Life Sciences Commons^™

Effects Of Temperature On Growth And Molting In Blue Crabs (Callinectes Sapidus) And Lesser Blue Crabs (Callinectes Similis), Abigail Ann Kuhn

Master's Theses

Temperature can exert impacts on many processes in ectotherms. With global temperatures rising due to climate change, many ectothermic species may exhibit changes in growth rates and size at maturity, and these changes can have population-level effects. Predicting responses of species to climate change will require not only knowledge of thermal tolerance limits, but also effects of temperature change on growth rates and other life history parameters. For arthropods that exhibit discontinuous growth (i.e., molting), this includes both intermolt period and growth per molt. Previous laboratory and field experiments suggest that temperature affects both intermolt period (IMP) and growth per …

Morphological, Genetic, And Environmental Characterization Of An Unusual Population Of Isoetes (Isoetaceae, Lycopodiophyta), Shannon L. Walker

Honors Theses

A large and unusual population of Isoetes (Isoetaceae, Lycopodiophyta) in the DeSoto National Forest, Wayne County, Mississippi, was studied to determine if the individuals there represent a new species or if they represent part of the variation of the one primary species of the longleaf pine belt of Mississippi, Isoetes louisianensis, which it most closely resembles. The unusual population and specimens of known Isoetes louisianensis were examined comparatively based on morphology, megaspore ornamentation, examination of habitat characteristics, and phylogenetic analysis of DNA sequence data from the nuclear internal transcribed spacer 1 and 2 (ITS) and the 5.8S ribosomal gene. No …

Salinity Tolerance Of Gambusia Affinis, Sarah Rubelowsky

Honors Theses

Developmental plasticity refers to changes during development as a result of environmental contributions. Salinity is a varying environmental condition in freshwater and estuarine habitats that can mediate developmental plasticity in Gambusia affinis, which can increase their tolerances as an invasive species. For my study, estuarine and freshwater populations of Gambusia affinis were sampled in March of 2017 using dip nets. Both populations were then brought back to the laboratory where pregnant females were acclimated to three different salinities (0‰, 15‰, 25‰) until they gave birth. I predicted that the estuarine population of Gambusia affinis would have a greater salinity tolerance …

Effects Of Trophic Relationships On Oyster Reef Restoration Success In The Mississippi Sound, Virginia Robin Fleer

Dissertations

Natural and anthropogenic changes resulting from altered hydrology, hurricanes, variable precipitation, and the BP oil spill have all taken their toll on oyster reefs in Mississippi. In response, oyster reef restoration efforts are currently underway within the Northern Gulf of Mexico. In order to understand why these efforts succeed or fail, it is crucial to consider predator-prey relationships within the context of the trophic dynamics of oyster reefs. Thus, for this dissertation study I integrated a multidisciplinary approach to understanding key trophic interactions affecting oyster recruitment, growth and survival, comprising field sampling, manipulative lab experiments, and individual-based modeling. Spat settlement …

Ecological And Oceanographic Influences On Leatherback Turtle Behavior And Scyphozoan Jellyfish Distributions In The Gulf Of Mexico, Katrina Aleksa

Dissertations

Leatherback turtles (Dermochelys coriacea) are a wide-ranging, oceanic species that feed exclusively on gelatinous zooplankton. Leatherback have been spotted in the Gulf of Mexico (GoM) for several decades and consistently had a high level of interactions with longline fisheries. However, no quantitative studies have been performed to address the spatiotemporal distribution of these turtles in the GoM. This research determines 1) leatherback movements and high-use areas in the GoM, 2) their association with oceanographic features, 3) the distribution and density of two abundant medusae in the northern GoM and any association with biophysical parameters, and 4) the body …

Historical Change Of Seagrasses In The Mississippi And Chandeleur Sounds, Linh Thuy Pham

Dissertations

Seagrasses are important coastal resources facing numerous stressors, and losses have been documented from local to global assessments. Under the broad theme of habitat loss and fragmentation, a study of historical change in total area and landscape configuration of seagrasses in the Mississippi and Chandeleur Sounds was conducted. Mapping data was collated from a multitude of previous projects from 1940 to 2011.

Comparisons of seagrass area among various studies that used different mapping methods can result in overestimation of area change and misleading conclusions of change over time. The vegetated seagrass area (VSA) data were generalized to a common resolution …

Escorting Of Mother-Calf Pairs Of Humpback Whales (Megaptera Novaeangliae) In The Colombian Pacific During The Breeding Season, Natalia Botero Acosta

Dissertations

Humpback whales (Megaptera novaeangliae) belonging to the “breeding G-stock” annually migrate from the Antarctic Peninsula and southern Chile to the southeastern Pacific to reproduce. Associations between mother-calf pairs and escorts were examined in the Gulf of Tribugá, northern Colombian Pacific, using photo-identification and behavioral/spatial sampling. Research hypotheses included: 1. The association between cows and escorts is short-lived, consistent with a male reproductive strategy, 2. The presence of escort(s) elicits a behavioral response from mother-calf pairs and, 3. The patterns of spatial distribution reflect the spatial segregation of maternal females. Groups were classified as mother-calf pairs (Mc), mother, calf …

Thresholds Of Sea-Level Rise Rate And Sea-Level Rise Acceleration Rate In A Vulnerable Coastal Wetland, Wei Wu, Patrick D. Biber, Matthew Bethel

Understanding the Trajectory of Mississippi Coastal Salt Marsh Structure Function, and Processes in the face of Sea Level Rise: Data and Information Repository

Feedbacks among inundation, sediment trapping, and vegetation productivity help maintain coastal wetlands facing sea-level rise (SLR). However, when the SLR rate exceeds a threshold, coastal wetlands can collapse. Understanding the threshold helps address key challenges in ecology—nonlinear response of ecosystems to environmental change, promotes communication between ecologists and resource managers, and facilitates decision-making in climate change policies. We studied the threshold of SLR rate and developed a new threshold of SLR acceleration rate on sustainability of coastal wetlands as SLR is likely to accelerate due to enhanced anthropogenic forces. Deriving these two thresholds depends on the temporal scale, the interaction …

Environmentally-Driven Variation In The Population Dynamics Of Gulf Menhaden (Brevoortia Patronus), Grant D. Adams

Master's Theses

Gulf Menhaden (Brevoortia patronus) is an abundant forage fish distributed throughout the Northern Gulf of Mexico (NGOM). Gulf Menhaden support the second largest fishery, by weight, in the United States and represent a key linkage between upper and lower trophic levels. Variation in the population dynamics can, therefore, pose consequences for the ecology and economy in the NGOM. Here we aim to understand variation in the individual and population dynamics of Gulf Menhaden throughout ontogeny and how such variation relates to environmental processes. We utilized a suite of fishery-dependent and –independent, remote sensing, modeled, and in situ data …

Evidence Of Multidecadal Recruitment In The Ocean Quahog, Arctica Islandica In The Western Atlantic Ocean, Sara M. Pace

Master's Theses

Ocean quahogs (Arctica islandica) are the longest-lived, non-colonial animals known today, with a maximum life span exceeding 500 years. Limited information is available regarding recruitment, making the sustainable management of this valuable fishery a challenge. The objective of this research was to describe the age structure and growth rates for four populations of ocean quahogs from the mid-Atlantic stock to evaluate long-term recruitment trends. Clams were sectioned for age estimation to develop population age frequencies. Initial colonization began approximately 175-250 years ago depending upon site. All sites experienced an increase in recruitment beginning in the late 1800’s to …

Effects Of Temperature Gradient, Substrate Composition, And Canopy Cover On The Spatial Distribution Of Topminnow Species: Fundulus Notatus And Fundulus Olivaceus, Austin M. King

Honors Theses

Hybrid zones are locations where two interbreeding species coexist and hybridize. The spatial distribution of ecologically similar species is of primary interest in understanding the formation and stability of hybrid zones. These hybrid zones are of significance as they allow for insight into how speciation occurs naturally within the environment. A variety of factors may play a role in determining the spatial distributions of species within hybrid zones. Examples of these factors include variations in temperature gradients, substrate composition, and changes in canopy cover. Fundulus olivaceus and Fundulus notatus are generally found within upstream and downstream habitats respectfully. These habitats …

Phylogenetic Relationships Of The Genera Of Achariaceae Based On Analyses Of Morphological And Dna Data, Corey L. Pagart

Honors Theses

Achariaceae are a mostly tropical family of flowering plants consisting of about 29 genera and 150 species of trees and shrubs. Although they are closely related to passionflowers (Passifloraceae), violets (Violaceae), and willows and cottonwoods (Salicaceae), phylogenetic relationships of the genera remain unclear because the only studies have been focused on particular genera or had limited sampling. Few studies of the family in general have been conducted, except for some on species that produce chaulmoogra oil, a commonly used historical treatment for leprosy. For my study, I investigated the relationships of the genera within the family using morphological and molecular …

The Effect Of Boat Type On Bottlenose Dolphin (Tursiops Trucatus) Behavior In The Mississippi Sound, Maria Zapetis

Master's Theses

Increases in oceanic shipping are a global phenomenon, and a leading cause of concern for marine animal welfare. While it may be difficult to assess the effect of boat traffic on all species in all contexts, it is vital to report anthropogenic impacts where longitudinal data is available, and doubly so where a dearth of information exists. The purpose of this study is to describe how dolphin behavior changed in the presence of boats in the Mississippi Sound between 2006 and 2012, and more specifically, to detail how different boat types impacted dolphins’ behavioral states. This study is unique in …

Population Structure, Connectivity, And Phylogeography Of Two Balistidae With High Potential For Larval Dispersal: Balistes Capriscus And Balistes Vetula, Luca Antoni

Dissertations

The gray triggerfish (Balistes capriscus) and the queen triggerfish (Balistes vetula) are two exploited reef fish distributed in tropical and temperate shelf waters of the Atlantic Ocean and the Mediterranean Sea. Both species are highly sedentary as adults but disperse pelagic larvae for extended periods of time potentially allowing connectivity across long distances under the action of oceanic currents. In this work population structure, phylogeography, and migration patterns were examined in the two species and contrasted with predictions of larval transport based on surface circulation data. A total of 1,017 gray triggerfish from twelve sampling localities …

Luminescent Syllid (Odontosyllis Sp.) Courtship Display Densities Vary Across Marine Habitats Around South Water Caye, Belize, Mitchel Mccloskey, Joshua Scheil, Gregory J. Sandland, Gretchen A. Gerrish

Gulf and Caribbean Research

Bright—green luminescent clouds frequently occur at the surface of shallow waters of the Caribbean Sea. These clouds are produced by syllid polychaetes during courtship. Although temporal variation in the occurrence of these courtship displays has been documented throughout the diurnal and lunar cycle, other factors such as habitat type have not been well studied. In this study, we investigated how syllid courtship—display densities varied across 3 substrate types (grassbed, rubble and coral) over a 3 day period. In line with previous studies, we found that syllid courtship displays occurred over seagrass and rubble substrates; however, we also found that display …

Occurrence Of A Colorful Prejuvenile Mountain Mullet (Agonostomus Monticola) In Brackish Water Of Montserrat, Lesser Antilles, Robert E. Schmidt, Erin R. Mcmullin

Gulf and Caribbean Research

Brightly colored prejuvenile Mountain mullet (Agonostomus monticola) immigrating into brackish water on Montserrat are described. Mugilidae may be unique among Caribbean amphidromous fishes in having a brightly colored pelagic marine stage.

Occurrence Of Atlantic Tarpon, Megalops Atlanticus, Leptocephali In The Mississippi Sound Estuary, Patrick M. Graham, James S. Franks, Jason D. Tilley, Dyan P. Gibson, Evan J. Anderson

Gulf and Caribbean Research

No abstract provided.