The Role of Plankton in the Vertical Flux in the East Siberian Sea Shelf

The role of plankton in the vertical flux in the East Siberian Sea was studied in the 69 cruise of the RV “Akademik Mstislav Keldysh” in September 2017. Vertical fluxes were measured in sediment traps on two buoy stations in the area of the Indigirka River plume and in the marine shelf area. Mass vertical flux and particulate organic carbon flux varied from 80 to 530 mg/m 2 /d and from 16 to 49 mgС/m 2 /d, accordingly. Phytoplankton in sediment traps was dominated by cysts and spores of diatoms and dinoflagellates. Phytoplankton flux increased with depths from 0.22–0.33 to 1.2–1.3 mgС/m 2 /d. Fecal pellet fluxes (7–12 mgС/m 2 /d) were similar at two studied stations and did not change with depth. Zooplankton in the traps was dominated by larvacean houses and carcasses of copepods Jashnovia tolli and Calanus glacialis. Flux of zooplankton varied from 3 to 17 mgС/m 2 /d. The influence of the continental runoff reflected in a decrease of the proportion of planktonogenic components in the vertical flux of organic carbon. In the river plume area, their total contribution to organic carbon flux did not exceed 30%; on the marine shelf it reached 80% of organic carbon flux.