Project Title: Trophic Plasticity of Kemps Ridley Turtles in the Ten Thousand Islands: Long-term Trends in Diet and Stable Isotope Analyses
Project Manager: Dr. Jeff Schmid
Organization: Conservancy of Southwest Florida (Non-Profit Organization)
Grant Amount: $27,065.00
Summary: The purpose of this project is to investigate the trophodynamics of Kemps ridley turtles inhabiting the Ten Thousand Islands, Florida. Earlier studies found turtles in this region preyed upon solitary tunicates (sea squirts), which had not been reported in other diet analyses. More recent studies found Kemps ridleys had shifted their diet first to sponges and then to colonial tunicates, also novel food items for the species, followed by consumption of crabs. In addition to the ongoing diet study, stable isotope analyses of Kemps ridleys, their prey, and habitat components are being used to characterize the food web in this estuarine complex. A simplistic isotope model was consistent with the corresponding turtle diet studies. Kemps ridley and crabs occupied a similar trophic level (carnivores) whereas sponges and colonial tunicates, the primary prey for turtles, occurred at a lower trophic level (benthic-filter feeders). We would expect turtles feeding on crabs to occupy a higher trophic level (secondary carnivore) than those feeding on sessile invertebrates. The objectives of the study are to document the dietary plasticity of Kemps ridleys in this foraging area, to investigate temporal trends in the stable-carbon, -nitrogen, and -sulfur isotopic signatures of skin and plasma samples for turtles, and to determine whether trends in isotopic compositions of turtles reflect those of the corresponding prey items identified in fecal samples.