Bridging marine productivity regimes: How Atlantic advection affects productivity, carbon cycling and export in a melting Arctic Ocean

CarbonBridge focus on the Atlantic water inflow region to the Arctic Ocean, and how primary production and carbon cycling is impacted in this region. It has been projected that reduced sea-ice extent can result in increased production and food availability for higher trophic levels. The potentially increased production and food web distribution is not yet fully understood. A key is an increased understanding of the energy distribution among the smallest organisms. CarbonBridge provide new and interesting results. Based on field studies and experiments in January, May and August 2014 west and north-west of Spitsbergen, using RV Helmer Hanssen, data collected has been integrated with historical data and physical-biological coupled model simulations to extend the results beyond the time and spatial scales set by the field work and project frames. The most important findings from CarbonBridge includes: Advection of energy into the Arctic Basin -The advection of primary production and algal biomass with the Atlantic current into the Arctic Basin is 5-50 times the local production -The advection of mesozooplankton with the Atlantic current into the Arctic Basin is >10 times the local production -The advection of mesozooplankton is surprisingly large also in winter, and results from a relatively large surface component of copepod populations expected to overwinter at depths of several hundred meters -The advective energy supply to the shelf-break region north of Svalbard provide large amounts of food for fish and other organisms in the region -Mesozooplankton that is advected into the Arctic Basin in September, may originate from the Lofoten-Vesterålen region, and make the Norwegian coast and the Arctic Ocean a contiguous domain Increased production with reduced sea ice extent -Primary production can increase with reduced sea-ice cover and longer open water periods -When light is no longer limited, nutrients may be -The main nutrient supply in the region results from deep-winter convection bringing nutrients from the deep water to the surface waters. The turbulent mixing during summer provides higher nitrate fluxes compared to Pacific Arctic regions, but is still limited. -The harvestable part of the primary production (new-production) is not expected to increase due to stratification and nitrate limitation -Regenerated production (ammonium based) may increase considerably, but will mainly fuel the microbial food web, and losses to respiration will be high -Increased local primary production along the shelf break north of Svalbard may therefore not provide a substantial increase in food supply for high trophic levels Improved model tools -Increased knowledge on how carbon and nitrogen pools exchange between particulate and dissolved in the microbial food web provide increased insight to degradation and regeneration of nutrients for regenerated production. This compartment and process will be improved in the SINMOD model Future productivity -Projections of future climate suggest increased temperature and primary production along the shelf break north of Svalbard -The advective transport will still be considerable -Models suggest increased future CO2 uptake and storage. The value of this ecosystem service will be estimated. CarbonBridge has educated one PhD and two post docs, and contributed to additional Master and PhD projects. The project results are disseminated at several conferences and arrangement for different target groups, including children, management, general public, artists and scientists. Activities include exhibitions, panel debates and a PhD course. The scientific results are presented in scientific papers. A book At the Edge provide popular scientific presentations on the northern region. The results will be of importance for science, management and other with interest in productivity and advective transport in a future Arctic Ocean. The project has been a collaboration between UiT the Arctic University of Norway, Norwegian Polar Institute, SINTEF, Institute of Marine Research, University of Bergen, UNI Research, UNIS, Scripps Institution of Oceanography (USA), Laval University (Canada), University of Tartu (Estonia), University of Akron (USA), Institute of Oceanology (Poland), University of Århus (Denmark), Mediterranean Institute for Advanced Studies (Spain), International Arctic Research Center, University of Fairbanks (USA), Arctic and Antarctic Research Institute (Russia), Alfred Wegner Institute (Germany).

The retreat of sea ice into the Arctic Ocean Basin opens for changes in ecosystem production and composition along the shelves. While there is increased interest in exploiting the area north of Svalbard with respect to harvest, petroleum and ship traffic, we lack sufficient knowledge for appropriate risk assessments and resource management of this area. CARBON BRIDGE addresses productivity and pathways of carbon flow in the marine ecosystem lower trophic levels in regions projected to be new productive ho t spots in the Arctic Ocean resulting from the sea ice retreat. We quantify the advective supply via the Atlantic Water (AW) inflow (WP1) and the local production and export processes (WP2) being the basis for the ecosystem production in the new ice-free shelf and basin regions north of Spitsbergen. We address the limiting factors and regulation mechanisms (WP3) to provide an understanding of how the organisms and processes are controlled from the physical and biological environmental conditions. These pa tterns along with existing data sets and modelling tools provide the basis for up-scaling to address larger scale patterns and future maps of productivity as basis for higher trophic levels and harvestable production (WP4). The patterns of future physical conditions and drivers and resulting productivity and food web transfer to deeper waters, to the microbial community or to higher trophic levels, will be evaluated in light of the increasing interest for activities in northern marine regions, and the pot ential for conflicts of interest (WP5). Results from all WPs will be communicated to reach relevant communities and users at many levels (WP6). Ecosystem-services provided by this region will be sensitive to the productivity regime. With a strong team of pan-Arctic researchers, we identify characteristics and quantify the regime north of Svalbard in terms of basic ecosystem production, carbon sequestration and its role in the Arctic carbon chemistry cycle.