Sex Ratio Estimation of Green Turtle Hatchlings in Kazanlı Beach, Türkiye

Abstract

Sea turtles are distributed worldwide and have temperature-dependent sex determination. For hatchlings with a female:male ratio of 1:1, the pivotal temperature is usually around 29°C, with female hatchlings being observed at higher values and male ones at lower values. It is expected that wildlife threatened by global warming will be more severely affected, especially species that sex is determined by temperature. This study was carried out by measuring air, sand and nest temperatures during 2008 and 2009 nesting seasons at Kazanlı Beach, one of the largest nesting sites of Chelonia mydas (Green turtle) in the Mediterranean. Sand grain size was also measured, and gonads of dead hatchlings were examined histologically. Both sand (n=4) and nest (n=6) temperatures were above the pivotal temperature (between 29.131.6°C) in the study area. According to the estimation based on temperatures, hatchlings were female (♀>50%) biased. Of the hatchling samples, 75 were examined histologically. According to histological examination, the female:male ratio was 2:1. According to the direct examination and indirect estimation; the sex ratio of green turtle hatchlings in Kazanlı Beach, one of the highest hatchling producing nesting sites of the Mediterranean, was reported for the first time in this study. There is a need to fill the data gaps regarding sex ratios, especially for major beaches with high hatchling production. Knowing the temperature profiles in and around the nest and sex ratios of hatchlings is critical for the development of conservation measures for endangered sea turtles.