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A sea turtle crawls into the sea in Oaxaca, Mexico
Photo: Edgar Santiago García/ dpa
Almost every sea turtle born on Florida beaches in the past four years is female.
Obviously the hot sand is to blame.
"It's scary: The last four summers have been the hottest on record," Bette Zirkelbach told Reuters.
Zirkelbach is the director of a turtle clinic in Marathon, a town in the Florida Keys, a chain of tropical islands in southern Florida.
"Scientists studying sea turtle hatching have not found any male turtles in recent years."
Feminine through hot sand?
According to the US National Ocean Service, the sex of sea turtles depends on how warm the eggs are stored.
When the ambient temperature is below 27 degrees Celsius, the baby turtles become male.
At over 31 degrees Celsius they become female.
Temperatures in between result in a mix of both sexes.
So the hotter the sand, the more female sea turtles there are.
"In the face of climate change, increased temperatures could lead to distorted or even deadly breeding conditions, which could impact turtle species as well as other wildlife," warns the National Ocean Service.
That's exactly what Melissa Rosales Rodriguez, an employee of the recently opened turtle clinic at the Miami Zoo, fears.
"Over the years we should see a sharp decline in the population," she told Reuters.
Already in 2018 in Australia
A 2020 study on the connection between temperature, sex and climate change in sea turtles puts forward the thesis that the excess of female animals in heat should actually be aimed at survival: the more heat, the more turtles die, so it takes more offspring to survive more female animals.
Similar observations were made in Australia four years ago.
There, too, after a very hot summer, 99 percent of the newly hatched turtles were female, as reported by "National Geographic" with reference to a scientific study in the journal "Current Biology".
The sex of most species of turtles, alligators, and crocodiles is determined only after fertilization and is affected by the temperature surrounding the eggs.
This connection is referred to as »TSD«, »temperature-dependent sex determination«, temperature-dependent sex determination.
mgo/Reuters