Hollibaugh 9315639 The goal of the project is to understand the relationship between: 1) the taxonomic composition of microbial communities; 2) their metabolic capabilities and the presence of characteristic metabolic pathways; and 3) the sources of organic matter fueling bacterioplankton production. To do this, we propose to continue development and testing of a technique for describing bacterioplankton community structure based on an analysis of variable regions of the 16S rRNA gene. We will characterize the metabolic capabilities of bacterioplankton communities by assessing their abilities to grow on single carbon sources and by the metabolic fate of exogenously supplied thymidine. The statistical procedure of principal components analysis will be used to compare these community characteristics and to develop a matrix of the metabolic capabilities and phylogenetic characteristics of bacterioplankton population. The sources of C fueling bacterioplankton production will be assessed by comparing the C and N stable isotope signatures of bacterioplankton DNA with those of organic matter fraction form the same location. The work will be conducted in San Francisco and Tomales Bays, in coastal waters around San Francisco and in estuaries and coastal water off the East coast over a 3 year period. ***
