There is a certain disjunction in range of different hydrobionts between Europe and Asia, for example, Cyprinus carpio L. For macroseaweeds a significant gap in range is registered for Aegagropila linnaei Kutz [10]. Later in their article С. Boedeker и B.F. Sviridenko [9] point out a kind for North of Caucasus (lake Schuchie at the level of 388m above the sea) that partially fills the range gap. According to C. Boedeker and co-authors [10, p. 9] “the disjunct distribution between Japan and Europe could be the result of extinction on the Asian continent east of the Urals... The Siberian landmass was never glaciated during the Weichselian (Wurm) glaciations due to its dry continental climate... Accordingly, Siberia was lacking widespread refugial habitats for A. linnaei, possibly leading to extinction in this area, in contrast to glaciated Europe which had abundant refugia in the south and west of the ice sheet and in the form of extensive ice-dammed lakes [12; 14]”.
Separate publications that refer to history of relief formation and setting of downfall accumulation in beds of Siberian, study conditions of emergence for a cascade of enormous ice cap lakes with discharge along water-dividing spillways from Yakutiya (bed of river Lena) to the West into water area of Black sea and further to Atlantic during all periods of glaciation in the second half of Neo-Pleistocene [2]. According to Groswald and Kotlyakov [1], total area of these Siberian water bodies could reach up to 3 million km2. At the territory of over-Baikal a vast over-Baikal ice cap water body was formed during the period of maximum Samarovskoye glaciation in result of iceberg borrage in origin of river Angara when the floating ice cap occupied a significant part of Baikal water area [7]. This ice cap water body emerged 150 thousand years earlier than ice cap water water bodies of Europe. In its maximum level of 1020 m (stabilized – 880–900 m) lake water area far exceeded the boundaries of Eastern over-Baikal area to the South and East. The dump from this water body took its way in direction of the Pacific. In periods of paleolake level drop below the mark of 1000 m it was divided into two water storages – Selengiskaya [5; 6] and Nerchinskaya Dauriya [3; 8]. The former refers to Baikal range of dump, the latter – to water area of Amur river system. Dump of over-Baikal paleolake waters to the East provoked introduction of Amur river system into the area of closed lake basins of over-Baikal and Northern territories of Mongolia and China. During the further glaciations (Tazovskoye, Muruktinskoye, Sartanskoye) ice cap water bodies of regional significance were formed only in the North of over-Baikal territory (paleolakes Vitimskoye, Olekminskoye, Charskoye) [3].
The greatest interest in terms of studying biogeography of А. linnaei is drawn for by modern water bodies deeper than 10 m, located in height range of 900–1020 m. To such water bodies we can refer lakes Arey and Arakhley, located in saddles of continental water division. In our opinion, they are what remains of a vast over-Baikal ice cap water body (picture) that existed in the age of maximum Samarovskoye glaciation (picture 1) when a vast glacier surface emerged at the territory of by-Baikal and over-Baikal territory [3; 11]. Nowadays the lakes are described by the following parameters: lake Arey has the area of 4,6 km2, depth of 13,5 m and mirror level of 996,2 m, it is adjunct to the wide saddle of water division that divides Enisey and Amur districts of dump between Yablonoviy and Malkhanskiy ridge. Lake Arakhley has the area of 58,5 km2, its maximum depth equals 19,5 m, it is the largest lake in Ivano-Arakhley system of Lena-Enisey water division. During high water periods the lake gives origin to brook Kholoy that runs down to lake Shashkinskoye.
In lakes Arakhley and Arey we discovered Cladophora aegagropila (L.) Rabenh [4; 13] that is synonymous to A. linnaei. It is known that is widely spread in lakes and rivers of moderate latitudes of Northern hemisphere. Aquarium analysis revealed that optimal parameters are pH 6–7, temperature 18–20 °С. Under water temperature above 22 °С A. linnaei begins to grow rapidly and in 2–3 months dissolves into separate parts that give birth to a new green ball in certain time.
Discovering A. linnaei in lakes Arakhley and Arey allows us not only to partially fill in disjunction in the range, but also determine ways of introducing the kind into the territory of Europe, Kazakhstan, and Japan. Formation of ice cap water bodies in Europe and Asia, differences in dump direction from over-Baikal ice cap water body requires additional research that will allow us to define place of A. linnaei emergence, period and ways of its settlement throughout the territories of Palearctic.
Thank you. The work was carried out within the limits of Federal scientific research project IX.137.1.1.