Nitrogen uptake and phytoplankton productivity in the changing Arctic Ocean

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The recent decline of Arctic sea ice is one of the most pronounced examples of contemporary physical climate change on Earth. The newly-funded Arctic PRIZE project (Arctic PRoductivity in the seasonal Ice ZonE) aims to determine how these sea ice changes will affect biological and biogeochemical systems in this climatically-sensitive region.Despite the recognised importance of DON as a nutrient for phytoplankton growth, there is little information on the relative utilisation of different forms of inorganic and organic N and possible links to the phytoplankton community composition, especially in Arctic waters. The aim of this study is to evaluate the relative utilisation of different forms of DIN and DON by different phytoplankton size fractions and functional groups, to identify patterns in phytoplankton community composition and abundance associated to these chemical (as well as physical) drivers, and hence to evaluate their influence on Arctic phytoplankton productivity and community composition.Hypothesis Organic N has the potential to act as a major N source for Arctic phytoplankton populations.