Warming climate will change turtle sex, but some like it hotter than others
It has long been known that warmer weather makes marine turtle eggs produce female turtles, but researchers find that global climate change will not simply lead to all-female populations.
Print text onlyPrintCancelIt has long been known that warmer weather makes marine turtle eggs produce female turtles, but researchers are finding that global climate change will not simply lead to all-female populations.Key points:The sex of marine turtle hatchlings is determined by the temperature at which the egg incubates
Different species of turtle and turtles in different locations have different temperatures for sex determinationThe Australian flatback turtle is potentially more adaptable than other species to future climate changeFor some reptiles the sex is not determined until after the egg is laid, but it is the temperature at which the egg incubates, buried in its underground nest, that determines if a baby turtle will hatch as a male or female.
The burning question for Blair Bentley from the University of Western Australia has been what this means for the future of marine turtles where climate change is driving up average temperatures."It's been known for about 40 years that the temperature influences the sex of sea turtles," Dr Bentley said.
"We wanted to look and see whether this differed between and within species throughout north-western Australia."Race against timeLarge marine turtles are a spectacular and common sight in the warm coastal waters off northern Australia, and some species are important to Indigenous culture and as a traditional food source.
At various times of the year, mature female turtles will crawl out of the sea to dig holes above the high tide mark to lay their eggs.It is in these nests that the temperature of the eggs will decide whether they will be male or female.To find out exactly what was happening at this critical point in their life cycle, Dr Bentley had to go to extreme lengths and rely on the knowledge and skill of Aboriginal ranger groups.
"We went up to a few rookeries throughout north-western Australia, which if you've ever been up that way you'll know how remote it is," Dr Bentley said."There was a whole range of ways to get out to the islands and the mainland rookeries — we'd have to take helicopters, float-planes, and boats."
To understand the way turtle sex is determined by temperature, Dr Bentley had to collect eggs as they were being laid, and then rush them back to carefully controlled incubators in the laboratory."We've got 72 hours from when we collect the egg from a nesting female to get it back to the incubator in Perth," he said.
"It was always a race against time, but it was a lot of fun."Find more local newsA newly hatched flatback turtle gets its first taste of the sea.()Turtles ain't turtlesBack in the lab, Dr Bentley was able to study how different species and populations from different parts of the Australian coast responded to different incubation temperatures.
He focused on two of the most common species — the green and the flatback turtle — and looked at what temperature the eggs changed from male to female, known as the 'switch-point'.Green turtles are found around the world, while the flatback turtle is the only marine turtle found exclusively in Australian waters, which biologists call endemic to Australia.
Dr Bentley found that green turtles were more particular in their egg incubation temperatures and had a lower switch-point, while the Australian flatback turtle appeared more adaptable to a range of temperatures and had a higher switch-point on average.
"Flatbacks were quite interesting because we found about a degree of difference between two populations," Dr Bentley said."So this has a lot of implications for climate change where, as the temperature is increasing, the population with the higher switch-point is probably a little bit more resilient in terms of maintaining male output."
Case by caseDr Bentley said other research had found that adult flatback turtles were more resilient to high temperatures as well, and could switch from the more usual summer nesting to winter nesting in warmer parts of Australia."So at Cape Domett on the Northern Territory border we've got winter nesting, and then anywhere south of about King Sound we've got summer nesting," Dr Bentley said.
"So there might be some evidence there that they may be able to adapt by shifting the timing of their nesting, which might be able to help them in the future."A mature female green sea turtle laying eggs at night.(Supplied: Cairns Turtle Rehabilitation Centre
)There was some good news for green turtles as well.Although different populations had very similar switch-point temperatures, populations further north in warmer climates had a wider range of temperatures in the middle that produced both sexes."This population that's got the wider range of temperatures that produces both sexes, that's expected to have a higher adaptive capacity," Dr Bentley said.
The upshot of these findings was that different populations of marine turtles were likely to respond differently to a changing climate."It really shows that we need to consider these populations on a case-by-case basis, especially when you're considering climate change impacts," Dr Bentley said.
"Overseas, there are procedures such as shading the nests to ensure more males are produced … but this all depends on the individual rookery and what we expect to happen in the future." Read more: ABC News »
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More bogus predictions Turtle sex.... an odd read for 9am. But these are odd times. So why not hey! Can the staff at the ABC stop drinking bong water. I will believe this story if the abc will admit that there are only two genders. Absolute rubbish And some people suggest the should have funding cut 🤦♀️ How could we live without content like this
Fakenews The climate or sex?
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