Diversity of invertebrate fauna in littoral of shallow Myczkowce damreservoir in comparison with a deep Solina dam reservoir

This is the first assessment of bottom fauna in littoral of shallow dam reservoir Myczkowce (191 ha, 12 m deep) and deep Solina reservoir(2105 ha, 65 m deep). Both reservoirs were formed in the 1960s in Carpathian Mountains. The reservoirs differ much in terms of size, range and regime of water level changes, water exchange rate and temperature. Quantitative samples were taken monthly using Morduchaj-Boltovski cylindrical bottom sampler from 3 stations in Myczkowce and 4 stations in Solina reservoir. In Myczkowce, 8-14 taxonomic groups of invertebrates were found in each site. Numbers of littoral fauna incerasedduring the season. There was no strong dominance of any particular group during summer, while in spring and autumn there was a slight prevalence of Diptera larvae and Isopoda. Total numbers of fauna in littoral of Solina reservoir were almost 3 times lower than those in the Myczkowce littoral. Only 1-7 taxa (systematic groups) were found in each site, of Solina reservoir. The dominant groups were easily assessed: Diptera larvae (mainly Chironomidae) and, a subdominant group, Oligochaeta. In Myczkowce reservoir, the Shannon-Weaver index of biodiversity was high (0.4-0.95). The index in stations in Solina reservoirwas much lower (0.05-0.7). In Myczkowce, the course of index of equitability corresponded closely with that of biodiversity. In Solina, it showed higher values than the Shannon-Weaver index. This may indicate that the potential biodiversity in this environment was utilised by the communities in high degree. In general, the invertebrate fauna of littoral zone of Myczkowce reservoir is richer, both in terms of numbers and diversity than that of Solina reservoir. The main cause ofthese differences is a different character of water level changes. In Myczkowce, these changes reach 2 m and have a short term character,while in Solina water level varies (up to 10 m) and remains low all winter, this causes destruction of littoral which has to form again next s [ABSTRACT FROM AUTHOR]