Seamounts are often thought to function as a major hotspot for megafauna accumulation due to their unique topology and environmental characteristics. However, comprehensive assessments of megafauna communities inhabiting seamounts, including diversity, abundance and biomass are seldom available. We investigated the vertical distribution of epibenthic megafauna over a newly discovered seamount region West of Cape Verde. Utilizing OFOS-dives, calibrated videos were taken as a horizontal transect from the northeastern flank of the seamount, distinguishing between the upper (-1354/-2358m) and deeper section (-2358/-3218m). Taxa were morphologically distinguished, their diversity, abundances and biomasses estimated and related to habitat parameters. Both the upper and lower seamount region hosted unique communities with significantly higher megafauna richness at the seamount’s top. While megafauna abundances differed significantly between the upper and deeper community, no significant differences were detected concerning the estimated biomass. The complete seamount showed a vertical zonation with dense aggregations of cold-water corals dominating the seamount’s upper and colonies of the glass sponge Poliopogon amadou dominating the lower region. Special for our study is that abundance and biomass data are provided for a continuous survey of a seamount down to 3,200m. The results are discussed in light of detected substrate preferences, co-existence of species and comparisons with literature data on comparable seamounts.

Primary Presenter: Dominik Scepanski, University of Cologne (dscepan1@uni-koeln.de)

Authors:

Dominik Scepanski, University of Cologne, Institute of Zoology, General Ecology  (dscepan1@uni-koeln.de)

Nico Augustin, Helmhotz Zentrum für Ozeanforschung GEOMAR  ()

Joana R. Xavier, Department of Biology, Centre for Geobiology, University of Bergen  ()

Hartmut Arndt, University of Cologne, Institute of Zoology, General Ecology  ()