For decades, a deadly fungal disease called chytridiomycosis has been killing off the world’s amphibians. One estimate is that the disease has wiped out at least 90 amphibian species.
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“Chytrid is an unprecedented wildlife pandemic,” said Anthony Waddle, a conservation biologist at Macquarie University in Sydney, Australia.
But chytrid has a weakness. The main fungus responsible — Batrachochytrium dendrobatidis, or Bd — thrives in cold climates and can’t handle the heat. A new study suggests that conservationists could combat the fungus by giving frogs a warm habitat during the winter.
The green-and-golden bell frog, once common in southeastern Australia, is now endangered in New South Wales state. In one experiment, Waddle and his colleagues placed fungus-infected frogs in various climates. Some frogs spent weeks in relatively cold weather, in habitats at 19 degrees Celsius. Those frogs harbored high levels of the fungus for weeks. Over the next few months, more than half died.
But frogs housed in warmer environments, or given access to a wide range of temperatures, recovered quickly from their infections.
The scientists then stacked bricks filled with holes in outdoor enclosures, covering each stack with a small greenhouse. Half of the greenhouses were exposed to the sun and the rest were in the shade. Frogs that had access to sun-warmed bricks maintained body temperatures about 3.3 degrees higher than frogs in the shade. That was enough to reduce the amount of fungus they harbored.
Frogs that had survived previous encounters with chytrid also suffered relatively mild infections, even when they were not given access to sun-warmed shelters.
The results suggest thermal shelters could act as a kind of “crude immunization,” Waddle said. He has installed shelters at Sydney Olympic Park, home to a wild population of frogs, and is encouraging locals to “build a frog sauna” in their backyards.
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