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Full-Text Articles in Biology

Seagrass Epibiont Biodiversity In The Northern Gulf Of Mexico, Kathryn Wyssmann Dec 2023

Seagrass Epibiont Biodiversity In The Northern Gulf Of Mexico, Kathryn Wyssmann

University of New Orleans Theses and Dissertations

Epibionts on seagrass leaves contribute substantially to productivity and trophic interactions in seagrass ecosystems. Differences in epibiont assemblages and factors that contribute to epibiont diversity have been little studied on the seagrass Halodule wrightii in the northern Gulf of Mexico (nGoM). We used a metabarcoding approach to describe epibiont assemblages on H. wrightii leaves in four bays across the nGoM and to test whether epibiont assemblages differed spatially at local levels (within bays) or regional levels (from west to east). Furthermore, we tested if epibiont diversity was related to environmental conditions and/or seagrass productivity. Epibiont assemblages differed significantly between bays …


Legacy Habitat Suitability Of Eastern Oysters (Crassostrea Virginica) In Louisiana: A Prelude To Mississippi River Delta Freshwater Diversions, Tasia Mv Denapolis Dec 2018

Legacy Habitat Suitability Of Eastern Oysters (Crassostrea Virginica) In Louisiana: A Prelude To Mississippi River Delta Freshwater Diversions, Tasia Mv Denapolis

University of New Orleans Theses and Dissertations

The Louisiana oyster industry is greatly impacted by freshwater and sediment diversions that are part of the effort to restore the state’s coastline. A habitat suitability index (HSI) proposes species-habitat relationships that can be instrumental in creating impact assessments and suitability predictions for management as new diversions are implemented. An oyster (Crassostrea virginica) HSI was developed using three variables crucial to oyster sustainability: average annual salinity, minimum monthly salinity, and average salinity during the spawning season. These Legacy HSI visualizations show annual fluctuations in the distribution of zones suitable for oyster cultivation prior to proposed diversions in Pontchartrain …


Genetic Diversity In An Invasive Clonal Plant? A Historical And Contemporary Perspective, Elliot D. Weidow Aug 2018

Genetic Diversity In An Invasive Clonal Plant? A Historical And Contemporary Perspective, Elliot D. Weidow

University of New Orleans Theses and Dissertations

Introduced populations of Eichhornia crassipes (Pontederiaceae) possess extremely low levels of genetic diversity due to severe bottleneck events and clonal reproduction. While populations elsewhere have been well studied, North American populations of E. crassipes remain understudied. We used Amplified Fragment Length Polymorphism markers to assess genetic diversity and population structure in North American E. crassipes populations. Patterns of diversity over the past fifty years were analyzed using herbarium specimens. Furthermore, we sampled populations across the Gulf Coast of the United States throughout a year to determine contemporary genetic diversity and assess potential seasonal effects. Genetic diversity was found to be …


Assessing The Responses Of Adult, Juvenile, And Larval Fish Assemblages To The Closure Of The Mississippi River Gulf Outlet, An Artificial Tidal Pass In Southeastern Louisiana, Rebecca Weatherall Cope Dec 2013

Assessing The Responses Of Adult, Juvenile, And Larval Fish Assemblages To The Closure Of The Mississippi River Gulf Outlet, An Artificial Tidal Pass In Southeastern Louisiana, Rebecca Weatherall Cope

University of New Orleans Theses and Dissertations

The creation of the Mississippi River Gulf Outlet (MRGO) in 1963 by the U.S. Army Corps of Engineers (USACE) represents one of the most catastrophic, anthropogenic stressors ever to impact the Lake Pontchartrain estuary in southeastern Louisiana, USA. The artificial tidal pass provided a direct route from the Gulf of Mexico to New Orleans. It allowed for high saline waters to enter Lake Pontchartrain, resulting in detrimental changes to the biotic community of the Lake and surrounding wetland areas. In July 2009, the USACE closed the MRGO in hopes of restoring natural ecosystems. This study assesses changes in the adult, …


Statistical And Comparative Phylogeography Of Mexican Freshwater Taxa In Extreme Aquatic Environments, Lyndon M. Coghill Dec 2013

Statistical And Comparative Phylogeography Of Mexican Freshwater Taxa In Extreme Aquatic Environments, Lyndon M. Coghill

University of New Orleans Theses and Dissertations

Phylogeography aims to understand the processes that underlie the distribution of genetic variation within and among closely related species. Although the means by which this goal might be achieved differ considerably from those that spawned the field some thirty years ago, the foundation and conceptual breakthroughs made by Avise are nonetheless the same and are as relevant today as they were two decades ago. Namely, patterns of neutral genetic variation among individuals carry the signature of a species’ demographic past, and the spatial and temporal environmental heterogeneity across a species’ geographic range can influence patterns of evolutionary change. Aquatic systems …


Occurrence And Genetic Diversity Of Lemon Sharks (Negaprion Brevirostris) At A Nursery Ground At The Chandeleur Islands, Louisiana., Jonathan F. Mckenzie May 2013

Occurrence And Genetic Diversity Of Lemon Sharks (Negaprion Brevirostris) At A Nursery Ground At The Chandeleur Islands, Louisiana., Jonathan F. Mckenzie

University of New Orleans Theses and Dissertations

Anecdotal evidence suggested that immature lemon sharks (Negaprion brevirostris) occur at the Chandeleur Islands in southeastern Louisiana. From May 2009 to August 2011, the Nekton Research Laboratory at the University of New Orleans regularly sampled habitats at the Chandeleur Islands to confirm the presence of immature individuals of this species. During these efforts, 147 immature lemon sharks (neonates, young-of-the-year, and juveniles) were collected. Each shark was PIT tagged and a tissue sample was taken for genetic analyses. Sizes ranged from 56 – 177 cm total length. Sharks showed a preference for sandy substrate and smaller individuals showed significant preference …