‘Like a Mini Med Spa for Frogs’: Biologists Develop Shelters to Help Vulnerable and Endangered Amphibians Fight Disease

Biologists have created small hotspot shelters that operate like little saunas to help vulnerable and endangered amphibians fight off a fast-spreading and deadly fungal disease that has been a major threat to amphibians for decades.

Researchers from Macquarie University and the University of Melbourne developed the shelters as a way to help amphibians ward off chytridiomycosis, a fungal disease of the skin. 

As explained by Amphibian Ark, a conservation group, the fungi that cause the disease can grow in the skin of an infected amphibian. The fungi inhibit the ability for water to move through the amphibian’s skin, leading to heart failure. Outbreaks of chytridiomycosis have led to major declines in some amphibian species around the world, particularly in Australia, Mexico, Central America, the Andes region of South America and the western U.S., Amphibian Ark reported.

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Globally, 90% of amphibians that are threatened by chytridiomycosis have become extinct in the wild or altogether, and 124 affected species have seen population declines of 90% or higher, Macquarie University reported.

In response, researchers found a low-cost way that they determined to be effective in improving the frogs’ resiliency to the disease. They used whatever materials were already available, such as bricks or PVC, to build small shelters for the amphibians. The idea is that the shelters will become warm enough that the fungal disease will not be able to grow or spread.

“The whole thing is like a mini med spa for frogs,” Anthony Waddle, lead author of the study and a Schmidt Science Fellow at Macquarie University’s Applied BioSciences, said in a statement. “In these simple little hotspots, frogs can go and heat up their bodies to a temperature that destroys the infections. As with many human diseases, such as influenza, chytridiomycosis is seasonal. Winter is a particularly vulnerable time for frogs, given there are few opportunities to heat themselves up. By making hot spots available to frogs in winter, we empower them to cure their infections, or not even get sick at all.”

In a 15-week test with vulnerable green and gold bell frogs (Litoria aurea), which have experienced more than 90% shrinkage of their native habitat in Australia, the researchers found that the unshaded shelters they built were around 4.5 degrees Celsius warmer than shaded shelters. The frogs that used the unshaded shelters were more effective at warding off the fungal disease compared to frogs that used the shaded shelters. 

These frogs also showed improved immunity to the disease after recovery, making them less vulnerable to the fungi in the future. After being re-exposed to the fungus, frogs that had recovered in the shelters had an 86% survival rate in the study, compared to a 22% survival rate in frogs that had not been previously infected. The researchers published their findings in the journal Nature.

“Lowering mortality rates and boosting their immunity to chytridiomycosis is the key to protecting amphibians from this disease, which is now endemic around the world,” Waddle explained.

Because the shelters are made with simple and affordable materials, they are easier to scale by both wildlife professionals and everyday people at home who want to help vulnerable species.

Although the shelters can help the frogs adapt to the widespread fungal disease, the authors noted in the study that such habitat intervention is only one part in preventing extinctions of the species vulnerable to this disease.

“Habitat protection alone cannot protect species that are affected by invasive diseases, but simple manipulations to microhabitat structure could spell the difference between the extinction and the persistence of endangered amphibians,” the study concluded.