Benthic-pelagic coupling in the Barents Sea: an integrated data-model framework

The Barents Sea is experiencing long-term climate-driven changes, e.g. modification in oceanographic conditions and extensive sea ice loss, which can lead to large, yet unquantified disruptions of ecosystem functioning. This key region hosts large fraction of Arctic primary productivity. However, processes governing benthic and pelagic coupling are not mechanistically understood, limiting our ability to predict the impacts of future perturbations. We combine field observations with a Reaction-Transport Model approach to quantify organic matter processing and disentangle its drivers. Sedimentary organic matter reactivity patterns show no gradients relative to sea ice extent, being mostly driven by seafloor spatial heterogeneity. Burial of high reactivity, marine derived organic matter is evident at sites influenced by Atlantic Water, whereas low reactivity material is linked to terrestrial inputs on the central shelf. Degradation rates are mainly driven by aerobic respiration (40–75%), being greater at sites where highly reactive material is buried. Similarly, ammonium and phosphate fluxes are greater at those sites. The present-day Atlantic Water dominated shelf might represent the future scenario for the entire Barents Sea. Our results represent a baseline systematic understanding of seafloor geochemistry, allowing anticipating changes that could be imposed to the pan-Arctic in the future if climate14 driven perturbations persist.