Role of zooplankton dynamics for Southern Ocean phytoplankton biomass and global biogeochemical cycles

International audienceGlobal ocean biogeochemistry models currently employed in climate change projections use highly simplified representations of pelagic food webs. These food webs do not necessarily include critical pathways by which ecosystems interact with ocean biogeochemistry and climate. Here we present a global biogeochemical model which incorporates ecosystem dynamics based on the representation of ten plankton functional types (PFTs): six types of phyto-plankton, three types of zooplankton, and heterotrophic pro-caryotes. We improved the representation of zooplankton dynamics in our model through (a) the explicit inclusion of large, slow-growing macrozooplankton (e.g. krill), and (b) the introduction of trophic cascades among the three zoo-plankton types. We use the model to quantitatively asses