Temporal Variation in Organic Carbon Utilization by the Deep-Sea Sediment Community at the Hawaii Ocean Time-Series Station

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The Joint Global Ocean Flux Study (JGOFS) was initiated to study the oceanic carbon cycle on time scales of days to decades. Two long time series stations were established, one in the North Atlantic and one in the North Pacific, to represent the expansive subtropical oceanic gyres. Although considerable effort has been expended to resolve the cycling of carbon in the upper water column at these two stations, the fluxes of carbon at the sea floor remain largely unstudied. Of particular interest is the coupling between the production and export of organic carbon from surface waters and the utilization of organic carbon by the deep sea sediment community. Rapid transport of surface derived particulate matter in episodic pulses to the abyssal sea floor occurs in both the Atlantic and Pacific Oceans. These episodic events are superimposed on a slower `rain` of particulate matter sinking to the sea floor throughout the year. Once this material reaches the sea floor, it is transformed biochemically by the organisms comprising the sediment community. The rate at which this organic matter is utilized by the sediment biota can be estimated by measuring sediment community oxygen consumption (SCOC). We will measure SCOC at the JGOFS Hawaii Ocean Time series station (Station ALOHA). Using the unique capabilities of the ROVER (a unique, autonomous, bottom-transecting vehicle), we will address the following questions: 1) Is there temporal variability in the utilization of organic carbon by the sediment community, as estimated from SCOC, on time scales of days to months? And, considering data collected by other investigators in the Hawaii Ocean Time series program (HOT), 2) is there a temporal relationship between the utilization of organic carbon by the sediment community and the production and downward flux of particulate matter through the water column? These measurements will be made with unprecedented temporal resolution over a two year period, in concert with ongoing monitoring by other investigators of surface productivity, downward particulate fluxes, and a variety of other upper ocean parameters. This combined effort will constitute the first long time series study to provide such a complete suite of measurements from surface waters to the abyssal sea floor with similar, high temporal resolution. The results of this study will be valuable for modeling carbon cycling at the deep sea floor.