A turtle that was thought to be locally extinct has been discovered spilling its DNA all across Australia’s highest discharge river. Any species’ rediscovery is excellent news for ecology, but the chelidae in issue is a special favorite for breathing through its back end. Because the lower Burdekin river is vast and muddy, and turtles spend most of their time at depth, TV host Steve Irwin and his father didn’t catch one until 1990. When it was confirmed that this was a new species, it was given the name Irwin’s turtle (Elseya irwini).
It was later discovered to live in the Burdekin’s tributaries, but it hadn’t been observed in the lower Burdekin for over 25 years, leading to worries that it had lost its largest home. However, according to a report published in the journal BMC Ecology and Evolution, the turtle may still be seen in numerous places along the river. DNA was discovered in water samples gathered along the river as proof. Freshwater turtles in Queensland, especially Irwin’s, have developed a unique style of breathing to prevent having to come to the surface too often, reducing the chance of being eaten.
They utilize their cloaca to absorb water (the whole reptiles and birds use for reproduction and defecation). Their digestive systems have gill-like appendages that collect oxygen dissolved in the water. No known turtle species can survive only on anally supplied oxygen; they all need to surface every now and then to breathe normally. Bum-breathing, on the other hand, delays the urge to do so. Some turtles can receive up to 80% of their oxygen needs this manner under ideal conditions, while this proportion is lower for other species.
Bum-breathing, on the other hand, need oxygen-rich water, which necessitates fast-moving streams. It was thought that a dam on the Mary River would cause the extinction of species in the basin by reducing the oxygen supply. The first time their capacity had become publicly recognized beyond herpetological circles was during the fight to oppose the dam, in which the uncommon and endangered turtle played a prominent part. As a result, there were concerns that the Burdekin Falls Dam, which was finished in 1987, would have caused a devastating reduction in the number of Irwin’s turtles on the river. Dr. Cecilia Villacorta-Rath, Professor Damien Burrows, and co-authors, on the other hand, sampled 37 locations throughout the Burdekin River and its tributaries and discovered turtle DNA across the basin.
The turtle, however, is not unaffected by the dam. Turtle DNA was found more frequently in the Broken and Bowen tributary rivers, indicating a higher abundance there than below the dam. Despite this, turtle DNA was discovered at four locations below the dam but above the Bowen River’s confluence. “We didn’t have any formal documents to establish that the Irwin’s turtle was still surviving in the lower Burdekin River until this rediscovery,” Burrows said in a statement. “That river has altered a lot since the construction of the Burdekin Falls Dam.” “Knowing they’re still there gives me comfort.” The presence of crocodiles in the lower Burdekin discourages scientists from diving into the waterways.
Because the river below the falls is murky, underwater cameras are ineffective, and all that bum-breathing makes it difficult to notice them on the surface. The ability to gather environmental DNA (eDNA) and amplify it to the point where the source of the DNA can be traced has been a game-changer in the search for the turtles, much as it did for extinct human species. “All we had to do was take a water sample and look for their DNA,” says the researcher “Burrows said.” We don’t know anything about this population’s demographics,” Vilacorata-Rath said, but the fact that they are still living shows that more research isn’t futile.
