Role of Biomass, Bioturbation, and Remineralization in Determining the Fate of Carbon in the Arctic Ocean

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9400092 Ambrose Research supported by this grant is under the auspices of the Arctic Systems Science (ARCSS) Global Change Research Program and is jointly sponsored by the Division of Ocean Sciences and the Office of Polar Programs. The research will be centered around a unique and intensive, multidisciplinary research expedition to parts of the Arctic Ocean that have never been extensively studied. The 1994 U.S./Canada Arctic Ocean Section is a collaborative effort with Canada that will involve approximately 60 scientists on a Canadian and a U.S. icebreaker during summer 1994. NSF-funded projects will focus on hydrography, biology, paleo-, and sea-ice studies. Data collected will be amongst the first ever from several regions of the Arctic Ocean and will be highly relevant to improving our understanding of how the Arctic is an indicator of changing global climate conditions and how it affects the physical, chemical, and biological features of the more temperate oceans and regions. This work is a component of the collaborative biology program. Work will be undertaken to examine the fate of organic matter reaching the seafloor and model cycling between the various carbon pools. The fate of carbon fixed in the Arctic Ocean is largely unknown, but it is surmised that a greater portion reaches the bottom than in other oceans. Low abundance and slow feeding rates of zooplankton, and reduced importance of the microbial loop, may explain why the majority of primary productivity falls to the benthos at high latitudes. Research will focus on some of the possible fates of carbon reaching the benthos by examining patterns of benthic biomass and rates of remineralization, irrigation, and particle mixing. Replicate box cores will be collected along the Section. Abundance and biomass of macro and meio-fauna and depth profiles of Eh and particulate carbon will be determined from these cores. Subcores will be incubated on-board to determine rates of remineralization and bioirrigation. Particle mixing rates will be determined directly from down-core 210Pb distribution and will be compared with mixing estimates obtained from carbon depth-profiles and bioirrigation rates. This study provide insights to the role of benthos in mediating geochemical processes and will provide a model of carbon cycling in Arctic sediments which can be used to make predictions of the consequences of global warming. ***