Phytoplankton Community at the Polar Front of the Eastern Part of the Barents Sea during the End of a Growth Season
Phytoplankton community and its distribution were investigated in the south part of the Polar Front in the eastern Barents Sea in October 2014. Analysis of the spatial differences in the phytoplankton structure was performed in connection with changes of the temperature, salinity and biogenic regime. At the end of the growing season in the phytoplankton community was dominated by destruction processes and the concentration of nutrients in the upper mixed layer was higher than the limiting level. Coccolithophores (Emiliania huxleyi and Discosphaera cf. tubifer) dominanted over investigated area. The maximum values of abundance and biomass of coccolithophores reached 90.4 mln cell/m3 and 30.8 mgC/m3, drawing up 82% of the total number and 93% of the total biomass of phytoplankton. Influence of the transformed waters of Atlantic origin was observed in the western part of the investigated area. The number of species in the phytoplankton community here was 1.5–2 times lower than in the eastern part occupied mostly by Barents Sea water. In the eastern part of the presence of large dinoflagellates Neoceratium spp. and Dinophysis spp., lower values of chlorophyll a concentration, a higher proportion of pheophytin in the amount of pigments chlorophyll + pheophytin, the high content of ammonia in the upper mixed layer showed that in this area the phytoplankton was at a later seasonal succession stage than in the western part.