Ensconced in tiny holes in the masonry bricks, which warm their bodies to around 30C, you’d think Australian green and gold bell frogs would be uncomfortable.
But new research says amphibians love it, and that these DIY dry saunas — made of spray-painted bricks placed in plastic greenhouses — could give them an edge in fighting a deadly mold.
“This is really exciting,” said Anthony Waddle, a biologist at Macquarie University in Sydney, Australia and lead author of the new study published in Nature. “If frogs are given the chance, they can [help] themselves”.
Waddle and his team designed experiments involving readily available materials, placing these makeshift saunas in a semi-wild habitat on Macquarie University’s campus to see if frogs would use them to fight off a global killer.
Mushrooms are Batrachochytrium dendrobatidis (abbreviated to Blvdbut also referred to as a chytrid, pronounced kit-rid), and is responsible for the population declines of more than 500 amphibian species—and the extinction of at least 90 others.
“I think it has been 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 interferes with their ability to move water and gases through their skin,” Davy explained.
Waddle compared the effects of chytrid to an athlete drinking too much water, disrupting sodium and potassium levels in the body, eventually leading to cardiac arrest.
Davy adds that chytrid is fast-acting, hardy, can spread without a host and is found worldwide. When entering a new area, previously uninfected and endangered species may become extinct.
A brick house
But before you imagine an amphibious version of the spores in the The last of uschytrid has preferences – and really hot temperatures, close to 30 C, are not among them.
Waddle and his team worked with green and golden bell frogs, an endangered species native to New South Wales. After infecting the frogs with chytrid, they created mesocosms—a controlled outdoor environment—of different frog habitats. These included so-called frog saunas, and the resulting ripe, humid climate was much preferred by the frogs, Waddle explained.
But he also found that when “frogs had access to these shelters, their body temperatures were higher and over time they had lower infections.” Furthermore, frogs that cleared their infections using this high heat were more resistant to re-infection.
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 scale up to other species and in nature.
“Amphibians are so diverse and they have so many different habitat preferences,” she said from Gainesville, Fla.
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 anti-fungal treatments.
“We need bold measures at this point,” Longo said. “We know that [a] A single measure will not be effective in all species. So I think we should try different things.”
Waddle says the materials cost him about A$70. Both Davy and Longo appreciated how accessible and affordable this solution could be for anyone building.
Why save frogs?
Amphibians are part of many food webs, and Waddle says they benefit aquatic environments in their early life as larvae and tadpoles, as well as land once they mature.
Both predators and prey, they are critical to healthy snake populations as well as maintaining insect populations. In fact, when chytrid killed frog populations in Costa Rica and Panama, there was an increase in malaria cases.
While his team’s solution isn’t permanent, it would give the frogs a fighting chance during the colder seasons where the chytrid thrives.
“Right now, they just hit every winter. There’s just dead and dying frogs everywhere,” Waddle said, describing what he’s seen in Sydney. “Populations are just trying to get some individuals over the winter to breed.”
While the decline of chytrid frog species has been observed around the world for decades, Davy at Carleton University says it doesn’t always kill. it own research found it to be widespread in Ontario in frogs and salamanders, and does not result in mass death.
But she warns that tolerance may not apply to newer strains.
“There is real concern now about bringing a new species of chytrid fungus into North America,” Davy said. “And there’s real concern if it would [the continent] … it can also be really destructive.”