Scientists capture a species of turtle considered extinct thanks to environmental DNA

Scientists have not observed this turtle  for 25 years, but they know that it still exists thanks to water samples.

DNA recovered from water samples has helped rediscover an iconic species of turtle  last seen more than 25 years ago in a river in north Queensland, Australia.

Water samples taken from the lower Burdekin River by a team of researchers led by James Cook University and analyzed for environmental DNA ( eDNA ) confirmed the presence of Irwin’s tortoise at many sites along the river, which has not been formally registered in the area for more than 25 years.

Breathe underwater through the sewer

The tortoise , first discovered in the Burdekin Basin by the late Steve Irwin and his father Bob in the early 1990s, is among a number of freshwater species that use their cloaca (equivalent to their butt) to breathe underwater, allowing you to stay submerged underwater for longer.

“Until this rediscovery, we had no formal record to show that Irwin ‘s tortoise still lived in the lower Burdekin River, and that river has changed a lot since the Burdekin Falls Dam was built,” said Professor Damien Burrows. , director of the Tropical Waters and Aquatic Ecosystems Research Center (TropWATER). “It’s reassuring to know that they still live there.”

The survey findings were published this week in the journal BMC Ecology and Evolution following two years of research comprising three separate survey periods during 2020 and 2021. 37 sites across the three river basins were investigated, some of which they involved the use of helicopters to get in and out.

Professor Burrows said eDNA technology was vital to the rediscovery of the tortoise in the lower Burdekin River and had the potential to revolutionize the way researchers tracked and located both aquatic and terrestrial animals.

“Previously, it has been very difficult to sample Irwin’s tortoise because they only live in places where there are crocodiles or in upland tributaries that are very difficult to access,” he said. “They also don’t fall easily into traps and the water they live in at Burdekin isn’t clear, so you can’t set up underwater cameras to see them. But now with eDNA , all we had to do was take a water sample and Analyze your DNA .”

With the new process, the DNA itself can be extracted and amplified directly from environmental samples such as soil, sediment and water without having to capture the target organism.

“We don’t know anything about the demographics of this population, but the fact that we’ve found their eDNA now, even though the dam was built in the 1980s, could indicate that adult Irwin’s tortoises can survive in these harsh conditions. cloudier water. This rediscovery has now challenged the previous hypothesis that the species could not survive in these conditions.” ( EuropaPress )