Sediment cores were taken using a box corer. The sediment was subsampled using a 20 x 20 x 12 cm and incubated for 12 days. At the end of incubation, the macrofauna retained (500 um sieved) from each aquarium were fixed in 10% phosphate buffered formalin (4% formaldehyde) and stored in sealed plastic buckets for a minimum of three months. Prior to identification samples were rinsed and preserved in 70% industrial methylated spirit (IMS). Using a stereo microscope, all the animals were picked out of the residue, stored in vials containing 70% IMS, and identified to the lowest possible taxon with abundance and biomass per taxon noted. Biomass was obtained using blotted wet weight (+/- 0.0001g). The individual numbers of each taxa were counted to give abundance data. This was determined by the presence of a head in cases where specimens had been damaged. Any badly damaged specimens or parts of specimens where no head was present were separated into major group debris (annelid, mollusc and crustacea) pots and their presence noted as YES/NO for abundance). All molluscs were weighed inclusive of shells, tube dwelling polychaetes were weighed without tubes, and sediment was removed from the body cavity of specimens of Ctenodiscus crispatus prior to weighing.

Samples were collected on cruises JR16006 and JR17007.

Funding was provided by ''The Changing Arctic Ocean Seafloor (ChAOS) - how changing sea ice conditions impact biological communities, biogeochemical processes and ecosystems'' project (NE/N015894/1 and NE/P006426/1, 2017-2021), part of the NERC funded Changing Arctic Ocean programme.