Meeting Abstract
Sea turtles have been historically classified as capital breeders, so they should possess a store of energy (e.g., fat) at the beginning of the breeding season that they draw from to fuel reproductive effort. However, several studies have questioned whether they may continue to feed during nesting. We are employing a physiological approach, including lipid mobilization and endocrine endpoints, to assess this hypothesis. These blood metrics in combination with reproductive ultrasound and a newly-validated ultrasound technique for measuring subcutaneous fat depth non-invasively provide new methods to assess energy balance in sea turtles. Reproductively-active turtles, including mating couples and nesting females, were sampled in Ostional, Costa Rica. Female turtles were recaptured when possible during subsequent nesting events in order to monitor blood and ultrasound profiles at several time points during the reproductive season. Results have shown that subcutaneous fat depth and the ketone body beta-hydroxybutyrate (BHB) are detectable and potentially useful metrics for fat mobilization in sea turtles. Fat depth analysis via ultrasound showed that females do not have a significant decline in the fat layer at resampling periods. Also, olive ridleys have no significant change in BHB concentrations early versus late in their reproductive season, in contrast to the expected result of lipid mobilization that should occur under a capital breeding strategy. Analysis of hormones that regulate feeding may provide more dynamic assessment of feeding changes and fat storage. These data indicate that olive ridley sea turtles may instead be income breeders, obtaining nutrients throughout the nesting season.
