In assessing the impact of increased exposure to UV-B radiation (290-320 nm) for crops and terrestrial ecosystems, it must be recognized that existing knowledge is in many ways deficient. Despite uncertainties resulting from the complexities of field experiments, the data presently available suggest that crop yields are potentially vulnerable to increased levels of solar UV-B radiation. Existing data also suggest that increased UV-B radiation will modify the distribution and abundance of plants, and potentially change ecosystem structure. Unfortunately, neither a quantitative nor a qualitative prediction of how these ecosystems might be altered can be determined from the current knowledge base. For components of marine ecosystems, various experiments have demonstrated that UV-B radiation causes damage to fish juveniles, shrimp larvae, crab larvae, copepods, and plants essential to the marine food web. These damaging effects include decreased fecundity, growth, survival, and other reduced functions in these organisms.