There are fears that platypus populations might have been wiped out by recent floods in greater Brisbane, sparking new calls for the species to be nationally recognised as threatened.
While the platypus is endangered in South Australia and was listed as vulnerable in Victoria last year, the iconic monotreme is not officially considered threatened in Queensland and New South Wales.
But platypus ecologists in those latter states believe much of Victoria’s platypus listing may come down to the fact the species has been better and longer monitored there.
They have issued a call to arms, enlisting citizen scientists to try to spot the cryptic creature and provide the raw data required to protect and manage its habitat.
Dr Gilad Bino, a researcher at the University of NSW, said the impact upon platypuses from a series of natural disasters that have ravaged the east coast of Australia were being magnified by urban sprawl, land clearing and habitat degradation.
“With this sequence of extreme droughts, fire, floods, you are going to have areas where the platypus is going to go extinct,” Bino said.
Bino, whose research largely focuses on the NSW mid-north coast, said he feared silent extinctions have occurred. But the platypus, he said, is an elusive creature that lacks nationwide population monitoring.
“So we’re reliant on a handful of good surveys,” he said.
Among those surveys is that of Tamielle Brunt, a PhD student at the University of Queensland. For seven years Brunt has been using environmental DNA (eDNA) technology to detect traces of platypuses in the waterways of greater Brisbane.
She described this year’s testing as among the most important, given the severe floods that ripped through her survey sites. Some of the results make for grim reading.
A summary of her eDNA data handed to the Ipswich council last month indicated a “severe decline” in its platypus populations.
Of 21 sites sampled in the Ipswich local government area in June, none returned definitive traces of the platypus. Seven of the sites that returned negative results had previously returned traces of platypuses.
Brunt said the nature of eDNA testing meant she couldn’t yet be sure if platypus in those waterways were now in very low numbers or had “completely disappeared”.
“Either way, it’s of massive concern,” she said.
Brunt said flooding was magnified in urbanised areas where water rushed off hard surfaces into raging torrents, stripping banks of vegetation and drowning baby platypuses – known as puggles – in their burrows. Sediment from cleared land could also smother riverbeds and fill the deep pools which hold water through times of dry.
The Ipswich council report noted vegetation clearing, development and construction had “continued to intensify” over the last 12 months in areas that did not return traces of platypus eDNA this year.
Brunt said that making sure developers were acting to control sediment runoff was crucial to retaining peri-urban platypus populations, but because the species weren’t currently listed as a threatened species in Queensland they “didn’t get much of a look in when it comes to development assessments”.
Brunt urged people to get involved in platypus spotting campaigns and report and photograph sightings.
“Don’t keep it secret,” she said. “A lot of people don’t want people to disturb them, but we’re doing so much damage to their environment that we can’t just leave [it] alone any more.
“They are a species that will just disappear and we will not know that they’ve gone.”
Bino said “local extinctions happen”, but in healthy ecosystems a group of platypuses lost or displaced by disaster could be recolonised by neighbouring populations.
In a landscape fragmented by dams and roads, or by patches of “good habitat and bad habitat”, that recolonisation often can’t occur.
“So those platypuses are gone for ever,” Bino said.
