United States - August 28, 2024

In a comprehensive study spanning 37 beaches across the globe, researchers from Florida Atlantic University and the University of Tübingen have uncovered how rainfall significantly influences the size and development of sea turtle hatchlings. This research, published in BMC Ecology and Evolution, delves into the delicate balance of environmental factors affecting two endangered species: the loggerhead (Caretta caretta) and green (Chelonia mydas) sea turtles.

Sea turtles, after laying their eggs, leave them to incubate in nests buried in beach sand, where they are at the mercy of environmental conditions. The study highlights that while both air and sand temperatures are known to impact hatchling development, rainfall plays a more pivotal role in determining hatchling size.

"Rainfall cools the beach surface and increases moisture, which is crucial for egg development," explained Jeanette Wyneken, Ph.D., a co-author from FAU. "This makes rainfall a better predictor of hatchling body size than temperature alone." The findings reveal that for loggerhead turtles, increased rainfall leads to hatchlings with smaller carapaces but greater weight, whereas green turtle hatchlings show smaller carapaces without a change in body mass.

The research was segmented into three parts: initial data collection in Boca Raton, Florida, followed by a broader study across 19 beaches for loggerheads and 17 for green turtles, and finally, an examination of hatchlings in Cabo Verde after significant rainfall during their dry season. This global approach allowed scientists to understand how varying climatic conditions affect these species differently.

In regions like the Mediterranean, where dry seasons are pronounced, the effects of precipitation on green turtle hatchlings are only noticeable post-dry season. Conversely, Florida's consistent precipitation during the nesting season, despite occasional droughts, shows a different pattern of impact.

The implications of this study are profound for sea turtle conservation, especially in the face of climate change. "As rainfall patterns shift, making wet areas wetter and dry areas drier, the nesting sites for sea turtles could see significant changes," Wyneken noted. This could necessitate a reevaluation of conservation strategies to better protect these species.

The study underscores the need for localized data to inform conservation efforts. "Effective management units should regularly update and include important nesting sites," Wyneken emphasized, advocating for the creation and sharing of local databases to enhance our understanding and support conservation initiatives.

This research not only sheds light on the intricate relationship between climate and wildlife but also calls for a more nuanced approach to conservation, adapting to the changing environmental conditions that affect these ancient mariners of the sea.