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LADOGA LAKE AND ONEGO LAKE (LAKES LADOZHSKOYE AND ONEZHSKOYE) Nikolai Filatov1, Leonid Rukhovets2 1 Northern Water Problems Institute, Karelian Research Center, Russian Academy of Sciences, Petrozavodsk, Karelia, Russia 2 Saint-Petersburg Institute for Economics and Mathematics, Russian Academy of Sciences, St.Petersburg, Russia

Introduction Lake Ladozhskoye and Lake Onezhskoye (Ladoga and Onego, respectively; Onego on the contrary river Onega in Archangelsk Region) are the greatest lakes in Europe. Ancient names of Lake Ladoga are Nevo, Al’desk, Al’da, Al’dagas, Al’doga, Al’dagen, Aldea, and Veniemmeri. In ancient times, Lake Onego was called Anizskoye from Finnish name Ääninen järvi, ääni means voice or sound. These European lakes were called the Great because their dimensions are larger than of any other lakes in Europe (Gusakov and Petrova, 1987; Rukhovets and Filatov, 2010). Lakes Ladoga and Onego located between 58
540 –61
470 N and 60
550 –62
550 N, respectively, are of the northernmost lakes among the world Great lakes. These lakes with river system represent the unified lake system. Lake Onego is connected with Lake Ladoga via River Svir, Lake Saimaa via River Vuoksi (Burnaya), and Lake Il’men via River Volkhov (Figure 1). Lake system is linked with Gulf of Finland in the Baltic Sea via River Neva. The surface area of Lake Ladoga is 17,891 km2, average depth is 51 m with a maximum of 230 m, and volume 908 km3; it ranks among the top 15 world’s freshwater lakes (Chernjaeva, 1966) (Another dimensions published by (Naumenko 2001)). Lake Onego surface area is 9,600 km2, average depth is 30 m with a maximum

of 120 m, and volume 292 km3. The watershed of Great European Lakes is 258,500 km2 which extends through North-western European Russia (80%), the eastern part of Finland (19.9%), and Byelorussia (0.1%). The watershed includes the large lakes Il’men and Saimaa. Lakes Ladoga and Onego are an important link in the Caspian-Baltic-White Sea waterway system. Ladoga and Onego are also a key section in the drainage basin of the Baltic Sea. The catchment is made up of four secondary watersheds: Ladoga (28,400 km2); Onego-Svir (83,200 km2); Saimaa-Vuoksi (66,700 km2); and Il’menVolkhov (80,200 km2) watersheds (Rumyantsev and Drabkova, 2002). The system of Great European Lakes was generated between contrasting crystalline Fennoscandian (Baltic) shield and Russian plates composed with Paleozoic rocks. In the area of crystalline shields, the ancient Earth rocks granites and gneisses are found at the surface with age of up to 2 billion years. The history of Ladoga and Onego Lakes development is linked with the initial stage of the Baltic Sea formation – the Baltic system of near-glacial lakes. After complete release from glacial cover about 4.5 thousand years ago, the northern shores of the lakes underwent the isostatic rise, which continues with low rate up to date. At the end of Pleistocene, pre-Ladoga and preOnego were oligotrophic cold water bodies (Davidova and Subetto, 2000). Nearly 4–5 thousand years ago, the