West Atlantic Cold- Water Coral Ecosystems: The west side story - Cruise No. MSM20/4 - March 14 - April 07, 2012 - Bridgetown (Barbados) - Freetown (Bahamas) (English)

Leg MSM 20-4 focussed on the investigation of cold-water coral (CWC) ecosystems in the West Atlantic Ocean (Gulf of Mexico, Florida Straits) with special emphasis on their distribution, appearance, faunal assemblage and vitality under present and past (glacial) conditions. The overarching objective was to identify the main physical and biological factors that are important in controlling CWC occurrence. Based on detailed mapping with the shipboard multibeam echosounder and PARASOUND systems, five working areas were selected for detailed studies: (1) Campeche Bank (NE Yucatan Peninsula), (2) West-Florida Slope, (3) Southwest-Florida Slope, (4) Bimini Slope, and (5) Great Bahama Bank Slope. During 17 dives with the Bremen ROV CHEROKEE (MARUM) a detailed characterisation of the existing facies and fauna was conducted on these selected CWC occurrences. Moreover, a total of 49 CTD profiles were measured comprising single casts and three so-called Yoyo-CTDs with repeated casts over 13 hours covering one complete tidal cycle complemented by bottom water samples at all sites will help to assess the recent environment of the CWC. Finally, a series of grab samples, box cores and gravity cores (total core recovery: ~60 core meters) will enable to study the development of CWC ecosystems in the West Atlantic under changing environmental conditions, e.g., over glacial-interglacial cycles. The results of the expedition will contribute to the international TRACES initiative (Trans-Atlantic Coral Ecosystem Studies) which aims to compare the coral ecosystems of the West Atlantic with the well-known CWC sites of the East Atlantic with respect to their recent situation and a potential linkage between both occurrences regarding their temporal development during the last glacial-interglacial cycle.