Green and Golden Bell Frog (Litoria aurea) Photo By Bernard Spragg. NZ – https://www.flickr.com/photos/volvob12b/15254781805/, CC0, https://commons.wikimedia.org/w/index.php?curid=79218054

Dear Readers, nothing cheers me up more than hearing that a simple and cheap way to help an endangered species has been found, and when the animal concerned is a frog that lifts my heart even more. Frogs and other amphibians have seen their populations plummet for a variety of reasons, but mostly due to chytridiomycosis, a deadly fungal disease that has killed off more than 100 species of frogs, toads and salamanders worldwide.

The Green and Golden Bell Frog (Litoria aurea) was once a common Australian species, but is now limited to a small area in the south-east of the country. It is described as a ‘large, stocky frog’, and although technically a tree frog it actually spends most of its time on the ground. It is often found on golf courses, in gravel pits and brownfield sites, and a population was discovered on the site for the tennis courts that were due to be built for the Sydney Olympics in 2000. Fortunately, the decision was made to build the tennis courts elsewhere (well done, Sydney!) The frog is still common in New Zealand, but could easily disappear altogether from Australia.

Chytrid disease seems to be most liable to infect frogs in cold conditions: temperatures above 28 degrees centigrade inhibit the growth of the spores, but it’s unusual for it to be this warm in winter, even in Australia. Scientist Anthony Waddle placed captive Green and Golden Bell Frogs, who were infected with chytrid, in greenhouses which contained brick shelters with holes in them. One of the greenhouses was in the sun, and temperature rose to over 40 degrees. The other greenhouse was in the shade, and temperatures didn’t go above 35 degrees.

The differences were astonishing. The frogs in the hotter greenhouse had 100 fold less chytrid fungus on their skins than the frogs in the colder greenhouse, and the heat also seemed to activate the frogs’ immune systems – Waddle observes that the frogs who have been ‘heat-treated’ have a 22 times greater chance of surviving a subsequent infection, even in cold conditions.

The bricks that make up the frog ‘sauna’ can be bought for as little as 60/70 Australian dollars, and Waddle is hopeful that people all over Australia will give it a go – he says that he can think of at least six species of frog in the country who could benefit from some winter heat. This will be an interesting project to watch!

You can read the whole article here and the link to the article in Nature is here.

Frogs in their ‘sauna’ – Photo by Anthony Waddle via New Scientist