9801785 MITCHELL There is now strong evidence that ultraviolet (UV) radiation is increasing over certain locations in Antarctica and the Southern Ocean as a result of ozone depletion. A reduction in ozone concentration selectively limits stratospheric adsorption of UV radiation and results in a higher UV irradiance reaching the earth's surface. Research on the impact of increased UV radiation due to ozone depletion has focused primarily on phytoplankton, with a much smaller effort being directed to other trophic levels. This collaborative project will address UV radiation induced damage and UV radiation effects on bacterioplankton. Studies will examine interactions between bacterioplankton and photochemical processes and interactions with higher trophic groups such as phytoplankton and zooplankton. Topics to be addressed will include whether bacterial-phytoplankton coupling modifies bacterial response to UV radiation, how seasonal changes in UV radiation affect bacterial community dynamics and how chemical photoproducts impact bacterial production.. This research project will elucidate the molecular determinants responsible for changes in productivity and the molecular and physiological responses to changing UV radiation. The overall goal is to provide a greater understanding of the potential impact that changes in UV radiation have on marine microbial communities.
