The stratospheric ozone layer has been diminished as a consequence of anthropogenic release of chlorofluorocarbons. The thinning ozone results in increased levels of harmful ultraviolet B (UV-B) radiation relative to less harmful ultraviolet A (UV-A) and visible light (VIS). Ultraviolet damage to marine phytoplankton cells have been limited to bulk calculations which do not take into consideration variability of damage between individual cells. The single cell gel (SSG) comet assay is capable of measuring DNA damage and repair in individual cells. We propose to use this technique to measure the effects of UV-B radiation on DNA damage in marine phytoplankton species and in their capacity to repair. Phytoplankton growing under culture conditions will be exposed in the laboratory to ambient irradiance levels of UV-B, UV-A and VIS to stimulate present and enhanced UV radiation. The ability of phytoplankton cells to repair DNA will be estimated to subsequent exposure to white light, to induce repair; and yellow light, to suppress repair. Results of these experiments will make an important contribution regarding the usefulness of a novel method to measure UV-induced DNA damage and repair in phytoplankton.
