[Eoas-seminar] Oceanography Thesis Defense - Anthony Gillis - April 13, 3:00 - 327OSB

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Wed Apr 4 16:18:17 EDT 2018


FORAGING ECOLOGY AND DIET SELECTION OF JUVENILE GREEN TURTLES (CHELONIA MYDAS) IN WESTERN BAHAMAS: INSIGHTS FROM STABLE ISOTOPE ANALYSIS AND PREY MAPPING

Anthony Gillis

   April 13
    3:00pm
    327OSB

Species' foraging choices influences their somatic growth rates, age at maturity, and time spent in vulnerable early life stages. Thus, differences in population demographics are often attributed to variability either in diet type, quality or quantity ingested. Elucidating the foraging ecology can enhance our understanding of the roles of marine herbivore species in marine ecosystems and elucidate how nutrition and diet influences their growth and productivity. Additionally, diet selection indices provide finer-scale understanding of species preferentially selected diet items of species, however this information is limited. Marine green turtles (Chelonia mydas) are considered to be herbivores, predominantly consuming seagrass and some algae. However, recent studies have suggested they may exhibit omnivory in certain forage areas. Using juvenile green turtles as a case study, I coupled stable isotope analysis with a diet preference index to provide insights into the selection and plasticity of their diet. The study was conducted within two sites (Bonefish Hole and South Bimini) in Bimini, Bahamas in 2016. Habitat surveys were conducted to gather habitat data and determine resource availability. A dichotomy in diet was found between the sites: at Bonefish Hole, turtles exhibited a more generalist omnivorous diet, selecting for sessile filters feeders and green algae, whereas turtles in South Bimini had a more specialist herbivorous diet, primarily consuming seagrasses and selecting for red algae, when available. The foraging dichotomy found in this study by green turtles expands our understanding of the spatial differences in their biology in the Bahamas and provides novel information for turtle foraging in Bimini. Knowledge about differences in intra-specific diet, with a focus on diet selection and potential drivers, can elucidate the factors that influence critical life history traits and ultimately inform species management.

Major Professor: Mariana Fuentes
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