Productivity and timing of the main phenological states of the Arctic phytoplankton communities

Following receding of sea-ice cover, pelagic ecosystems are expanding to new ice-free regions at the expense of sympagic ecosystems. Consequently, many questions arise regarding the pelagic productivity regimes that could occur in the Arctic Ocean, i.e., either (1) an extension of oligotrophic areas associated with the presence of freshened and stratified Pacific waters, or (2) the extension of productive waters related to Atlantic waters. Using satellite-derived observations, biogeographic scenarios for the future of the annual primary production (APP), which is closely related to phenology, can be defined in response to the current receding sea-ice cover. In summary, highly stratified and oligotrophic regions (i.e., Chukchi and Beaufort seas) are expected to be characterized by a greater contribution to APP of post-blooms conditions with the occurrence of subsurface chlorophyll maximum. In contrast, in well-mixed Arctic regions (i.e. Greenland and Norwegians seas), spring and fall phytoplankton blooms seem to contribute largely to the APP. These predictions will allow us to better anticipate the possible changes in phytoplankton productivity and community structure, and the potential cascading repercussions on the carbon cycle and marine Arctic ecosystems.