Impacts of nest temperatures on leatherback reproductive success, hatchling morphology, and performance in South Florida

Leatherback turtles Dermochelys coriacea are experiencing population declines due to various anthropogenic threats. Beaches play a crucial role in the survival of sea turtle species since reproductive success is affected by environmental conditions inside the nest. Climate change is predicted to increase sand temperatures and affect rainfall, which will change the nest microenvironment, and thus may alter not only hatch and emergence success but also hatchling morphology and performance. This study examined the relationship between nest incubation temperatures and leatherback hatchling terrestrial performance, as the crawl from the nest to the sea is a critical phase for hatchling survival. Temperature data loggers were placed in 12 leatherback turtle nests on the day they were laid across the early, middle, and late South Florida nesting season. Upon emergence, hatchlings were tested for righting ability and crawling speeds. Mean nest temperatures ranged from 29.0 to 32.5°C and were significantly higher in mid- and late-season nests compared to early-season nests. Hatching and emergence success correlated with temperature, where the mid-season nests were the most successful. Hatchling morphology also correlated with temperature; nests with lower temperatures produced larger hatchlings than nests with hotter temperatures. Righting response scores were significantly lower in hatchlings from late-season, hotter nests, while there was no correlation between crawling speeds and temperature. However, more studies are needed to investigate these relationships since the sample size of this study was relatively small. Our data provide insight into how rising nest temperatures may impact hatchling performance and, in turn, affect their survival.