Disappearing Frogs, Salamanders May Be a Warning for Man : Environment: Scientists at UC Irvine conference blame species’ disappearance on acid rain or other pollutants. One scientist calls situation a biological ‘emergency.’

From Yosemite National Park to the Australian rain forest, many species of frogs and salamanders are rapidly disappearing, and their extinction may be an early warning of environmental dangers facing mankind, according to scientists attending a conference at UC Irvine Tuesday.

A panel of 20 U.S. and foreign scientists cited cases where large populations of frogs and salamanders have been killed by acid rain or acid snow, deforestation, pesticide use or the pollution of water by heavy metals.

The scientists expressed particular concern that along with the disappearance of many amphibians from industrialized areas, the past decade has seen a significant diminishment of frogs and salamanders from pristine environments such as ponds formed from snow melt high in the Rocky Mountains or forests in Brazil and Costa Rica.

University of Miami biologist Marc Heyes, echoing many of his colleagues, called the decline of frogs around the world a biological “emergency.”

Not only are they an important part of the food chain, he said, but some frogs exude substances in their skin that have been found to have medicinal properties. “Who knows, the answer to recovering from AIDS may lie in some amphibian,” he said.

The scientists were invited by the biology board of the National Academy of Sciences to spend Monday and Tuesday comparing their research.

In many of the cases where species of frogs and salamanders have vanished, the causes are still a mystery, the scientists said.

In the early 1980s, bufo canorus, also known as the Yosemite toad, suddenly disappeared from California’s High Sierra. “We do not know why,” said UC Berkeley biologist David B. Wake, who chaired the conference.

“I’m alarmed as an amphibian biologist and alarmed as a citizen of California to see our environment degraded,” Wake said. “I go to the High Sierras and I almost weep at the loss, I guess, for the bio-diversity of nature.”

Wake organized the UC Irvine conference after attending the first world herpetology congress in Canterbury, England, where he compared notes with other scientists and was shocked by the findings.

Like the canaries that died when exposed to poisonous but odorless gases in coal mines, dying frogs and salamanders may be an unusually sensitive “bio-indicator,” an early-warning system for unseen environmental poisons, he and other scientists said.

Wake noted, however, that although some species of Mexican salamanders have completely disappeared recently, salamanders are thriving in other parts of the world.

Even in Orange County, Wake found four species of salamander in south Laguna Beach and along the Ortega Highway on Monday, he said.

But most of the conference was devoted to reporting studies of vanishing amphibians--what one scientist termed “bizarre” events of nature.

Canadian biologist Richard Wassersug described how he watched a population of leopard frogs in Nova Scotia “virtually disappear.”

In the summer of 1988, he had found three populations of albino tadpoles, which normally are supposed to be green. A year later, when he checked the same ponds, “there were no tadpoles” at all, he said.

“That’s pretty scary,” he said.

Australian zoologist Michael Tyler said that in the mid-1970s, he was studying an unusual species of frog, rheo batrachus silus , that gives birth through the mouth. Tyler was hoping this “gastric-brooding” frog would help scientists create a drug that could heal gastric ulcers in humans, when “suddenly the species disappeared.”

Other frogs in the Connondale Ranges, which Tyler described as a pristine rain forest 100 miles north of Brisbane, Australia, also suddenly died at about the same time, he said.

Tyler said he has been researching the cause of their death since, but still does not understand what happened. “It has to be something associated with the physical environment,” he said.

Heyes, the University of Miami biologist, showed slides of endangered Costa Rican frogs, including a creature called the golden frog, which has lived in that country’s Elfin Forest, 5,000 feet above sea level. In the last several years, there have been fewer golden frogs--less than a dozen at one site recently, none at another, he said.