Effects of local hydrophysical conditions on the spatial variability of phytoplankton in the White Sea

Abstract

The species composition and biomass of phytoplankton, chlorophyll a concentration (Chl), and hydrophysical characteristics of water masses have been studied in Onega and Kandalaksha bays (Chupa Inlet and Knyazhaya Inlet) of the White Sea at 16 stations June 17–26, 2012. Structural analysis of the phytoplankton community according to the Bray-Curtis similarity index has revealed two groups of stations. The first group united stations in stratified waters in Kandalaksha Bay; all stations located in Onega Bay formed another group. In turn, the stations in Onega Bay were separated into two subgroups corresponding to mixed (MWs) and stratified (SWs) waters. The total phytoplankton biomass and the biomass of diatoms and small unidentified flagellates were higher in Onega Bay. The biomass of dinoflagellates and cryptophytes, as well as Chl, did not differ significantly in Kandalaksha and Onega bays. In Onega Bay, the total phytoplankton biomass, Chl, and contribution of dinoflagellates to the total biomass were higher in SWs than in MWs. The contribution of diatoms was higher in SWs. The study addresses the role of the frontal zones in shaping the structure and distribution of the phytoplankton community.