Sedimentary Microbiological Communities Across the Equatorial Pacific Carbon-Flux Gradient: Biomass, Composition, Carbon-Utilization Rates, and Production

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The central equatorial Pacific (EQPAC) is a very large region of overall high primary productivity that exhibits distinct latitudinal gradients in the flux of organic material from surface waters to the seafloor. A problem in modeling global carbon budgets is that the rate of organic-carbon mineralization at the seafloor in this region is not directly related to surface productivity. Therefore, a better understanding is needed of the processes controlling the destruction of organic matter falling from surface waters. In this regard, it is critical to study the role of sedimentary microorganisms, especially bacteria. This project will sample the microbiological communities on a USJGOFS EQPAC cruise in 1992. The study will employ a multifaceted approach will be used in order to address four hypotheses concerned with the effects of changes in carbon flux to the benthic environment on: 1) sedimentary microbial biomass; 2) the functional-group composition of the microbial community; 3) bacterial utilization of carbon (glutamic acid); 4) the growth rate and productivity of the microbial community. An ultimate goal of this project is to combine these microbiological data with those generated by other EQPAC researchers and to determine the role of bacteria in the mineralization and formation of organic matter in these oceanic sediments.