Multiscale climate forcing on green and hawksbill turtle nesting dynamics in Malaysia

Abstract

Sea turtles play critical roles in marine ecosystems, yet they face numerous threats, not only of anthropogenic origin but also those exacerbated by environmental changes. This study investigates the impacts of both local and global climatic forcing on green (Chelonia mydas) and hawksbill (Eretmochelys imbricata) turtle populations in Malaysia. Using 17 years of nesting data from Tioman Island, we examined nesting abundance, spatial distribution, temporal trends, and egg abundance in relation to local climatic conditions (temperature and precipitation) and global climatic conditions (El Niño Southern Oscillation – ENSO), through Wavelet Analysis. Our study demonstrates that both local and global climate variables significantly influence turtle egg abundance, with local factors driving short-term seasonal variability and global factors like ENSO affecting long-term multiannual cycles. Additionally, we found that warmer temperatures during El Niño events negatively impact green turtles egg abundance 2 years and a half later but positively impact hawksbill turtles 2 years post–event. These contrasting responses emphasize species-specific reproductive adaptations to climatic variability. Understanding these dynamics is critical for developing adaptive conservation strategies that mitigate the effects of climate change and promote sustainable population management for both species.