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Amphibian Declines Complicated, Disturbing
Source: Oregon State University
Date: Posted 2/22/2000, Washington D.C.

People who are looking for a magic bullet that will explain all of the amphibian deaths and declines around the world are going to be disappointed, a leading expert said Friday at the annual meeting of the American Association for the Advancement of Science. It's now a certainty that there are multiple causes contributing to this problem, said Andrew Blaustein, a professor of zoology at Oregon State University and one of the pioneers in this field of study. But the lack of a single, definite cause does not diminish the seriousness of this alarming ecological phenomenon, he said. "At this point we can say for sure that there are several causes of amphibian declines, which include rising levels of UV-B radiation in sunlight, pathogens, pollutants, habitat destruction, introduced predators and most recently, crop fertilizers," Blaustein said. "But the overall result is that this group of animals which has been around since the time of the dinosaurs is now in serious decline all over the world. And some of the things that are killing frogs almost certainly have implications for other animal species, including humans."

The multiple causes of amphibian declines, in fact, helps to illustrate how ecological changes may have a synergistic effect to compound problems, Blaustein said. In various instances it might be that UV-B radiation, or pathogens, or high nitrate levels by themselves would not be enough to cause death or deformity.

Put them all together and you have far more serious impacts, he said, such as: The 14 species of amphibians that have disappeared from Australia in recent years. The five species of amphibians in the Pacific Northwest of the United States that are listed as candidates for the endangered species list. The extinction of the golden toad in Costa Rica. Massive egg mortalities of the Cascades frog in Oregon. Amphibian declines in Europe, South America, Asia, Africa. Even problems in the pristine confines of Yosemite National Park.