The Changing Arctic Ocean (CAO) programme has ended now. Researchers of Hereon were co-lead investigators of the projects EISPAC and MiMeMo. The CAO consortium has published a special issue in the Ambio Journal.
Following articles were contributions by Hereon scientists. For further information please contact the marked authors and co-authors:
Sanders, T., Fiencke, C., Fuchs, M., Haugk, C., Juhls, B., Mollenhauer, G., Ogneva, O., Overduin, P., Palmtag, J., Povazhniy, V., Strauss, J., Tuerena, R., Zell, N., & Kirstin Dähnke, K. (2021): Seasonal nitrogen fluxes of the Lena River Delta. Ambio, doi:10.1007/s13280-021-01665-0
Abstract:
The Arctic is nutrient limited, particularly by nitrogen, and is impacted by anthropogenic global warming which occurs approximately twice as fast compared to the global average. Arctic warming intensifies thawing of permafrost-affected soils releasing their large organic nitrogen reservoir. This organic nitrogen reaches hydrological systems, is remineralized to reactive inorganic nitrogen, and is transported to the Arctic Ocean via large rivers. We estimate the load of nitrogen supplied from terrestrial sources into the Arctic Ocean by sampling in the Lena River and its Delta. We took water samples along one of the major deltaic channels in winter and summer in 2019 and sampling station in the central delta over a one-year cycle. Additionally, we investigate the potential release of reactive nitrogen, including nitrous oxide from soils in the Delta. We found that the Lena transported nitrogen as dissolved organic nitrogen to the coastal Arctic Ocean and that eroded soils are sources of reactive inorganic nitrogen such as ammonium and nitrate. The Lena and the Deltaic region apparently are considerable sources of nitrogen to nearshore coastal zone. The potential higher availability of inorganic nitrogen might be a source to enhance nitrous oxide emissions from terrestrial and aquatic sources to the atmosphere.
Townhill, B.L., Reppas-Chrysovitsinos, E., Sühring, R., Halsall, C.J., Mengo, E., Sanders, T., Dähnke, K., Crabeck, O., Jan Kaiser, J., & Silvana N. R. Birchenough, S.N.R. (2021): Pollution in the Arctic Ocean: An overview of multiple pressures and implications for ecosystem services. Ambio, doi:10.1007/s13280-021-01657-0
Abstract:
The Arctic is undergoing unprecedented change. Observations and models demonstrate significant perturbations to the physical and biological systems. Arctic species and ecosystems, particularly in the marine environment, are subject to a wide range of pressures from human activities, including exposure to a complex mixture of pollutants, climate change and fishing activity. These pressures affect the ecosystem services that the Arctic provides. Current international policies are attempting to support sustainable exploitation of Arctic resources with a view to balancing human wellbeing and environmental protection. However, assessments of the potential combined impacts of human activities are limited by data, particularly related to pollutants, a limited understanding of physical and biological processes, and single policies that are limited to ecosystem-level actions. This manuscript considers how, when combined, a suite of existing tools can be used to assess the impacts of pollutants in combination with other anthropogenic pressures on Arctic ecosystems, and on the services that these ecosystems provide. Recommendations are made for the advancement of targeted Arctic research to inform environmental practices and regulatory decisions.
Tuerena, R.E., Mahaffey, C., Henley, S.F., de la Vega, C., Norman, L., Brand, T., Sanders, T., Debyser, M., Dähnke, K., Braun, J., & März, C. (2021): Nutrient pathways and their susceptibility to past and future change in the Eurasian Arctic Ocean. Ambio, doi:10.1007/s13280-021-01673-0
Abstract:
Climate change is altering nutrient cycling within the Arctic Ocean, having knock-on effects to Arctic ecosystems. Primary production in the Arctic is principally nitrogen-limited, particularly in the western Pacific-dominated regions where denitrification exacerbates nitrogen loss. The nutrient status of the eastern Eurasian Arctic remains under debate. In the Barents Sea, primary production has increased by 88% since 1998. To support this rapid increase in productivity, either the standing stock of nutrients has been depleted, or the external nutrient supply has increased. Atlantic water inflow, enhanced mixing, benthic nitrogen cycling, and land–ocean interaction have the potential to alter the nutrient supply through addition, dilution or removal. Here we use new datasets from the Changing Arctic Ocean program alongside historical datasets to assess how nitrate and phosphate concentrations may be changing in response to these processes. We highlight how nutrient dynamics may continue to change, why this is important for regional and international policy-making and suggest relevant research priorities for the future.
Heath, M.R., Benkort, D., Brierley, A.S., Daewel, U., Laverick, J.H., Proud, R., & Speirs, D.C. (2021): Ecosystem approach to harvesting in the Arctic: Walking the tightrope between exploitation and conservation in the Barents Sea. Ambio, doi:10.1007/s13280-021-01616-9
Abstract:
Projecting the consequences of warming and sea-ice loss for Arctic marine food web and fisheries is challenging due to the intricate relationships between biology and ice. We used StrathE2EPolar, an end-to-end (microbes-to-megafauna) food web model incorporating ice-dependencies to simulate climate-fisheries interactions in the Barents Sea. The model was driven by output from the NEMO-MEDUSA earth system model, assuming RCP 8.5 atmospheric forcing. The Barents Sea was projected to be > 95% ice-free all year-round by the 2040s compared to > 50% in the 2010s, and approximately 2 °C warmer. Fisheries management reference points (FMSY and BMSY) for demersal fish (cod, haddock) were projected to increase by around 6%, indicating higher productivity. However, planktivorous fish (capelin, herring) reference points were projected to decrease by 15%, and upper trophic levels (birds, mammals) were strongly sensitive to planktivorous fish harvesting. The results indicate difficult trade-offs ahead, between harvesting and conservation of ecosystem structure and function.