Trace metals & the Artic-Atlantic gateway in a changing world

Though often regarded as toxic contaminants, metals are also essential micro-nutrients. They are required for the growth of all organisms, including phytoplankton that form the base of the marine food web, and as such metals can drive global marine productivity. In large regions of the ocean, the amount of primary production is limited by the availability of trace metals that occur at vanishingly low concentrations. Notably iron is a limiting micro-nutrient, but other metals play a role as well in controlling phytoplankton productivity and community composition. The earth system is changing rapidly, especially at the high latitudes. This not only affects temperatures, but also global biogeochemical cycles such as the marine iron cycle. Our current understanding of the marine iron cycle does not allow reliable biogeochemical modelling to predict and evaluate the consequences of these changes. Over the last decades, advances have been made in our understanding of marine iron cycling, but some key ocean regions remain understudied and crucial processes are ill understood. The latter processes include microbial metal uptake, remineralisation and dissolved-particle interactions in the water column and the benthic boundary layer, and the susceptibility of these processes to change. In the Metalgate project we aim to unravel the cycling of metals with specific attention for these crucial processes in the Greenland-Iceland-Norwegian-Sea region, the main gateway between the Arctic and Atlantic Ocean. Besides sampling at sea and analysis at NIOZ, we also use temperature controlled bio-assays to enhance our understanding of the processes important for local biogeochemical cycles and their role in driving global climate and marine ecosystems. This will result in better predictions of the likely impact of imminent Arctic and sub-Artic climate change and the consequences for the future.