Amphibian Obituary

Amphibian species are disappearing at a dramatic rate and their plight reflects the declining health of the planet, according to a comprehensive study of known amphibians.

The study finds 122 species of frogs, toads, salamanders and legless amphibians have probably become extinct since 1980 and warns that a third of all amphibian species currently face the same fate.

The Global Amphibian Assessment is the product of work by scientists from Conservation International, the IUCN-World Conservation Union, and NatureServe, who analyzed research by some 500 of the world's leading amphibian specialists from more than 60 nations.

The health of amphibians is considered a key gauge for the overall health of an ecosystem because their highly permeable skin makes them more immediately sensitive to environmental changes and pollutants than other creatures.

"Amphibians are one of nature's best indicators of overall environmental health," said Russell Mittermeier, president of Conservation International (CI). "Their catastrophic decline serves as a warning that we are in a period of significant environmental degradation."

The Global Amphibian Assessment, published online by the journal Science last week, includes analysis of the distribution and conservation status of all 5,743 known amphibian species. The scientists say 1,856 – or 32 percent – amphibian species are now considered threatened with extinction and caution that the true picture is probably even far worse.

The study determined some 43 percent of all amphibian species are in population decline, 27 percent are stable, and less than one percent are increasing. The scientists found insufficient data to accurately assess the status of the remaining 1,300 other amphibian species, but they believe most of them are also threatened.

"We already knew amphibians were in trouble, but this assessment removes any doubt about the scale of the problem," said Bruce Young, a zoologist with the conservation group NatureServe.

Throughout the world, amphibians are suffering from habitat destruction, air and water pollution, as well as consumer demand and disease.

Colombia has 208 threatened amphibian species – the most in the world – followed by Mexico with 191, Ecuador with 163, Brazil with 110, and China with 86. Haiti has the highest percentage of threatened amphibians, with 92 percent of its species at risk of extinction.

The study notes that in the Americas, the Caribbean and Australia, a highly infectious disease called chytridiomycosis has hit amphibians especially hard. New research is showing that in some regions outbreaks of the disease may be linked to sustained drought, in part caused by global warming. But in most parts of the world, including Europe, Asia and Africa, chytridiomycosis is currently less of a problem and the decline of amphibians is cause for concern about the planet's health.

"Since most amphibians depend on fresh water and feel the effects of pollution before many other forms of life, including humans, their rapid decline tells us that one of Earth's most critical life support systems is breaking down," said Simon Stuart, senior director of the IUCN/CI Biodiversity Assessment Unit, and leader of this research.

Amphibians are the third group of species to be evaluated on a global scale and their status adds to a worrying picture of global biodiversity. Earlier studies found 12 percent of all bird species and 23 percent of all mammal species are threatened with extinction.

"The fact that one third of amphibians are in a precipitous decline tells us that we are rapidly moving towards a potentially epidemic number of extinctions," said Achim Steiner, director general of IUCN-The World Conservation Union.

Steiner added that the study provides a vital baseline "from which we can monitor our impact on the environment over time."