Rising Temperatures Could Drive Sea Turtles to Extinction

A new study from the College of Science at Swansea University revealed that global warming brought about by climate change could negatively influence the population of sea turtles in some parts of the world, potentially pushing them at the edge of extinction.

The study, published in the journal Global Change Biology, showed that the rising temperatures could result to higher number of female turtles and potentially increase the risk of nest failure.

"In recent years, in places like Florida--another important sea turtle nesting site--more and more turtle nests are reported to have lower survival rates than in the past.," said lead author Dr Jacques-Olivier Laloë, from Swansea University, in a press release. "This shows that we should really keep a close eye on incubation temperatures and the in-nest survival rates of sea turtles if we want to successfully protect them."

The sex of a sea turtle can be determined by the temperature during its incubation period, a process known as Temperature-Dependent Sex Determination (TSD). At 29 degrees Celsius, the likelihood of becoming male or female is equal. However, temperatures exceeding 29 degrees Celsius increase the chance of female offspring while lower than 29 degrees Celsius make it more likely to male.

Rising temperatures could result to more female sea turtles. It has been known that male sea turtles can mate with more than one female. Higher number of females means more eggs being laid in beaches. However, too many females and too little males could eventually threaten population viability.

For the study, the researchers recorded the sand temperature at a nesting site in Cape Verde over six years, as well as the survival rates of over 3,000 nests in the area. The researchers then develop a model that determines how turtle populations are likely to change throughout the century.

The researchers found that the increasing temperatures could be beneficial for the sea turtles as it will promote more females. In the long run, however, warmer temperatures could result to development failure in eggs. They noted that the optimal incubation temperature for the eggs is between 25 and 35 degrees Celsius. If the incubation temperature is low, the embryo does not develop. If it gets too high, the development of the embryo also fails.