Picophytoplankton distribution at the Ob section and in western part of the Kara sea

Abstract

The spatial distribution of picophytoplankton abundance, biomass, chlorophyll a and contribution of picoalgae to total chlorophyll a was studied in the outer Ob estuary with an adjacent shelf and in the western part of the Kara Sea. In August-September picophytoplankton abundance and biomass varied from 0.1 to 17.3106 cell/l and from 0.06 to 9.20 mg С/m3, respectively. Cyanobacteria dominated in plankton picofraction, its contribution to total picophytoplankton biomass did not exceed 11%. The highest contribution of picophytoplankton to the total phytoplankton abundance was observed at a lower (11 mg/m2) chlorophyll a concentration in the euphotic layer. The spatial heterogeneity of picoforms contribution was determined by the silicon concentration.