Life Sciences Commons^™

Population Parameter Estimation And Stable Isotope Analysis Of Gulf Sturgeon (Acipenser Oxyrinchus Desotoi) In The Pascagoula River, Alfonso Cohuo

Master's Theses

Gulf Sturgeon (GS), Acipenser oxyrinchus desotoi, are a threatened, anadromous fish species in the northern Gulf of Mexico. Their range is from the Pearl River, LA, in the west to the Suwannee River, FL, in the east with a longitudinal divide at Mobile Bay, AL, creating a western population unit (WPU) and an eastern population unit (EPU). Sturgeon belonging to the WPU exhibit lower abundances, higher mortality rates, and are overall less studied than their EPU counterparts. Notable data gaps for the WPU includes the absence of recent population parameter estimations and confirmed feeding habitat. My thesis aims to …

Spatial And Seasonal Patterns Of Above- And Belowground Vegetation Biomass And Potential Drivers In The Pascagoula River Delta, Ms, Evan Grimes

Master's Theses

Coastal wetlands provide a valuable wealth of services to the greater coastal ecosystem and human communities. However, threats such as sea level rise and conservation projects, such as freshwater diversions, have the potential to alter coastal wetlands in different ways. In this thesis, I describe the effects of inundation and nitrogen on vegetation productivity using a field-sampling approach and an in situ controlled mesocosm experiment, called a marsh organ. The West Channel of the Pascagoula River contained significantly higher belowground biomass than the East Channel, which is more anthropogenically modified. Vertical distribution of belowground biomass did not strongly vary between …

How Historic Shipwrecks Influence Dispersal Of Deep-Sea Microbiomes, Rachel Moseley

Master's Theses

This thesis investigates how historic shipwrecks potentially shape dispersal of deep-sea microbiomes. Processes impacting dispersal of microbiomes around artificial structures in the ocean and how they connect to other deep-sea habitats is unknown. Dispersal processes are explained for some macroorganisms by theories in ecology, specifically the Theory of Island Biogeography and the Wooden Stepping Stone hypothesis. These have not been investigated for microorganisms, and thus this work will probe if they are applicable to microbial biogeography in this habitat. Experiments were conducted to establish new “island-like” features in near proximity (25-125 m) to wooden-hulled historic shipwrecks in the northern Gulf …

Trophic Ecology Of Mesopelagic Fish Larvae And Juveniles In The Northern Gulf Of Mexico, Emily Gipson

Master's Theses

The deep-pelagic environment encompasses ocean waters below 200 m depth, and comprises 90% of the volume of the Gulf of Mexico. Deep-pelagic fishes are important prey for many oceanic consumers, but relatively little is known about their early life history, including larval fish trophic ecology. An understanding of the role deep-pelagic fish larvae have in oceanic food webs is important in the development of ecosystem models that examine the connectivity (via vertical migrations) between the deep-pelagic and epipelagic environments with respect to trophic interactions, nutrient cycling, and carbon sequestration. In this study, archived plankton samples collected during 2010 and 2011 …

Development And Use Of An Environmental Dna Tool To Monitor Recovery Of The Critically Endangered Smalltooth Sawfish, Pristis Pectinata, In The Northwest Atlantic, Ryan N. Lehman

Master's Theses

The Critically Endangered Smalltooth Sawfish, Pristis pectinata, was once common in the tropical and subtropical waters of the Atlantic Ocean; however, following global declines in range and abundance over the past century, individuals were restricted to the waters of south and southwest Florida (SWFL) by about the 1980’s. Recently, public encounter reports have emerged in historically occupied habitats in United States waters, suggesting individuals are present in, or re-occupying, these areas, although the status of P. pectinata outside of SWFL is not currently well understood. Targeted environmental DNA (eDNA) surveys were chosen to assess the occurrence of P …

Assessment Of Genetic Diversity In Largetooth Sawfish, Pristis Pristis, Populations Over The 20th Century, Ann Fearing

Master's Theses

The Critically Endangered Largetooth Sawfish, Pristis pristis, experienced global declines in range and abundance over the past century and Australia is now their last stronghold. This research aimed to understand whether these declines have been accompanied by a reduction in levels of genetic diversity. Using P. pristis tissue samples sourced from natural history specimens, three fragments (616-bp, 386-bp, 141-bp) in the mitochondrial DNA (mtDNA) control region were PCR-amplified. At each fragment, significant genetic structure was found in P. pristis overall (Φ_ST=0.946, N=9; 0.813, N=54; 0.771, N=99). The Indo-West Pacific and Atlantic/Eastern Pacific each harbor genetically distinct lineages of …

Microplastic Abundance, Distribution And Impacts On Sargassum-Associated Juvenile Fishes In The Gulf Of Mexico, Olivia Lestrade

Master's Theses

Microplastics are a concern in marine environments because they are highly durable, ubiquitous, and can be mistaken for food and ingested by small organisms. Pelagic Sargassum, an important habitat for larval and juvenile stages of many fish species, is found in large surface aggregations, and may provide complex structure in which microplastics become trapped. This could lead to greater risk of microplastic ingestion by fish early life stages associated with Sargassum habitats. To better understand the impacts of microplastics within Sargassum communities, this study examined 1) microplastic concentrations and ingestion by juvenile fishes associated with Sargassum; 2) the microbial …

Assessing The Nursery-Role Function Of Pelagic Sargassum For Juvenile Fishes In The Northern Gulf Of Mexico, Courtney Stachowiak

Master's Theses

Sargassum, a genus of holopelagic brown algae, floats at the ocean’s surface using air-filled bladders and forms a complex comprised of two species, S. natans and S. fluitans. Oceanic processes (e.g., Langmuir circulation, etc.) aggregate Sargassum into mats and weedlines, and primarily distribute the algal complex throughout the North Atlantic Ocean and the Gulf of Mexico (GOM). These floating habitats provide shelter and feeding opportunities for a diverse community of invertebrates and fishes. Sargassum is a presumed nursery habitat for juvenile stages of commercially- and recreationally-targeted fishery species. In this study, I estimated the standardized abundances of juvenile …

Determining The Trophic Role Of Red Snapper (Lutjanus Campechanus) In Mississippi State Waters Using Stomach Content And Stable Isotope Analysis, Branden Kohler

Master's Theses

The goal of this study was to determine the diet composition, trophic position and ecological role of red snapper (Lutjanus campechanus) in Mississippi state waters utilizing stable isotopes (δ¹³C and δ¹⁵N) and stomach content analysis. Stable isotope analysis of fish and their prey can provide information on species-specific basal resource utilization, diet composition and trophic position which can improve food web models and inform fisheries management decisions. Particulate organic matter (POM), the presumed base of the food web, red snapper muscle tissue, and red snapper stomach contents were collected from 25 sites in 2016 and …

Effects Of Infection Of The Protist Parasite, Dermomycoides Sp., In Dusky Gopher Frog Tadpoles, Jaime Smith

Master's Theses

Infections of the protist parasite, Dermomycoides sp. are thought to have caused several years of low recruitment in the dusky gopher frog (Rana sevosa) populations. I evaluated the effects of density of the infective zoospores, host developmental stage, and tadpoles' ability to acquire resistance to Dermomycoides sp. on dusky gopher frog tadpoles. Tadpoles were exposed to zoospore densities of 0, 250, 500, and 750 zoospores/µL at Gosner stage 25, and we found no significant differences among treatments in tadpole mortality. In evaluating susceptibility by development stage, I exposed R. sevosa to 50 zoospores/µL as eggs, embryos, hatchlings, and …

Do Mosquito Pesticides Harm Their Natural Enemies? Ecological Impacts And Non-Target Effects Of Larvicides On Mosquito Predators, Joseph Nelsen

Master's Theses

Larvicides are chemicals used to kill juvenile mosquitoes. When applied to an area, other aquatic organisms are exposed to these chemicals. The removal or impairment of top insect predators could be beneficial to mosquito populations once harmful pesticide levels dissipate. Two common larvicides were examined: growth regulators (IGRs) and surface films (SFs). The goal of this project was to determine if larvicides harm mosquito predators common to southern Mississippi. I surveyed aquatic sites before and after IGR and SF treatments, and then compared changes in insect community structure. Community evenness was lower in SF treated habitats. When analyzing prey taxa …

Interrelationships Among Monorchiid Trematodes With Special Emphasis On Some Northwestern Atlantic Genera, Apryle Panyi

Master's Theses

The Monorchiidae Odhner, 1911 is a cosmopolitan family of flukes (Trematoda: Digenea) comprising species that parasitize the digestive tract of estuarine and marine fishes as adults. Compared with other oceans, recent morphological or molecular taxonomic work conducted on monorchiid species from the northwestern Atlantic Ocean has been sparse (Manter, 1931; Overstreet, 1969; Andres et al., 2018; Wee et al., 2018, 2019, 2020). Therefore, the present work investigated the interrelationships of some monorchiids from the northwestern Atlantic Ocean with emphasis on several genera and investigated if Lasiotocus minutus (Manter, 1931) Thomas, 1959 constitutes a complex of cryptic species. New morphological and …

The Effect Of Constant Relative Growth Rate Versus Constant Specific Growth Rate On Oocystis Sp, Rachel Kriner

Master's Theses

In this study, a strain of Oocystis sp. (S002) was grown using two different growth strategies at three different temperatures (15°C, 20°C, 25°C). One strategy (GS1) kept a constant specific growth rate (µ) and the other (GS2) kept a constant relative growth rate (µ/µ_max). In both strategies, the cultures were grown following the protocols of a hybrid growth system. The Dilution Phase is an initial semi-continuous growth phase that involves daily dilutions until set growth criteria are met. Followed by a batch culture growth protocol where the cultures were diluted at the onset of the first day and …

Mosquito Communities And Insect-Specific Viruses In A Heterogenous, Urban Landscape In Puerto Rico, Nicole Scavo

Master's Theses

The goal of my thesis was to investigate the relationships between mosquito diversity, Aedes aegptyi populations, and socioeconomic factors (SEF) in an urban setting and to characterize the virome of Ae. aegypti in San Juan, Puerto Rico. Mosquitoes were collected in three periods during late 2018 and early 2019 and were identified to the species level. Socioeconomic factors were measured using foot surveys and U.S. Census data. Some Ae. aegypti females were processed for sequencing and sent to Quick Biology for RNA sequencing to identify viruses. Results showed a link between SEF and Ae. aegypti abundance as well as between …

Elucidating The Molecular Pathways Involved In The Fitness And Water Stress Response Of Pseudomonas Synxantha 2-79 In The Plant Rhizosphere, Clint Henry D. Pablo

Master's Theses

Pseudomonas synxantha 2-79 is a biocontrol agent that represents beneficial indigenous rhizobacteria that are broadly distributed in the Pacific Northwest, USA and flourish in the rhizosphere of commercially grown wheat under surprisingly arid conditions. The molecular adaptation of 2-79-like bacteria to plants growing in dry soils is poorly understood. We hypothesized that the ability of 2-79 to colonize and persist in the rhizosphere of water-stressed plants is underpinned by the formation of hydrating biofilms and the utilization of root exudates that contain plant-derived osmoprotectants called quaternary ammonium compounds (QACs). We tested this hypothesis by identifying waters stress response pathways in …

Characterizing Erad And Antioxidant Response In Ixodes Scapularis Ise6 Cells During Borrelia Infection, Latoyia Downs

Master's Theses

Ticks are hematophagous ectoparasites that transmit a multitude of diseases to humans. Borrelia burgdorferi (BB) and Borrelia miyamotoi (BM) are both tick-borne pathogens that cause disease in humans and are transmitted by the black-legged tick (Ixodes scapularis). A byproduct of blood digestion generates reactive oxygen species that are toxic and cause oxidative stress which promotes cellular damage and dysfunction. The endoplasmic reticulum (ER) is especially affected by oxidative stress, resulting in a buildup of improperly folded proteins in the ER lumen called ER stress. To prevent cellular damage, the tick utilizes an antioxidant system to neutralize ROS and mechanisms …

Historical And Contemporary Variables Affecting The Range And Distribution Of Aedes Aegypti, The Yellow Fever Mosquito, In The United States, Nicole Mackey

Master's Theses

Aedes aegypti, the primary mosquito vector of the yellow fever virus, threatens global health by passing on this virus, as well as chikungunya, dengue, and Zika viruses. Through its natural tendency to live in highly urban areas and bite human hosts; understanding the factors that affect the historical and current range of the pest is invaluable (Gubler, 1998). Although these viruses are not normally found in the United States, lack of vaccinations and wide-spread presence of the mosquito could lead to these diseases being reintroduced with potentially devastating effects (Monath, 2001). To determine a partial historical range of A. aegypti …

Development Of An Attenuated Zika Virus By Editing The 5’ Untranslated Region, E. Ashley Thompson

Master's Theses

Zika Virus (ZIKV) is a mosquito-transmitted flavivirus that usually causes no symptoms to mild febrile in humans, and it has been regarded as an insignificant pathogen to public health. However, recent outbreaks of ZIKV infection have revealed that ZIKV can cause severe neurological effects in adults, such as Guillain-Barre Syndrome (GBS), and in infants whose mothers acquired the virus during pregnancy, causing Congenital Zika Syndrome (CZS). Currently, no approved vaccine is available and there is a critical need to develop an effective and safe vaccine. While most vaccine developmental strategies target the viral prM-E protein of ZIKV, we aimed to …

Maturation Spawning And Larviculture Of Atlantic Croaker (Micropogonias Undulatus) At Low Salinity, Edithrose Fairweather

Master's Theses

Atlantic Croaker is a popular baitfish among anglers targeting a variety of gamefish in the Gulf of Mexico. Aquaculture of this species could help meet the demand for Croaker, especially during winter when wild-caught Croaker are unavailable. Currently, Croaker aquaculture involves broodstock maturation, spawning, and larval culture at high salinity. This protocol prevents the direct use of coastal water for culture along the Mississippi Gulf coast where salinity is low. This study examined the feasibility of performing hatchery production of Atlantic Croaker at low salinity.

Culture of Croaker broodstock at 10, 20, and 30 psu during the maturation period was …

An Analysis Of Dredge Efficiency For Surfclam And Ocean Quahog Commercial Dredges, Leanne Poussard

Master's Theses

Between 1997 and 2011, The National Marine Fisheries Service conducted 50 depletion experiments to estimate survey gear efficiency and stock density for Atlantic surfclam (Spisula solidissima) and ocean quahog (Arctica islandica) populations using commercial hydraulic dredges. The Patch Model was formulated to estimate gear efficiency and organism density from the data. The range of efficiencies estimated is substantial, leading to uncertainty in the application of these estimates in stock assessment. Analysis of depletion experiment simulations showed that uncertainty in the estimates of gear efficiency from depletion experiments was reduced by higher numbers of dredge tows per experiment, more tow overlap …

Vegetative Community And Health Assessment Of A Constructed Juncus-Dominated Salt Marsh In The Northern Gulf Of Mexico, Nickolas R. Murphy

Master's Theses

Deer Island is a coastal habitat which provides a buffer from storm and flood damage as well as shore-line stabilization to the mainland of Biloxi, Mississippi. A third of the land has been lost since 1850, largely driven by tropical storm and hurricane impacts as well as sea level rise. The United States Army Corps of Engineers and Mississippi Department of Marine Resources have targeted the shores of the island as sites for restoration using beneficial use dredged material, and two sites of differing age have since been planted with Spartina alterniflora, Juncus roemerianus, Uniola paniculata, S. patens, and Panicum …

Development And Employment Of Environmental Dna Methods For The Detection Of Bull Sharks (Carcharhinus Leucas) In A Freshwater And Estuarine Interface In The Mobile-Tensaw Delta And Mobile Bay, Alabama, Katherine Schweiss

Master's Theses

Species conservation and management is influenced by the quality of monitoring methods employed, especially when targeting elusive, but ecologically significant species, like elasmobranchs. Bull Sharks (Carcharhinus leucas) are highly mobile predators that rely on estuaries and freshwater rivers for maturation, resources, and refuge; their ability to withstand changing environmental conditions may mean they are linking ecosystems through their habitat usage and movements. Rather than setting nets or attaching acoustic monitoring devices, which can be expensive, time-consuming, and invasive, the analysis of environmental DNA (eDNA) for tracing species presence was used to target C. leucasDNA. The present research …

Early Recruitment Of Crassostrea Virginica To Restored And Natural Oyster Reefs In The Western Mississippi Sound: Larval Supply And Post-Settlement Success, Leah Morgan

Master's Theses

The eastern oyster (C. virginica) is a foundation species that improves water quality, protects shorelines, provides refuge for other organisms, and contributes to commercial fisheries. Successful early recruitment of eastern oyster is vital for resupplying adult populations in the face of habitat loss. Coastal oyster populations are challenged by freshwater input, hypoxia, predation and overfishing. Consequently, substantial efforts have been dedicated toward oyster restoration within the northern Gulf of Mexico. The overall objective of this study was to consider the role and importance of early recruitment to oyster restoration in western Mississippi Sound. During the summer 2018 recruitment period, we …

Effects Of Water Table Depth And Edaphic Characteristics On Plant Diversity In A Southern Mississippi Pitcher Plant Bog, Patrick Kirby

Master's Theses

This study examined the effects that water table depth and soil characteristics have on plant species richness and species composition within pitcher plant bogs across seasons. Eight piezometers were installed at random distances to monitor long-term water table depth and pressure fluctuations along a ~710-meter line transect traversing upland and bog habitats. Vegetation sampling quadrats (n=128) were set up near each piezometer. Cover data and water table depths were collected in spring and late summer. Soil samples collected from each treatment group were used to obtain soil texture and nutrient data. The summer collection period yielded a total gdiversity of …

The Thiol Specific Antioxidant (Tsa1) Gene Is Required For Survival In Macrophages And Oxidative Stress Resistance In Histoplasma Capsulatum, Lauren Kennedy

Master's Theses

Histoplasma capsulatum(Hc) is a pathogenic fungus that causes one of the most common invasive fungal respiratory diseases, Histoplasmosis. Histoplasmaundergoes a dimorphic shift from mold to yeast which is crucial to pathogenesis of the organism.

The thiol specific antioxidant gene, Tsa1,is strongly upregulated in the yeast (pathogenic) morphotype. This data led to the hypothesis that this gene plays a role in protecting Hcfrom host mediated oxidative attack. To characterize Tsa1 function, a knockdown strain (tsa1-RNAi) was created by RNAi gene silencing. Expression of Tsa1in the tsa1-RNAistrain was reduced to 10% that …

Distribution, Abundance, And Trophic Ecology Of Anguilliform Leptocephali In The Northern Gulf Of Mexico, Lillian Collins

Master's Theses

All species of anguilliform eels have pelagic leptocephalus larval stages, which provides a means of monitoring the population dynamics of these otherwise cryptic and hard to study species. The goals of this study were to: 1) describe the distribution and abundance of anguilliform eel leptocephali across the northern Gulf of Mexico, and 2) examine the trophic ecology of leptocephali using stable isotope values of carbon and nitrogen (δ13C and δ15N). A 25-year (1990-2014) ichthyoplankton dataset provided by the National Oceanic and Atmospheric Administration (NOAA) Southeast Area Monitoring and Assessment Program (SEAMAP) was used to examine interannual variations in leptocephalus distribution, …

The Effect Of Historic Shipwrecks On Sediment Microbiomes In The Northern Gulf Of Mexico, Melissa Brock

Master's Theses

Microorganisms are ubiquitously distributed across all aquatic habitats, but it is the environmental conditions of a habitat that determine which microorganisms can thrive in terms of abundance or metabolic activity. Habitats that experience consistent physical and chemical environmental conditions repeatedly favor specific taxonomic groups which may result in a microbial assemblage that is commonly associated with that habitat (i.e., a core microbiome). Core microbiomes have been identified for a variety of natural marine habitats including methane seeps, wood falls, octocoral, and deep-sea sediments. However, it was unknown if the presence of man-made structures on the seafloor, including historic shipwrecks, also …

The Evolutionary Diversity And Biological Function Of Phenazine Metabolite Biosynthesis In Burkholderia Spp, Samuel Hendry

Master's Theses

Burkholderia encompass a group of ubiquitous Gram-negative bacteria that include numerous saprophytes, as well as several species that cause infections in animals, immunocompromised patients, and plants. Some species of Burkholderia produce colored redox-active secondary metabolites called phenazines (Phz). In the model opportunistic pathogen Pseudomonas aeruginosa, phenazines strongly contribute to the competitiveness, formation of biofilms, and virulence in multiple models of infection. Similar depth of knowledge on the diversity, biosynthesis, and biological functions of phenazines in Burkholderiais missing. This project aimed to bridge this gap in knowledge by focusing on phenazine pathways of B. lata and closely related …

The Ecology And Evolution Of The Freshwater Turtles Of Southern Mississippi, Gabrielle Berry

Master's Theses

Turtles are one of the most threatened group of animals in existence today. The Southeastern United States is one of two global biodiversity hotspots for turtle species, including the state of Mississippi, where over 30 species can be found. However, very few studies have occurred within the state. This lack of research is even more startling given the ongoing decline, or even extirpation, of numerous turtle species across the world, due to a number of factors, including habitat degradation, and harvest for food or the pet trade.

The overarching goal of this project was to perform a species inclusive freshwater …

Acute Cardiovascular Response To Low-Load Unilateral, Bilateral, And Alternating Resistance Exercise With Blood Flow Restriction In The Lower Body, Daphney Stanford

Master's Theses

Resistance exercise with blood flow restriction (BFR) has been suggested to exaggerate the exercise pressor response over traditional non-BFR exercise. While applying BFR relative to an individual’s arterial occlusion pressure (AOP) and exercising at low-loads seems to produce a comparable cardiovascular response to traditional moderate or high-load training, it is beneficial to identify modifications for reducing the cardiovascular response to BFR exercise. PURPOSE: To determine if unilateral (UNI), bilateral (BI), or alternating (ALT) exercise modalities elicit different cardiovascular responses during BFR exercise. METHODS: 18 participants (13 male and 5 female) performed four sets of UNI, BI, and ALT knee-extensions at …