Habitat use of nesting female olive ridley turtles (Lepidochelys olivacea) inferred by stable isotopes in eggs

Olive ridley sea turtles (Lepidochelys olivacea) can use a vast number of different habitats and food sources throughout their life cycle. This species is one such organism that changes both the environment and diet during different life stages. Based on stable isotope analysis (& delta;13C and 815N) of the components of fresh eggs (yolk, albumen, and shell) and unhatched eggs (contents and shell), the habitat use of females nesting in the eastern Atlantic Ocean, Brazil, was elucidated. As the yolk is formed months before migration to the nesting areas, it was possible to infer that they originated from both high- and low-latitude feeding areas. For albumen and shell, both carbon and nitrogen isotopic values indicated either the neritic environment at the latitude of the breeding area, tissues of turtles catabolized due to fasting during breeding, or differences in tissue-specific metabolic routing. The contribution of potential prey such as jellyfish for yolk and demersal prey for both albumen and shell demonstrated the plasticity of habitat use of this population and the use of both pelagic and neritic waters. High individual variability further reinforces the need for preservation of the habitats utilized by olive ridley turtles in both neritic and oceanic environments over a vast area of the tropical ocean up within 20 degrees south and north of Equator.