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Invasive Species Research In Compensatory Wetland Mitigation: Investigating Plant Community Composition And Environmental Correlates With Three Invasive Plants, Dakota Hunter Jan 2019

Invasive Species Research In Compensatory Wetland Mitigation: Investigating Plant Community Composition And Environmental Correlates With Three Invasive Plants, Dakota Hunter

Dissertations, Theses, and Masters Projects

Invasive plant species can alter natural communities and degrade ecosystem function, yet the factors influencing species invasion are poorly understood. Understanding how environmental factors affect plant invasion on compensatory wetland mitigation sites would allow wetland managers to approach invasive species management using a proactive approach (prior to invasion), thus minimizing the likelihood of invasive plants colonizing the system and degrading ecosystem function. In Chapter 1, I introduce the concepts and relevant literature used repeatedly in my project. In Chapter 2, I examine which key environmental factors are associated with altered plant community structure and invasive species prevalence on compensatory wetland ...


An Exploration Into The Identification, Etiology, And Distribution Of Idiopathic Blindness In The American Lobster, Homarus Americanus, Addison T. Ochs Jan 2019

An Exploration Into The Identification, Etiology, And Distribution Of Idiopathic Blindness In The American Lobster, Homarus Americanus, Addison T. Ochs

Dissertations, Theses, and Masters Projects

Idiopathic blindness is an environmental disease observed in the American lobster, Homarus americanus H. Milne Edwards, 1837. The only diagnostic assay for idiopathic blindness has been the histological assessment of the eye, which is a time consuming, invasive, and a delicate procedure. I investigated several tools, including the otolaryngoscope and enhanced counterstaining using Bouin’s fixative as alternative, rapid methods for the detection of idiopathic blindness in lobsters. I applied these new diagnostic techniques to toxicology studies to explore a possible lead on the etiology of this condition. Divalent manganese is a well-established neurotoxin released from sediments under hypoxic conditions ...


Partitioning Of Hydrophobic Organic Contaminants And Microbial Communities On Microplastics, Kelley Ann Uhlig Jan 2019

Partitioning Of Hydrophobic Organic Contaminants And Microbial Communities On Microplastics, Kelley Ann Uhlig

Dissertations, Theses, and Masters Projects

Microplastic contamination of aquatic environments has only recently caught the attention of scientists, regulators and the public. Microplastics are typically more recalcitrant than naturally occurring polymers and so have the potential to cause a range of issues, including increased exposure of marine life to chemical contaminants sorbed to or leached from microplastics, negative impacts due to ingestion of microplastics by biota, and the potential to carry and transport pathogenic and invasive species long distances. Bio-based, bio-degradable polymers have begun to gain market share as an alternative to traditional petrochemical-based plastics, but not much is known about their impacts in marine ...


Ecology And Evolution Of Common Milkweed, Angela Ricono Nov 2018

Ecology And Evolution Of Common Milkweed, Angela Ricono

Dissertations, Theses, and Masters Projects

All organisms must interact with and adapt to their surrounding environment. There are myriad ways in which species accomplish this; ultimately resulting in the vast diversity of life on earth today. Changes in the environment can have profound impacts on an organisms' ability to compete and utilize their surroundings. Plants are particularly impacted by local environmental differences because of the fact that they are immobile. This environmental variation exists at both large and small spatial scales. For example, on larger scales, forces such as fire and grazers can remove dominant plant competitors. on smaller scales, variation in resource availability (e ...


The Effects Of Dietary Mercury Exposure On Male Fertility In The Zebra Finch, Ananda Menon Nov 2018

The Effects Of Dietary Mercury Exposure On Male Fertility In The Zebra Finch, Ananda Menon

Dissertations, Theses, and Masters Projects

Sperm traits, including morphology, number and function, have been linked to fertilization ability and offspring quality in several species. However, many of these traits are artificially influenced by anthropogenic pollutants. Mercury, a globally distributed heavy metal pollutant, has been linked to altered testicular morphology and reduced fertility in many vertebrates. in this study, we exposed domestic male zebra finches (Taenopygia guttata) to dietary mercury at concentrations found in prey species in a highly polluted watershed region. We then compared sperm traits from these males to those of controls, and found a significant effect of mercury on sperm length and variability ...


Immune Changes In The Anterior Kidney Of Spawning Sockeye Salmon, Meaghan K. Smith Oct 2018

Immune Changes In The Anterior Kidney Of Spawning Sockeye Salmon, Meaghan K. Smith

Dissertations, Theses, and Masters Projects

During the return journey to their spawning grounds, sockeye salmon are exposed to various pathogens and undergo major endocrine changes. Little is known about how these changes affect their immune system. The immune system of salmon is similar to mammals; myeloid lineage cells provide the first response to infection and B lineage cells protect against specific pathogens. After activation by pathogen, B cells may differentiate into long-lived plasma cells (LLPCs) in the anterior kidney, where they can survive for years, continuously secreting protective antibody. This research focused on salmon from two rivers, the Kenai and the Copper River, and characterized ...


Investigating The Spatiotemporal Distribution Of A Tick-Borne Pathogen, Ehrlichia Chaffeensis, Dylan Simpson Aug 2018

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 ...


The Role Of Ecological Interactions In Saltmarsh Geomorphic Processes, Bethany Lynn Williams Apr 2018

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 Apr 2018

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 ...


Impacts Of Atmospheric Nitrogen Deposition And Coastal Nitrogen Fluxes On Chesapeake Bay Hypoxia, Fei Da Mar 2018

Impacts Of Atmospheric Nitrogen Deposition And Coastal Nitrogen Fluxes On Chesapeake Bay Hypoxia, Fei Da

Dissertations, Theses, and Masters Projects

Although rivers are the primary source of dissolved inorganic nitrogen (DIN) inputs to the Chesapeake Bay, direct atmospheric DIN deposition and DIN fluxes from the continental shelf can also significantly impact Chesapeake Bay hypoxia. The relative role of these additional sources of DIN has not previously been thoroughly quantified. In this study, the three-dimensional Estuarine-Carbon-Biogeochemistry model embedded in the Regional Ocean Modeling System (ChesROMS-ECB) is used to examine the relative impact of these three DIN sources. Model simulations highlight that DIN inputs from the atmosphere have roughly the same impact on hypoxia as the same gram for gram change in ...


Individual- And Population-Level Effects Of Temperature And Hypoxia On Two Demersal Fishes In Chesapeake Bay, Benjamin Marcek Jan 2018

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 ...


Improving Stock Assessments And Management Advice For Bluefin Tunas And Other Highly Migratory Species, Lisa Elma Ailloud Jan 2018

Improving Stock Assessments And Management Advice For Bluefin Tunas And Other Highly Migratory Species, Lisa Elma Ailloud

Dissertations, Theses, and Masters Projects

For years bluefin tuna has been the poster child for overfishing and poor management. However, recent improvements in data collection, catch monitoring and international cooperation are providing an opportunity to reverse the perception of a fishery that is doomed to collapse. Stock assessments are conducted routinely to monitor the abundance and productivity of exploited fish stocks so managers can determine how many fish can be sustainably harvested each year. Should a stock be declared overfished or under-going overfishing, the science behind stock assessments also equip managers with the knowledge necessary to make decisions about what short-term and long-term management measures ...


Genetic Analyses Of Striped Bass In The Chesapeake Bay: An Investigation Of Connectivity Among Virginia Subestuaries And An Evaluation Of Close-Kinship Mark Recapture Methodology To Estimate Spawning Abundance., Savannah Michaelsen Jan 2018

Genetic Analyses Of Striped Bass In The Chesapeake Bay: An Investigation Of Connectivity Among Virginia Subestuaries And An Evaluation Of Close-Kinship Mark Recapture Methodology To Estimate Spawning Abundance., Savannah Michaelsen

Dissertations, Theses, and Masters Projects

The striped bass (Morone saxatilis) is an anadromous fish distributed along the eastern coast of North America that currently supports one of the most lucrative and important commercial and recreational fisheries in the region. Since the recovery of the Atlantic stock after a collapse in the late 1970s, studies have focused on understanding the connectivity of major spawning grounds and improving methods of abundance estimation. Studies support strong site fidelity of striped bass to major estuaries along the Atlantic coast, but there has been disagreement about connectivity within the largest spawning ground, the Chesapeake Bay. Additionally, no estimates exist for ...


The Development Of Fiddler Crabs (Uca Spp.) As A Comparative Model System For The Parasitic Dinoflagellate, Hematodinium Perezi And Its Natural Host The Blue Crab, Callinectes Sapidus, Patricia Anne O'Leary Jan 2018

The Development Of Fiddler Crabs (Uca Spp.) As A Comparative Model System For The Parasitic Dinoflagellate, Hematodinium Perezi And Its Natural Host The Blue Crab, Callinectes Sapidus, Patricia Anne O'Leary

Dissertations, Theses, and Masters Projects

Herein, I have completed several experiments which encompass developing fiddler crabs as a model system, as well as sentinel and temperature studies to investigate biotic and abiotic factors in parasite transmission. My studies show which factors prevent, delay, or accelerate transmission and progression of H. perezi. The fiddler crab experiments by chapter are as follows: Chapter 1. I screened adult and juvenile fiddler crab populations for naturally occurring H. perezi infections at endemic and non-endemic sites. No natural infections were found in the adult or juvenile populations (Chapter 1 and 3). I completed inoculation trials with U. minax, U. pugnax ...


Assessing The Impact Of Land Use And Climate Change On Streamflow And Nutrient Delivery To The New River Estuary, Nc, Shanna Williamson Jan 2018

Assessing The Impact Of Land Use And Climate Change On Streamflow And Nutrient Delivery To The New River Estuary, Nc, Shanna Williamson

Dissertations, Theses, and Masters Projects

Freshwater inflow influences numerous physical, chemical, and biological characteristics of estuaries. The influx of freshwater to an estuary typically serves as an important source of allochthonous material from which primary producers derive their energy and transfer this energy to higher trophic levels. Any changes to freshwater flow subsequently impacts nutrient delivery and indirectly impacts organisms across multiple trophic levels. Anthropogenic changes to coastal land use and climate both act to threaten the integrity of estuarine systems by influencing freshwater inflow and dissolved nutrient input. Watershed loading models such as the Regional Nutrient Management (ReNuMa) model offer the ability to estimate ...


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 Jan 2018

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 ...


Consumption Patterns Of Chesapeake Bay Fishes, Christopher James Sweetman Jan 2018

Consumption Patterns Of Chesapeake Bay Fishes, Christopher James Sweetman

Dissertations, Theses, and Masters Projects

As fisheries management moves away from single-species approaches and towards more holistic, ecosystem-based approaches, physiological and ecological interactions need to be explicitly considered and mechanistically understood. Accurate portrayals of food web interactions and the direction and magnitude of energy flow between predator and prey populations are fundamental components to further develop ecosystem-based fisheries management (EBFM). to bolster information that is required within an EBFM framework in the Chesapeake Bay, I conducted research designed to advance traditional dietary studies and better understand the form and structure within the Bay's food web. This research relied on controlled feeding experiments, comprehensive sampling ...


Reproductive Investment In Crassostrea Virginica As An Indicator Of A Tolerance Response To Perkinsus Marinus, Lauren Irene Huey Jan 2018

Reproductive Investment In Crassostrea Virginica As An Indicator Of A Tolerance Response To Perkinsus Marinus, Lauren Irene Huey

Dissertations, Theses, and Masters Projects

The Chesapeake Bay region values oysters for the ecosystem services, lucrative fishery, and historical significance that the species embodies; however, over the last half century, oyster abundances have been reduced to historical lows. Two protozoan parasites, Perkinsus marinus and Haplosporidium nelsoni, have been major influences on oyster populations, especially in high-salinity regions. Today, the population is recovering; catches have increased and oysters have expanded spatially. to investigate the cause of the recovery, three measurements were made on slides of oysters from a histological archive collected during summer at Wreck Shoal in the James River from 1988–2017: oocyte diameter, oocyte ...


The Relationship Between Reproduction And Mortality In Triploid Crassostrea Virginica, Joseph L. Matt Jan 2018

The Relationship Between Reproduction And Mortality In Triploid Crassostrea Virginica, Joseph L. Matt

Dissertations, Theses, and Masters Projects

Unusual mortalities of cultured Crassostrea virginica in late spring have been reported from farms in the Chesapeake Bay from 2014 to 2017. None of the usual causes (e.g. disease, poor husbandry) were likely responsible, and mortalities occurred without clear signs of biological or physical stressors. Mortalities in the spring of 2014 were particularly high on over a dozen farms in Virginia, most of which were on the bayside of the Eastern Shore. Estimated losses were over 50%; however, mortalities only occurred within a four-week period between mid-May and early June. Farmers that had unusually high mortality in their crop ...


Subcellular Localization Dynamics Of Thyroid Hormone Receptor And Mediator Complex Subunit 1, Matthew Robert Femia Jul 2017

Subcellular Localization Dynamics Of Thyroid Hormone Receptor And Mediator Complex Subunit 1, Matthew Robert Femia

Dissertations, Theses, and Masters Projects

Intracellular trafficking of transcription factors is an essential cellular function that has implications in regulating gene expression. For thyroid hormone receptor (TR), nuclear localization is fundamental to its function of mediating gene expression in response to thyroid hormone (T3). Yet, we’ve previously shown that TR contains both nuclear localization signals and nuclear export signals, and shuttles rapidly between the nucleus and cytosol. Mislocalization of TR, and loss of transcriptional control, may lead to negative consequences for growth, development, and metabolism. Here, we explore factors that enhance nuclear retention of TR. Emerging studies suggest that Mediator complex subunit 1 (MED1 ...


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 Jun 2017

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 ...


The Effects Of Timing Of Mercury-Induced Developmental Stress On Songbird Reproductive Success, Ohad Jonathan Paris Jun 2017

The Effects Of Timing Of Mercury-Induced Developmental Stress On Songbird Reproductive Success, Ohad Jonathan Paris

Dissertations, Theses, and Masters Projects

This thesis explored two questions – Does developmental exposure to methyl-mercury affect the later reproductive success of songbirds? Does the timing of such developmental exposure affect the severity of any effects on reproductive success? The second question was formulated to test the Developmental Stress Hypothesis (DSH), which states that early developmental conditions incur later-life fitness consequences. Methyl-mercury (MeHg), a potent environmental toxicant, may induce stress in developing organisms, and have far-reaching negative effects on adult fitness. I tested the DSH by investigating whether the timing of MeHg-induced stress, early vs. late in development, affected later-life reproductive success (a strong measure of ...


Misregulation Of Genomic Imprinting Drives Abnormal Seed Development In Hybrid Monkeyflowers (Mimulus), Taliesin Kinser May 2017

Misregulation Of Genomic Imprinting Drives Abnormal Seed Development In Hybrid Monkeyflowers (Mimulus), Taliesin Kinser

Dissertations, Theses, and Masters Projects

Genomic imprinting is the preferential expression of one allele over the other. It is an epigenetic phenomenon that occurs in the placentas of mammals and the endosperm of angiosperms. Endosperm, like placentas, is a nutrient rich tissue that supports the growing embryo within the seed. All grains are predominantly composed of this tissue. It is the product of a second fertilization event, resulting in both maternal and paternal alleles. Some alleles are regulated differentially, resulting in imprinted genes. There are both paternally expressed imprinted genes (PEGs) and maternally expressed imprinted genes (MEGs) in the endosperm. In general PEGs tend to ...


Superoxide Dismutase In Songbirds: Effects Of Mercury, Exercise, And Sex On An Enzymatic Antioxidant, Juan Mateo Botero May 2017

Superoxide Dismutase In Songbirds: Effects Of Mercury, Exercise, And Sex On An Enzymatic Antioxidant, Juan Mateo Botero

Dissertations, Theses, and Masters Projects

Anthropogenic activities such as burning of fossil fuels, mining, and industrial processes continue to increase the levels of mercury circulating in the environment. Once methylated, mercury can be incorporated into animal tissues, causing it to biomagnify up the food web. Deleterious fitness impacts are commonly associated with increased mercury content in birds. The mechanistic pathway to those effects on fitness needs further research in order to develop appropriate remediation efforts and predict future harm on bird populations. Oxidative stress is proposed as one of the primary ways though which mercury causes accumulation of cellular damage. Well-documented cases of mercury induced ...


Juvenile Blue Crab (Callinectes Sapidus) Response To Altered Nursery Habitat, Megan Wood Jan 2017

Juvenile Blue Crab (Callinectes Sapidus) Response To Altered Nursery Habitat, Megan Wood

Dissertations, Theses, and Masters Projects

Habitats of Chesapeake Bay have been altered due to anthropogenic impacts and climate change. Due to these human disturbances, seagrasses have been extirpated from many areas in lower Chesapeake Bay and persisting beds face future losses as water temperatures continue to rise. Further loss of seagrass habitat will negatively impact juvenile blue crabs (Callinectes sapidus) that use seagrass beds as nursery grounds. Habitat degradation allows for more successful introductions of exotic species, and the communities formed from the mixing of native and exotic species are known as emerging ecosystems. Gracilaria vermiculophylla, an exotic macroalga, may be an emerging nursery habitat ...


Using High-Resolution Glider Data And Biogeochemical Modeling To Investigate Phytoplankton Variability In The Ross Sea, Daniel Edward Kaufman Jan 2017

Using High-Resolution Glider Data And Biogeochemical Modeling To Investigate Phytoplankton Variability In The Ross Sea, Daniel Edward Kaufman

Dissertations, Theses, and Masters Projects

As Earth’s climate changes, polar environments experience a disproportionate share of extreme shifts. Because the Ross Sea shelf has the highest annual productivity of any Antarctic continental shelf, this region is of particular interest when striving to characterize current and future changes in Antarctic systems. However, understanding of mesoscale variability of biogeochemical patterns in the Ross Sea and how this variability affects assemblage dynamics is incomplete. Furthermore, it is unknown how the Ross Sea may respond to projected warming, reduced summer sea ice concentrations, and shallower mixed layers during the next century. to investigate these dynamics and explore their ...


Juvenile Blue Crab Survival In Nursery Habitats: Predator Identification And Predation Impacts In Chesapeake Bay, Amanda Marie Bromilow Jan 2017

Juvenile Blue Crab Survival In Nursery Habitats: Predator Identification And Predation Impacts In Chesapeake Bay, Amanda Marie Bromilow

Dissertations, Theses, and Masters Projects

Predator populations can have significant impacts on prey recruitment success and prey population dynamics through consumption. Young, inexperienced prey are often most vulnerable to predation due to their small size and limited evasion capabilities. to reduce the risk of predation, new recruits and young juveniles typically settle in structured nursery habitats, such as seagrass beds, which promote higher survival by acting as refuges from predators. Thus, successful recruitment to the adult portion of the population is often dependent on the availability of suitable nursery habitat. In this thesis, I used field tethering experiments and gut content analyses to assess the ...


Ecosystem Services Of Restored Oyster Reefs In A Chesapeake Bay Tributary: Abundance And Foraging Of Estuarine Fishes, Bruce William Pfirrmann Jan 2017

Ecosystem Services Of Restored Oyster Reefs In A Chesapeake Bay Tributary: Abundance And Foraging Of Estuarine Fishes, Bruce William Pfirrmann

Dissertations, Theses, and Masters Projects

Oyster reef restoration may enhance the production of ecologically or economically important fish species, an ecosystem service, by providing refuge and foraging habitat. Predicting the effects of oyster habitat restoration on fisheries production in Chesapeake Bay requires a better understanding of fish habitat use, trophic dynamics, and the processes leading to production on a habitat-scale. The objective of this thesis was to evaluate the influence of restored subtidal oyster reefs on the abundance and foraging patterns of mobile estuarine fishes. Specifically, I compared the 1) abundance, 2) stomach fullness, 3) diet composition, and 4) daily consumption rate of fishes collected ...


Age, Growth And Reproduction Of Western North Atlantic Butterfly Rays (Myliobatiformes: Gymnuridae), With The Description Of Two New Species, Kristene Teal Parsons Jan 2017

Age, Growth And Reproduction Of Western North Atlantic Butterfly Rays (Myliobatiformes: Gymnuridae), With The Description Of Two New Species, Kristene Teal Parsons

Dissertations, Theses, and Masters Projects

Batoid fishes are among the most threatened and least understood chondrichthyan species worldwide due to their large body size, conservative life-history characteristics, and predominantly coastal distributions where fishing and habitat degradation threaten the stability of populations. A lack of empirical life history data is widespread across batoid taxa — nearly half of all species are considered data deficient, thus hindering species assessments and the development of effective management strategies. Furthermore, many batoid taxa are in need of taxonomic re-examination. Increasing our understanding of life history traits that determine population productivity, such as age and size at maturity, growth rate, and fecundity ...


The Eastern Oyster Microbiome And Its Implications In The Marine Nitrogen Cycle, Ann Arfken Jan 2017

The Eastern Oyster Microbiome And Its Implications In The Marine Nitrogen Cycle, Ann Arfken

Dissertations, Theses, and Masters Projects

Microbial communities associated with a particular space or habitat, or microbiomes, play significant roles in host health and the regulation of biogeochemical cycles. In oysters these microbiomes may be important contributors in the removal of biologically available nitrogen (N) from the coastal and marine environment through the process of denitrification. Denitrification is the microbially mediated step-wise reduction of nitrate (NO3-) or nitrite (NO2-) to N2 gas. Excess nitrogen in the Chesapeake Bay has been implicated in the increase of eutrophication and other detrimental effects including harmful algal blooms, hypoxia, and loss of benthic communities. Oyster reefs have been shown to ...