Global insights from a decade of nesting data for olive ridley, green, hawksbill, and leatherback turtles: Implications for conservation in the face of climate change

Abstract

Sea turtles have existed on Earth for approximately 150 million years, during which time they have adapted to various environmental and oceanographic changes. However, the effects of current climate change on these reptiles are of concern due to the direct impact of temperature on sex ratio and hatching success. Low temperatures generally produce male offspring, while high temperatures favor the development of females, with an upper limit of thermal tolerance ranging between 33 and 35 °C. Global warming poses both a long-term risk of feminization of sea turtle populations and a short- and medium-term risk of decreased hatching success. The objective of this study was to evaluate the reproductive parameters of four species of sea turtles (Lepidochelys olivacea, Chelonia mydas, Dermochelys coriacea and Eretmochelys imbricata) during the last decade by carrying out a systematic review, in which 100 published articles were analyzed following the PRISMA methodology. The results revealed a significant bias towards female offspring in all species, with recorded values of up to 100 % (Lepidochelys olivacea) and 98 % (Chelonia mydas). When analyzing hatching success, it was observed that no species reaches 100 % success and that Chelonia mydas has the highest average (68.9 %), while Dermochelys coriacea records the lowest values (50.4 %). It important to note that reproductive parameters vary between species and populations. The undeniable tendency towards female offspring in all species is evident. However, this dynamic may result not only from recorded temperatures but also from the evolutionary history of sea turtles.

Keywords: Cheloniidea; Climate change; Hatching success; Sea turtles; Sex ratio; Temperature.