Project CARIACO

Overall Objectives
    The main objective of CARIACO is to examine how large-scale phenomena and changes in climate affect the vertical flux of carbon and nutrients at a continental margin site. This requires 1) systematic observation of a few core parameters over a long period, to be able to distinguish the long-term trends from short-term variations, and 2) numerical models to examine the controlling processes that affect the values of these parameters and to infer possible variability between hydrographic cruises.  

    There is evidence that the tropical Atlantic, and particularly the Caribbean Sea, experience marked El Niņo teleconnections  and function as barometers of global change. The Cariaco Basin is ideal for a study of the impact of such processes on carbon and nutrient fluxes because it forms a natural sediment trap in a continental shelf area where advection below 150 m is restricted. Therefore, the sinking flux of organic matter is largely confined to the Basin, making it easier to quantify here compared to other continental margins. Indeed, Cariaco is a natural recorder of climate change and provides an unusually strong signal of storage of carbon and other elements in aphotic waters and sediments of >300 m depth. This Basin is the only permanently anoxic basin in the world's oceans and it therefore also provides a unique environment to test hypotheses of material decomposition across an oxic-anoxic gradient. It serves as an analog of anoxic sediments with a reducing gradient spread over tens of meters, rather than over scales of millimeters. Cariaco is also an oceanic analog of the estuarine Black Sea, except that it is much more accessible from the US.  

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