Grant: 24-047R
Project Title: Foraging ecology and diet selection of sympatric marine turtles in the Gulf of Mexico
Project Manager: Mariana Fuentes / Alexa Putillo
Organization: Florida State University (Research and Educational Institute)
Grant Amount: $26,371.00
Completion Date: 2026-02-12
Summary: An understanding of differences in intra/inter-species diet, with a focus on diet selection and potential drivers, can provide insights into the factors that influence critical life traits and ultimately inform species management. Given the relative ease of using SIA, several studies to date have used SIA of marine turtle skin and scute samples to determine their ecological niche. However, most of these studies do not incorporate stable isotope values of potential prey items into their analysis, which consequently hinders the ability to determine the contribution of specific prey items to an individual's/population diet and determine diet selection. This can be problematic since information on diet selection, which requires the comparison of prey use/consumption with availability of items to consumers, can enhance our understanding of the roles of marine turtles in marine ecosystems and, at a finer scale, inform how nutrition and diet influence growth and productivity of marine turtles. To provide further insights into the foraging ecology and diet selection of green, kemps and loggerhead turtles we will couple stable isotope analysis of both turtle skin tissues and their prey items, characterize food availability, and use diet preference index analysis. Our approach will also allow us to explore niche partitioning among the three species and investigate how these species use habitat and dietary resources within a shared foraging area. This can help determine the mechanisms of species coexistence and provide evidence of habitat and trophic partitioning.
Results: All tasks and deliverables mentioned above have been accomplished. Monthly field trips were conducted (May to October 2024) to collect sea turtle epidermis and prey item samples for stable isotope analysis (SIA). Samples were prepared (July to October 2024) and sent to the Fish and Wildlife Research Institute (FWRI) in St. Petersburg, Florida for SIA. All habitat surveys were conducted in August 2024. SIA data were delayed due to hurricanes Milton and Helene affecting the lab and SIA equipment at FWRI, but all data were received in Spring 2025. Data analysis continued in the Spring and Summer of 2025. A draft manuscript is in progress that includes a characterization of prey availability with diet composition and selection for all three sea turtle species.