The stratospheric ozone layer shields the earth from biologically damaging solar ultraviolet radiation. Chlorofluorocarbons (CFCs), used in refrigerants, etc. and halons, used in fire extinguishers, escape into the lower atmosphere and migrate to the stratosphere, destroying the ozone layer by photochemically catalyzing the conversion of ozone to oxygen. Global decreases in stratospheric ozone have been observed in recent years. As a result, UV-B radiation is likely to increase over the next few decades, having a very real potential for significant impacts on marine ecosystems. It would take decades to complete all the research necessary for a definitive assessment of the overall long-term effects of stratospheric ozone depletion. However, a research program focusing on the major uncertainties could provide an assessment adequate for informed decision-making within five years.