Habitat Use and Foraging Ecology of Three Sea Turtle Species Nesting in Northwest Costa Rica

Abstract

Sea turtle species, even when sharing nesting beaches, exhibit distinct at-sea movements and Foraging behavior. At Playa Cabuyal, a sea turtle nesting beach in northwest Costa Rica, we utilized satellite telemetry to reveal the post-nesting movement of green turtles (Chelonia mydas, n = 9) alongside carbon and nitrogen stable isotope analysis of skin samples of green (n = 28), olive ridley(Lepidochelys olivacea, n = 20), and leatherback (Dermochelys coriacea, n = 4) turtles. Green turtles (2012–2015) undertook three migratory strategies: moving northward to Nicaragua and the Gulf of Fonseca (n = 6), remaining resident near Cabuyal in the Gulf of Papagayo (n = 2), or migrating south to the Gulf of Guayaquil in Ecuador (n = 1). There was no significant difference in the δ13C values of green turtles (mean: −14.7‰, range: −16.8‰ to −12.8‰) and olive ridley turtles (mean: −15.1‰, δ13C: −16.6‰ to −14.2‰) suggesting that both species forage across a range of coastal and offshore habitats, while δ13C values for leatherback turtles (mean: −15.5‰, range: −15.9‰ to −15.0‰) suggest exclusively offshore habitat use. In contrast, δ15N values of green turtles(mean: 16.0‰, range: 13.7 to 17.4‰) were significantly higher than those for olive ridley turtles (mean: 14.2‰, range: 12.3‰ to 15.7‰) suggesting that green turtles may be predominately carnivorous. The notably wide range of δ15N values in leatherback turtles (mean: 14.9‰, range: 12.2‰ to 16.8‰) also suggests that this species feeds across many different trophic levels of gelatinous prey. Evidence that the sea turtles nesting on Playa Cabuyal utilize a broad range of foraging areas in the East Tropical Pacific underscores the need for coordinated, multinational conservation efforts for these species.