Hydrography and cold-water coral geochemistry in the Gulf of Mexico and adjacent waters

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The proposed project will enable for the first time a North Atlantic wide assessment of the environmental boundary conditions of cold‐water coral (CWC) growth in response to present and past oceanographic conditions. Furthermore we will investigate the potential of CWCs as climatic archives of basin‐wide intermediate water mass variability. The trans‐Atlantic comparison of data sets collected with identical tools will yield detailed information on the environmental conditions needed for healthy coral/coral‐reef growth in the deep. While the past years have yielded an enormous increase in knowledge on NE Atlantic CWC occurrences and their biological, geochemical, geological, and hydrographic boundary conditions, studies on CWCs on the western side of the Atlantic have been more sparse. Especially the application of ‘long‐term’ measurements provides new insights with respect to hydrographic controls which are of great importance for growth and occurrences. Furthermore, hydrographic and environmental signals are recorded in the skeletons of CWCs which form mounds and reefs, some of them reaching several 100 m of elevation. Geochemical investigations on CWCs such as Lophelia pertusa indicate the potential of these organisms as high‐resolution archives of environmental parameters of intermediate and deeper water masses. However, the correlation of established proxies such as δ18O and δ13C with temperature is difficult since there is no direct temperature equation applicable as in shallow‐water corals. Hence, new studies regarding proxy calibration are still needed.