For some animals, climate change is expected to become a major threat to their survival. For others, a warmer world may actually be beneficial. For the loggerhead sea turtle, it’s a little bit of both.
The loggerhead sea turtle’s vast range stretches across the globe and is composed of nine ‘distinct population segments’ according to the National Oceanographic and Atmospheric Administration (NOAA). Despite the loggerhead’s expansive range, five of the population segments are considered endangered, while the remaining four are considered threatened.
Given the poor state of loggerhead sea turtle populations worldwide, researchers want to understand how predicted changes in climate will further harm, or benefit, the species.
To do so, researchers at Florida State University investigated 17 beaches in Brazil where loggerhead sea turtles nest. Specifically, they determined the success of hatchling production at each beach, or how many of the laid eggs ultimately resulted in a baby turtle. The beaches spanned over 1000 miles of Brazilian coastline and varied in temperature accordingly, with the northern-most beaches closest to the Equator experiencing the hottest conditions.
The environment encountered by a loggerhead turtle egg, particularly local variations in temperature, precipitation, and humidity, is important in determining a turtle hatchling’s sex, body shape, and chance of survival. Given the known environmental sensitivity of turtle eggs, climate change is predicted to have a particularly important effect on future loggerhead breeding success.
Currently, more than 75% of loggerhead turtles in Brazil nest on the warm northern coast. However, this study anticipates increases in rainfall, combined with additional warming of the north coast, will surpass the ‘tipping point’ for these loggerhead hatchlings. In other words, climate change is predicted to make the northern coast inhospitable for loggerhead hatchlings.
Hatchlings on Brazil’s southern coast may fair better. “These cooler beaches are also predicted to experience warming air temperatures; however, productivity is predicted to increase under both the extreme and conservative climate change scenarios” said Natalie Montero, who led the study.
The perks of warmer nesting beaches are not expected to last long, though. “These beaches could also become too warm for successful [hatchling] production, much like the warmer beaches in our study,” Montero said.
Loggerhead sea turtles will need to adapt quickly to survive the long-term predicted impacts of climate change.
“Sea turtles have been around for a long time and have survived many changes to the global climate,” said Montero. “However, climate changes of the past took a long time, allowing sea turtles to adapt to the changing conditions. Today’s climate change is happening very quickly, and therefore sea turtles must adapt quickly or perish.”