Corticosterone in Keratinized Matrices (Claws and Scutes) of Sea Turtles

Sea turtles have adapted to diverse ecosystems that are continually modified naturally and by anthropogenic activity. Within the adaptation mechanisms, the activity of the hypothalamic-pituitary-adrenal axis (H-H-A) has the purpose of maintaining homeostasis through the release and regulation of glucocorticoids, however, the prolonged release of these hormones during chronic stress has harmful effects on immune function, reproduction and longevity in turtles. In some species, corticosterone concentrations have been measured in keratinized matrices, making a retrospective analysis of the release of this hormone; however, there is no information in this regard in sea turtles. The aim of this study is to measure the concentration of corticosterona in keratinized matrices (carapace scutes and claws) of two species of sea turtles (Chelonia mydas; n=70 and Eretmochelys Imbricata; n=37). Corticosterone concentrations were measured in 61.68% of the scutes and 83.17% of the claws. Concentrations of 0.021 to 1.78 ng g-1 were obtained in scutes and 0.09 to 4.94 ng g-1 in claws of the two species of sea turtles. No significant differences were found in corticosterone concentrations due to species, coloration pattern, lesions and size. The claws presented higher concentrations of corticosterone than the scutes in both species. Corticosterone concentrations in both species and matrices were not significantly correlated with morphometric variables. This study demonstrated that it is possible to measure corticosterone in the keratinized matrices of nesting sea turtles. This technique can be a useful tool to measure chronic stress situations in a non-lethal and minimally invasive way.