This DIY Stone Sauna Helps Frogs Fight Disease

Wedged into the tiny holes of masonry bricks, which heat their bodies to almost 30 degrees Celsius, you’d think Australian green and gold bell frogs would be uncomfortable.

But new research says the amphibians love it, and these DIY dry saunas – made from spray-painted bricks in plastic greenhouses – could give them an edge in the fight against a deadly fungus.

“This is really exciting,” says Anthony Waddle, a biologist at Macquarie University in Sydney, Australia, and lead author of the new study published in Nature. ‘If frogs get the chance, they can do it too [help] himself.”

Waddle and his team designed experiments with easily available materials. They placed these makeshift saunas in a semi-wild habitat on the campus of Macquarie University to see if frogs would use them to combat a global killer.

The fungus is Batrachochytrium dendrobatidis (abbreviated to Bdbut also called chytrid, pronounced kit-rid), and is responsible for the population decline of more than 500 species of amphibians – and the extinction of at least 90 others.

“I think it’s one of the most devastating pathogens that Western science has recorded,” said Christina Davy, a biologist at Carleton University in Ottawa who was not involved in the study.

“It infects the skin of amphibians and disrupts their ability to move water and gases across their skin,” Davy explains.

Waddle compared the effects of chytrid to an athlete drinking too much water, which disrupts the body’s sodium and potassium levels, ultimately leading to cardiac arrest.

Davy adds that chytrid is fast-acting, hardy, can spread without hosts and is found all over the world. When it enters a new area, previously uninfected and endangered species can be wiped out.

A brick house

But before you imagine an amphibious version of the tracks The last of usChytrid does have preferences – and really high temperatures, around 30 degrees Celsius, are not one of them.

Waddle and his team worked with green and gold bell frogs, an endangered species native to New South Wales. After infecting frogs with chytrid, they created mesocosms – a controlled outdoor environment – ​​of different frog habitats. These included the so-called frog saunas, and the resulting warm and humid climate was highly preferred by the frogs, Waddle explained.

But he also found that when “frogs had access to these shelters, their body temperatures were higher and they had fewer infections over time.” Furthermore, frogs that cleared their infections using this high heat were more resistant to reinfection.

Ana Longo, an amphibian disease expert and biologist at the University of Florida, called the experiment simple but elegant, but warned that it faces challenges in how it would spread to other species and into the wild.

“Amphibians are so diverse and have so many different habitat preferences,” she says from Gainesville, Florida.

However, Longo says that when it comes to a threat as devastating as chytrid, there are few tools available outside of a controlled zoo environment, such as antifungal treatments.

“We need bold action at this time,” Longo said. “We know that [a] One single measure is not going to be effective for all species. So I think we just have to try different things.”

Waddle says the materials cost him about $70. Both Davy and Longo appreciated how accessible and affordable this solution could be for anyone to build.

Why save the frogs?

Amphibians are part of countless food webs, and Waddle says they provide benefits to the aquatic environment in their early lives as larvae and tadpoles, but also to the land once they reach adulthood.

Both predator and prey, they are crucial for healthy snake populations and for keeping insect populations down. When chytrid wiped out frog populations in Costa Rica and Panama, there was a spike in malaria cases.

While his team’s solution isn’t permanent, it would give the frogs a fighting chance during the colder seasons when chytrid thrives.

“Right now they get hammered every winter. There are dead and dying frogs everywhere,” said Waddle, describing what he saw in Sydney. “Populations just have a hard time getting a few individuals through the winter to breed.”

Although declines in chytrid frog species have been observed around the world for decades, Davy of Carleton University says it is not always fatal. Her My own research showed it was widespread in Ontario in frogs and salamanders, and does not lead to mass mortality.

But she cautions that tolerance may not apply to newer species.

“There is currently great concern about bringing a new species of chytrid fungus to North America,” Davy said. “And there is great concern that if it comes to that [the continent] … it can also be very devastating.”