Fatty Acids, carotenoids, protist community and environmental parameters collected during a phytoplankton blooms in the Hudson Bay Complex.

The study was part of larger multidisciplinary investigations in the HBC aimed to understand (i) the effect of climate change on the quality of the Inuit local marine food (project BriGHT; Bridging Global Change, Inuit Health and the Transforming Arctic Ocean) as well as (ii) the contributions of climate change and hydroelectric regulation to the freshwater–marine coupling (project BaySys; The Hudson Bay System Study). Samples were collected from 7 to 12 July 2017 (BriGHT) and from 1 June to 12 July 2018 (BaySys) onboard the Canadian Coast Guard Icebreaker CCGS Amundsen using a Rosette system equipped with 12-L Niskin-type bottles and a conductivity, temperature, and depth (CTD) profiler (SBE-911, Sea-Bird Scientific, Bellevue, WA). The rosette was also equipped with a photosynthetically active radiation (PAR, 400 – 700 nm) sensor (scalar radiometer QSP-2300, Biospherical Instruments Inc., San Diego, CA) while a surface reference (QCR-2200, Biospherical Instruments Inc., San Diego, CA), measure incoming scalar PAR, was mounted to the ship’s main mast. In both years, discrete water samples for nutrients, taxonomy, pigments and lipids were collected at the surface and the deep chlorophyll maximum (DCM) directly from 12-L Niskin-type bottles that were closed on the upward cast then pre-filtered using a 200-μm Nylon. The duration (in days) since the ice breakup were extracted, for each station, from Nimbus-7 SMMR and DMSP SSM/I-SSMIS passive microwave data produced daily by the National Snow and Ice Data Center (Parkinson et al., 1996, updated yearly). In the current study, we defined the sea ice breakup by the day that the total ice concentration fell below 15%. We investigated 21 stations in 5 sub-regions (North-Western Hudson Bay, Eastern Hudson Bay, Narrows Strait, Hudson Strait as well as Ungava Bay. At the time of sampling, the sub-regions studied had different environmental settings conditioning their bloom stages. Pre- and post-bloom stages were associated with relatively low concentrations of bioactive molecules (either fatty acids or carotenoids) while bloom stages were associated with high concentrations of bioactive molecules.