Amphibian populations harmed by ozone exposure.

A new study has found that elevated ozone found in lower layers of the atmosphere could be yet another contributing factor to the ongoing decline and disappearance of many populations of amphibians. The study was published in a recent issue of Environmental Toxicology and Chemistry (Volume 27, Issue 5).

Declines of many amphibian populations over the past two decades have received significant attention from biologists, in part because amphibians are viewed as monitors or sentinels of pollution and other anthropogenic changes to the environment. Their importance as potential indicators of environmental health is well recognized for watersheds but is more problematic for air quality.

Ozone ([O.sub.3]) is a common air pollutant in many urban settings. Consequently, in adjacent wildlife habitats, [O.sub.3] levels can frequently exceed U.S. federally recommended levels. It is a highly reactive gas that can be elevated at ground level by a chemical reaction between oxides of nitrogen and volatile organic compounds in the presence of sunlight.

In studying the feeding, escape, and exploratory behavior of toads after acute and chronic exposure to [O.sub.3] the researchers concluded that [O.sub.3] affects many aspects of toad behavior and physiology in a manner consistent with the extensive literature on humans and other mammals. The study results indicate that exposure to oxidant air pollution might be a contributing factor to declines in amphibian populations.