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Amphibian species facing extinction, new study warns

By Juliet Eilperin
The Washington Post

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The rapid drop — the equivalent of tens of thousands of years worth of extinctions in just a century — is being caused by factors that include deforestation, pollution, habitat loss and climate change, the researchers said.

But they added that the phenomenon also tells a disturbing tale of broad environmental degradation that may ultimately threaten humans and other animals as well. Amphibians are often considered "canaries in the coal mine" because their permeable skin makes them especially sensitive to changing environmental conditions.

"It's entirely possible other groups of biodiversity may go down the drain," said Claude Gascon, a scientific adviser to the study who serves as vice president for regional programs at Conservation International, an environmental group.

The survey found that 32 percent of amphibian species face extinction, compared to 12 percent of bird species and 23 percent of mammal species. The three-year, $1.5 million study, which involved 500 scientists from 60 countries, is being published today in the journal Science.

Scientists began noticing the disappearance of amphibians in the late 1980s and early 1990s, but before this study they'd never conducted a worldwide assessment of the frogs, toads, salamanders and legless caecilians, also called rubber eels.

"We've never documented anything like this for any other species. When species become rare and begin disappearing, we nearly always know why," said Simon Stuart, leader of the global assessment team. "This has taken the scientific world completely by surprise."

Amphibians are under assault for three major reasons, according to the report. Habitat decline, from deforestation to water pollution and wetlands destruction, threatens them because the animals live both on land and in water. Overharvesting of amphibians for food and medicine is a second threat. The third is more enigmatic, but it has resulted in catastrophic declines, often linked to a fungal disease called chytridiomycosis, particularly in cooler habitats that are experiencing drought.

Surveys showed the amphibian population of Costa Rica's Monteverde Cloud Forest, for example, was stable until 1987. The next year it began to crash and by 1989, 40 percent of its amphibian species had gone extinct, including the striking golden toad. Stuart said it is widely believed chytridiomycosis played a pivotal role in the devastation, which took place in a dry period.

Humans are responsible for amphibians' decline in other regions of the world, including China, where many are sought as a delicacy. The Chinese giant salamander — at 6 feet the largest amphibian in the world — sells for at least $300 and makes for several meals, and it has now disappeared from nearly all its range.

Gascon, at Conservation International, said "there are some actions we can take today to prevent the immediate extinction of many species as we work on a longer-term solution." These include creating parks and ecological reserves, working to reduce emissions that contribute to climate change and breeding animals in captivity in order to sustain vulnerable species.

Copyright © 2004 The Seattle Times Company

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