Coral-reefs off North and West Africa – Environmental settings

As part of the EAF Nansen Program, three cold-water coral sites have been studied along the West African coast: in Mauritania-Morocco and Ghana/Côte d'Ivoire. The aim was to investigate their health status in contrasting environment to obtain knowledge on the physiological ranges and adaptive capacity to multiple stressors. The used data concerns the landscape, depth, water masses, temperature, dissolved oxygen concentration (DO), carbonate chemistry (pH, aragonite saturation WAr), macronutrients and particles (visual). The results are compared to the health status of other Lophelia pertusa reefs in such contrasting environments. The results show that large healthy reefs of L. pertusa reside off Ghana and Mauritania in the oxygen minimum zone (OMZ) with DO concentrations between 1.1 and 1.6 ml L− 1. They are located in corrosive waters with the lowest pH and WAr and high nutrient levels. The reefs off Morocco reside in waters similar to the Norwegian reefs in well oxygenated waters with oversaturated WAr but was showed to be less healthy (dead) compared to the reefs in the other two sites that resided in the OMZ. This study demonstrates that L. pertusa thrives in OMZ and corrosive aragonite waters, suggesting local adaptation to these conditions and supporting recommendations to continue research work on the same species in contrasting environments for potential effects of climate change.