The influence of climate variability and change on the ecosystems of the Barents Sea and adjacent waters: Review and synthesis of recent studies from the NESSAS Project

The Norwegian Component of the Ecosystem Studies of Sub-Arctic Seas (NESSAS) was funded by the Research Council of Norway from 2005 to 2008. Its aim was to quantify the impact of climate variability on the structure and function of the marine ecosystem of the Barents Sea and adjacent waters in order to predict the ecosystem responses to possible future climate change and their possible economic impact. This paper reviews research highlights dealing with climate forcing and its influence. New insights were provided on the role of large-scale atmospheric forcing on the physical oceanography including the effect of Arctic and Atlantic cyclones on the variability of the ice extent in the Barents Sea and the non-linear response of the sub-polar gyre to North Atlantic Oscillation (NAO) forcing. In addition, the NAO was also shown to influence the biology, for example shrimp recruitment in the Barents Sea and primary production in the Nordic Seas, with the strength and sign of the correlations being spatially dependent. The importance of longer term climate variability in the form of the Atlantic Multidecadal Oscillation (60-80 years period) was stressed, as it leads to significant changes in fish production, shifts in distribution and changes in spawning sites in the Barents Sea as well as other northern Atlantic ecosystems. Results from comparative studies between several US ecosystems and those of the Norwegian and Barents Seas are presented, including evidence of increased primary productivity in the Barents Sea in recent years and the poleward movement of zooplankton and fish. In addition recruitment patterns of major demersal and pelagic species in the Barents Sea generally show synchrony with those in the Gulf of Maine indicating a common external forcing. Possible ecosystem scenarios for the Barents Sea under anthropogenic-induced future climate change were developed including expectations of structural and functional changes due to distributional changes of many species. Of particular note is the likelihood of increases in the productivity of several fish species, including cod and herring, which potentially could result in higher fisheries yields. (c) 2011 Elsevier Ltd. All rights reserved.