FS Meteor “Deep Convection” (M87/1) will study processes that affect carbon fluxes in the region of the north-western European continental slope and adjacent coastal and marginal seas (North Sea and Baltic Sea). The research cruise will mainly investigate the importance of winter convection on winter primary producers, fate of sinking biomass and the impact on the following spring bloom in distinct hydrographical regions in the north-eastern Atlantic and the northern North Sea.
Recent studies suggest that winter convection contributes to a high biomass of phytoplankton in the deep convective layer, which is in contradiction to the classical spring bloom critical depth model of phytoplankton bloom dynamics. In order to investigate the implications of these two regimes for biogeochemical fluxes and ecosystem dynamics we will investigate the mechanisms influencing winter phytoplankton production and biomass, resolve the fate of phytoplankton biomass produced during the winter convective period (i.e. flux to depth) and examine its impact on exit from diapause of Calanus finmarchicus, a key secondary producer in this system. Upon the onset of stratification convection is reduced and the system shifts to a classical spring bloom system dominated by large phytoplankton cells, contributing to the production of higher trophic levels, and to a second flux of carbon to the deep ocean, which is potentially mediated by higher trophic levels. In order to assess the magnitude of these fluxes throughout the course of evolution of these two regimes, the proposed multinational, interdisciplinary cruise will use state-of-the-art techniques to measure biogeochemical fluxes, and ecosystem structure and functioning. This cruise is a component of the EU contribution to the International BASIN (Basin-scale Analysis, Synthesis, and INtegration) program.