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

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

ecological transition zones within and between terrestrial, freshwater and oceanic ecosystems. Freshwater ecosystems are undergoing rapid change in response to both environmental and anthropogenic drivers. Freshwater is found throughout the Barents area, covering about 5.5% of the area in total and reflecting the entire climatic gradient, with July temperatures ranging from4°C to 15°C and precipitation of less than 200mm (i.e. well within the definition of polar desert) to over 1700 mm along parts of the Norwegian coast. Coastal freshwater fish communities in Norway are dominated by salmon ( Salmo salar ), and by trout and char (both members of the genus Salvelinus ),all of which are cold-water species.High latitude lakes generally have low fish abundance and diversity. According to Sierszen et al. (2003), Arctic lakes typically have low productivity, supporting small fish populations with slow growth rates, such as Arctic char ( Salvelinus alpinus ), lake trout ( S . namaycush ), and lake whitefish ( Coregonus clupeaformis ), although biomass may be high (Power et al., 2008). Planktonic and benthic communities inArctic lakesmay be very productive (Vincent and Laybourn-Parry, 2008), although this decreases with increasing latitude.The number of species present ranges from 20 to 150 per lake, correlating with latitude, altitude, or water temperature, whereas species composition mainly follows water chemistry (Moore, 1979; Forsström et al., 2009). According to O’Brien et al. (2004), zooplankton density and biomass can be considerable,mainly limited by food availability and fish predation. Inland waters show great variety in physical and chemical properties. They include glacier-fed rivers, snow-melt streams, cold oligotrophic lakes, and shallow temporary or permanent ponds. Running freshwaters receive large amounts of glacial meltwater, producing large braided river systems with high sediment loads and fluctuating flow (even no flow after the main snow-melt period) with low temperatures, also in summer. In coastal, glacier-free areas, the streams are snowmelt- and spring-fed and for these as well as for lake outflows (Füreder and Brittain, 2006), conditions can be more favorable for plants and animals, although many snowmelt streams dry up in summer. Temporary thaw ponds, permanent shallow ponds and small lakes are numerous and owing to their shallow depth (usually <2 m) or small catchments, will freeze to the bottom in winter and dry out in summer; both conditions limit permanent residence by biota. Abundant representatives of freshwater invertebrates are springtails (Collembola) and crane flies (Chironomidae) (CAFF, 2013). The Pechora River is the largest river by volume in the Barents area, with a length of 1809 km and a drainage basin about the size of Finland. This mighty river flows north into the Arctic Ocean on the west side of the Ural Mountains. It lies mostly within the Komi Republic but the northernmost section crosses the Nenets Autonomous Okrug. The Pechora River has the second largest catchment area in the Barents area,exceeded only by the Northern Dvina River. The latter has a drainage basin that includes major parts of the Vologda and the Arkhangelsk Oblasts,as well as areas in the western part of the Komi Republic and the northern part of the Kirov Oblast, and small areas in the north of Yaroslavl and Kostroma Oblasts.

Wetlands Wetlands occur throughout the Barents area (Figure 2.3) and are an important contributor to the mosaic nature of the landscape. Open wetlands cover 14% of the area, although this percentage increases if tree-covered wetlands are also included. In this context,wetlands are as defined by the NationalWetlands Working Group (1988), as the area in the transition between land, in the conventional sense, and open water. Ecosystems are dominated by the constant presence of excess water. They are also characterized by a water table near the ground surface and so have poorly aerated soil requiring the dominant plants and other organisms to be adapted to wet and anoxic conditions. Wetlands comprise a mixture of habitats, shaped by past and present management in combination with the physical and biological conditions of each site. Peatlands are a dominant wetland type within the Barents area; here defined as areas where the peat is at least 30 cm deep and often up to 40 cm deep (Joosten and Clarke, 2002). Plants, bacteria, and more than 500 species of fungi, liverwort, lichen and algae occur in peatlands. The most important groups, represented by several hundred species are the green algae (including desmids) and diatoms (for reviews see Hingley, 1993; Gilbert and Mitchell, 2006). Factors such as water chemistry, continuously open water and gradients of calcium and sediment iron-content are important for determining species groups and overall diversity (Rydin and Jeglum, 2013). Peat mosses dominate low-pH peatlands but as pH and nutrient levels increase, peat mosses are replaced by another ecological group, brown mosses. Vascular plants such as graminoids, herbs, shrubs and trees are also present in wetland areas. Ecotone transitions are the most species-rich (see Box 2.1),such as occur between rich fen and calcareous meadow, and between swamp and upland forest.Mowing and cattle grazing are likely to increase diversity by holding back the tallest plants and possibly creating small patches of barren soil that provide habitat for less competitive species.Where species occur depends on their needs for water depth, with a gradient from species growing in waterlogged soil (e.g. Myriophyllum ) to those partly or fully submerged in water (e.g. Potamogeton , Nymphaea ). In dryer areas, such as wooded bogs and hummocky parts of open bogs, evergreen dwarf shrubs ( Erica , Calluna , Empetrum , Vaccinium ) are common. Peatland fauna covers a wide range of species from peatland specialists to generalists, such as mollusks (Mollusca), tardigrades (Tardigrada), annelids (Annelida), nematodes (Nematoda), flatworms (Platyhelminthes), and rotifers (Rotifera). Amphibians, such as frogs, toads (both Anura ), and salamanders (Salamandridae), often depend on wet habitats but generally prefer wetlands other than peatlands. For large parts of the Barents area the climatic conditions are not suitable for amphibians; and summer is too short for most amphibian offspring to reach adulthood. Wetlands are crucial for many types of bird, and species richness increases northward in open boreal mires probably due to the high productivity of insects (Järvinen andVäisänen, 1978) combined with long days for foraging during summer. Moving north, peatlands also become bigger offering a mosaic of habitats over large areas, which results in increased species diversity. High numbers of waders and passerine birds attract