Shifts in benthic megafauna communities after glacial retreat in an Antarctic fjord

Abstract

Underwater imagery survey was conducted to address changes in Antarctic benthic megafauna communities by recent glacial retreat in Marian Cove, where distance from the glacier was proportional to retreat period. Benthic megafauna communities showed lesser variation due to frequent ice-scouring at 10 m than deeper seabed. At deep seabed (50–90 m), where glacier impacts decreased, benthic megafauna was scarce right in front of the glacier, but near the glacier (~10 years after seabed exposure), density peaked (128 ind. m−2) with pioneer species. At the outermost site, pioneer species were extremely limited (5 ind. m−2) while late-successional species were abundant (42 ind. m−2). Taxonomic and functional diversities peaked near the glacier and outermost site, respectively, indicating different mechanisms of structural and functional change after glacial retreat. This study showed a four-step successional process of benthic megafauna communities after glacial retreat in Antarctic nearshore: high disturbance, colonization, transition, and maturing stages.