Cold-Water Coral Reefs in the Oxygen Minimum Zones Off West Africa

The discoveries of large reefs within cold-water coral mound provinces revealed that the West African margin is a coral hotspot area in the Atlantic Ocean. The most striking observation is that cold-water corals thrive in extensive oxygen minimum zones under extreme conditions. This points to a wide tolerance of cold-water corals in these regions to low oxygen concentrations. The coral mound provinces off Mauritania, Angola, and Namibia, which are located in the centre of the local oxygen minimum zones, were selected as key study areas, and their regional oceanographic, bio-ecological, and geo-morphological settings are described in detail. Even though all three provinces are characterised by highly productive, oxygen-depleted, and relatively warm environmental conditions, they differ considerably with respect to the present-day reef status and the timing of mound formation during the last glacial-interglacial cycle. Today’s bottom-trawl fishing and oil and gas exploration pose severe threats to the coral communities, and together with predicted ocean warming and deoxygenation, these areas may not continue to support living coral reefs. To fully understand the ecology of the West African cold-water corals and the regional environmental control mechanisms, research strategies following a multidisciplinary and integrated approach are needed.