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Biomes and Regions of Northern Eurasia

The Arctic Environments

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Fauna

Fauna of the Arctic Seas and islands is characterized by the domination of invertebrates among which benthos species (about 2000) are best represented (Gerasimov, 1970). They have adapted to severe conditions; some can tolerate temperatures as low as a few tens of degrees below zero. One significant adaptation is the shift of life cycles towards summer; many species winter in a larval or egg form. Vertebrates account only for 10 per cent of the entire species diversity. There are nearly 300 species of side-swimmers (Amphipoda), 200 species of bristle worms (Polychaeta), 200 species of bryozoans (Bryozoa), and such groups as gastropods (Gastropoda) and forams (Foraminifera) include over 100 species each. Nearly 300 species of zooplankton are known with Capepoda, Coelenterata, and Infusoria among them. There are practically no insects on the Arctic islands, but they are abundant on the mainland, and their quantity and number of species increases inland.

There are few fresh-water fish species in the Arctic because the entire depth of many lakes and rivers freeze in winter (Andriyashev and Chernova, 1994). Loach is found in some isolated fresh water bodies on Novaya Zemlya and Novosibirskie islands. Diadromous fishes, which spawn in fresh water but have sea water as their main habitat, include 11 species (Gerasimov, 1970). Sea fishes include 30 species (Andriyashev and Chernova, 1994) and among the most common species are cod (Gadus morhua), black halibut (Reinhardtius hippoglossoides), and haddock (Melanogrammus aegkfinus) which inhabit the southern part of the Barents. Eelpouds (Lycodes) are endemic to the central sector of the Arctic Ocean (Andriyashev and Chernova, 1994).

Many birds have their nesting grounds on the islands of the high Arctic migrating to the Arctic in summer and wintering in other regions. Their diversity reduces northwards in line with poor forage reserves. Compared to the mainland tundra, species numbers of nesting and passage birds is reduced by 70-80 per cent on Franz Josef Land and Severnaya Zemlya, and by 30-40 per cent on Novaya Zemlya and Novosibirskie islands (Uspenskiy, 1964). There are 17 species of nesting birds on Franz Josef Land, 15 species on Severnaya Zemlya, 46 species on Novaya Zemlya and Novosibirskie islands where, respectively, 80 and 70 species are known in all (Gerasimov, 1970). The most common species of the high Arctic are McKay's bunting, long-tailed jaeger, brent goose, barnacle goose, little auk, snowy owl, ivory gull, king eider, and thick-billed murre.

Among the sea mammals, Pinnipedia species are most common. There are nine species in the Arctic Seas. The largest representative is the Atlantic walrus (Odobenus rosmarus). Atlantic walrus and Greenland seal inhibit the Barents and the Kara Seas; the Chukchi Sea provides habitats for the Pacific variety of walrus and to ribbon seals. The most common species is the ringed seal which occurs far north in the Arctic Ocean. Only two whale species, narwhal and the white whale, winter in the Arctic waters; the others migrate into the Arctic Seas in summer. Thirteen species of terrestrial mammals are known in the islands of the high Arctic including seven of Carnivora, five of Rodentia species, and reindeer (Uspenskiy, 1964). Lemmings are very important to the Arctic food chain because they provide the principal forage reserves for predatory animals and large birds. Reindeer is found in the wild on Severnaya Zemlya, Novaya Zemlya, Novosibirskie islands and on the mainland it is common as a domestic animal. Polar bear and arctic fox are the native species of the high Arctic; other predators, such as wolf, fox, and glutton, migrate from tundra to the Arctic islands in spring via landfast ice and return to the mainland in autumn. Commercial hunting of the polar bear was prohibited in 1956 and at the beginning of the 1990s their population was estimated as 4200-5700 animals in the Spitzbergen — Novaya Zemlya region, 800-1200 in the Laptev sector and 2000-5000 in the Chukchi Sea-Alaska regions (Belikov, 1993). The distribution of the polar bear follows the distribution of seal which in turn depends on the sea ice regime, hi summer, polar bears are found mainly along the southern border of the pack ice. However, they are often trapped on the mainland or on the islands where they migrate in winter.

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