Using Biomarkers to Assess the Migratory Ecology and Reproduction of the Florida Green Turtle (Chelonia mydas)

Migratory connectivity between breeding and foraging areas is a vital component of the ecology of a diverse collection of marine vertebrates. Habitat quality, composition, and resource availability at these locations have direct ramifications for individual fitness. The green turtle (Chelonia mydas) is a long-lived, highly migratory species of conservation concern. Important green turtle nesting habitat in Florida is protected, but more information is needed to identify foraging habitats and the influence these habitats have on reproduction. Here, I used stable isotope analysis of δ13C, δ15N, and δ34S and satellite telemetry validation to determine the number of putative foraging areas used by the breeding aggregation at the Archie Carr National Wildlife Refuge (ACNWR), and the relative contribution of each foraging area. I evaluated the influence of foraging area and other variables on egg size, clutch size, hatching success, and emerging success using model selection frameworks. Isotopic values of skin and eggs were used to build conversion equations between the two tissue types. Results suggest strong migratory connectivity between the ACNWR and the Florida Keys/Florida Bay complex. I found that the influences of foraging area are likely to be more detectable when evaluating female-centric fitness metrics like clutch size and egg size; these influences are more muted in hatching and emerging success, which are strongly influenced by nest incubation conditions. These are the first green turtle-specific tissue conversion equations for δ13C and δ15N, and the first δ34S equation for any marine turtle species. These will allow researchers to have a common currency between frequently collected samples to better compare results