Foraging ecology and diet selection of juvenile green turtles in the Bahamas: insights from stable isotope analysis and prey mapping

Species' foraging choices influence 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, and/or quantity ingested. Knowledge of diet selection, though currently limited, can enhance our understanding of the roles of marine turtles in marine ecosystems and, at a finer scale, elucidate how nutrition and diet influence their growth and productivity. To investigate this relationship, we coupled stable isotope analysis with a diet preference index to provide insights into the selection and plasticity of juvenile green turtle Chelonia mydas diet. The study was conducted at 2 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 filter 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 expands our understanding of the spatial differences in green turtle 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 shed light on the factors that influence critical life history traits and ultimately inform species management.