Vodné mäkkýše ochranársky významných lokalít na Podunajskej nížine [Freshwater molluscs of water bodies with a high conservation value in the Danubian lowland (SW Slovakia)]

In the autumn of 2014, we conducted a malacological survey at 23 freshwater bodies in the Danubian lowland, SW Slovakia. We aimed to conduct a malacological inventory of semi-natural sites of a high conservation value. During the fieldwork, we used conventional methods of sampling; mostly sweeping by a hemispherical metal kitchen strainer from both natant and submerged vegetation and also from bottom sediments. At each site, ten people have collected molluscs for 60 to 90 minutes (except site No. 3, 5 and 15 – 1 person/2 hrs.). During the sampling we did not use any destructive methods. A total of 67 species were found in the whole surveyed territory (43 gastropods, 24 bivalves), which is the complete current species richness of the aquatic mollusc fauna in the Danubian lowland. The most species rich sites include the Číčovské rameno Oxbow lake (36 species, No. 2), Klátovské rameno Side arm (32 spp., No. 10) and Parížske močiare Swamp (24 spp., No. 11). Bithynia tentaculata and Planorbarius corneus were the most frequent species (i.e. found at +65% of sites) and the following eight species were recorded at 44–52% of sites (i.e. 10–12 individual sites; given in a descending order): Anisus vortex, Lymnaea stagnalis, Planorbis planorbis, Anisus vorticulus, Bithynia leachii, Stagnicola palustris, Viviparus acerosus and V. contectus. In contrast, Bithynia transsilvanica, Gyraulus riparius, Pisidium personatum, Planorbis carinatus, Sphaerium nucleus and Valvata macrostoma were found at only one site (species recorded only in flood debris of the Danube River were not considered).