Modern sedimentation, circulation and life beneath the Amery Ice Shelf, East Antarctica

• Diatoms and organic matter are transported far beneath the Amery Ice Shelf.
• Seabed biota have been imaged 200 km from open water.
• Depositional regimes and sediment properties may differ greatly between ice shelves.
• Paleo-records of ice shelf extent need to consider the oceanographic context.

The surface sedimentary record from six cores collected from beneath the Amery Ice Shelf, East Antarctica, provides a unique view of the sedimentary and oceanographic processes in this sub-ice shelf setting. The composition and age of the surface sediments indicate spatial variations in ice shelf cavity–ocean interaction, which are consistent with patterns of ocean inflow and outflow modelled and observed beneath the ice shelf. Sediments within 100 km of the ice shelf front (site AM01) show the greatest open ocean influence with a young surface age and the highest total diatom abundance, compared to older ages and lower diatom abundances at sites deeper in the cavity (AM03–AM06). The variable marine influence between sites determines the nature of benthic communities. Seabed imagery indicates the existence of sessile suspension feeders in areas of strong marine inflow (site AM01b), while grazers, deposit feeders and a few suspension feeders occur at sites more distal from the shelf calving front where the food supply is lower (sites AM03 and AM04). Understanding the sedimentary and oceanographic processes within the sub-ice shelf environment allows better constraint of interpretations of down core sediment records, an improved understanding of the nature of biological communities in sub-ice shelf environments, and a baseline for determining the sensitivity of the system to any future changes in ocean dynamics.