Site name:
Lake Druksiai with adjacent territories

Location:
Ignalina and Zarasai Municipalities, Utena Region, Lithuania

Geographical coordinates:
55°37´N, 26°36´E

Total area:
4,500 ha

Site description

The site includes Lake Druksiai, floodplains of the Druksa and the Smalvele Rivers and adjacent floodplains and forests. Lake Druksiai is the largest lake in Lithuania. It is of a fluvio-glacial origin and was formed during the last glacial period. The total area of the lake is 4,480 ha. The area of the lake basin is 613 km². It stretches in Lithuania, Belarus and Latvia. The lake is 14.3 km long and 5.3 km wide. There are seven islands in the lake. The maximum depth of the lake - 33.3 m and the average depth - 7.0 m. Lake Druksiai is a typical moderately deep mesotrophic lake. Increased eutrophication and marked anthropogenic load are characteristic for areas located near the Ignalina Nuclear Power Plant (INPP). Thermal stratification, high water transparency, low concentration of phosphorus compounds and presence of a complex of glacial relicts are typical of this lake. Bottom water layers are well saturated with oxygen. The pH varies from 7.32 to 8.49 and the CO² concentration does not exceed 15.5 mg/l.

The lake is used as a cooler for the INPP. The INPP is connected with the lake by two channels used to supply a cooling system of the Plant with water and to discharge warm water back into the lake. The water volume annually used for cooling up to nine times exceeds the natural water volume of the lake and up to 27 times - the natural annual influx of water into the lake.

High biological diversity is characteristic of the site.

More than 500 species of higher vascular plants were registered in the site. Ninety-five species of aquatic and semi-aquatic plants were recorded in the lake in recent years. The wetland complex supports numerous rare and protected plant species, protected in Lithuania and Europe. Six rare in Europe types of habitats listed in the EU Habitats Directive are characteristic of the Druksiai site.

Lake Druksiai is distinguished by several relict species of fishes and crustaceans, very rare in the Eastern Baltic region. 250 species were recorded in a micro- and macro-zooplankton composition of Lake Druksiai in recent years. Twenty-five species of fishes are found in the lake. The territory holds several species of mammals, protected in Lithuania and in the EU. Birds of more than 140 species have been found in the site. 27 breeding species listed in the Annex I of the EU Birds Directive were recorded in the site in recent years.

The pollution of Lake Druksiai caused by industrial wastewaters from the Ignalina Nuclear Power Plant is the major threat. The accumulation of polluted sediments has been recorded in deeper parts of the lake. A considerable impact on flora and fauna of the territory is caused by the thermal water pollution. The thermal pollution accelerates eutrophication of the lake and negatively impacts the most valuable relict species inhabiting the lake. Functioning of the INPP has affected the natural hydrological regime of the lake. Termination of functioning of the INPP (planned in 2009) may cause new changes in the entire ecosystem of the site.

 

Research history

Fragmentary data on hydrology, flora and fauna of Lake Druksiai are available since the beginning of the 20th century. Integrated ecological research of Lake Druksiai - the cooler of INPP - was carried since 1976. Six Lithuanian research institutes, as well as other scientific institutions of Lithuania, Russia and Belarus participated in long-term investigations of various abiotic and biotic parameters of Lake Druksiai and adjacent areas. This large-scale multidisciplinary research resulted in a series of monographs and other publications.

 

Key references

Jurgeleviciene I., Lasinskas M., Tarvydas A. 1983. Hydrogeography of Druksiai region. Vilnius: Mokslas (in Lithuanian).
Lekavicius A. (ed.) 1991. Terrestrial plant communities in the zone of Ignalina Nuclear Power Plant before its start-up. Vilnius: Mokslas (in Russian).
Mazeika J., Marciulioniene D., Dusauskiene R., Joksas K., Galkus A., Gudelis A., Jasiulionis R. and Motiejunas S. 1999. Technogenic radionuclides and some heavy metals in the ecosystem of Lake Druksiai, a cooling basin of the Ignalina Nuclear Power Plant. In: Lovejoy D. A. (ed.) Heavy metals in the environment: an integrated approach. Vilnius: 32-45.
Mazeika J., Motiejunas S. 2003. Evaluation of aquatic routine radioactive releases from the Ignalina Nuclear Power Plant. Ekologija, Vol.4: 36-42.
Marciulioniene D., Dusauskiene R., Motiejuniene E., Svobiene R. 1992. Radiochemo-ecological situation of Lake Druksiai - the cooler of the Ignalina Nuclear Power Plant. Vilnius: Akademia (in Russian).
Shevcova T., Nechaeva T., Golodec A. 1983. The status of ichthyofauna of Lake Drisviaty before the startup of the Ignalina Nuclear Power Plant. In: Biological and ichthyological investigations of Eastern Baltic water bodies. Vol. 2: 34-37. Pskov (in Russian).
Svazas S., Drobelis E., Balciauskas L., Raudonikis L. 1999. Important wetlands in Lithuania. Vilnius: OMPO Vilnius.
Svazas S., Kozulin A., Grishanov G., Maximenkov M., Rasomavicius V., Raudonikis L., Baichorov V., Skuratovich A., Balciauskas L., Drobelis E., Grishanov D. 2004. Important transboundary Belarusian-Lithuanian and Lithuanian-Russian wetlands. Vilnius: OMPO Vilnius & Institute of Ecology of Vilnius University.
Virbickas J. (ed.) 1986. Thermal power generation and environment. Vol. 5. Basic state of aquatic animal populations and communities in Lake Druksiai. Vilnius: Mokslas (in Russian).

 

The main fields of research:

Information management

Detailed data on biodiversity of the site (long-term data on populations of aquatic invertebrates and fish populations, and detailed data on distribution of all rare species plotted on maps, multi-species maps and other information) are compiled in databases of the Institute of Ecology of Vilnius University. Long-term data on key abiotic parameters of the site are stored in the databases of the Institute of Geology and Geography.

 

Cross-border research

Lake Druksiai is shared by Lithuania and Belarus. The Institute of Ecology of Vilnius University and the Institute of Zoology of Belarusian Academy of Sciences (in collaboration with other research institutes of both countries) coordinate the cross-border integrated research program of this ecosystem - the cooler of the Ignalina Nuclear Power Plant.

 

Principal contacts

Habil. dr. Mecislovas Zalakevicius, Institute of Ecology of Vilnius University; e-mail: mza@ekoi.lt

Dr. Valerijus Rasomavicius, Institute of Botany; e-mail: floraval@botanika.lt

Dr. Petras Sinkunas, Institute of Geology & Geography; e-mail: sinkunas@geo.lt