Adaptation Actions for a Changing Arctic: Perspectives from the Barents Area

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Chapter 2 · Status of the natural and human environments

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Figure 2.9. Distribution of Atlantic cod in 2004 and 2013 recorded in autumn during the joint IMR-PINRO ecosystem survey (Prozorkevich and Gjøsæter, 2013).

pelagic fish (e.g. sand-eel Ammodytes spp., capelin, herring and polar cod) and cephalopods (Fauchald et al., 2011). More than 50% of the Barents Sea is usually ice-covered in winter. Thus, most species breeding in the region are to some extent migratory. Although many populations leave the region during autumn and winter, they are replaced by other populations from breeding areas further to the east, to winter in the Barents Sea. Areas off Iceland, south-west Greenland and Newfoundland are important wintering areas for seabirds breeding in the region (Strøm et al., 2009; Fauchald et al., 2011). The composition of seabird communities in the Barents Sea reflects the environmental gradient from the warm Atlantic water masses in the south to the cold ice-filled Arctic water masses in the North.Atlantic puffins ( Fratercula arctica ), black- legged kittiwakes ( Rissa tridactyla ) and common guillemots ( Uria aalge ) dominate the seabird communities south of the Polar Front while more-Arctic species such as Brünnich’s guillemot ( U. lomvia ), little auk ( Alle alle ) and northern fulmar ( Fulmarus glacialis ) dominate in the north (Strøm et al., 2009). The diet of breeding seabirds also reflects the environmental gradient fromAtlantic to Arctic water masses.The colonies of Atlantic puffin and common guillemot in the south feed on cod, haddock and herring larvae drifting from the spawning areas along the Norwegian coast and in to the Barents Sea. Pelagic fish such as young herring, sand-eel and capelin are important prey items in the southern colonies (Fauchald et al., 2011).North of the Polar Front, the colonies of little auk, fulmar and Brünnich’s guillemot are closely linked to the marginal ice zone where they prey on polar cod and the energy-rich Arctic crustaceans (Mehlum et al., 1998). The population status and trends for several species breeding in the western Barents Sea (i.e. Norwegian mainland and Svalbard) was recently assessed from monitoring and census data (Fauchald et al., 2015).This showed subarctic pelagic auk species (common guillemot, razorbill Alca torda and Atlantic

In coastal areas of Svalbard, recent warming with less sea ice has been associated with a two-fold increase in the number of species found intertidally on rocky shores, and a three-fold increase in macrophyte biomass. Subarctic boreal species occupied new areas, while Arctic species retreated (Weslawski et al., 2010). In Svalbard fjords, rapid and extensive structural changes in rocky-bottom communities have occurred along with an abrupt increase in macroalgal cover (Kortsch et al., 2012). Simultaneous changes in the abundance of benthic invertebrates suggest that macroalgae play a key role in structuring these communities. Previous studies in the Barents Sea have shown that trawling activities are causing a reduction in the total biomass of benthic fauna,which can be as high as 70% (Denisenko,2001;Wassmann et al., 2006a) and that the actual reductions are correlated with trawling intensity (Lyubin et al.,2011).Other factors influencing benthic community change include two introduced top- predator species, king crab ( Paralithodes camschaticus ) and snow crab ( Chionoecetes opilio ), both of which feed on benthos (Jørgensen and Primicerio, 2007; Agnalt et al., 2011) (for more details see Section 2.2.3). 2.2.2.4 Seabirds TheBarents Sea regionsupports someof the largest concentrations of seabirds in the world (Anker-Nilssen et al., 2000). About 20–25 million seabirds harvest approximately 1.2 million tons of prey biomass annually from the area (Barrett et al., 2002). A total of 33 seabird species breed regularly in the region and belong to five different systematic groups including Gaviiformes (divers),Procellariiformes (petrels and fulmars),Pelicaniformes (cormorants and gannets), Anseriformes (seaducks), and Charadriiformes (shorebirds, skuas, gulls, terns and alcids) (Strøm et al., 2009). Food preferences in the Barents Sea include meso-zooplankton (e.g. Calanus spp.), large crustaceans (e.g. krill and amphipods), juvenile fish (e.g. cod and herring), small