Role of microorganisms and viruses in the vertical flux in the East Siberian Sea and Laptev Sea

The study of the contribution of bacteria (BAC), heterotrophic nanoflagellates (HNF) and viruses (VIR) to vertical matter fluxes on the shelves of the East Siberian Sea (ESS) and the Laptev Sea (LS) was carried out using sediment traps placed on buoy stations at depths of 18–55 m for 4–19 days. The value of the total organic carbon flux (TOC) contained in the cells of bacteria (BAC), heterotrophic nanoflagellates (HNF) and virus particles (VIR) in the ESS varied from 0.5 to 2.4 mg C m–2 day–1 and amounted to 1.1–4.9% of the total TOC flux, in the LS – from 0.7 to 5.2 mg C m–2 day–1 and amounted to 1.1–6.2% of the total TOC flux. The maximum values of flows were measured near the Lena River delta, the mouths of the Khatanga and Indigirka Rivers. The contribution of BAC, GNF and VIR to the total biomass of the microbial community attached to sinking particles was, on average, 59 ± 11%, and 28 ± 8%, 13 ± 9% for VSM and ML, respectively.