One-third of amphibians face threat of extinction

A third of the world's amphibian species are in danger of extinction, according to the first-ever global survey of the animals.

Scientists think the mysterious collapse in numbers might be a warning that our environment may be in a worse state than we think -- amphibians are known to be the most sensitive of all animals to subtle changes in their ecosystems.

There is also a new spectre that has come to haunt the frogs, toads, salamanders and newts that live in and out of water -- a fungus that has already destroyed entire populations in many parts of the world.

Scientists have known since the 1980s that the many of the world's amphibian species are vanishing but the scale of decline revealed by the new survey, published yesterday in the journal Science, has stunned them. Nobody knows what is causing the devastation but it is likely to be loss of habitat to pollution, climate change and increasing competition with humans.

More than 500 scientists from more than 60 countries took part in the three-year Global Amphibian Assessment, a study of the world's 5,743 known amphibian species. One in three -- a total of 1,856 species altogether -- are threatened with extinction, they say.

The latest count shows 122 amphibian species have become extinct in the past 20 years.

At the global level, scientists say that the drop in amphibian numbers could be an indicator of the poor state of our environment.

"Amphibians feel the effects of water pollution and climate change before other forms of life, including mankind," said Neil Cox, a program officer with the joint World Conservation Union and Conservation International biodiversity assessment unit, which coordinated the survey.

But damage to the environmental is not the whole story. Many species have disappeared from pristine habitat. "This is thought to be a response partly to outbreak of the disease chytridiomycosis," Cox said.

The disease is caused by a fungus of the chytrid family called batrachochytrium dendrobatidis and it infests the skin of adult amphibians and the mouth-parts of their larvae.