Green Turtles In Great Barrier Reef Turning Female Because Of Climate Change

Green Turtles In Great Barrier Reef Turning Female Because Of Climate Change

Unlike humans and many other species that develop into males and females based on sex chromosomes, green sea turtles' embryos develop sex depending on the temperature outside of the embryo's egg. That means the temperature surrounding on the beach, also known as a rookery. Only a few degrees Celsius lie between the temperatures producing 100 percent male and 100 percent female hatchlings. And among the juvenile and sub-adult northern turtles collected, 99 percent were female.

The results of the study have alarmed scientists and wildlife conservation workers, as the green sea turtle is considered one of the most endangered species in the world, and the Great Barrier Reef is the Pacific Ocean's largest and most important green sea turtle rookery.

There are two genetically distinct populations of green turtles on the Reef.

For the study, researchers with NOAA, California State University and Worldwide Fund for Nature Australia examined two populations of green sea turtles living in the northern and southern part of the Great Barrier Reef. As the sand's temperature increases the ratio of females by birth will be more than that of males.

"There are a lot of sea turtle populations that are female biased, and in fact that's a great method for them to reproduce in greater numbers", Ms Allen said.

"This is extreme ― like capital letters extreme, exclamation point extreme", Camryn Allen, marine biologist and co-author of the study, .

"That transitional range, from 100 percent males to 100 percent females, spans a very narrow band of only a couple of degrees", Jensen said.

In one population towards the southern end of the reef, the turtles skewed 65-69% female, according to the researchers.While that's bad for that populatio' survival rate, it's not almost as alarming as what the researchers found in a genetically distinct population in the warmer areas toward the northern tip of the Great Barrier Reef. For every one male, there are two females, according to the new research.

Green sea turtle
The turtles play a crucial role in keeping their habitat healthy. Reuters

The research, that was facilitated by the Rivers to Reef to Turtles project and led by WWF Australia, was published in the journal. Sea and air temperatures at the population's nesting area have been steadily rising for the last 50 years, the report claims, leading the authors to conclude that climate change is responsible.

Some green sea turtle populations are becoming increasingly 'feminized, ' that is, with a disproportionate number of females, like the one pictured here.

David Owens, a professor emeritus from the College of Charleston in SC, was not involved in the new study but said he has dreamed of doing such research for years.

", Owens told The Washington Post.

"Is this species liable to go extinct? Common sense tells you: One male and a hundred females ― that's going to be a very exhausted boy". Turtles seem to target their breeding periods to times when the sand is slightly warmer than their pivot temperatures, resulting in populations moderately skewed female. "I sure hope so and I'm sure there will be", Ms Allen said. But the researchers found that if they brought blood plasma samples back to their lab, they could use hormonal differences to distinguish male and female turtles. It is not a trend backed up by real-world data. Researchers found that adult-sized turtles in the northern population were around 87% female.

WWF Australia chief executive Dermot O'Gorman has encouraged more intensive and urgent action to save the Pacific green sea turtle population. The gender shift suggests climate change is having a significant effect on one of the biggest green-turtle populations in the world.

"The degree of temperature and habitat change that has happened is likely unprecedented due to how quickly these changes are happening now with the rapid warming of the earth", she told HuffPost in an email.

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