This study is based on sampling conducted partially within the framework of the (1) Arctic Biological Station program-Biological Oceanography Section (ABS-BOS) from 1973 to 1975, (2) CCGS Sir Wilfrid Laurier program and CASES from 2002 to 2004, (3) IPY-CFL from 2007 to 2008, (4) through research collaborations among the CCGS Amundsen program, ArcticNet, BP Exploration Operating Company Limited, ExxonMobil and Imperial Oil from 2009 to 2011, and (5) BREA in 2012. Macrobenthos communities were sampled at 235 stations from 1973 to 2012 between April and November through different scientific programs and onboard different research vessels. Faunal samples were collected mostly with a USNEL box corer (0.25 m2), except from 1973 to 2002 where different grab models were used. Due to shared sediment requirements, on average 0.12 ± 0.05 m2 of sediment were sieved from each box core or grab sample. All box core and grab catches were washed under running seawater onboard over a 0.4 mm sieve during the CASES program and over a 0.5 mm sieve during all other programs, resulting in all macrobenthic invertebrates considered here being ≥ 0.5 mm size. Taxa were preserved in a 4 to 5 % seawater-formaldehyde solution buffered with sodium tetraethylborate for later identification in the lab and then transferred in 70 % ethanol for long-term storage.

Benthic fauna were sampled at 78 stations between June and October from 2007 to 2011 onboard the Canadian research icebreaker CCGS Amundsen. Station depths ranged from 34 to 1024 m, all below the average ice scouring zone. All faunal samples were collected with an Agassiz trawl (effective opening of 1.5 m and a 40 mm net mesh size, with a 5 mm cod end liner) with average trawling time and speed of 5 min and 1.5 knots, respectively.

Agassiz trawl was deployed from the CCGS Amundsen to collect macrofauna. Catches were passed through a 2 mm mesh sieve. When possible, specimens were identified to the lowest taxonomic level, then count and weight. The unidentified specimens were preserved in a 4% seawater-formalin solution. Box corer was deployed to quantitatively sample diversity, abundance and biomass of infauna and to sample sediment. Sediments of a surface area of 0.125 m2 and 10-15 cm in depth were collected and sieved through a 0.5 mm mesh and preserved in a 4% formaldehyde solution for further identification in the laboratory. Sub-cores of sediments were collected for sediment pigment content, organic matter, sediment grain size, porosity; for sediment pigments, the top 1 cm was collected, although for sediment grain size, the top 5 cm was collected. Sediment pigment samples were frozen at -80°C, and porosity, organic matter and sediment grain size samples were frozen at -20°C.