Dermochelys coriacea

Hatchling marine turtles exhibit a positive phototaxis by crawling toward the lowest and brightest horizon when they emerge from nests on the beach at night, which should lead them to the ocean (“seafinding”). Previous research with cheloniid (loggerhead and green turtle) hatchlings demonstrated that the perceptual spectral sensitivities are well below the light available on the beach regardless of lunar phase. The goal of this research was to determine the perceptual spectral sensitivities of leatherback hatchlings, the most distantly related of all extant sea turtle species. This study revealed that, like cheloniids, leatherbacks are most sensitive to shorter wavelengths (< 500 nm). However, leatherbacks were 10 – 100x less sensitive than cheloniids at all tested wavelengths. This difference in sensitivity corresponds with increased crawl duration and circling behavior under new moon conditions when light levels are lowest and the difference in radiance between the landward and seaward direction is small.

The leatherback sea turtle (Dermochelys coriacea) is facing global declines; however, the Florida stock is generally increasing. Various studies have identified threats to sea turtles, but there is a need to quantify population-level threats. I used external examination and blood analyses of leatherbacks nesting on northern Palm Beach County, Florida beaches to understand the impact(s) that physical injuries have on this population. Notable injuries were present on 118 of 167 (70.7%) turtles. Fisheries injuries were more prevalent than other anthropogenic injuries; however, there was a higher overall prevalence of natural injuries. There were no notable findings from my blood analyses. My results suggest that while natural injuries are more common than anthropogenic injuries in the nesting population of Florida leatherbacks, anthropogenic injuries are more likely to result in severe traumatic wounds. Future investigation of overlap in leatherback migratory routes and foraging grounds with various threats could further protect this species.

The migratory behavior of North Atlantic leatherback turtles (Dermochelys
coriacea) has been documented in the Wider Caribbean, but the migratory movements of
leatherbacks nesting in South Florida are relatively understudied. Our knowledge of their
migrations is currently limited to ten nesting females tracked from the east coast of
Florida that either moved north to the Northern Atlantic or east to the coast of Western
Africa. These results bring to light the need for further investigation and larger sample
sizes to identify and determine the relative importance of the different foraging areas for
the leatherbacks nesting in South Florida. Here, I analyzed stable carbon (δ13C) and stable
nitrogen (δ15N) values in whole blood and skin of leatherbacks nesting in South Florida
between 2014 and 2017 to estimate the putative foraging origins of these nesters prior to
coming to South Florida to nest. This study provides some of the first stable isotope
inferences and insights into the variable pre-nesting foraging habitat locations of
Florida’s leatherback population.