The Arctic Mediterranean is the area north of the ridge between Scotland and Greenland and includes the Nordic Seas and the Arctic Ocean. Three species of Calanus are dominant herbivorous copepods in this sea area. Calanus finmarchicus and Calanus hyperboreus are basin species with core areas in the Norwegian Sea and Greenland Sea respectively. Calanus glacialis is a shelf species found on the surrounding Arctic shelves. The three species differ in size and life history features. Calanus finmarchicus is the smallest (weighs about 0.25 mg dry weight as CVs and adults) and Calanus hyperboreus the largest (around 4 mg) with Calanus glacialis being intermediate in size (about 1 mg). All three species accumulate high lipid content which they use as fuel for a long period of overwintering at high latitudes. Calanus finmarchicus has a predominant annual life cycle and has about the minimum size for this type of life history with passive (non-feeding) overwintering. The larger size of Calanus hyperboreus and Calanus glacialis offers them greater flexibility and the possibility to have multi-annual life cycles under variable and unpredictable Arctic conditions. All three species grow and develop, nourished by phytoplankton production during the short summer season at high latitudes. Calanus finmarchicus and Calanus glacialis have their main spawning activity during the spring bloom whereas Calanus hyperboreus can spawn in winter based on internal lipid reserves. The three Calanus species provide important linkages to higher trophic levels, in part mediated through planktivorous fish. There is evidence of a complex pattern of climate-driven bottom-up and predation-driven top-down effects on the mesozooplankton biomass in the Barents and Norwegian seas.
Hein Rune Skjoldal has been working at the Institute of Marine Research since 1981, where he also has held the position as Research director and head of Department of Marine Environment. He has also held positions at the University of Bergen, latest as Associate professor at Institute of Fisheries and Marine Biology. He has participated in several national committees and expert groups, such as: Chairman of advisory committee on marine protected areas, Chairman of expert group on marine eutrophication (1995-99), Member and chairman of the steering committee for the Norwegian Research Program on North Norwegian Coastal Ecology (MARE NOR) (1992-96, chairman 1994-96), Member of the steering committee for the Norwegian Research Program on Marine Pollution (1991-96). Skjoldal has also been participating in a number of international committees and expert groups, such as: Member of Steering Group, Bergen Conference on Implementation of the Ecosystem Approach to Fisheries, Bergen, 26-28 September 2006, Regional Vice-Chair for Western Europe of the IUCN Commission on Ecosystem Management (2005- ), Co-Chair of ICES/EuroGOOS Planning Group on the North Sea Pilot Project NORSEPP (2004-present), Member of the Scientific Committee for the FAO Reykjavik Conference on Responsible Fisheries in the Marine Ecosystem (2001), Chairman of ICES Advisory Committee on Ecosystems (ACE) (2001-2003), Chairman of ICES Advisory Committee on Marine Environment (ACME) (2000), Co-chair for Workshop on Ecological Quality Objectives for the North Sea (OSPAR/NSC/ICES), 1-3 September 1999. Skjoldal has published more than 40 scientific papers, of which more than 30 in refereed journals. In addition he is the author of a number of printed reports and manuscripts.