Microbial dynamics in the ocean: An integrated approach

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Marine bacteria utilize over 50% of primary production in the ocean, their biomass often exceeds that of primary producers, they have important roles in major biogeochemical processes and these processes have important feedbacks to global climate. Marine microbial communities drive most globally important ecological and biogeochemical processes, such as the marine carbon, nitrogen and sulfur cycles, yet we know very little about the compostion of the commuity and their specific role in the ocean. The questions we propose to address are quite simple. We are asking who is there, what are they doing and how will they change when ocean climate changes! Although the questions seem simple and straightforward, the answers are not! Until the introduction of culture-independent techniques using the analysis of 16S RNA gene sequences directly PCR amplified from environmental DNA (i.e. metagenomics), our ability to characterize "who is there" and "what they are doing" was very limited. The proposed research will use a combination of taxonomic, physiological, isotopic and molecular techniques in coastal and offshore marine environments to examine the spatial and temporal variation in individual bacterial species, the mechanisms underlying changes in community structure and their contributions to microbial mediated carbon and elemental flow. This research will be answering some fundamental ecological and evolutionary questions about whether the observed spatial or temporal changes in the microbial community are are due to an adaptations or a change in the structure of the assemblage. This has profound implications about the how microbial communities are influenced by climate process and in turn influence biogeochemical processes in the upper ocean.