Equipment Supplement for the Cariaco Ocean Time Series

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ABSTRACTOCE 0432616The Cariaco oceanographic time series program collects systematic oceanographic measurements at 10'30N 64'40'W in order to understand the interrelationships between changes in climate, hydrography and sediment production and accumulation in Cariaco Basin. Cariaco is a 1,400-m deep depression on the Venezuelan continental margin that is openly connected to the surface Atlantic Ocean above a shallow (~140 m) sill. Because turnover of basin waters is slow (Deuser, 1973), decomposition of the sinking material leads to permanent anoxia below about 275 m. An excellent sediment record that is widely used to study Holocene and late Pleistocene changes in climate is preserved in this natural continental-shelf sediment trap. In this context, the Cariaco time series provides information on modern biogeochemical processes that will serve as a basis for accurately interpreting this sediment archive of climate change.The recently funded continuation of the Cariaco project for an additional five years (2003- 2008) will yield (1) a time series of the variability of the upwelling of Subtropical Underwater in the Cariaco Basin, including lateral motion, and its impact on primary productivity and the vertical flux of particulate matter; (2) the first direct calibration and concurrent cross-reference of various proxies of sea surface temperature of the Cariaco Basin; (3) clarification of the relative importance of lateral transport and chemoautotrophy as sources of particulates, (4) an assessment of whether variability in the particle flux is driven primarily by local winds or by regional oceanographic processes at the scale of the Tropical Atlantic, and (5) an evaluation of whether changes in nutrient availability/limitation result in major ecosystem changes.With funding through this small award, researchers from the University of South Carolina will purchase of an additional sediment trap and associated supplies. This sediment trap will be added to our existing array of four traps and will address the problem of not having a trap at a shallow enough depth (~150 m) to get an accurate estimate of export flux. Broader Impacts: The Cariaco time series program has significant educational impact on students in the US and on students and scientists in the Caribbean and Latin America. Three PhD students at U.S. universities have completed their degrees working on the Cariaco Project and four more are currently involved in this study. The Venezuelan Ministry for Science and Technology considers CARIACO the most significant oceanographic research program ever conducted in Venezuela, and uses it as a model program to provide direction for funding in other disciplines.