In addition to warming our oceans and beaches, climate change is also altering the ratio of male to female sea turtles.
Female sea turtles come ashore to lay their eggs beneath the sand. Once the eggs are deposited into the underground nests, the females head back into the water, leaving the eggs to develop completely unattended for several months.
Development of the eggs is impacted by several factors, including rainfall, sunshine, shade, and even the kind of sand they are buried in. The eggs are so sensitive to environmental conditions, that the sex of the future turtle is actually determined by these things. Warmer conditions produce more females and cooler conditions produce more males. As our climate continues to change, this could be bad news for sea turtles. New research from Florida Atlantic University (FAU) examined the impact these changes are already having on loggerheads.
“The shift in our climate is shifting turtles as well, because as the temperature of their nests change so do their reproduction patterns,” Dr. Jeanette Wyneken, professor of biological sciences in FAU’s Charles E. Schmidt College of Science, explained in a news release. “The nesting beaches along Florida’s coast are important, because they produce the majority of the loggerhead hatchlings entering the northwestern Atlantic Ocean.”
Loggerheads are of particular concern because life for their young isn’t easy; only roughly one in 5,000 makes it to adulthood. Now, the turtles are still facing all the same challenges (predation, bycatch, etc), but the ratio of males to females is becoming increasingly uneven.
“If climatic changes continue to force the sex ratio bias of loggerheads to even greater extremes, we are going to lose the diversity of sea turtles as well as their overall ability to reproduce effectively. Sex ratios are already strongly female biased,” said Wyneken. “That’s why it’s critical to understand how environmental factors, specifically temperature and rainfall, influence hatchling sex ratios.”
Wyneken and her team recorder rainfall, temperature, and hatchling sex ratios at a nesting beach in Boca Raton, Florida during 2010 to 2013 nesting season.
They found that while earlier in the season and in went years, nest temperatures were cooler and capable of producing males, “the majority of hatchlings in the sampling were female, suggesting that across the four seasons most nest temperatures were not sufficiently cool to produce males,” Wyneken said.
To learn more:
- Read the full news release: Sex and Sea Turtles: Climate Change, Sea Level Rise Impacts.
- Read the full paper: Effect of rainfall on loggerhead turtle nest temperatures, sand temperatures and hatchling sex.
Copyright © 2015 by Marine Science Today, a publication of Marine Science Today LLC.