FL - As the Earth heats up, male sea turtle hatchlings could become more rare
As intense heat becomes more common around the world, the potential threat to biodiversity increases. One species at particular risk to a warming climate is found on the beaches of Florida.
Each morning during sea turtle nesting season, scientists and citizen volunteers with Mote Marine Laboratory in Sarasota comb 35 miles of shoreline looking for turtle tracks from mothers coming ashore to lay their eggs or evidence that sea turtle hatchlings have emerged.
Florida has the largest aggregation of loggerhead sea turtle nesting in the world.
Thousands of the marine reptiles lay eggs each year and Mote scientists study and tag these endangered and threatened species to help protect their future.
Their biggest threat right now is coastal development and beachfront lighting, which disorients baby turtles causing them to wander inland.
But scientists say a fast-developing risk to the species is global warming.
That's because the sex of sea turtles is determined by the temperature in which their eggs incubate.
"Warmer temperatures will produce more females and cooler temperatures will produce more males. The adage is hot chicks and cool dudes,” said Jake Lasala, a research fellow with Mote Marine's Sea Turtle Conservation & Research Program.
Studies from his colleagues on Florida’s east coast, show that for the past several years, the vast majority of turtle hatchlings have been female.
Sea turtles that incubate in sand that is 81.6 degrees Fahrenheit or lower, will be male. Those in sand that is 88.8 degrees Fahrenheit or higher, will be female. Anything in between that range will produce a mix of offspring.
As Florida’s summers become hotter -- the last four have been the hottest on record -- beach sand is also getting warmer.
Lasala says that can be problematic for many reasons.
“If there are too many females, then your population can start to decline because the males can't keep up with the number of females,” he said. “If the temperature continues to increase further than currently projected, then you will start to see the death of hatchlings because eggs can't develop after a certain temperature."
Lasala says Florida isn’t the only place where the sex of sea turtles is being altered. A 2018 study found that 99 percent of the green sea turtles that hatched on the warmer, northern Great Barrier Reef nesting beaches in Australia were female.