1) the role of environmental variation in dictating plants traits, and 2) how those variations affect herbivores. We quantified intraspecific trait variation in 53 natural common milkweed populations, then remeasured these traits when population representatives were regrown in a common garden to control for environmental variation. We then measured growth, performance, and survival of monarch larvae feeding on these …
Movements, Habitat Utilization, And Post-Release Survival Of Cobia (Rachycentron Canadum) That Summer In Virginia Waters Determined Using Pop-Up Satellite Archival Tags (Psats), Douglas Jensen
Dissertations, Theses, and Masters Projects
Cobia (Rachycentron canadum) is a cosmopolitan marine fish inhabiting tropical, sub-tropical, and temperate marine and estuarine waters. Recent changes in U.S. cobia management have sparked controversy and highlighted limitations in our understanding of seasonal movement patterns and problems with estimating recreational harvests. Consecutive years (2015 and 2016) of estimated overharvests from the Atlantic Migratory Group stock triggered accountability measures to prevent overfishing by recreational anglers. My project employed pop-up satellite archival tags (PSATs) to study cobia movements, habitat utilization, and post-release survival. It was, therefore, designed to enhance knowledge of cobia biology and aid sustainable management. We deployed 36 PSATs …
Individual- And Population-Level Effects Of Temperature And Hypoxia On Two Demersal Fishes In Chesapeake Bay, Benjamin Marcek
Individual- And Population-Level Effects Of Temperature And Hypoxia On Two Demersal Fishes In Chesapeake Bay, Benjamin Marcek
Dissertations, Theses, and Masters Projects
Anthropogenically-induced climate change has resulted in increases in water temperature and the frequency and severity of hypoxic events in coastal areas worldwide. Temperature and hypoxia affect fishes' energetics which can, in turn, be reflected in changes in reproductive success and shifts in spatial distributions. in an effort to quantify these changes in Atlantic croaker (Micropogonias undulatus) and spot (Leiostomus xanthurus) in Chesapeake Bay. I: (1) estimated standard and maximum metabolic rates and hypoxia tolerances at five temperatures (10, 15, 20, 25 and 30°C) using intermittent-flow respirometry, (2) examined the effects of hypoxia exposure on metrics of reproductive potential and, (3) …
Impacts Of Sea Level Rise On Tidal Wetland Extent And Distribution, Molly Mitchell
Impacts Of Sea Level Rise On Tidal Wetland Extent And Distribution, Molly Mitchell
Dissertations, Theses, and Masters Projects
Tidal marshes are a major ecological resource in Virginia and a driver of many estuarine functions. Therefore, the long term sustainability of tidal marsh ecosystems is a question of great interest in the research community. Sea level is rising at an unusually high rate in the Chesapeake Bay relative to most of the Atlantic coastline, putting Bay marshes at high risk from drowning and erosion. Sea level rise-driven salinity changes communities and alters ecosystem services. Understanding the patterns of change and the importance of different drivers of change is critical to tidal marsh sustainability. The overarching goal of this research …
Predicting The Impact Of Sea Level Rise On The Distribution Of Phragmites Australis And Spartina Alterniflora And Changes In Community Compositions In Tidal Freshwater Marshes Of James City County, Va, Abbey Humphreys
Dissertations, Theses, and Masters Projects
With ongoing sea level rise (SLR), tidal freshwater marshes (TFMs) eventually will be flooded with more brackish water. The impact of more water and salt on the plant community of TFMs, however, is unknown. With SLR, both the invasive reed Phragmites australis and the native salt marsh grass Spartina alterniflora could become dominant species in TFMs. I am looking at determining how increases in salinity and inundation caused by sea level rise will impact the relative distribution of Phragmites and Spartina in tidal freshwater marshes in Southeastern Virginia. Using GIS, I summarized past expansion patterns by mapping the current and …