Scientists sound alarm for world's amphibians

Fungus could bring wave of extinctions

July 07, 2006|By John Biemer, Tribune staff reporter

Fearing a mass extinction of the world's frogs, toads, newts and salamanders, 50 international amphibian experts are sending out an unprecedented SOS calling for an urgent global mission to avert a cataclysm.

The plea, published in Friday's edition of the journal Science, is meant to be a wake-up call for a broader range of scientists and policymakers about threats to the earth's amphibians, considered canaries in the coal mine for all of nature.

"For the first time in modern history, because of the way that humans are impacting our natural world, we're facing the extinction of an entire class of organisms," said Claude Gascon of Conservation International. "This is not the extinction of just a panda or a rhino, it's a whole class of organisms."

Amphibians are more susceptible to changes in the environment than other animals because they have permeable skin that absorbs water and oxygen, and their lives depend on clean, fresh water. Almost a third of the 5,743 known amphibian species worldwide already are threatened by a combination of habitat loss, climate change, pollution, pesticides, ultraviolet radiation and invasive species, with up to 122 having become extinct since 1980. But scientists believe both figures could be underestimates because they cannot evaluate species quickly enough.

The latest, most pressing threat is a rapidly spreading fungal disease predicted to wipe out about half the amphibian species exposed to it within six months of its entering a new ecosystem. Chytridiomycosis, which damages the skin, is being described as the final straw--leading to Friday's unusual appeal.

Global climate change, the commercial wildlife trade and pollution are some of the factors that may be contributing to both the fungus' spread and amphibians' susceptibility to it.

"It's unprecedented in terms of the magnitude of the problem, just how many species are being hit," said Bob Lacy, Brookfield Zoo's population geneticist and chairman of the Conservation Breeding Specialist Group. "It's unprecedented in the global impact, the sites around the world, and it's unprecedented the speed of it--species are going extinct very fast."

"These are bioindicators that something is wrong with the planet," said Andrew Blaustein, a zoology professor at Oregon State University and one of the pioneers in the field.

Signers to the statement include many leading herpetologists, but they also include disease experts, field ecologists, physiologists, evolutionary biologists and representatives of government agencies and non-profit conservation groups.

They are calling for a five-year $400 million project to pluck certain susceptible species out of harm's way and put them in safe regional breeding and research centers, as well as in zoos and universities around the world--a program some have described as a modern Noah's Ark. The money, they hope, will come from the public and private sectors.

Amphibians consume insect pests that can carry diseases harmful to humans, and they provide meals themselves for other animals. But as the amphibians disappear, that sets off ripple effects that can disrupt the ecosystem.

The secretions of amphibian skin also hold potential for biomedicine and biotechnology.

Although scientists are trained to be skeptical--waiting for ironclad evidence before reaching conclusions and taking action--Lacy said enough data now suggest time is too precious to wait any longer. There is no known way to stop the fungus disease, which already has spread down Central America and wiped out populations in Australia. The project should have started "last year," he said.

Because the problem is so vast, the idea is to create an Amphibian Survival Alliance to organize an overarching strategy to prioritize jeopardized species, rather than approaching each animal on a piecemeal, localized basis. Preserving habitat and mitigating environmental decline are still crucial, they say, but triage comes first.

"It's the only idea we've all been able to come up with in 20 years of studying this problem," said Southern Illinois University zoologist Karen Lips. For 15 years, Lips has studied amphibians in the remote mountain cloud forests of Panama. About two years ago, the disease moved through that biologically diverse region. Within four months, the researchers found 38 different kinds of dead frogs. About 80 percent of the individual amphibians and half the species disappeared.

"If we do nothing, we'll just continue to see this thing chew its way through all the amphibians in the world, essentially, in one way or another," Lips said.

- - -

Endangered amphibians

Among the amphibian experts' findings:

32.5 percent of 5,743 described species are threatened.

At least nine, and perhaps 122, have gone extinct since 1980.

A fungal disease, chytridiomycosis, is predicted to kill off about half the amphibian species and 80 percent of the individual amphibians within six months of arriving at a place where the fungus has not previously been present.

Of the 113 species of harlequin toads (a small, colorful Central and South American toad), 30 are possibly extinct and only 10 have stable populations.