Digital Commons Network^™

Climate Change And Mountaintop Removal Mining: A Maxent Assessment Of The Potential Dual Threat To West Virginia Fishes, Lindsey R F Hendrick

Theses and Dissertations

Accounts of species’ range shifts in response to climate change, most often as latitudinal shifts towards the poles or upslope shifts to higher elevations, are rapidly accumulating. These range shifts are often attributed to species ‘tracking’ their thermal niches as temperatures in their native ranges increase. Our objective was to estimate the degree to which climate change-driven shifts in water temperature may increase the exposure of West Virginia’s native freshwater fishes to mountaintop removal surface coal mining. Mid-century shifts in habitat suitability for nine non-game West Virginia fishes were projected via Maximum Entropy species distribution modeling, using a combination of …

Red-Headed Woodpecker Full Annual Cycle Ecology At Fort A.P. Hill, Virginia, Benjamin Nickley

Theses and Dissertations

The red-headed woodpecker is a primary cavity excavator found throughout the Eastern Deciduous Forest and parts of the Great Plains. Although widespread, the red-headed woodpecker is generally considered uncommon, with patchily distributed populations. Over the past 50 years, this species has experienced precipitous, range-wide declines. The red-headed woodpecker uses a variety of cover types to meet resource needs across the annual cycle, ranging from oak savannas and wetlands, to mature beech forests and urban parks. Given their apparent adaptability to such a wide range of habitats, causes of declines are perplexing. To understand and stem declines, recent studies have focused …

Assessing The Relative Influences Of Abiotic And Biotic Factors On A Species’ Distribution Using Pseudo-Absence And Functional Trait Data: A Case Study With The American Eel (Anguilla Rostrata), Taylor E. Woods

Theses and Dissertations

Species’ distributions are influenced by abiotic and biotic factors but direct comparison of their relative importance is difficult, particularly when working with complex, multi-species datasets. Here, we present a flexible method to compare abiotic and biotic influences at common scales. First, data representing abiotic and biotic factors are collected using a combination of geographic information system, remotely sensed, and species’ functional trait data. Next, the relative influences of each predictor variable on the occurrence of a focal species are compared. Specifically, ‘sample’ data from sites of known occurrence are compared with ‘background’ data (i.e. pseudo-absence data collected at sites where …

Determining Tidal Characteristics In A Restored Tidal Wetland Using Unmanned Aerial Vehicles And Derived Data, Victor Thornton

Theses and Dissertations

Unmanned aerial vehicle (UAV) technology was used to determine tidal extent in Kimages Creek, a restored tidal wetland located in Charles City County, Virginia. A Sensefly eBee Real-Time Kinematic UAV equipped with the Sensor Optimized for Drone Applications (SODA) camera (20-megapixel RGB sensor) was flown during a single high and low tide event in Summer 2017. Collectively, over 1,300 images were captured and processed using Pix4D. Horizontal and vertical accuracy of models created using ground control points (GCP) ranged from 0.176 m to 0.363 m. The high tide elevation model was subtracted from the low tide using the ArcMap 10.5.1 …

Identification Of Taxonomic And Functional Ichthyofaunal Zones Within The James River Basin, Virginia, Joseph L. Noel

Theses and Dissertations

Environmental gradients structure ichthyofaunal communities longitudinally along river networks via the selective filtering of species’ traits. In many instances, these environmental influences have created distinct zones of co-occurring fish species. Zonation studies have most often been conducted with taxonomic data (species x site matrices), but the increasing availability of functional trait data creates an opportunity to build more rigorous understanding of species’ co-occurrence patterns. Notably, zonation studies that use taxonomic data may not reveal the same patterns as studies based on trait data. In this study, we tested for distinct ichthyofaunal zonation in James River Basin, VA using a combination …

Second Law Analysis Of Dual Fuel Low Temperature Combustion In A Single Cylinder Research Engine, Hamidreza Mahabadipour

Theses and Dissertations

A detailed second law analysis of dual fuel LTC is not yet available in the open literature even though dual fuel low temperature combustion (LTC) has been studied before. To address this gap, a previously validated, closed-cycle, multi-zone, simulation of diesel-natural gas dual fuel LTC was used to perform a second law analysis. In the current study, a 2.4-liter single-cylinder research engine operating at a nominal load of 6 bar BMEP and 1700 rpm was used. Zone-wise thermodynamic irreversibilities as well as total cumulative entropy generated and lost available work over the closed cycle were quantified. Subsequently, two convenient second-law …

Ion Trajectory Simulations And Design Optimization Of Toroidal Ion Trap Mass Spectrometers, Jessica Marie Higgs

Theses and Dissertations

Ion traps can easily be miniaturized to become portable mass spectrometers. Trapped ions can be ejected by adjusting voltage settings of the radiofrequency (RF) signal applied to the electrodes. Several ion trap designs include the quadrupole ion trap (QIT), cylindrical ion trap (CIT), linear ion trap (LIT), rectilinear ion trap (RIT), toroidal ion trap, and cylindrical toroidal ion trap. Although toroidal ion traps are being used more widely in miniaturized mass spectrometers, there is a lack of fundamental understanding of how the toroidal electric field affects ion motion, and therefore, the ion trap's performance as a mass analyzer. Simulation programs …

Analysis Of The Role Of The Jackson Prairie In Prehistoric/Protohistoric Settlement Patterns Using Survey Data From The Bienville National Forest, Jennifer Ivy Ryan

Theses and Dissertations

Archaeological surveys using the subsurface testing method known as “shovel-testing” have been performed sporadically across the Bienville National Forest in central Mississippi. However; no research-oriented analysis has ever been performed for this area. The Bienville National Forest is located primarily in two physiographic regions: the Jackson Prairie and the Southern Pine Hills. These two regions are distinctly different in topography, soils, and vegetation. No settlement pattern study has been performed in the Jackson Prairie and it has been viewed as an area of low probability. Soils in this region are often heavy clays with high shrink/swell capabilities and poor drainage. …

Desorption Electrospray Ionization (Desi) Mass Spectrometric Imaging Of Spatially Regulated In Vivo Metabolic Rates, Charlotte Reininger Lewis

Theses and Dissertations

Desorption electrospray ionization (DESI) is an ambient ionization technique used for mass spectrometric imaging of biological samples. When coupled with isotopic ratio measurements of deuterium-labeled tissues, DESI provides a means of measuring metabolic rates on a spatially resolved basis. In vivo metabolic rates are desired to better understand diseases such as Alzheimer's, Parkinson's, Huntington's, and various forms of cancer that negatively impact metabolic rates within different organs of the human body. Although DESI has been used to image lipids and metabolites of a variety of tissues and other imaging techniques, such as NIMS, have been used to study kinetic turnover …

Optimal Configurations For Aerosol Monitoring With Multi-Rotor Small Unmanned Aerial Systems, Inna D. Chavez

Theses and Dissertations

Applicability of aerosol sampling on multi-rotor unmanned aerial systems (UAS) platform was investigated. Multi-rotor UAS have impacts of wind speed, turbulence, and orientation possibly contributing to sampling bias. The SKC IMPACT sampler, Tecora C.A.Th.I.A., and modified three-dimensionally printed Universal Inlet for Airborne-Particle Size-Selective Sampling were selected based on particle size-selectivity and operational independence to wind. Airflow visualizations concluded that below UAS fuselage was optimal sampler placement. Tests were conducted with Arizona Road Dust in a still-air chamber, and aerosolized sugar in a wind tunnel. Inlet mounting was evaluated in, upright, upside-down, and horizontal orientations. Horizontal orientations of all inlets resulted …

Subsurface Transport In A North Inlet, South Carolina Salt Marsh: A Porewater Salinity Model, Carolyn Ryan

Theses and Dissertations

Subsurface transport in coastal salt marshes influences the nutrient budget of coastal environments, but is not fully understood. To expand our understanding of this transport, a simple numerical model was developed. The model simulated vertical transport of salt through the surficial muds at a North Inlet marsh on the coastal plain of South Carolina. To improve the model, a tracer study was utilized to calculate the average velocity of groundwater flow through the system. The model was compared with porewater salinity measured using tension samplers and passive diffusion samplers. Each method produced different, uncorrelated results. However, accounting for macro-pores in …

Impact Of Wetlands Loss On The Long-Term Flood Risks Of Devils Lake In A Changing Climate, Sergey Gulbin

Theses and Dissertations

Endorheic (terminal) lakes with no water outlets are sensitive indicators of changes in climate and land cover in the watershed. Since 1990 Devils Lake watershed in North Dakota experienced a dramatic change of local climate: wet phase. This change yielded in a 10-m water level rise in just two decades. The Lake’s water level increase caused flooding of adjacent areas, including towns, agriculture fields and houses of Native Americans, costing over $1 billion in mitigation.

While the climate change contribution to flooding has been established, the role of large scale land conversion to agriculture has not been researched. The purpose …

Chromatographic Analysis Of Low Molecular Weight Polar Compounds In Complex Environmental Matrices And Renewable Materials, Jana Rousova

Theses and Dissertations

One of the challenges in characterization of complex environmental matrices and renewable materials is the determination low molecular weight polar compounds (LMWPCs). Depending on the matrix, the targeted LMWPCs include acids, aldehydes, sugars, sugar alcohols or aminoacids. To investigate the role and impact of these species, a development of accurate and precise analytical protocols is essential. One of the challenges in analysis of LMWPCs is their volatility and thus potential losses during sample preparation. The various matrices including renewable materials may contain >100 compounds that are either non-targeted (i.e., their identity is not known prior to the analysis) or targeted …

Short-Term Effects Of Nutrients On A Barrier Island Grassland Community, Ashley Moulton

Theses and Dissertations

Increased nutrient availability globally has the potential to affect community functional composition of plants in nutrient limited environments, such as coastal grassland systems. Stability of these systems are threatened worldwide by urbanization, as well as effects of sea level rise and increased frequency and intensity of storms, and atmospheric N deposition, associated with climate change. Annual net primary productivity (ANPP), species composition, and functional traits (community weighted specific leaf area (CWSLA), leaf area index (LAI), growth form and photosynthetic pathway) were measured across four treatments to assess multiple resource limitation of nitrogen (N) and phosphorus (P) and functional community response …

Effects Of Prescribed Fire On Cope’S Gray Treefrog (Hyla Chrysoscelis) Across Habitat Scales And Life Stages, Logan Mcdonald

Theses and Dissertations

Fire may alter both aquatic and terrestrial habitat used by all amphibian life stages, yet, our knowledge of its effects on amphibians is primarily limited to adult responses. I present an integrated approach to test the response of Cope’s Gray Treefrog (Hyla chrysoscelis) to fire by examining responses in tadpole performance and survivorship, adult abundance, and oviposition. Tadpoles raised with burned leaf litter had similar survival, but total mass and total length were 440% and 170% greater, respectively, for tadpoles raised in unburned litter. I assessed terrestrial and aquatic oviposition cues by embedding burned and unburned litter treatments within burned …

A Comparative Analysis Of Geometric Morphometrics Across Two Pseudemys Turtle Species In East Central Virginia, Kristin C. Dillard

Theses and Dissertations

The phylogeny of the turtle genus Pseudemys is poorly understood. In Virginia, many turtles have been found with indicator traits of both eastern river cooters (Pseudemys concinna concinna) and northern red bellied cooters (Pseudemys rubriventris). This study explores morphological evidence for hybridization between the two species across three riverine sites in east central Virginia.

Museum voucher groups for each species were analyzed for relative shell height and plastron length. The shape of the plastral scutes and upper jaw were analyzed using landmark-based morphometric software. These metrics were compared with measurements taken from 188 field-caught Pseudemys specimens. …

Deletion Of Cardiac Mir-17-92 Cluster Increases Ischemia/ Reperfusion Injury Via Pten Upregulation, Meeta B. Prakash

Theses and Dissertations

The miR-17- 92 cluster is necessary for cell proliferation and development of the cardiovascular system. Deletion of this cluster leads to death in neonatal mice. The role of this cluster still needs to be defined following ischemia and reperfusion. Methods and Results: Adult male mice were injected with Tamoxifen- was to induce inducible cardiac-specific miR-17- 92-deficient (miR-17- 92-def: MCM:TG:miR-17- 92 flox/flox ) and wild type (WT: MCM:NTG:miR-17-92 flox/flox ) mice were subjected to 30 minutes of myocardial ischemia via left anterior descending coronary artery ligation followed by reperfusion for 24 hours. Post I/R survival (48%) and ejection fraction were reduced, …

A Study Of Sediment Accretion Dynamics In Mature And Restored Tidal Freshwater Forested Wetlands In The James River Watershed Using Surface Elevation Tables And Marker Horizons, Ronaldo Lopez

Theses and Dissertations

Sediment accretion and elevation change in tidal forests, and the corresponding ability of these wetlands to keep pace with sea-level rise (SLR), represent data gaps in our understanding of wetland sustainability. Surface Elevation Tables and marker horizons were installed in three mature tidal forests and a restored tidal marsh, allowing us to measure elevation change, accretion, and subsidence. Additionally, we measured predictor variables to test for their significance in explaining accretion and elevation change rates. Mean accretion at our sites was 11.67 +/- 3.01 mm yr^-1 and mean elevation change was -20.22 +/- 8.10 mm yr^-1, suggesting …

Quantifying Current Sediment Deposition, Legacy Sediments, And Pre-Impoundment Vertical Accretion And Carbon Dynamics Following Dam Removal In A Recently Restored Tidal Freshwater Wetland, Melissa J. Davis

Theses and Dissertations

Damming disrupts natural sediment flow to downstream resulting in legacy sediment accumulation. Legacy sediments have been well investigated in streams throughout the Piedmont region; however, there is no research of legacy sediments following dam removal in low-gradient Coastal Plain streams. Research objectives were to: characterize legacy sediments in a low-gradient stream restoration, quantify pre-impoundment accretion and carbon dynamics, and assess current sediment deposition rates via ¹⁴C analyses within sediment cores and sediment collection tiles. Carbon accumulation and accretion rates of modern tidal sediment have reached that of the tidal relic benchmark and current sediment deposition rates are similar between …

Pelagic Fish Diversity And Density On And Off Restored Oyster Reef Habitat, Danielle Mcculloch

Theses and Dissertations

The heterogeneity provided by structured habitats is important in supporting diverse and dense fish communities. The biogenic reefs created by the native Eastern Oyster, Crassostrea virginica, were once the dominant structural habitat in Chesapeake Bay, and have since declined to less than 1% of historic estimates. Conflicting results on the effects of oyster reef restoration on pelagic fish assemblages make further investigation necessary. Incorporating multiple sampling strategies may help elucidate oyster reef habitat influence on fish assemblages. This study used multi-panel gillnets, hydroacoustic technology, and day-night sampling to describe pelagic fish assemblages on and off oyster reef habitat in the …

Exploratory Modeling Of Environmental And Anthropogenic Impacts On Mercury In Fish Tissue For Select Watersheds In South Carolina, Julia Mcguire

Theses and Dissertations

Fish tissue from various sampling locations in South Carolina rivers has shown elevated levels of mercury (Hg). A number of variables may impact this Hg in fish tissue and this study evaluated the impact of these variables using a predictive model. Over 341 variables were assembled from 6 different databases describing land use, water chemistry, point source pollutants, watershed characteristics and more. One dataset describes the location of historical gold mines throughout the sample site, which have been shown to increase Hg in fish tissue in other locations. The variables were assembled in ArcGIS to evaluate variable significance and to …

Moderate Severity Disturbance Has Similar Effects On The Production Of Three Forests Nested Within The Upper Great Lakes Landscape, Benjamin Tai Sagara

Theses and Dissertations

Moderate severity disturbances, which only kill a subset of canopy trees (e.g., via insects, pathogens, and windthrow), are increasingly widespread, and can alter forest structure and production. Whether moderate severity disturbance similarly affects the net primary production (NPP) of different forest stands within inherently heterogeneous landscapes, however, is unknown. We experimentally disturbed three, 2-ha stands varying in forest structure and primary production, reducing stand basal area 38 to 66 % by stem girdling all mature early successional aspen (Populus) and birch (Betula). For nearly a decade, we examined how the forest stands restructured and recovered, and linked post-recovery physical and …

A Comparison Of Computational Methods For Estimating Estuarine Production And Respiration From Diel Open Water Dissolved Oxygen Measurements, Spencer Tassone

Theses and Dissertations

Diel dissolved oxygen (DO) data were used to characterize seasonal, inter-annual, and longitudinal variation in production and respiration for the James River Estuary. Two computational methods (Bayesian and bookkeeping) were applied to these data to determine whether inferences regarding DO metabolism are sensitive to methodology. Net metabolism was sensitive to methodology as Bayesian results indicated net heterotrophy (production < respiration) while bookkeeping results indicated net autotrophy (production > respiration). Differences in net metabolism among the methods was due to low seasonal variation in respiration using the Bayesian method, whereas bookkeeping results showed a strong correlation between production and respiration. Bayesian results suggest a dependence on allochthonous organic matter (OM) whereas …

Community Gardens: Exploring Race, Racial Diversity And Social Capital In Urban Food Deserts, Jennifer F. Jettner

Theses and Dissertations

Study purpose. The study examined race and racial diversity in community gardens located in Southern urban food deserts, as well as the capacity of community gardens to generate social capital and promote social justice. Methods. A mixed-methods approach was used to describe characteristics of gardeners and community gardens located in urban food deserts, and test Social Capital Theory hypotheses. A convenience sample of 60 gardeners from 10 community gardens was obtained. Data was collected using surveys and semi-structured interviews. Analyses. Univariate and bivariate statistics were used to describe gardeners and gardens. Leader rationales for garden characteristics were analyzed using thematic …

Effects Of Hydraulic Dredging And Vessel Operation On Atlantic Sturgeon Behavior In A Large Coastal River, Michael R. Barber

Theses and Dissertations

The tidal James River, a focus of VCU's Atlantic Sturgeon program, supports both commercial shipping and hydraulic dredging. These anthropogenic threats present documented but preventable sources of mortality to the endangered species. Using three separate VEMCO Positioning System (VPS) receiver arrays, spatial data of previously-tagged fish were collected. ArcGIS and Programita software were used to analyze fish spatial distributions in the presence and absence of potential threats, using additional data including automatic identification system (AIS) vessel locations, vessel passages compiled using camera footage, and dredge records provided by the US Army Corps of Engineers. The data showed a change in …

A Range-Wide Assessment Of Migratory Connectivity For The Prothonotary Warbler Using Stable Hydrogen Isotopes, Jessica Reese

Theses and Dissertations

Populations of many species of migratory birds are declining, and an understanding of how populations are linked between the breeding and nonbreeding grounds is necessary in order to determine drivers of declines. While all current tracking technologies to study the movements of small songbirds are limited by their coarse resolution, tracking birds by measuring stable isotopes in keratin offers an advantage because it requires only a single capture and is cost-effective, which leads to robust sample sizes. While this tracking method is accurate, stable hydrogen isotope values measured in feathers (δ²H_f) are known to be variable …

Behavioral Responses Of Sub-Adult Atlantic Sturgeon (Acipenser Oxyrinchus Oxyrinchus) To Electromagnetic And Magnetic Fields Under Laboratory Conditions, Andrew Mcintyre Iii

Theses and Dissertations

Electromagnetic fields (EMF) produced by high voltage (HV), submarine transmission cables leading from offshore wind energy generation facilities could affect foraging or migratory behaviors of electro-receptive fishes, including endangered Atlantic Sturgeon. However, no published studies have quantitatively evaluated the possible behavioral effects of EMF exposure on sturgeon during residence in coastal waters. This study evaluated behavioral responses by sub-adult Atlantic Sturgeon to electromagnetic and magnetic fields under controlled laboratory conditions. Fabricated EMF generators were used to emulate a range of field EMF conditions that migratory fishes could encounter in proximity to submarine HV sources. Sensor arrays and digital video recorders …

The Effect Of Chronic Nutrient Addition From Wastewater On Forest Ecosystems At The Rice Rivers Center, Michael Beck

Theses and Dissertations

Wastewater application to land can be a useful tool for mitigating impacts of nutrient enrichment on aquatic systems. A land application treatment system at VCU’s Rice Rivers Center in Charles City County, VA provided an opportunity to study the impact of wastewater addition on the biogeochemistry of forests representative of the Mid-Atlantic Coastal Plain. Nutrient concentrations in throughfall and leachate were measured at Treatment and Control sites to assess differences in nutrient deposition and retention. Wastewater amended plots from the Walter L. Rice education building received 20-fold (N) and 6-fold (P) higher inputs relative to Control plots and plots located …

Landfill Elevated Internal Temperature Detection And Landfill Fire Index Assessment For Fire Monitoring, Aurora Musilli

Theses and Dissertations

Landfill fires are becoming a real threat to both people and environment due to lack of predictions and control methods. Processing of the infrared band from level-1 satellite images was employed and decades worth of archived data from USGS Earth Explorer databases were analyzed to obtain surface temperature values of Atlantic Waste Landfill, Virginia and Bridgeton Landfill, Missouri. Multitemporal thermal maps and frequency of maxima analysis maps of these two landfills showed the hotspots spreading through the waste site. A Landfill Fire Index (LFI) was created by investigating eight factors that give information about the hazardousness of the landfill conditions …

A Study Of Wheat Flour Tortillas, Combustion, Selected Gaseous And Nuclear Surrogate Samples Using Laser-Induced Breakdown Spectroscopy (Libs), Charles Tarshi Ghany

Theses and Dissertations

Laser-induced breakdown spectroscopy (LIBS) is an efficient tool for identification of elemental composition and characterization of materials. The concept of this technique is to focus a laser pulse of sufficiently high power on to a sample to create a plasma plume of atoms, ions, and molecules. The measurement of the resulting optical emission from these species provides the basis of the spectral analysis. Spectroscopic analysis of the plasma generated by Nd:YAG laser irradiation of wheat flour tortillas was carried out. A careful selection of spectral lines of Ca, Na and K which do not suffer from spectral interference was made. …