Predicting The Platypus

“It’s an obvious fraud!,” the poet Ronald Strahan once wrote of the platypus. “Someone has stuck the front end of a duck, with the skill of a weaver, to part of a beaver.” But the unique water-loving, egg-laying creature might not adapt so well to climate change, a new study from Australia warns.

The platypus is found in the freshwater ecosystems throughout eastern Australia, where it feeds almost exclusively underwater, at night, on aquatic invertebrates. It digs burrows in streambanks where it can rest and keep cool during the heat of the day. And despite ecological changes that have wiped out many other unusual Australian animals, the platypus “still persists throughout much of its historical range,” Melissa Klamt and colleagues from Monash University report in Global Change Biology. As a result, it is listed as a species of “least concern” by international conservation experts.

But the researchers wondered: How might the platypus cope with a changing climate?

To make that forecast, the team collected nearly 9,600 records of platypus sightings between 1800 and 2009, and then combined them with computer models of Australia’s future climate. The mash-up showed that both rainfall and maximum air temperature are “important factors influencing the distribution of platypus.” And it suggests that a shift occurred in the 1960s as southeastern Australia became warmer: Prior to that decade, rainfall played a key role in determining the availability of suitable river habitats; more recently, however, “thermal tolerance” – the ability to withstand the hottest part of the day – has become a more important predictor of where the animals thrive.

That’s a worrying finding, they say, given predictions that Australia may get even hotter. “Increased temperatures are likely to have direct physiological impacts on the platypus,” the authors notes. “It is covered in highly insulating fur, but cannot pant or utilize saliva spreading for thermoregulation, and can only cool itself by immersion in cool water, seeking refuge in burrows or through limited sweating.” And needing to hole up means that warmer, dryer conditions could “result in a greatly reduced food intake due to a reduction in foraging opportunities.” And other stresses – such as the animal’s limited ability to flee to new habitats, and growing demand for water from farms and cities, “may render them highly vulnerable to the impacts of a changing climate, particularly from loss of aquatic habitats due to drying and elevated water temperatures.”

There are strategies for keeping the platypus cool, the authors note, including restoring riverside vegetation, making sure users don’t take too much water out of rivers, and using small dams to create the deep pools that platypus like. “Climate adaptation strategies,” they argue, “must give highest priority to ensuring the enduring conservation of this globally significant animal.”David Malakoff | June 21, 2011

Source: Klamt, M., Thompson, R., & Davis, J. (2011). Early response of the platypus to climate warming. Global Change Biology DOI: 10.1111/j.1365-2486.2011.02472.x

Image Copyright Dr. Bass