When Charles Darwin visited Ascension Island towards the end of his famous voyage in 1836, turtles were a valuable source of meat for passing sailors. Nowadays the green turtle (Chelonia mydas) is strictly protected. The hatchlings (pictured here) have to escape threats from other sources though—specifically, predation by birds, crabs, and fish. It is estimated that less than one hatchling in a thousand will survive until adulthood to return to Ascension and complete the breeding cycle.
The sex of hatchlings is determined by the temperature at which the green turtle eggs incubate in the sand; more females are produced in warmer temperatures. Research has shown that on Ascension Island most of the hatchlings are female—an imbalance that might get worse as temperatures rise under current climate change predictions.
Earth Day is on April 22, 2016
Sam Weber, PhD., Darwin Research Fellow, Ascension Island Government and Exeter University, UK.