DOC and its relationship to algae in bottom ice communities

The seasonal development of algal biomass and dissolved organic carbon (DOC) in bottom ice was determined for two widely separated areas of annual sea ice, Saroma-ko in northern Japan and Resolute Passage in the Canadian High Arctic, to determine the importance of DOC to estimates of primary production in sea ice communities. As algal biomass, measured either as chlorophyll a (Chl a) or particulate organic carbon (POC), increased, DOC concentrations increased to extremely high values (up to 40 mg Cl−1 DOC). The highest algal biomass and DOC concentrations were observed at Resolute under thin (4–8 cm) snow cover. Highly significant double-log linear relationships (r2 = 62–80%, p < 0.01) existed between DOC and both Chl a and POC, suggesting much of the DOC originated from the ice algae. A highly significant global relationship between DOC and POC (r2 = 74%, p<0.01) was also found when previously published data for Frobisher Bay were included, indicating substantial consistency in the relationship between DOC and algal biomass among widely separated locations and differing climatic/hydrodynamic regimes. The significance of the apparently rich production of substrates for microheterotrophic processes in the ice is unclear until the nature and origin of the DOC are better resolved. It is clear, however, that estimates of organic production in ice based only on accumulation of particulate organic material will be seriously biased if dissolved material is ignored.