Macrobenthic fauna of the Agulhas Bank shelf edge

Abstract

The deep sea (>200 m depth) off South Africa is largely unexplored, with most benthic macrofauna samples limited to depths shallower than 100 m. The benthic infaunal diversity of the Agulhas Bank shelf edge has not yet been studied. We analysed seven grab samples that were opportunistically collected along the shelf edge at depths of 290‒533 m. A total of 136 macrofauna items representing 75 species were identified, and the first species list of the infauna of the shelf edge was compiled. Polychaetes comprised 48% of total abundance, and the sites had an average similarity of 7% based on species abundance. Spearman rank correlation showed that depth and sediment particle size are important environmental drivers of community abundance and biomass variation on the shelf edge. Habitat heterogeneity is likely high along the Agulhas Bank shelf edge. Greater sampling effort in habitats for which data are scarce provides crucial information for offshore biodiversity assessment and management.