Climate change driving platypus out

By Beau Gamble 15 July 2011
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One of Australia’s most iconic species is under threat from rising freshwater temperatures.

ONE OF AUSTRALIA’S MOST curious and much-loved species, the platypus, is under a new threat from rising freshwater temperatures, according to new research.

The warmer water, researchers from Victoria say, may drive the platypus (Ornithorhynchus anatinus) from 30 per cent of its current habitat. The thick fur coat of the platypus makes it particularly vulnerable to rising temperatures, says Dr Ross Thompson, an ecologist at Monash University and co-author of the study.

“They’re stunningly well insulated,” Ross told Australian Geographic. “They evolved in a very cool time in Australia’s history and so they needed to stay warm in cold water. Unfortunately they have a real issue with getting rid of heat.”

The scientists used records of platypus distribution from 1800 to 2009
to understand how the species responds to changes in temperature and
rainfall. By combining this information with projections of future
climate change, the team predict that rising temperatures across
south-east Australia will radically reduce the area of viable habitat
for the platypus.

Losing habitat

The platypus spends much of its time foraging for food in streams and rivers, and previous increases in water temperature have already put it under pressure, says Ross. “From about the mid-1960s, there’s been quite a profound warming and drying trend in Australia,” he says. “And associated with that trend has been a decline in the platypus’s range. But looking forward, [the decline] is going to be really quite profound.”

If current trends continue, the platypus should continue to thrive in the colder parts of its distribution – Tasmania, Kangaroo Island and King Island.

The echidna and platypus comprise the ‘monotreme’ group of mammals – the only mammals that lay eggs. But its most curious feature is its sixth sense, called ‘electroreception’, which helps it search for hidden food. It’s a feature exclusive to the platypus and some fish.

As a carnivore, the platypus keeps populations of other species lower in the food chain in check. Ross believes that if the species is driven from its current range, whole freshwater ecosystems could be affected. “Platypuses are incredibly important, strong-interacting species within freshwater food webs,” he says.

Shy and secretive

Dr Joanne Connolly, a wildlife researcher from Charles Sturt University, says that scientists still have much to learn about the platypus. “Even though we’ve been aware of it since the 1800s, we still know so little about it,” she says. “Because it’s so shy and secretive; it’s not always easy to see them or to estimate their population.”

That’s why it’s fortunate, she says, that we have extensive records of its past distribution for predicting the effects of climate change.

Ross hopes that this study and others like it will encourage Australians to act more readily to combat climate change. “[The research] shows we’ve already been too slow to act, and it shows we don’t have spare time,” he says. “We need to be doing things now.”

The study is published online in the journal Global Change Biology.