Analysis of the effect of Sun / Shade treatment on the success of hatching, the emergency success, and the morphology of the specie Lepidochelys olivacea marine turtles, in a hatchery on the Piro beach (Peninsula of Osa, Costa Rica)

Abstract

This study presents an incubation success’ analysis (success of hatching and emergency success) of the Olive ridley turtle (Lepidochelys olivacea) on the beach of Piro (Osa Peninsula, Costa Rica), according to the different treatments that each nest received (sun and shade) in a hatchery built in the nesting season of 2017 (from June to December). The main objective of the study is to evaluate if these different treatments had a significant effect on the biometric variable, the success of the nest (emergency and hatching), the hatching time and the different developmental stages of the embryos. For this purpose, it was determined if the use of a shady part in the hatchery was beneficial for the survival of the species. Considering that environmental and anthropological threats of the area affect the species, the changes planned in the environment a few years from now should also be taken into account. To carry out these objectives, each nest in the hatchery was carefully observed and the incubation temperature was strictly controlled. The total of the turtles released in each nest was counted and the biometric measurements of a group of hatchlings were taken. Thanks to an exhumation that was carried out in all nests of the hatchery, it was possible to calculate the hatching and emergence success of each nest. Subsequently, the results were analyzed statistically with the program R commander. The results obtained show that there were significant differences between sun and shade treatment for different variables like length and width of the hatchling, success of emergence and hatching, duration of the nest to be born and in two stages of the embryonic development (the 1th and 3th stages). Moreover, the incubation temperature influences nest survival. The analysis shows that the lower shade temperatures negatively affect the survival of the nest. In any case, considering the parameters of the beach, the morphology of the turtles and the effect of climate change in the area, the use of a shaded area in a hatchery would bring benefits for the survival of the species in a long term.