BIODIVERSITY OF ZOOPLANKTON INRILA MOUNTAIN GLACIAL LAKES IN NATURA 2000 ZONES -BG 000495 AND BG 000496
GEORGICA ILIEVA1*, MARIETA STANACHKOVA1,DIMITAR KOZUHAROV1
1 – Department of General and Applied Hydrobiology, Faculty of Biology, Sofia University “St. Kliment Ohridski”, Sofia, Bulgaria
* Corresponding author: georgica_ilieva@abv.bg
Keywords: Mountain glacial lakes, relict species, zooplankton
Abstract: Rila mountain glacial lakes are included in protected area, according to Bulgarian legislation; they are part of the European ecological network Natura 2000.The management of the zones complies with the EU Directive for Conservation of Wild Birds (79/409/EEC), the Directive for Conservation of Natural Habitats and this of Wild Flora and Fauna (92/43/EEC), the Bern Convention (in effect since 1991), and the Biodiversity Convention (in effect since 1996). Assuredly, the mountain glacial lakes are characterized with high conservation significance. The conclusion is supported by the existence of some relicts and rare species. In the investigated lakes Hexarthra bulgarica (Wiszniewski, 1933), Acroperus elongatus (Sars, 1862), Daphnia rosea (Sars, 1862) and Arctodiapthomus alpinus (Imhof, 1885) were found. Despite of the considerable faunistic diversity, high mountain lakes are threatened by rapid eutrophication processes caused by a combination of anthropogenic impact and climate changes. Introduction of non-native fish species like Phoxinus phoxinus (Linnaeus, 1758), Oncorhynchus mykiss Walbaum, 1792 and Salvelinus fontinalis Mitchill, 1814 into previously fishless waters, altered zooplankton community too. Another sign of the lake‘s status is the composition and structure of zooplankton, which is used to assess the changes in trophic conditions in relation to water quality. Determination of trophic level was made based on RCC index (Kozuharov et al. 2013). Increasing of trophic state was observed according to 50 zooplankton samples from 23 lakes located in Natura 2000 zones - BG 000495 and BG 000496. The results are sufficient to evaluate the plankton diversity and conservation importance of glacial lakes in Rila Mountain. The presented new information also can be useful to update Rila National Park Management Plan.