MADDIE SOFIA, HOST:
You're listening to SHORT WAVE...
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SOFIA: ...From NPR. Today - a scientist who found herself in the middle of a disturbing scientific mystery. It's the early 1990s, and Karen Lips is a graduate student studying frogs in the mountains of Costa Rica.
KAREN LIPS: And I had set up camp in this little shack that had no running water or electricity. So this is an old-growth oak forest. And it's a cloud forest, so it's moist and there's moss everywhere. And amphibians love it.
SOFIA: Karen lived alone, spending her days studying the reproductive behavior of Isthmohyla calypsa, a tiny tree frog the color of emeralds.
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SOFIA: And then, a couple years into her research, Karen found some dead frogs.
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LIPS: Seven - seven is not very much.
SOFIA: She wasn't too worried about it, but she couldn't figure out why they died. So she sent the frogs off for, essentially, a frog autopsy. Then she headed home for Christmas break.
LIPS: And when I got back, I expected to see the beginning of the rainy season, which is usually when you see the greatest number of frogs. And I kept waiting and waiting, and the rains came and there just weren't very many frogs at all. And so I started questioning myself. Like, well, maybe I disturbed them. Maybe the flashlight for two years - one little flashlight, you know, bothered them and they went away. Or maybe it's not rainy enough. I just simply could not imagine what could have caused them to disappear.
SOFIA: Yeah. It was not the flashlight's fault - not according to the frog autopsy results.
LIPS: They said, we don't know why they died. They seem fine. They got something weird in their skin. Now, at that point, there was nothing known that would kill a frog that was something, quote, "weird in their skin."
SOFIA: Coming up on SHORT WAVE, scientists untangle a scientific mystery of the amphibian world, one that goes from kind of weird to devastating.
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SOFIA: Here's the thing you need to know right away about amphibians. There's a lot of them, and that's important because they live right in the middle of the food web.
LIPS: They are food for all the mammals and the birds and the snakes and the predators. And they are the predators of all the insects and flies and mosquitoes. So those two things mean that they are really, like, a key lynchpin in the entire ecosystem.
SOFIA: So when groups of amphibians start disappearing, scientists get nervous. By the time Karen had noticed those dead frogs in Costa Rica, there had already been these reports of frogs disappearing in large numbers around the world. And the reports kept coming, but nobody knew what it all meant.
LIPS: Nobody knew. Why are they disappearing? Where are they disappearing from? How quickly do they disappear? You know, what's the cause of it?
SOFIA: Years after Costa Rica, Karen set up another field site in the cloud forests of Panama. At first, it was wonderful - hundreds of frogs every night, all kinds of different species.
LIPS: And then it wasn't two or three years later I went back, and they would be acting very weird. Frogs that were supposed to only come out at night, we'd find them during the day. Frogs that would be sit - were supposed to sit only on the leaves and the plants, we'd see them on the ground. And so we'd pick them up because we always measure them and identify them and then let them go. And a lot of times we'd pick these things up, and they wouldn't struggle. They wouldn't try and escape. And oftentimes, they'd make one jump and then they'd be dead.
LIPS: And this happened - we were there for like three weeks. And in three weeks, we found 50-some dead or dying frogs.
SOFIA: Had you ever seen anything like that before?
SOFIA: The seeing part is important because, typically, researchers would get to a field site and all the frogs would just be gone. Nobody really witnessed them in the act of dying, rarely even saw the bodies. But this time, Karen had a front-row seat. More importantly, she had a lot of evidence to work with.
LIPS: And so on the one hand, it is horrible and sad. On the other hand, you're like, this is it. We have evidence. No matter what, we've got something we can take back. We can collect them. We can preserve them. We can send them to a lab, and they can look at them and see what they have.
SOFIA: Karen sent the dead frogs off to a pathologist to be tested, and again...
LIPS: The vast majority of them seem to have something weird in their skin. And when he said that, I said, I have heard this before.
SOFIA: But Karen still had no idea what the weird skin thing was. And she wasn't alone. Scientists from all over, working in countries thousands of miles apart, were also trying to figure it out. They didn't realize yet just how connected it all was.
LIPS: And this is where the media comes in.
SOFIA: A New York Times reporter interviewed Karen and some other scientists about the disappearing amphibian problem.
LIPS: And the reporter published a picture of this weird thing in the skin. And then a team here in D.C. at the National Zoo saw the picture, and they wrote us, and they said, we have the same thing, and we know what it is.
SOFIA: It took a bunch of scientists from all over the world, help from the media and several decades to figure it all out, but they finally had it. The culprit is a fungus.
LIPS: Chytrid fungus.
SOFIA: We're not talking, like, mushrooms. We're talking infectious fungus that burrows into the skin of an amphibian and messes with their ability to breathe and stay hydrated and regulate their body temperature. The infection can be passed directly from frog to frog or it can travel through water.
LIPS: Today, what we know is that there is at least one kind of chytrid fungus almost everywhere in the world.
LIPS: We know that globally, something like 40% of amphibians are in decline. Now, not all of that is from the chytrid, but I suspect that probably quite a bit of it is, in fact, from chytrid because it's - many of the extinctions that have occurred in amphibians are recent, like, in the past 20 or 30 years, which is when this chytrid, we believe, sort of emerged and spread around.
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SOFIA: The reason why it's spreading now isn't entirely clear. Karen says it's probably because of us - humans. We're shipping things from one place to another faster than ever before, which makes it easier for organisms like chytrid fungus to hitch a ride and infect vulnerable habitats hundreds or even thousands of miles away. This year, the journal Science published a report estimating that chytrid has resulted in the greatest recorded loss of biodiversity ever caused by a disease. The sad truth is there's no feasible way for us to get chytrid out of the environment, and that's a tough pill to swallow.
So how do you wake up every morning and do work on this, knowing that you are fighting a losing battle?
LIPS: Well, (laughter) - yeah, I mean, after a while, it's incredibly demoralizing to know that you spent 25-some years on something, and you have not actually saved a single frog. On the other hand, you know, for me, as a biologist, I know that evolution works. And having studied human attempts to intervene and save things, we're really good at sort of really discrete problems like saving the condor. Or things where there's a discrete problem, we can attack it.
These diseases that are invisible and spread globally are very difficult. And so what gives me peace is knowing that things evolve. Whatever made it through the epidemics, they are survivors. And they have something that allowed them to get through the worst of it. And so evolution happens. And I suspect that the frogs will figure it out before the people do.
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SOFIA: Karen Lips is a professor of biology at the University of Maryland. We'd like to thank the Macaulay Library at the Cornell Lab of Ornithology for loaning us audio recordings of the frog Isthmohyla calypsa. And thank you to former public radio reporter turned children's book author Mary Losure for sharing her audio recordings of frogs in Fortuna, Panama. Lastly, thanks to Alexandra Gardner, who let us use her music.
This episode was produced by Rebecca Davis and edited by Viet Le. I'm Maddie Sofia. We're back next week. Thanks for listening to SHORT WAVE from NPR.
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