Characterization of the coccolithophore community off Cabo Verde archipelago, including the Senghor Seamount (Eastern North Atlantic)

A systematic investigation of the extant coccolithophore community around Cabo Verde archipelago was performed during the cruise MSM49 of RV Maria S. Merian, which took place in the late fall of 2015. The description of the spatial and vertical distributions of coccolithophores was based on a survey performed to the north, east and south of Cabo Verde archipelago, between the surface and 150 m water depth. The total cell densities obtained for the studied region were relatively low, reaching to a maximum of 30 × 103 cell L−1 in the upper 50 m over the southeastern slope of the Senghor seamount. Emiliania huxleyi and Gephyrocapsa oceanica were the dominant species, followed by Florisphaera profunda. The coccolithophore distribution off Cabo Verde was essentially explained by relatively warm and nutrient-depleted waters in the region during the surveyed interval, in result of the weaker NE trade winds and the northward migration of the Intertropical Convergence Zone. In these conditions, a notable zonation of coccolithophores along depth was depicted, in consequence of the inferred general well-stratified water column. Four typical depth-related groups were identified: (i) a Shallow oligotrophic (10–30 m), represented by Discosphaera tubifera and Umbellosphaera spp.; (ii) an Intermediate (40–50 m), formed by the three placolith-bearing species E. huxleyi, G. ericsonii and G. oceanica, and by Algirosphaera robusta, Helicosphaera spp., Michaelsarsia spp., Syracosphaera spp. and Umbilicosphaera spp.; (iii) a Deep (60–75 m) with F. profunda, Ophiaster spp., Oolithotus spp. and Reticulofenestra sessilis as typical members; (iv) and The Deepest (>80 m), composed by Gladiolithus flabellatus and Syracosphaera lamina. In addition, high abundances of G. oceanica related with the Eddy station were attributed to the transport and thriving of the coastal coccolithophore community, dominated by this species, from the African coast towards Cabo Verde. •Existence of well defined coccolithophore assemblages-depth zonation.•Identification of four typical depth-related coccolithophore groups.•Transport of costal coccolithophore community, trapped into an eddy, from the African coast towards Cabo Verde.•Overall shallowing of the entire coccolithophore community, with the UPZ compressed within the first 60 m.•Role of the weak NE trades and the migration of the ITCZ in the species distribution.