Effects of egg mass and local climate on morphology of East Pacific leatherback turtle Dermochelys coriacea hatchlings in Costa Rica

Abstract

Global climate patterns are shifting due to anthropogenic causes, putting pressure on many species that are unable to adapt to such rapid changes. Sea turtle clutches, for example, normally develop between 26 and 33°C, but tolerate higher temperatures at the end of development. High temperatures, protracted rainfall, and droughts have been linked to fewer hatchlings. Likewise, climatic conditions can affect the size of sea turtle hatchlings, which could affect their probability of survival. We analyzed the effects of a biotic factor (egg mass) and environmental factors (precipitation and incubation temperature) on East Pacific leatherback turtle Dermochelys coriacea hatchling sizes in Costa Rica. Hatchling size (mass, straight carapace length, straight carapace width, and head width) was affected by both biotic and environmental factors. While egg mass was the strongest predictor for hatchling mass, temperature was the strongest for carapace length and head width. Carapace width was most strongly predicted by precipitation. Hatchling carapace length and width decreased with increases in temperature and increased with higher levels of precipitation. Hatchling mass also decreased with increasing temperature, although the relationship was not statistically significant. Head width decreased with greater precipitation during development. These findings suggest that increases in temperature and decreases in precipitation may not only decrease the number of hatchlings produced, but may also produce smaller leatherback hatchlings in Pacific Costa Rica, which may impair hatchling survival in the first hours after emergence.