Feminisation of green turtles
Global warming is the culprit.
One of the largest green turtle populations in the world is at risk of extinction through feminisation, according to a study reported in Current Biology.
More than 200,000 females make their nests in the far north of the Great Barrier Reef. The temperature and moisture of the sand determines the sex of green turtle hatchlings during incubation. Cooler temperatures and wetter sand tend to result in more males; warmer temperatures and drier sand produce more females. Rising temperatures are skewing the ratio.
A survey of green turtle numbers has found a massive sex bias in the northern region of the reef. More than 86% of adults are female, while among young turtles more than 99% are female, says the study “Environmental warming and feminisation of one of the largest sea turtle populations in the world”.
A similar trend has been observed among sea turtles in Florida.
The researchers from the National Oceanic and Atmospheric Administration in California, the Queensland Department of Environment and Heritage, California State University Stanislaus and Worldwide Fund for Nature say their results indicate the green turtle rookeries of the northern Great Barrier Reef have been producing primarily females for more than two decades, with “complete feminisation” possible in the near future.