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Ecoregion Description


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Species Richness


# of Endemic Species


Threats

610: Anadyr

Major Habitat Type:

polar freshwaters

Author:

Nina Bogutskaya

Countries:

Russia

Boundaries:

The ecoregion encompasses the drainage areas of Anadyr’ River and adjacent rivers of Anadyrskiy Liman Bay. It also includes Lake Elgygytgyn.

The border with the East Chukotka [611] ecoregion (Chukotka Peninsula) stretches between the Kanchalan River drainage and rivers of Kresta Bay and the northern coast of Anadyrskiy Bay. Further south, the border follows the ranges of the Chukotskiy [Anadyrskiy] Khrebet, which divides the Amguema drainage (in ecoregion 611) and headwaters of the Belaya and Tnyurer rivers (Anadyr’ tributaries). The eastern spurs of the Severnyy Anyu’skiy, Yuzhnyy Anuy’skiy, and Oloyskiy ranges form the border of the ecoregion with the Kolyma [609] ecoregion. The southwestern border follows the southern slopes of the Anadyrskoye Ploskogor’e Upland and northern slopes of the Koryakskiy Range, which divides the Anadyr’ and Bol’shaya drainages with rivers of the Koryakia [612] ecoregion.

Drainages flowing into:

Bering Sea (northern Pacific Ocean)

Main rivers or other water bodies:

The main water bodies include the Anadyr’ River, Belaya River, Mayn River, Lake Krasnoye, Lake Maynets, Bol’shaya River, Kanchalan River, Lake Elgygytgyn, and Enmyvaam River.

The Anadyr’ River basin includes all of the rivers flowing into the Anadyr’ Liman (Anadyr’ River estuary). The Anadyr’ River is the largest in the ecoregion and the largest drainage in the northeastern part of the Far East. Its length is about 1170 km, and the catchment area is almost 200 000 km2. The river starts on the Anadyrskoye Plateau and passes through two different geomorphological regions. As a result the river has a mountainous section, from its source down to Markovskaya Hollow (560 km), and a valley section down to the mouth (610 km). The largest tributaries of the mountainous part are Mechkireva, Bol’shaya Peledon, Yablon, and Yeropol. In Markovskaya Hollow the riverbed divides into multiple anabranches, forming a ramified lake-river network. The width of the floodplain in that area is up to 70 km.

The largest tributary of the Middle Anadyr’ is the Main River from the south. The Main River meanders through the lowland plain of the Anadyr Depression. Other large tributaries include: Tanyurer, Kanchalan, Krasnina, Bol’shaya and Volch’ya. Some of these originate in the mountains (Tanyurer, Bolshaya, and Volch’ya), but spread out into a wide valley and split into branches in their middle reaches.

The Lower Anadyr’ River valley is wide, attaining a width of 3-4 km. The river eventually flows into the Anadyr’ Liman, which extends for about 60 miles east to west, its maximum width being approximately 25 miles. The Bol’shaya (also known as Velikaya or Onemen) River flows into the relatively large, but shallow Onemen Bay. The Kanchalan, Tavaima, and Volch’ya rivers flow into Nerpichiy Bay.

Lake Elgygytgyn is located in the northern part of the Andyrskoye Plateau in the Upper Anadyr’ River. It occupies a hollow of a regular round shape 23 km in diameter. The lake itself is about 11 km in diameter. The cup of the lake can be subdivided into a coastal shallow zone 0.5-1.5 km wide and up to 10 m deep, zone of slope about 30 degrees steep up to a depth of 100 m, and a central flat part with a diameter of about 10 km. The maximum depth is 175 m. There are no large affluents into the lake; only the Enmyvaam River flows out of the lake.

Climate:

Lake Elgygytgyn is the only place in the terrestrial Arctic with a continuous 3.6 million year climate record. A record such as this is important to fully understand the Arctic’s role in global climate dynamics. Of primary interest is determining why and how the Arctic evolved from a warm forested ecosystem into a cold permafrost ecosystem between 2 and 3 million years ago. The lake’s continuous depositional record provides a way of determining how the Arctic climate evolved and adjusted from Milankovitch-driven glacial/interglacial cycles every 41ka, and later every 100ka. The present understanding of this lake system helps scientists interpret higher resolution climate change events across eastern Siberia on centennial to millennial scales, and test for atmospheric connections with climate records worldwide. 

Freshwater habitats:

The Anadyr’ River headwaters are steep, fast-running mountain streams. Middle and lower parts of the Anadyr’ River have former floodplain riverbeds. Thermocarst, glacial, and tectonic lakes are also numerous, with bog areas around the lake shores of thermocarst and glacial lakes. The Lower Anadyr’ River is impacted by tidal currents.

Rivers of the Anadyr’ drainage are characterized by spring floods (June) and by rain floods in August and September. Water temperature is low, reaching 13-14 °C only in July and August in the middle and lower reaches. By early October temperatures are at their minimum values, when ice cover is established. Ice thickness may be 140 cm, lasting 220-250 days. The average annual air temperature over the ecoregion is negative.

Lake Elgygytgyn is frozen 9.5-10 months a year, and sometimes the ice does not thaw at all. The thickness of ice reaches 2 m. The water temperature in summer at the shoreline does not exceed 6-7 °C. In June, under the ice the water temperature is 2.0-2.2 °C at a depth of 100-155 m. Water transparency is high and reaches 40 m, and mineralization is extremely low. Summer temperature stratification does not occur because of long winter cooling and permanent mixing of the water by strong winds. The climatic conditions are severe and are comparable to the conditions of Lake Hasen (Canada), the northernmost known water body inhabited by fish.

Terrestrial Habitats:

The ecoregion is comprised primarily of two terrestrial ecoregions: Chukchi Peninsula tundra along the northern border and Bering tundra throughout most of the ecoregion. The Kanchalan, Belaya, Tanyurer, Lower Anadyr’ and Velikaya rivers lie in the tundra zone with many of lakes and sphagnous marshes. The Middle Anadyr’ and Main rivers lie within the forest-tundra subzone, where arboreal vegetation is associated mainly with river valleys. The Upper Anadyr’ River falls within the northern taiga subzone, characterized by sparse deciduous forests and meadows in river floodplains.

Fish Fauna:

The fish fauna includes over 30 species from nearly 10 families. Primary freshwater fishes are only represented by a handful of species, including Eurasian minnow (Phoxinus phoxinus), lake minnow (Ph. Percnurus), northern pike (Esox lucius), round whitefish (Prosopium cylindraceum), and Thymallus mertensii. Other species are euryhaline with a clear predominance of migrating forms. Twelve species of the Siberian-Kolyma fauna are absent from this ecoregion, whereas the number of euryhaline semi-migrating and true anadromous forms are numerous (Pacific trouts, Petromyzontidae, Osmeridae, Gasterosteus, and Cottus cognatus). The most numerous species are salmoniformes represented by six genera. A remarkable feature is the species diversity of the genera Coregonus and Salvelinus, represented by eight species.

The Anadyr’ ecoregion fauna has high diversity for Northeast Asia. The distribution ranges of many Northeast Asia endemics extend here (e.g. common whitefish, Coregonus anaulorum, and Thymallus mertensii). There is one near-endemic form, Salvelinus cf. boganidae, if considered distinct from S. boganidae from Taymyr. Compared to the nearby large river drainages (Kolyma ecoregion [609]), Anadyr’ does not have 14 freshwater fishes. The ecoregion most resembles Penzhina (Koryakia ecoregion [612]) with common freshwater fishes such as Thymallus mertensii, round whitefish (Prosopium cylindraceum), northern pike (Esox lucius), and two species of Phoxinus; and common euryhaline fishes such as Far Eastern brook lamprey (Lethenteron reissneri), Hypomesus olidus, arctic rainbow smelt (Osmerus mordax dentix), capelin (Mallotus villosus), broad whitefish (Coregonus nasus), five species of Oncorhynchus, burbot (Lota lota), ninespine stickleback (Pungitius pungitius), and three-spined stickleback (Gasterosteus aculeatus). However, Anadyr’ is not inhabited by Coregonus subautumnalis, whitespotted char (Salvelinus leucomaenis), and Salvlinus levanidovi.

Lake Elgygytgyn contains only three species, all permanent inhabitants: Boganida char (Salvelinus boganidae), small-mouth char (Salvelinus elgyticus, a local endemic species distributed only in this lake), and long-finned char (Salvethymus svetovidovi, an endemic genus and species also only distributed in this lake). This relatively small lake is characterized by 50% endemism on the generic level and 66% endemism on the species level. Several more species rarely enter the lake from the Enmyvaam River (Thymallus mertensii, Oncorhynchus keta, Prosopium cylindraceum, and Coregonus anaulorum), but they do not actually occur in the lake.

Description of endemic fishes:

Long-finned char (Salvethymus svetovidovi) is an endemic genus and species. Hhowever, its generic status is doubtful; in terms of phylogenetic methodology it may fall within the genus Salvelinus. As a locally distributed endemic taxon it was included in the Red Data Book of the Russian Federation (2001). The fish is a highly specialized non-migratory deepwater bottom dweller that inhabits Lake Elgygytgyn’s slope at a permanently low temperature. It is most abundant at depths between 50-100 m, and feeds only on zooplankton. It is a source of food for Boganida char (Salvelinus cf. boganidae). There is an opinion that Salvethymus svetovidovi is one of the most ancient representatives of salmonid fishes, phylogenetically close to a hypothesized ancestral form of chars of the genus Salvelinus.

Small-mouth char (Salvelinus elgyticus) is also endemic to Lake Elgygytgyn. It feeds on zooplankton similar to long-finned char, and also prefers deep water (up to 100 m). However, it displays some migrations, and approaches the shores on still nights. It is included in the Red Data Book of the Russian Federation (2001). The species is considered to be the most specialized species in the genus Salvelinus.

Other noteworthy fishes:

Common whitefish (Coregonus anaulorum) is a near-endemic species in the Anadyr’ River drainage, rivers of the Anadyr’ Liman, and rivers of the Sea of Okhotsk coast of Koryakia. It is a relict of the common Anadyr-Penzhina river system, which had flowed during the pre-Pleistocene into the Sea of Okhotsk.

Boganida char (Coregonus boganidae, an undescribed Coregonus cf. boganidae) is found in lakes Elgygytgyn, Baran’e, and Pennoye (in the upper reaches of the Belaya and Tanyurer rivers), where it appeared relatively recently. In Lake Elgygytgyn it eats planktivorous long-finned and small-mouth chars. This fish has experienced heavy declines due to overfishing.

Other noteworthy aquatic biotic elements:

Freshwater Mollusca fauna is also diverse and abundant in the ecoregion. The ecoregion contains 23 species, including seven American species (two in the genus Beringiana) (Starobogatov 1986; Bogatov & Zatravkin 1990).

Ecological phenomena:

Anadyr’ fishes demonstrate high ecological plasticity and adaptability to low water temperatures, prolonged ice cover, and a relatively weak food supply. Characteristic phenomena include distant upstream migrations of anadromous salmonid fishes such as chum salmnon (Oncorhynchus keta) and dolly varden (Salvelinus malma), and also coregonid fishes such as sardine cisco (Coregonus sardinella), common whitefish (C. anaulorum), and humpback whitefish (C. pidschian). These are determined by the history of the drainage, namely by the transgressions of the sea that flooded the lower parts of the drainage for long distances during the Pleistocene.

Lake Elgygytgyn represents a rare example of an endemic simple fish assemblage consisting of two planktivorous species and one predator. According to data from 1994 (Chereshnev 1996), the lake was inhabited by 12,000 individuals (with a total weight of 17.35 metric tons) of the predator, and 60,000 individuals (with a total weight of 8.95 metric tons) of the zooplankton-eaters. Relative to the area of the lake (113.4 km2), the biomass of the fishes equals 2.33 g per m2 (Chereshnev 1996), corresponding to alpha-oligotrophic water bodies (Kitaev 1984).

Evolutionary phenomena:

The Anadyr’ River drainage was the largest refugium of freshwater fauna in northeastern Asia during crucial periods of Quaternary glaciations and transgressions of the sea. This is reflected in its richness and diversity. The ecoregion played an exceptionally important role as a refuge of relict fauna and morphoecological divergence.

The origin of Lake Elgygytgyn’s hollow is associated with an impact event, the nature of which (the fall of a meteorite or explosions of endogenic fluid) is not definitively established. The latest data confirms the presence of a meteorite substance in samples of heavy minerals taken from the Elgygytgyn Crater. Modeled parameters for the Elgygytgyn crater-forming impact: bolide of diameter 1.57 km, density 2900 kg/m3, velocity 25 km/s, volume 1.34 km3, energy 1.25 x 1021 J. The event occured 3-4 (3.6) million years ago.

The three endemic chars of the lake represent an area of scientific interest for studying a unique relict gene pool, phylogeny and speciation in salmonids, as well as the formation and existence of an ancient trinomial fish assemblage.

Justification for delineation:

The ecoregion encompasses the drainage areas of the Anadyr’ River and adjacent rivers of Anadyrskiy Liman Bay. This ecoregion represents a unique example of coldwater Palearctic fauna that is relatively rich in species. Belonging to the Pacific basin, the Anadyr’ system contains some affinities with the Kolyma River from the Arctic. Both river drainages had temporary connections in their upper reaches, and the Anadyr-Penzhina ancient system served as a route for some representatives of Siberian fish fauna down to Kamchatka.

Lake Elgygytgyn is a unique natural phenomenon. The lake was created during the Pliocene, about 3-4 million years ago. Since then, the lake has formed an exclusive ecosystem where plant and animal communities adapted to severe conditions of the Arctic Plateau (the name of the lake is translated as “lake where ice does not melt”). Geographically, the lake belongs to the Anadyr’ ecoregion, but it deserves evaluation as a distinct ecoregion since its fauna is different, and is characterized by 50% endemism on the generic level and 66% endemism on the species level. The lake may serve as a model for studying fish communities in extreme arctic conditions.

Level of taxonomic exploration:

Good. Besides some earlier studies (e.g. Kaganowskiy (1927-1928) provided an excellent collection of Anadyr’ fishes), there have been regular studies, observations, and expeditions conducted by the Magadan Branch and Okhotsk Branch of the Pacific Institute of Fisheries and Oceanology, and the Institute of Biological Problems of the North of the Academy of Sciences. A summarizing monograph was published (Chereshnev et al. 2001).

References/sources:

Chereshnev, I. A. (1996)"Cyclostomata and fishes" In Chereshnev, I.A. (Ed.). Vertebrates of the North-East of Russia. (pp. 21-61) Vladivostok: Dal'nauka.

Chereshnev, I. A. (1990). "Composition of fish fauna and distribution of freshwater fishes of the North-East of Russia" Vopr. Ichthyol 30(5) 836-844.

Chereshnev, I. A. (1996). "Biological diversity of freshwater fish fauna of the North-East of Russia" Vladivostok: Dal'nauka.

Chereshnev, I. A. (1992). "Rare, endemic and threatened freshwater fishes of the north-east of Asia" Vopr. Ichthyol 32(4) 18-29.

Chereshnev, I. A. (1998). "Biogeography of freshwater fishes of the Far East in Russia" Vladivostok: Dal'nauka.

Chereshnev, I. A., Shestakov, A. V., et al. (2001). "Guide to freshwater fishes of the North-East of Russia" Vladivostok: Dal’nauka.

Chereshnev, I. A., Shestakov, A. V., et al. (2001). "Freshwater fishes of Anadyr' Basin" Vladivostok: Dal'nauka.

Chereshnev, I. A., Volobuyev, V. V., et al. (2002). "Salmoniform fishes of the North-East of Russia"

Chereshnev, I. A.,Glubokovskiy, M. K. (Ed.) (1991). "Biology of chars of the Far East" Vladivostok: DVO RAN.

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