Effect of erosion on the nest depths of sea turtles and its impact on the egg chamber temperature

In Costa Rica every year thousands of female sea turtles emerge onto nesting beaches to lay nests, with their eggs hatching 6-8 weeks later. The impact of erosion is seen throughout the country, on both the Pacific and Caribbean coasts. During the middle trimester of incubation, the temperature inside the nest determines the sex ratio of the offspring. This study aimed to determine if a decrease in nest depth caused by erosion will change the temperature inside the nest, and therefore the sex ratio. Data loggers were buried at green and leatherback nest depths and in the different vegetation zones of Playa Norte beach in Costa Rica. The multiple regression showed that the temperature varies significantly with the depth and the zones, however, only 20% of the variation can be attributed to these variables. Despite this, results and observations in the field clearly showed that the beach was still impacted by erosion, but rather as an all-or-nothing phenomenon. Erosion leads to receding sand cliffs, washing out the eggs in the process, and this is considered to be the real danger of erosion, rather than its impact on nest temperature. This conclusion is positive as it shows the limited impact of erosion on the temperature within the nests. Conservation efforts can still be made to enhance the protection from erosion of the principal nesting beaches all over the world.