Influence of Sand Temperature on Hatching Success of the Green Turtle(Chelonia mydas), Tortuguero, Costa Rica

SEGURA, LUCIANO N.

Filadelfia, USA

Simposio; 21st Annual Symposium on Sea Turtle Biology and Conservation; 2001

International Sea Turtle Society

The beach at Tortuguero, Costa Rica contains the principal nesting colony of the Green Turtle (Chelonia Mydas) in the Atlantic.  In the months of August, September and October of the 2000 nesting season, an analysis of the effect of sand temperature on hatching success of Chelonia mydas was conducted.  The rainy season predominates over the course of the nesting season, but is interrupted by a brief dry season among August and beginning October, when the sand temperature is considerably higher, which allowed comparison of hatching and emergence data for different temperatures. Once the hatchlings reach the top of the egg chamber, the emergence process to the surface begins and lasts between three and five days, which is when the elevated sand temperature near the surface can suffocate the hatchlings, which would be manifested in a higher number of dead hatchlings.  This study found that sand temperature is not a limiting factor in the emergence process.  No correlation was found between sand temperature and hatching success, when temperature recordings were taken at the base depth of the nest, as well as just below the surface (P>0.05).  The regression analysis between number of dead hatchlings and near-surface sand temperature was only significant for nests in the border zone, with partial sun exposure (P=0.046; r*=0.138), and was not significant for nests in the open zone with complete sun exposure (P>0.05). No correlation was found between nest depth and hatching success (P>0.05); when nests with a depth much less than the average were analyzed separately, hatching success was considerably lower (approximately 40%); however, this was not statistically significant.