9500237 Hollibaugh This project will investigate the relationship between bacterioplankton community composition and community metabolic capabilities in the Arctic Ocean. They will examine the patterns of spatial variation in these properties of Arctic Ocean bacterioplankton communities and attempt to relate them to sources of organic matter fueling heterotrophic production. The investigation will be conducted using samples collected from a U.S. Navy submarine in March-May 1995, which will be dedicated to Arctic oceanography. Collected samples will be analyzed in the laboratory after the cruise. Community composition will be analyzed using a method developed at San Francisco State University based on separating partial sequences of the 16S rRNA gene. Community metabolic capabilities will be assessed by the ability of bacteria to grow on 95 different organic carbon sources. They will analyze water samples chemically to determine the concentrations of amino acids, carbohydrates and dissolved organic carbon, and conduct bioassays using native bacteria to determine directly the proportion of dissolved organic carbon that they can metabolize.