CONICET | Buscador de Institutos y Recursos Humanos

Sand temperature can play an important role in the survival of pre-emergent sea turtle hatchlings. High sand temperatures may inhibit coordinated muscle action in the ascent process to the sand surface and also may cause a decline in oxygen levels within the nest. These factors can increase mortality of hatchlings prior to emergence. In this study we analyze the effects of sand temperature on pre-emergent Green Sea Turtle (Chelonia mydas) hatchlings in Tortuguero, Costa Rica. We also analyze the relationship between sand temperature and egg incubation period, hatching success and hatchling emergence percentage. Nests were selected from June to August 2000, so that hatchlings would emerge during two distinct periods: a period of low temperatures and abundant rainfall mainly during August (wet period, WP) and a period of higher temperatures and lower rainfall mainly during September and early October (dry period, DP). Air and sand temperatures were significantly higher in the DP. Increases in sand temperature reduced incubation period from 58.6 ± 0.6 days in the WP to 56.4 ± 0.5 days in the DP. Mean hatching success and emergence percentage were 86 ± 3% and 96 ± 1%, respectively, and were not associated with the nest initiation date. However, a negative association was found between the emergence percentage and the mean sand temperature at 40 cm depth in the pre-emergence days. Pre-emergent hatchlings may experience increased mortality when sand temperatures at the egg chamber neck level exceed 33°C. When one takes into account global warming projections, hatchling mortality during pre-emergence days could increase and pose a serious threat to this green sea turtle population.