This article has been reviewed according to Science X's editorial process and policies. Editors have highlighted the following attributes while ensuring the content's credibility: Forty young sea turtles recently reached an important milestone at Florida Atlantic University: They were finally big enough to leave the university's marine science laboratory and return to the ocean. Their release was a reason to celebrate.
But for FAU researchers who have spent years studying loggerhead, leatherback and green sea turtle hatchlings, there is a growing concern about what the next generation of sea turtles may look like: They're almost all girls. In the laboratory of Jeanette Wyneken, Ph.D., professor of biological sciences and director of FAU's Marine Science Laboratory within the Charles E. Schmidt College of Science, she raises hatchlings from local nests to identify the sex ratio.
So far, every sea turtle currently being raised and studied is female. While female-biased sex ratios are normal for sea turtles, which develop as males or females depending on the temperature at which their eggs incubate, Wyneken is seeing an increasingly troubling pattern. Over more than two decades of monitoring hatchlings and documenting nest temperatures, she has observed repeated years with no males or only a tiny fraction of males among the turtles examined.
Unlike humans, sea turtles do not have sex chromosomes that determine whether they develop as male or female. Their sex is determined by the temperature inside the nest during incubation. Warmer temperatures produce females, while cooler temperatures produce males.
Or as Wyneken puts it, "Cool dudes, warm chicks." As Florida's nesting beaches become warmer, more nests are experiencing temperatures that favor female development, sometimes to the point that no males are produced. "We expect to see more females than males in sea turtle populations. What is not normal, and what worries me, is how many years we're seeing either no males at all or only 1% or 2%," said Wyneken.
"We've looked at what it takes to sustain a population, and we need approximately 25% males every three to four years. We're not even close." The implications may not become apparent for years. Florida's sea turtles take about 20 to 30 years to reach sexual maturity, meaning the consequences of today's sex ratios could emerge a few decades from now, when these hatchlings would be returning to Florida's beaches to reproduce.
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