INFLUENCE DE LA TEMPERATURE SUR LA DIFFERENCIATI ON SEXUELLE DES GONADES CHEZ LA TORTUE LUTH (DERMOCHELYS CORIACE A) ; ETUDE EN INCUBATION ARTIFICIELLE ET NATURELLE

Sexual differentiation of the marine leatherback turtle is sensitive to temperature. Incubation of eggs below 29° C results in 100 % males, whereas incu­ bation above 30° C results in 100 % potential females at hatching. Therefore, the threshold temperature lies between 29 and 30° C as has been found for other marine turtles (Caretta caretta* Chelonia mydas). Among hatchlings from natural nests in French Guiana, 10 % were males, 20 % were potential females and 70 % had an inter­ mediate phénotype. The sand temperature at 60 cm of depth, near one nest, was recorded and was found to vary between 29 and 30° C during the presumed thermo- sensitive period. These results will be useful to marine turtle hatcheries which seek to manipulate sex ratios among their neonates.