After a sea turtle lays their eggs on the beach, it’s the temperature of the sand that influences whether a male or a female will hatch.
According to the US National Oceanic and Atmospheric Administration (NOAA), Sea turtle eggs incubated in sand hotter than 88.8° Fahrenheit (31° Celsius) will be female.
In recent years that sand has been heating up, which has led to more females being produced. However, with the ongoing threat of climate change, this warming trend shows no sign of slowing, making male turtle births a rarity.
A turtle hospital in Florida recently indicated that every turtle it has examined for the past four years have been female.
As Science Alert reports, male sea turtles make up less than 10% of the overall population, a disparity that grows wider with each breeding season.
“There are seven species of sea turtles, and all of them produce more females as it gets warmer,” Lucy Hawkes, an ecologist from the University of Exeter, told Business Insider. “All of them have strongly female biased sex ratios,”
As Reuters reports, the last four summers in the Florida Keys have been the hottest on record.
“Scientists that are studying sea turtle hatchlings and eggs have found no boy sea turtles, so only female sea turtles for the past four years,” said Bette Zirkelbach, manager of the Turtle Hospital in Marathon.
The phenomenon is not limited to the waters around Florida. As Newsweek reports, a 2018 study found that 99% of turtles in Eastern Australia were female as well.
A dearth of males could lead to poor genetic diversity for the sea turtle population, but experts are divided on what the best balance of gender should be.
Melissa Rosales Rodriguez, a sea turtle keeper from the Miami Zoo, told Reuters that a group of sea turtle nests hatching about 90% females is not uncommon, while other studies indicate that only a few males are needed to fertilize all the eggs.
“Having lots of females could be an evolutionary adaptation to increase the population from being endangered,” Rodriguez said.
But will we ever reach a point where no males will be produced again? Potentially not. Even in hot sands, there is evidence that males could still be produced if the eggs are kept wet.
“If you ran out of all males, it would threaten the population – but we don’t think that’s going to happen too soon,” Rodriguez said.
Rising temperatures are not the only threat the sea turtles face, however. Climate change also disrupts global weather patterns, resulting in devastating storms that have wiped out sea turtle nests by the thousands. Rising sea levels threaten to do the same, potentially eliminating critical habitats forever.
Unless development on nesting beaches is limited, with fewer hotels and housing projects taking up nesting areas, sea turtles may be headed toward extinction faster than we think.
This article by Matthew Russell was first published by The Animal Rescue Site.
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