Sun's Rays Cause
Salamander Deformities
CopyRight ©1997
Copyright ©1997 Reuters
SEATTLE - A study of salamanders in Oregon's Cascade mountains provides evidence that depletion of the Earth's ozone layer is behind an alarming worldwide decline in amphibians, scientists said Monday.
More than 90 percent of long-toed salamander embryos left exposed to the sun's natural ultraviolet rays either failed to hatch or were born with physical deformities, scientists said in a report of an experiment conducted last spring.
By contrast 95 percent of embryos protected from the so-called UV-B radiation survived, and only 0.5 percent of those that hatched were deformed. Results of the study were published in the journal Proceedings of the National Academy of Sciences.
In the experiment, 200 salamander embryos in a pond near Sisters, Ore., were protected from the sun's UV-B rays by acetate filters, while 200 control embryos were placed under filters that let through 90 percent of the ambient ultraviolet radiation.
Of the 200 embryos left unprotected only 29 hatched, and 25 of those had deformities including curved tails, blistering and swollen, fluid-filled areas.
Andrew Blaustein, a professor of zoology at Oregon State University in Corvallis and lead author of the study, said the results were startling to scientists because the salamander embryos in the study were exposed only to natural sunlight.
"We didn't enhance any UV levels or make any changes except to shield some embryos," he said. "We suggest that ozone depletion and increased UV is probably playing a role in the decline in amphibian species."
A widespread decline in the numbers of some amphibians and even the extinction of some species has been reported since the late 1980s, especially in Australia, the Western United States and Central and South America.
The declines are particularly alarming to scientists because amphibians are seen as sensitive indicators of environmental stress and change.
Blaustein said increased levels of ultraviolet radiation caused by ozone depletion also is believed to be responsible for damage to coral reefs, a decline in some species of fish and a loss of plankton in waters surrounding Antarctica, where ozone depletion is most severe.

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