Green turtles nest survival: Quantifying the hidden predation

Abstract

Trindade Island is the largest nesting site for green turtles Chelonia mydas in Brazil and one of the most important in the Atlantic ocean. The terrestrial crab Johngarthia lagostoma forages almost everywhere on the island, including the green turtle nesting beaches. Nothing is known about crab predation on sea turtle eggs at the time of nesting. We obtained unprecedented records of crab predation at sea turtle nests during the breeding seasons of 2017/18 and 2018/19. We analyzed through images and videos the behavior of the predatory species. Not only that, but we observed an average loss of 3 eggs per nest. The period from 0:00 to 3:00 h presented the highest risk of predation. The mortality rate in the egg stage related to neonates was 5% per nest, with an estimated predation impact of 21,600 eggs per season reproductive.