Spatial variation in mesopelagic fish assemblage structure in the upwelling of the Canary Current Ecosystem

Mesopelagic fish communities remain under studied in the highly dynamic Canary Current Ecosystem. We analyzed mesopelagic fish assemblage structure based on 2,153 specimens representing 98 species across two distinct marine zones: Mauritania, characterized by high oxygen and chlorophyll-a concentrations, and Senegal, distinguished by high temperatures and low salinities. Our findings reveal clear biogeographic patterns, with Diaphus vanhoeffeni, Diaphus dumerilii, Argyropelecus gigas, and Sternoptyx diaphana showing high abundance in Senegalese waters but limited presence in Mauritania waters. Conversely, Diaphius rafinesquii, Benthosema glaciale, Argyropelecus hemigymnus, Lobiancha dofleini, and Hygophum taaningi exhibited higher abundances in Mauritania waters. Statistical analyses revealed significant correlations between species abundance patterns and physicochemical parameters specific to each marine zone. This pioneering study of mesopelagic fish community composition and structure in relation to environmental factors in the Canary Current Ecosystem provides valuable insights into a marine fauna, which holds potential for sustainable exploitation in aquaculture feed production and nutritional supplements, beyond its crucial role in the carbon cycle and marine food web.

Keywords: Mesopelagic fish, Canary Current Ecosystem, Upwelling, Environmental factors, West Africa.