Everything's not green for the green turtle: jellyfish as food for the herbivorous Chelonia mydas

GONZÁLEZ CARMAN VICTORIA; FLORENCIA BOTTO; DIEGO ALBAREDA; CLAUDIO CAMPAGNA; HERMES MIANZAN

Hiroshima

Simposio; Fourth Jellyfish Bloom Symposium; 2013

The green turtle (Chelonia mydas) exhibits an herbivorous diet after an ontogenetic shift that takes place when omnivorous juveniles move from oceanic to neritic habitats. The shift is thought to be abrupt and irreversible, and it might allow animals to reach sexual maturity sooner through and increased growth rate. Some studies suggest that neritic juveniles might feed on considerable amounts of soft-bodied animals such as pelagic tunicates and gelatinous plankton. But evidence remained sparse, partially due to methodological constraints to identify these kinds of preys. By conducting digestive tract examination and stable isotopes analysis, we studied the diet of juvenile green turtles inhabiting a neritic habitat off the coast of Argentina that lack of an herbivorous diet offer but abundant in gelatinous plankton. Results showed that gelatinous plankton represented more than 60% of the diet of turtles, and that vegetable matter was scarce. Neritic juveniles were found to be omnivorous, with a strong tendency to a gelatinous-dominated diet. Our findings suggest that diet can be adapted to the particular foraging area, and that turtles are not strict herbivores in Argentine waters despite being so in the rest of the species distribution