Distribution of foraging habitats of male loggerhead turtles (Caretta caretta) as revealed by stable isotopes and satellite telemetry

Abstract

Most studies on the foraging ecology of loggerhead turtles (Caretta caretta) have focused on adult females and juveniles. Little is known about the foraging patterns of adult male loggerheads. We analyzed tissues for carbon and nitrogen stable isotopes (δ13C and δ15N) from 29 adult male loggerheads tracked with satellite transmitters from one breeding area in Florida, USA, to evaluate their foraging habitats in the Northwest Atlantic (NWA). Our study revealed large variations in δ13C and δ15N and a correlation between both δ13C and δ15N and the latitude to which the loggerheads traveled after the mating season, thus reflecting a geographic pattern in the isotopic signatures. Variation in δ13C and δ15N can be explained by differences in food web baseline isotopic signatures rather than differences in loggerhead trophic levels. Stable isotope analysis may help elucidate residency and migration patterns and identify foraging sea turtle subpopulations in the NWA due to the isotopically distinct habitats used by these highly migratory organisms.