 More than three dozen species of amphibians have been studied , with severe effects reported in more than 40 publications in peer @-@ reviewed journals representing authors from North America , Europe and Australia . Experimental enclosure approaches to determine UVB effects on egg stages have been criticized ; for example , egg masses were placed at water depths much shallower than is typical for natural oviposition sites . While UVB radiation is an important stressor for amphibians , its effect on the egg stage may have been overstated . 
