Characteristics of benthic communities and algae aggregations on the seafloor and some environmental and sediment parameters.

Total density, total biomass, observed (S) taxa number, Simpson diversity index (1-λ), Shannon diversity index (H'(loge)), Pielou's evenness index (J')) and seafloor algal coverage (%) and algal freshness based on image analysis. Species number in trawl samples based on trawl data. Total number of taxa based on trawl and image data together. Dissolved organic carbon (DOC), total dissolved nitrogen (TDN), chlorophyll a (Chl a) from Rossel et. al. [53]. Sea ice coverage, sea ice thickness and ice age (first (FYI)/multiyear ice (MYI)) from Boetius et al. [71].