Even some of the places that could be considered untouched are still not safe havens for amphibians. This is due to the fact that a layer of gas in the earth s atmosphere that functions to shield harmful radiation from the sun is disappearing. This gas forms a protective stratospheric shield in our atmosphere that blocks Ultra-Violet radiation. The afore mentioned chemicals though, are effectively destroying this protective shield allowing more of this radiation to reach the earth s surface. In the temperate regions of this planet, eight percent of the radiation reaching the earth s surface is UV-radiation.
Many amphibians have to lay their eggs in warm places.
This usually means waters where there is direct sunlight. Most of them also lay their eggs at a time of the year when solar irradiation is intense and shading from the surrounding vegetation is low. Herpetologists have known for some time that UV radiation can damage DNA, and that an enzyme called photolyase can repair this damage. The research of Andrew Blaustein and John Hays, though is showing that the levels of photolyase in the eggs of amphibians that show no signs of decline are higher than those of amphibians who seem to be dieing out. Some amphibians that do not have very much photolyase in their eggs have found ways of protecting their eggs by other means.