In The Battle To Save Frogs, Scientists Fight Fungus With Fungus A deadly fungus is devastating frog populations around the world. In California, scientists are racing to find a way to immunize one species, mountain yellow-legged frogs, against the fungus.

In The Battle To Save Frogs, Scientists Fight Fungus With Fungus

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A deadly fungus is contributing to the devastation of frog populations around the world, not including BJ Leiderman, who writes our theme music. So far, it's wiped out 200 species. And scientists are racing to find a way to immunize frogs. As Lauren Sommer of member station KQED reports, that's being tested now in the mountains of California.

LAUREN SOMMER, BYLINE: Search and rescue is something Jessie Bushell does in a very unconventional way.


SOMMER: She gets up before dawn to meet a helicopter that's flying in from the Sierra Nevada.

JESSIE BUSHELL: The doors fly open. The firefighters start unloading these large white coolers.

SOMMER: Coolers filled with winkling, green tadpoles - they're mountain yellow-legged frogs, the only survivors of a deadly outbreak at their remote lake. The chytrid fungus had hit, just as it had in many other places.

BUSHELL: When it hits, it's within weeks that they're just gone - just literally gone.

SOMMER: So last summer, Bushell brought the survivors here to the San Francisco Zoo, where she's the director of conservation.


BUSHELL: This one's also, I think, really pretty if you look at his marbling on his back.

SOMMER: Those tadpoles are frogs now. And more than 200 of them are getting an experimental vaccine against chytrid fungus, one that could matter to frogs worldwide.

BUSHELL: So what we do is we expose them to small amounts of this fungus.

SOMMER: The frogs get sick. But that's what Bushell wants. It teaches their immune systems how to fight the fungus. Then before it kills them, Bushell clears it up with an anti-fungal treatment. The idea is that when the frogs get the fungus again out in the wild, they'll be ready.


SOMMER: That's the hope, at least. Bushell and a field crew are carrying the frogs up a rocky trail south of Lake Tahoe in an area called the Desolation Wilderness. They're loaded into backpacks, each frog in its own tiny Tupperware container. They wind their way up to a sapphire-blue lake...


SOMMER: ...And set the frogs free one by one.

BUSHELL: It's a new frog home, yeah.

SOMMER: The fungus is here. So their immunity will be tested.

BUSHELL: Three, two, one.


BUSHELL: Oh. (Laughter) It's like letting your kids go. Go. Be wild (laughter).

ROLAND KNAPP: Yeah. It's the best chance that we know how to give them.

SOMMER: That's Roland Knapp, a biologist with the University of California, Santa Barbara who has tracked frog die-offs across the Sierra.

KNAPP: I saw the biggest one I've ever seen last summer. Thousands of dying frogs - it was pretty rough to see.

SOMMER: Which is why this is a last-ditch effort to save yellow-legged frogs.

KNAPP: It sometimes seems a little crazy. It's a huge amount of work.

SOMMER: You couldn't do this for every frog species, Knapp says. But some frogs only live in captivity now. They're extinct in the wild. And they don't have much hope of going back unless treatments like this work.

KNAPP: We're staring at what could be the extinction of a significant fraction of the world's amphibians.

SOMMER: Preventing that extinction isn't hopeless, Knapp says. But it could depend in large part on the success of these mountain yellow-legged frogs. For NPR News, I'm Lauren Sommer in California's Desolation Wilderness.

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