Grant: 17-017R
Project Title: Diet characterization of green, loggerhead, and Kempís ridley turtles in Florida, Year 2
Project Manager: Erin E. Seney, Ph.D.
Organization: University of Central Florida (Research and Educational Institute)
Grant Amount: $11,068.00
Completion Date: 2019-12-19

Summary: The diet of an organism provides valuable information on its habitat, ecosystem role, and potential for interaction or competition with human activities. While the sea turtle diets are understood generally, specific dietary information is limited to very few foraging areas. Sea turtle strandings represent a relatively untapped opportunity to quantitatively assess diets of Floridaís three most common species. This project builds on a successfully-funded 2016 Sea Turtle Conservation Grant proposal by continuing in Year 2 to collect and analyze gastrointestinal (GI) contents from Florida Fish and Wildlife Conservation Commission necropsy sessions to: (1) characterize the green turtle (Chelonia mydas), loggerhead (Caretta caretta), and Kempís ridley (Lepidochelys kempii) diet in Florida; (2) examine spatial, temporal, and size-based trends and interspecific overlap in diet; and (3) as possible, complement state examinations of anthropogenic interactions. Additionally, we will (4) undertake a pilot study using archived green turtle samples to compare the results of visual food item identification to genetic barcoding. A compound metric, percent index of relative importance, will be used to examine contributions of different food types to each speciesí diet. Multi-year spatial, seasonal, and size-based analyses will provide valuable information for sea turtle management and conservation, including food and habitat requirements for each species. Results will also enable comparisons to live sea turtle diet studies and may be used to complement other ongoing research and examine any interaction or competition with fisheries. Green turtle GI samples archived after the Deepwater Horizon oil blowout will be divided into two portions, with one subsample examined visually and the other used for DNA extractions. The DNA will be sequenced and matched to a gene library, ultimately providing information on food items in each sample. Should the barcoding approach prove a viable option for stranded green turtles, it will provide a less time-intensive, possibly more accurate means of identifying the speciesí GI contents. Results from all four project components will provide better understanding of sea turtle diet and related habitat requirements, thereby enhancing conservation and recovery measures.

Results: This project had two main components: (1) new diet sample collection and data collection; and (2) comparison of visual and genetic identification using archived green turtle diet samples. Two diet project-related UCF media items were published in March 2018. Trips to necropsy sessions occurred in May 2018-June 2019. All collected loggerhead and ridley samples were fully sorted, and all green turtle samples were sorted to general categories. Green turtle visual identification was completed, and we worked with collaborators on an optimized metabarcoding protocol and preparation for sequencing. Three mentees worked on subprojects that will ultimately be part of comprehensive publications. Two poster presentations won awards: (1) green turtle visual identification (Tackett), Runner Up Best Student Biology Poster, 2019 International Sea Turtle Symposium, and (2) green turtle genetic identification (Sarkis), Judgeís Choice Award, 2019 UCF Showcase of Undergraduate Research Excellence. The third mentee (Lozada)will submit an abstract on Kempís ridley diet to the 2020 Southeast Regional Sea Turtle Meeting, and the PI (Seney) is drafting a sea turtle diet abstract for that meeting.