Sample collection: The sampling was part of the Canadian Arctic Shelf Exchange Study (CASES) in which CCGS Amundsen was frozen in Franklin Bay in the coastal Beaufort Sea (Station FB/200) during winter. Upper mixed-layer microbial plankton communities were sampled 5m below the water surface using the ship CTD rosette system equipped with 12L Niskins during openwater conditions. During the time that the ship was frozen in Franklin Bay from December 2003 to early June 2004, samples were taken using a 5L Niskin bottle from 3m below the bottom ice through a 300mm hole that had been drilled 500m upstream of the ship. HPLC pigment analysis: One to two liter samples of water were filtered onto Whatman GF/F filters and stored frozen at -80C until analysis. Phytoplankton pigments on the GF/Fs were extracted in 3mL of 95 percent MeOH and 100 uL of the extracts was injected into a Varian ProStar HPLC equipped with a Symmetry C8 column. The HPLC peaks were detected by diode-array spectroscopy (350-750nm) and absorbance chromatograms were obtained at 440 (for chls) and 450nm (for carotenoids). Chlorophylls were also detected by fluorescence (excitation: 440nm; emission: 650nm). The HPLC solvent protocol was based on gradient dilution with two solvent mixtures (Zapata et al. 2000): a methanol, acetonitrile, and aqueous pyridine (50:25:25 v:v:v) solution; and a methanol, acetonitrile, and acetone (20:60:20 v:v:v) solution. The flow rate was 1mL/ min, and the equilibration time was 7min.

This dataset consists of vertical profiles of discrete depth sampled weekly at a fixed station under the ice in Franklin Bay (Southeastern Beaufort Sea) to determine bacteria abundance. Sampling took place from December 2003 to May 2004 through the moon-pool of the CCGS Amundsen for depth ranging from 10m to the bottom and through a hole in the ice cover for the surface depth (3-10m). Bacteria concentrations were counted by flow cytometry.

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 dataset consists of vertical profiles of discrete depth sampled weekly at a fixed station under the ice in Franklin Bay (Southeastern Beaufort Sea) for chlorophyll a concentration of different size fractions: >0.7µm and >5µm. Sampling took place from December 2003 to May 2004 through the moon-pool of the CCGS Amundsen for depth ranging from 10m to the bottom and through a hole in the ice cover for the surface depth (3-10m). Chlorophyll a concentrations were determined by fluorimetry.

Microbial and environmental variables were collected from 8 depths at a 200-m deep site in Franklin Bay on 33 occasions, from 4 November 2003 to 6 August 2004, aboard the CCGS Amundsen. The following variables were measured: depth, temperature and salinity (Seabird 911+ CTD); CDOM (coloured dissolved organic matter) absorption coefficient at 320 nm (Varian Cary Bio 300 scanning spectrophotometer); chlorophyll a (ethanol pigment extraction); bacteria abundance (epifluorescence microscopy); tritiated leucine and thymidine incorporation rates (centrifugation method). Bacterial carbon production (BP) was estimated from leucine incorporation using the carbon conversion factor of 1.5 kgC/mol of leucine incorporation. BP was also estimated from thymidine incorporation using (1) the empirical carbon conversion factor of 2.0 x10^18 cells/mol of thymidine incorporated and (2) the bacterial cellular biomass of 10 fgC/cell.

This dataset consists of vertical profiles of underwater downwelling irradiances at several UVR (305, 313, 320, 340 and 380nm) and PAR wavelengths, from June to August 2004. Vertical light profiles were performed using a PUV-511 underwater radiometer (Biospherical Instruments) that provides a measure of cosine-corrected downwelling irradiance in the UVR and PAR. Irradiances were corrected by the dark values and normalized to the ambient conditions at the beginning of the profile, using ambient values given by a GUV-510 surface radiometer (Biospherical Instruments) mounted on the top of the wheelhouse of the CCGS Amundsen.

Geophysical data from a single-channel 3.5kHz sub-bottom profiler is acquired 24hrs during CCGS Amundsen’s cruises by a Knudsen 3260 sub-bottom profiler. The sounder is comped of 16 (4x4 array) transducers outputting a total of 10KW. The dataset consists of raw (keb and sgy) and processed (JPEG2000 and PNG images) data. Heave (TSS1 form the Applanix POS-MV) and GPS (ZDA, VTG, GGA from the CNAV GNSS Receiver) data are inputted to the raw data files directly during acquisition. The processing is made using the NRCAN software suite (SEGY to SGYJP2 and SegyJp2Viewer). The speed of sound is constantly set to 1500 m/s. The data are available in an ESRI ArcGIS geodatabase format where shiptrack lines are linked to jp2, sgy and png formats of the sub-bottom profiles.

This dataset consists of continuous records of downwelling irradiances at several UVR (305, 313, 320, 340 and 380nm) and PAR wavelengths, from September to November 2003 and from June to August 2004. The GUV-510 surface radiometer (Biospherical Instruments), mounted on the top of the wheelhouse of the CCGS Amundsen, provided a measure of cosine-corrected downwelling irradiance in the UVR and PAR.

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.

Microplastics (MPs) contaminate the oceans from the poles to the equators and from the sea surface to the deep sea. In addition, MPs have been recorded in freshwater systems, including in lakes, rivers and streams globally. Not only an aquatic issue, MPs infiltrate terrestrial ecosystems in landfills, agricultural settings, along beaches, and even in the air. It therefore comes as no surprise that MPs have been identified as a global pollutant of concern that is capable of long-range transport and causing adverse effects in wildlife, but limited information is available for Canadian Arctic regions. Consequently, the NCP has identified assessing the presence and distribution of MPs in Arctic marine ecosystems a priority. The Arctic Monitoring and Assessment Programme (AMAP) has also added Marine Plastics and MPs to their list of Chemicals of Emerging Arctic Concern. We planned on collecting water, sediment and zooplankton for MPs in the summer of 2020 as a part of ArcticNet from on board the CCGS Amundsen. Unfortunately, due to the COVID-19 pandemic sampling on board the CCGS Amundsen for our project was cancelled.