FLUXES: Constraining organic carbon fluxes in an Eastern Boundary Upwelling system (Cape Blanc; NW Africa): the role of non-sinking carbon in the context of the biological pump
The main goal of FLUXES is to quantify the relevance of labile and semi-labile dissolved (DOC) and suspended (POCs) organic carbon (i.e. non-sinking organic carbon) in the context of the biological pump (BP), in Eastern Boundary Upwelling Ecosystems (EBUE). The Cape Blanc region (NW Africa), characterized by a rich mesoscale variability resulting from the interaction of the upwelling system and the Cape Verde Frontal Zone that built up the Giant Filament, will be used as a case study. We want to test the hypothesis that offshore lateral advection of POCs, as well as secondary circulation at the submesoscale range and vertical mixing of DOC and POCs, contribute significantly to the export of organic carbon in EBUE. If we were correct, our results will invite reconsideration of regional and global models of the carbon cycle, including the non-sinking carbon as a major pool and flux. We presume also that the project will help to clarify some uncertainties and paradoxes on the imbalance beteween sources ans sinks of carbon in the global ocean. At the social level, we anticipate that our results would have profound implications for the estimation of new and export production in EBUE and, therefore, for the functioning of these systems as sources-sinks of CO2 to the atmosphere as well as seafood suppliers. We aim to provide a NEW LEVEL OF UNDERSTANDING of the functioning of the BP, greatly valuable for sustainable exploitation and management of marine resources in EBUE. To achieve our goals we propose an ambitiuous trans-disciplinary observation programme, with an inverse model output, based on two oceanograhic cruises: one focused on large scale variability and another on mesoscale /submesoscale variability. We will combine traditional oceanographic methods with new instrumentation to sample down to the submesoscale. We aim to address the coupled dynamics between food-web diversity and function, in relation to the hydrographic and chemical environment in distinct deep-water masses, the origin and composition of DOC and POCs and their contribution to remineralization rates in the dark ocean. The level of complexity of this project in terms of fieldwork activities, logistics and interdisiciplinary science (combining physical oceanography, biogeochemistry, and biological oceanography) will require the coordination of several research groups with a proven record of experience and skills in their respective fields of knowledge, that have been collaborating for more than a decade in the coupling between physical processes, plankton community structure and metabolism, and carbon biogeochemistry in the Canary Current EBUE.