A total of 19 stations were sampled between August and October 2011 onboard the Canadian research icebreaker CCGS Amundsen. Two stations were sampled both in August and October to assess seasonal variability in stable isotope composition. At each station, a USNEL box corer (0.25 m2) was deployed to collect seafloor sediments for the determination of stable isotope composition and pigment (Chl a + phaeopigments) concentrations. From each box core, surface sediments (upper 1 cm) were sampled as three sub-cores using a 60 ml disposable syringe (2.6 cm diameter with a cut off anterior end). Sediment samples were immediately frozen at -20 °C for stable isotope analysis and at -80 °C for pigment analysis. Megabenthic invertebrates were principally collected with an Agassiz trawl (effective opening of 1.5 m and a net mesh size of 40 mm, with a 5 mm cod end liner) with average trawling time and speed of 5 min and 1.5 knots, respectively. At three stations, invertebrates were collected with the box corer. Trawl and box corer catches were washed over a 2 mm sieve under running sea water onboard and 1 to 3 individuals of the most abundant community representatives were collected at each station. Specimens were frozen immediately at -80 °C and identified to the lowest possible taxonomic level in the lab.

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.

Here, we sampled five specimens of Chondrocladia and Cladorhiza as part of the Hidden Biodiversity project, using the SuperMohawk ROV on board the CCGS Amundsen. In October 2015, samples were collected from Scott Inlet and off Qikiqtarjuaq, and retrieved using a custom-built sample elevator. Samples were immediately dissected and processed for DNA and histological analyses. The analysis of these samples is currently in progress.

Sample collections were made aboard the CCGS Amundsen during the ArcticNet field campaigns in August 2013 (Leg 1), July, August and October 2014 (Leg 1 & 3) and October 2015 (Leg 4). Sediment samples retrieved from box cores were sliced into 0.5 cm increments and frozen separately, while benthic invertebrates were collected using a benthic trawl. Individual species including Gorgoncephelus arcticus, Psilaster andromeda, Ophiopleura borealis and Ctenodiscus crispatus were identified, sorted, packed and stored at -30C and shipped to Winnipeg. At the University of Manitoba samples were freeze-dried and homogenized. Samples were then extracted and analyzed for polycyclic aromatic hydrocarbons (PAHs) and n-alkanes using a LECO Pegasus gas chromatographer with a high resolution time of flight mass spectrometer (GC-HR TOFMS). Supplementary data was also generated, including stable isotope ratios of nitrogen and carbon, as well as lipid (inverts) and total organic carbon (sediment) to calculate biota-sediment accumulation factors (BSAFs). Statistical analysis is currently ongoing.

Samples were collected at two sites in the Eastern Canadian Arctic (Figure 1) aboard the scientific icebreaker CCGS Amundsen. The sampling positions at biogenic and non-biogenic habitats were defined during ROV video surveys at the two sites (Figure 2a-d). Positions were carefully selected to avoid overlap between the two types of habitats (i.e., when most of the camera’s field of view was dominated by a single habitat over the course of approximatively 5 meters). At each site, we deployed two box cores (0.5 × 0.5 m) per habitat (i.e., inside the biogenic structures and in the bare sediment; Figure 2e) approximately 200 m apart in FB site and 500 m apart in BB site. From each box core, we collected three sediment cores (i.d = 9.8 cm, H = 30 cm) for a total of six cores per habitat and 12 cores per site. Sediment cores sampled in biogenic structures habitats were visually exempted from biogenic structures. Bottom (10 m above the seafloor) temperature, salinity and oxygen saturation at each site were recorded with a conductivity-temperature-depth (CTD) probe. Sediment cores were incubated in the dark at a temperature-controlled room (2-4°C) until a maximum of 20% of available oxygen was consumed. Sediment samples for chlorophyll a, phaeopigments and sediment properties were also collected from each box core. sediment cores were sieved through a 500 µm mesh sieve to collect infauna. Organisms were fixed with 4% formaldehyde solution. They were sorted under a dissecting microscope in the laboratory and identified to the lowest possible taxonomic level.

Samples were collected at 5 sites ranging in water depth from 100 to 595 m at least once in each season (ice-covered and open-water condition) between March and August 2008 onboard the icebreaker CCGS Amundsen. At each sampling station, an USNEL box corer was deployed for collecting seafloor sediments. From each box core, 5 sub-cores of 11 cm diameter and 20 cm sediment depth were taken for assessing benthic carbon remineralisation in microcosm incubations and 3 additional subcores of 5 cm diameter and 10 cm length were taken for determining sediment properties. Incubations of sediment microcosms were run in a dark, temperature-controlled room (2-4 °C) for 24-48 h. Each sediment microcosm was sieved through a 0.5 mm mesh under running sea water at the end of incubations to determine biomass of macrofaunal communities. The sieve residue was preserved in a buffered 4% seawater-formaldehyde solution and analysed for species composition and abundance under a stereomicroscope in the lab.

Data were mainly collected from the CCGS Amundsen (2015 to 2019) and from the William-Kennedy (2019). An Agassiz trawl (1.5 m width × 0.7 m height, cod end of 0.5 cm mesh size) was towed on the seabed at a speed of 1.5-2 knots for 3 to 5 minutes to survey epibenthic species diversity, abundance, and biomass. Retrieved samples were washed with seawater in a sieve (2 mm mesh), and organisms were sorted and identified to the lowest taxonomical level possible. Each taxon was counted, and biomass was measured. A box corer was deployed to quantitatively sample diversity, abundance, and biomass of endobenthic organisms (macrobenthos > 0.5 mm). After retrieval of the box corer, a subsample of 0.125 m2 area and 12-15 cm depth was collected and passed through a 0.5 mm mesh sieve to separate sediment from endofauna. Organisms were immediately preserved in a 4% buffered formaldehyde solution for further taxonomical identification in the laboratory.

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.

A first survey was conducted in and around EL446 onboard the CCGS Amundsen from 16 July to 30 July, 2009. A total of 21 biophysical stations were sampled, involving 25 box core deployments and 18 Agassiz trawl tows. In addition, the Remotely Operated Vehicle (ROV) was deployed once (station 10) for epibenthos observation. A second survey was conducted in EL449 and EL451 onboard the CCGS Amundsen from 12 August to 26 August, 2010. A total of 18 biophysical stations were sampled, comprising 25 box core deployments and 18 Agassiz trawl tows. A third survey was conducted in EL451 and EL453 onboard the CCGS Amundsen from 7 September to 22 September 2011. A total of 13 biophysical stations were sampled, comprising 18 box core deployments and 13 Agassiz trawl tows. The box core was deployed to quantitatively sample diversity and abundance of endobenthic organisms. After retrieval of the box core, a subsample of about 0.125 m2 area and 12-15 cm depth was collected and passed through a 0.5 mm mesh sieve to separate sediment from endofauna. Organisms were immediately preserved in a 4% buffered formaldehyde solution for further taxonomical identification in the laboratory. The volume of sediments sieved from each box core was measured (depth × width × length) to the nearest 1 cm to estimate endobenthic fauna density in each sample. An Agassiz trawl (1.5 m width × 0.7 m height, cod end of 0.5 cm mesh size) was towed on the seabed at a speed of 1.5 - 2 knots for about 3 to 5 minutes to survey epibenthic species diversity and abundance. Retrieved samples were washed with seawater in a sieve (0.5 mm mesh), and organisms were counted and identified to the lowest taxonomical level possible.

Benthic grab samples and underwater towed video samples were collected at long-term ecology sites while onboard the Government of Nunavut vessel MV Nulialjuk and CCGS Amundsen in July and October 2016. On-board the MV Nulialjuk, benthic grab samples (triplicate samples) and underwater towed video samples were collected at 5 long-term ecology stations near Iqaluit. An additional 7 benthic grab samples (triplicate samples) and towed video samples were collected near Cairn Island. On-board the CCGS Amundsen, benthic grab samples were collected at two long-term ecology stations (triplicate samples) near Cairn Island. Sampling gear included a Van Veen grab sampler, box core, and HD GoPro video system. Initial observations suggest that these stations are predominantly muddy sand with some larger cobbles present. Towed video analysis and benthic grab samples indicate the presence of the algae Laminaria sp. and Agarum clathratum and bivalves Mya truncata, Yoldia hyperborea, Clinocardium ciliatum, and Serripes groenlandicus. Ophiuroid echinoderms and tubiculous polychaete worms and tubes are abundant. Once all benthic grab samples and towed video samples are processed, this data will be compared with the historic sample data to answer questions about the nature of long-term change of the benthos at this region in inner Frobisher Bay.