Amphibians dying out in droves from fungus

Biologists scramble to collect species for safekeeping


A devastating fungus is sweeping the planet, wiping out entire populations of amphibians at such a rate that biologists are helping pull together a huge "Noah's Ark" project to capture frogs, toads and salamanders and put them in safe places.

Various factors already have combined to cause more than 120 amphibian species to vanish since 1980, in what one biologist has called "one of the largest extinction spasms for vertebrates in history."

A third of the world's nearly 6,000 amphibian species are threatened - their populations weak and susceptible to disease. If they go, ecosystems will tilt out of balance and potential medical breakthroughs - such as potent painkillers or HIV inhibitors - could be lost.

It is hard to determine how many species have been affected by the fungus because they cannot be assessed fast enough, but it has factored into most of the recent extinctions and declines, said Bob Lacy, population geneticist at Illinois' Brookfield Zoo and chairman of the Conservation Breeding Specialist Group.

That leaves no time for anything but a triage attempt to get some of the animals out of harm's way until this "tragically unique" disease can be further studied and countered, he said.

"It is a race against time, and it's a matter of months," Lacy said.

Among zoologists, some have begun to face questions of which species should be saved and why.

"It's terrible. I've never experienced anything like this," said David Wake, a biology professor and curator of herpetology at the University of California at Berkeley, the first scientist to officially declare a pattern of global amphibian declines in 1989. "It's really an awful prospect."

When this fungal disease came along, amphibians already faced significant stress from global warming, pesticides and herbicides, acid rain and habitat destruction, experts said.

Some scientists point to them as bellwether animals for the Earth's health. Their slippery, porous skin absorbs moisture around them, making them more vulnerable to environmental changes than mammals, birds and reptiles with their fur, feathers or scales.

But chytridomycosis, caused by the chytrid fungus, is adding a confounding new level of peril that is pushing many species over the brink - even in areas mostly untouched by human hands.

"This is a totally unusual conservation dilemma - species going extinct in a relatively pristine environment," said Alejandro Grajal, Brookfield Zoo's senior vice president of conservation, education and training. "Now we're basically trying to save as many as we can as we try to figure out our next step."

Chytridomycosis was first identified in 1998 and is not well understood. As it moves around the globe, it has caused massive amphibian deaths in Australia and hit the population of boreal toads in the Rocky Mountains. In the Sierra Nevada, Berkeley researcher Vance Vredenburg found "piles" of mountain yellow-legged frogs dead from the disease two years ago.

The disease is filtering down Central America - one of the most biologically diverse areas on the planet - at a rate of about 17 miles a year, faster than a frog can hop to the next pond. With support from the Houston Zoo, Mauricio Caballero is leading an effort to build a field facility in Panama to preserve species, but the fungus caught up to his El Valle region before the roof was up.

"We knew what was going to happen, and now we're seeing the frogs starting to die," he said after a meeting with other Latin American experts Monday in Brookfield. "We weren't expecting it to hit so soon. We were predicting it was going to hit in the rainy season."

Scientists are scurrying to collect frogs and put them in temporary tanks in hotel rooms and people's houses until the building is ready, Caballero said. Plans to save 65 species have been downscaled to the dozen or so most endangered - including the beautiful, iridescent Panamanian golden frog. The species is a cultural image for its people as the bald eagle is for Americans - it's been depicted in jewelry since pre-Columbian times and is the inspiration of local festivals.

The Brookfield Zoo does not have the proper buildings to warehouse amphibians. So zoo experts there are providing training for researchers in the field, giving grant money and helping connect experts such as those visiting this week from Mexico, Ecuador, Colombia and Panama to ensure that the species are collected as quickly and efficiently as possible. Zoos that do have the capacity to take more amphibians need to do so, too, Lacy said.

Chytrid fungus is carried in water, but the disease is specific to amphibians, invisibly feeding on their skin's keratin and causing it to thicken. The exact mode of death is unknown - it may produce a toxin or it may impair the amphibian's ability to breathe and absorb water through its skin.

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