Advisory Committee Chair
James B McClintock
Advisory Committee Members
Charles D Amsler
Thomas Klinger
Stacy A Krueger-Hadfield
John M Lawrence
Stephen A Watts
Document Type
Dissertation
Date of Award
2022
Degree Name by School
Doctor of Philosophy (PhD) College of Arts and Sciences
Abstract
Luidia spp. (Family Luidiidae) are important predators in the benthic food web and are abundant in near-shore, shallow soft-bottom habitats throughout the northern Gulf of Mexico. Climate change-related environmental changes, such as ocean warming and acidification, are rapidly intensifying in this region and can have consequences for species diversity as well as individual sea star health through modification of host-associated bacterial communities. Our knowledge of sea star-associated bacterial community structure and dynamics is limited and conflicting genetic evidence has called into question the accuracy of species delimitation of five-armed Luidia in the northern GOM. The primary purpose of this dissertation was to investigate species delimitation between Luidia clathrata and L. lawrencei and to characterize the bacterial communities associated with these sea stars in the natural environment and under exposure to near-future warming under experimental conditions. Sequence divergence at the cytochrome oxidase subunit I (CO1) gene was sufficient to support the maintenance of L. lawrencei as a separate species from L. clathrata. Furthermore, the presence of some individuals that appeared to be L. lawrencei morphologically but were L. clathrata based on CO1 suggests the potential for hybridization. A significant shift in bacterial community composition with experimental exposure to projected end-of-century (32°C) warming was observed in stomach tissue of L. clathrata. Luidia lawrencei from the natural environment had tissue-specific bacterial communities which were also distinct from iv bacterial communities in the surrounding sand and seawater. Together, these results underlie the importance of obtaining and maintaining accurate records of species delimitation and of bacterial community composition associated with healthy hosts under non-stressful environmental conditions. This will provide a baseline from which to measure modification in diversity and community structure in a changing world.
Recommended Citation
Shilling, Michelle D., "Bacterial Community Structures and Species Delimitation of Five-Armed Luidia in the Northern Gulf of Mexico" (2022). All ETDs from UAB. 334.
https://digitalcommons.library.uab.edu/etd-collection/334