The effect of the predicted air temperature change on incubation temperature, incubation duration, sex ratio and hatching success of loggerhead turtles
Marine turtles are sensitive to temperature changes and thus are likely to be impacted by the predicted climate change. This study assesses the effect of the predicted air temperature change on incubation temperature, incubation duration, sex ratio and hatching success of the loggerhead turtle Caretta caretta at the Mediterranean nesting sites of Dalyan and Fethiye, Turkey. We recorded sand temperatures and used air temperatures at two nesting sites to estimate the sex ratio of hatchlings. The data showed that hatchling production was 59.1% and 77.7% at Dalyan in 2004 and 2009, respectively, and 72.2% and 72.3% at Fethiye at 2008 and 2009, respectively. Incubation temperature was positively correlated with both air temperature and distance to sea. Sex ratio estimation and incubation duration between the years 1993 and 2009 in Fethiye show polynomic trend lines. The best predictors of hatching success were distance to vegetation and wet depth of nest. We modelled the effects of incremental increases in the future air temperature of up to 10°C. We suggest that clutch death is not likely to begin until 3°C of warming, increasing from 5.3% to 100.0% with warming between 4°C and 10°C.