Cold-water coral mound development underneath an eastern boundary upwelling system - the great wall of(f) Mauritania

• Applicant: Dr. Jürgen Titschack
• Subject Area: Palaeontology
• Term: from 2015 to 2018
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 274220935

Cold-water corals (CWC) represent globally significant carbonate factories that can form large 3-dimensional structures along the continental margins, called CWC mounds. CWC mound formation primarily depends on (i) sustained coral growth under environmental conditions that promote the formation of coral frameworks with a high baffling capacity and (ii) sediment input that stabilises the coral framework, limits bioerosion of the coral skeletons by fast burial and favours fast CWC mound aggradation. The project will focus on CWC mounds off Mauritania, where numerous mounds occur along a spectacular 190-km-long transect (17-19° N), hence being one of the largest CWC mound provinces known so far. The Mauritanian mounds exhibit heights of up to 100 m and are organised in two slope-parallel mound chains in water depths between 360 and 550 m. The Mauritanian CWC mound province differs from all other studied mound provinces by being positioned underneath a tropical eastern boundary upwelling system and being directly influenced by a well-developed oxygen minimum zone (OMZ), which exhibits values below the preferred oxygen concentrations of the dominant framework-building coral Lophelia pertusa. Prior studies showed that even though living Lophelia-colonies occur rarely today, CWC mound formation seems to stagnate since the termination of the last glacial. The project will investigate: (i) The environmental controls of CWC mound formation off Mauritania with a special focus on the interplay of food delivery, the oxygen concentration of the surrounding bottom water mass, and the influence of variable sediment input on the CWC framework as potential key controlling factors. (ii) The oceanographic forcing of the development of two slope-parallel CWC mound chains. And (iii) the influence of potential latitudinal diachronous oceanographic changes on CWC mound formation phases along the Mauritanian continental slope. Beyond the aim to understand the long-term development of the Mauritanian CWC mound province in response to changing environmental settings, this project will contribute to our understanding of the processes controlling CWC vitality and mound formation in general. Most obvious features here will be the resilience of CWC to rather low oxygen conditions and the development of slope-parallel CWC mound chains.

• DFG Programme: Research Grants