According to several studies, general structure of the succession cycle of phytoplankton in the Barents Sea could be split up into different phases covering a time period of the year. These phases will be the winter phase (low activity), spring phase (covering the onset of and spring bloom maximum), summer phase, and the autumn phase. These periods shows characteristic species composition, abundance, and production.
It must be taken into consideration that due to the size of the Barents Sea area (large gradients east – west and north – south), the process of succession stages might not proceed the same way in all areas. Therefore, this selection of seasons over the entire Barents Sea can have only very general character. There will be interannually, as well as local, differences in the onset and duration of the different phases. There will also be differences in the species composition and biomass in different areas, but in most cases the taxonomical groups, even genus, will be similar over large areas.
In this general description of the succession the main focus is on the larger phytoplankton forms, such as diatoms and dinoflagellates. A group of the phytoplankton that is most likely underestimated in today’s monitoring program is nano- and pico-plankton flagellates, most likely due to methodological difficulties in covering all groups with one standard method. These groups are however found frequently all year around showing a annual pattern in abundance and with variable auto- and heterotroph composition. The larger phytoplankton groups like diatoms and dinoflagellates make up most of the variability and dynamics and dominate during blooms (Ratkova and Wassmann, 2002).