Life Sciences Commons^™

Quantifying Rates Of Autocompaction In The Pearl River Marsh, Louisiana, Jeremiah Nicholas Prouhet

Master's Theses

Annual rates of shallow autocompaction (< 1 m) were calculated in the upper ~one meter of sediment from six cores of a transect in the Pearl River Marsh (PRM), Louisiana, in order to determine the most significant sedimentary property controlling this process. Compaction-free wedge cores were sub-sampled at one centimeter intervals to collect the following data: age control, using 137Cs and 210Pb, and sedimentary variables, specifically, particulate organic carbon, bulk density, median grain size, porosity, and water content. An upper and an underlying sedimentary unit (named the 137Cs and 210Pb units) were defined between radiometric datum levels, and their sedimentary properties were statistically tested for significant differences using the non-parametric Mann-Whitney test. Rates of autocompaction were calculated from the model of Williams (2003), and both rates of autocompaction and sedimentation were tested for significant differences between the upper and lower sedimentary units.

The upper unit in the six cores generally had lower bulk density, higher water content, higher porosity, and higher particulate organic carbon than the underlying unit, but with some interesting exceptions. Additionally, annual autocompaction and sedimentation rates were greatest in the overlying unit at stations PR02 (0.39 ± 0.05 cm/y) and PR05 (0.42 ± 0.03 cm/y) and greatest in the underlying unit at stations PR02 (0.22 ± 0.08 cm/y) and PR03 (0.18 ± 0.06 cm/y). Based on Spearman correlations, rates of autocompaction were most strongly correlated to and influenced by rates of sedimentation rather …

Measuring And Comparing Quantum Yield In Two Species Of Marine Diatoms Subjected To Constant And Fluctuating Light Conditions, Matthew Leon Stone

Master's Theses

A small-scale study was conducted to determine the effects of light fluctuations on the photosynthetic efficiency of marine phytoplankton. Two species, Phaeodactylum tricornutum and Chaetoceros gracile were grown in specialized photobioreactors on a 12-hour:12-hour light:dark cycle. The cultures were diluted 50% daily to attain a specific growth rate of 0.70 d-1. To simulate vertical mixing in high turbidity habitats under various wind conditions, dense cultures were subjected to fluctuating light treatments with frequencies ranging from 0.10 Hz to 2.00 Hz. Parallel experiments subjected the cultures to static light conditions with equal total daily light doses as those of the cultures …

Phytoplankton Abundance And Species Composition In Relation To Environmental Paramenters In Coastal Mississippi Waters, Luz Karime Molina

Master's Theses

Phytoplankton pigments from Coastal Mississippi waters were measured to determine the spatial and temporal distributions and composition of phytoplankton communities. Concentration of phytoplankton pigments were analyzed using High Performance Liquid Chromatography (HPLC) and the compositional changes in phytoplankton communities were determined with CHEMTAX 1.95. Surface water was collected for two years (September 2007-November 2009) at three sampling sites on a monthly basis. The stations were located at the Bay of St. Louis (station 1), the Mississippi Sound (station 4) and the Mississippi Bight (station 8), following a salinity gradient. A time series of the observations documented the variability of different …

The Use Of Computed Tomography To Measure Biogenic Structures In Recently Hypoxic And Normoxic Sediments On The Louisiana Continental Shelf, Valerie Ann Hartman

Master's Theses

Over the past 60 years, seasonal hypoxia in the northern Gulf of Mexico has occurred with increased severity and over a greater area. To determine if biogenic structures in the northern Gulf of Mexico vary in response to hypoxic stress, the seafloor on the continental shelf of Louisiana was analyzed during the spring and fall of 2009 at four provinces of similar sediment type that differ in recent history of bottom water oxygen concentration. Subcores were analyzed by computed tomography (CT) to determine the number, diameter, length, volume, surface area, and depth of biogenic burrow structures in sediments where biogenic …

Influence Of Detritus Levels And Organic Pollution On Interspecific Resource Competition, Oviposition Behavior, And Larval Survival Of Two Tire-Inhabiting Mosquito Species (Diptera: Culicidae), David Wayne Allgood

Master's Theses

Mosquitoes (Diptera: Culicidae) are vectors of disease in the adult stage, but understanding the factors affecting distributions of the immature stages is important to the understanding and control of adult populations. Discarded automobile tires comprise important larval mosquito habitats. The Asian tiger mosquito (Aedes albopictus) and the southern house mosquito (Culex quinquefasciatus) are two medically important species commonly found in tires, but factors affecting their larval distributions in tires have not been studied, nor have their interspecific interactions. I investigated the effects of chemicals associated with organic pollution on oviposition preferences and larval survival of both …

Tick Infestations And Their Consequences For Migratory Songbirds During Spring Stopover, Johnny Michael Sellers Jr.

Master's Theses

Migratory birds face a number of challenges during their seasonal movement from tropical/sub-tropical Central and South America to more temperate North America. Maintaining health during migration is of particular concern. This study seeks to understand how haematophageous ectoparasites, such as ticks (Ixodida), impact host body condition as they feed on passerines during migration. We hypothesized that foraging location would impact tick acquisition by migrants and that tick burdens during migration would negatively impact body condition. We surveyed 2,064 birds during spring 2009 and 2010 and found that 2.4% of the surveyed birds were infested with one or more …

Thermal Tolerance Of Age-0 Gulf Of Mexico Striped Bass (Morone Saxatilis): Ontogenetic And Genetic Effects, Corey Robert Anderson

Master's Theses

Striped bass, Morone saxatilis, were historically abundant in the Gulf of Mexico region but were largely extirpated from most Gulf rivers by the early 1960s. Since 1967 hatchery stocking has supported populations in Mississippi rivers and to date there is no evidence of natural reproduction. Intolerance of striped bass to high water temperature is a potential factor negatively impacting Gulf striped bass survival and reproductive fitness, and may be a limiting factor to reintroduction of the species in Mississippi. This work contributed to restoration efforts by establishing molecular tools necessary for genetic monitoring of striped bass restoration, and evaluating …

An Analytical Study Of Air-Sea Co2 Gas Exchange In The Northwest Mississippi Bight Region, Andrea Kathryn Braatz

Master's Theses

With the continued increase of carbon dioxide (CO2) emissions, researchers are concerned with accumulation of excess CO2 within the atmosphere. The ocean is an important sink for the drawdown of atmospheric CO2 concentrations. Due to high spatial and temporal variability, CO2 fluxes in the coastal ocean are not as well characterized as those for the open ocean. More specifically, data for the northern Gulf of Mexico (GOM) coastal region is lacking. A time series analysis of air-sea CO2 flux rates from May through December 2009 was conducted using data collected by The University of Southern Mississippi’s Central Gulf Ocean Observing …

Temporal And Spatial Variability Of Phytoplankton Biomass In Coastal Mississippi Waters, Lorin Matthew Dornback

Master's Theses

Chlorophyll concentrations were measured in western Mississippi coastal waters to determine the spatial and temporal variability of phytoplankton. Nutrients (nitrate, silicate, phosphate), river discharge, temperature, salinity, stratification, tides, currents and winds were measured in concert with the phytoplankton concentrations. The purpose of this study was to determine the seasonal variability in phytoplankton and what was driving the variability. This study was comprised of a three year (September 2007-November 2010) time series where samples were taken once a month for eight stations. Profiles of each station were taken using a Conductivity, Temperature and Depth (CTD) sensor and a WET Labs FL-3 …

A Formative Evaluation For A Food Choices Intervention In A Mississippi Delta Community: A Focus Group Of Rural African American Adolescents, Jovan Chantrell Eugene Williams

Master's Theses

A needs assessment should be conducted to plan effective interventions. This study used a qualitative research approach to examine the eating patterns, food purchasing and preparation skills and practices, barriers and facilitators of dietary change, social and contextual influences on food choices, and preferences for communication and presentation channels and styles of low-income rural African American adolescents. Seven focus groups were conducted with a total of 33 participants, 21 girls and 12 boys, aged 13-18. Adolescents were grouped by age and gender. A moderator, who was trained in focus group methodology, conducted the session using a focus group discussion guide …

Diet And Feeding-Related Morphometrics Of The Blackstripe Topminnow, Fundulus Notatus, In Allotropic And Syntopic Populations With The Blackspotted Topminnow, Fundulus Olivaceus, Charles Michael Champagne

Master's Theses

The Fundulus notatus species complex consists of three described species: F. notatus, F. olivaceus and F. euryzonus. Both F. notatus and F. olivaceus have broad overlapping ranges with many populations being found within and outside of contact zones. Contact zones are generally found in midreaches with F. olivaceus dominating headwaters and F. notatus in larger rivers downstream. Both species share similar ecological niches so the mechanism allowing for stable coexistence in contact zones is unknown. The purpose of this study was to examine variability in diet and feeding morphology of F. notatus in syntopic and allotopic populations across …

Feeding Selectivity And Habitat Usage Of Esox Americanus, Scott Richard Clark

Master's Theses

Patterns of piscine prey selection and habitat usage of Esox americanus were assessed through a series of field and experimental studies. Although few detailed studies exist on the foraging behavior and habitat usage of E. americanus, throughout its range it may be an important trophic component in maintaining fish assemblage structure in many lower order streams. Across 17 sampled streams, the presence of E. americanus among reaches within streams was found to be strongly correlated with increasing levels of habitat complexity. Reaches occupied by E. americanus featured increased amounts of in-stream physical structure, increased variability in stream width and …

Ornamentation, Behavior, And Maternal Effects In The Female Northern Cardinal, Caitlin Winters

Master's Theses

This study seeks to understand the relationship between ornamentation, maternal effects, and behavior in the female Northern Cardinal (Cardinalis cardinalis). Female birds possess ornaments that indicate a number of important known aspects of quality and are usually costly to maintain. However, the extent to which female specific traits, such as maternal effects, are indicated is less clear. It is predicted by the Good Parent Hypothesis that this information should be displayed through intraspecific signal communication. Specifically, androgens and carotenoids are of interest in this study because both are linked to ornamentation, and are also important egg components that …

Mycorrhizal Colonization Of Native Salt Marsh Plants On Mississippi's Gulf Coast And The Effects Of Commercial Mycorrhizal Inoculants On Nursery-Grown Plants, Kathryn Rondot Mcbride

Master's Theses

Salt marshes are important economically and ecologically to the Gulf Coast and other coasts worldwide. Due to human activities, many coastal salt marshes have been degraded or destroyed. Restoration efforts, through the replacement or addition of naturally occurring salt marsh plants, are taking place worldwide. Most restoration plants are raised in nurseries and are not ready for transfer to restoration sites for eight or nine months. Once the plants are at the restoration site many die due to transplant stress. Arbuscular Mycorrhizal Fungi (AMF) may be able to shorten the time the restoration plants need to stay in the nursery …

Mycorrhizal Colonization Of Native Salt Marsh Plants On Mississippi's Gulf Coast And The Effects Of Commercial Mycorrhizal Inoculants On Nursery-Grown Plants, Kathryn Rondot Mcbride

Master's Theses

Salt marshes are important economically and ecologically to the Gulf Coast and other coasts worldwide. Due to human activities, many coastal salt marshes have been degraded or destroyed. Restoration efforts, through the replacement or addition of naturally occurring salt marsh plants, are taking place worldwide. Most restoration plants are raised in nurseries and are not ready for transfer to restoration sites for eight or nine months. Once the plants are at the restoration site many die due to transplant stress. Arbuscular Mycorrhizal Fungi (AMF) may be able to shorten the time the restoration plants need to stay in the nursery …

Investigating Mechanisms Of Co-Occurrence Between Two Similar Specis Of Predaceous Diving Beetles (Coleoptera: Dytiscidae) In Temporary Aquatic Habitats, Kristopher Alexander Pitcher

Master's Theses

Predaceous diving beetles (Coleoptera: Dytiscidae) are a model group of organisms for testing coexistence and exclusion mechanisms because numerous species of the family interact in isolated, aquatic habitats, and are ubiquitous throughout landscapes. Two morphologically similar species, laccophilus fasciatus rufus and Laccophilus proximus, co-occur in numerous habitats in South Mississippi, but are hypothesized to have strong interspecific interactions. I investigated several possible mechanisms that may promote such coexistence, including segregation in habitat domain, differences in behavior, and differences in dispersal that may allow co-occurrence between these two species of beetle. Habitat domain and behaviors such as activity and prey consumption …