Dr. Fűköh Levente szerk.: Malakológiai Tájékoztató 16. (Eger, 1997.)

STEFFEK, L: Molluscs (Mollusca) of the Morava river basin in Slovakia: Present state of the molluscs fauna

only on dunes (Stanová, V. - Seffer, J. 1994). This seems like an inconvenient environment for malacofauna because of its high acidity. Dry grass biotopes provide the habitat for thermophilous species, e.g. Truncatellina cylindrica, Pupilla muscorum, Monacha cartusiana. The forest-steppe formations with the occurrence of Euomphalia strigella and Cepaea vindobonensis also have a similar composition. A part of the original floodplain forest was changed to arable land and it is utilized intensely. Better conserved and slightly changed stands occur only in the form of islands, more continuous stands appear only in the southern part and at the confluence of larger streams. These belong to the Salici-Populetum floodplain forest mainly (Jarolímek, I. 1994) spreading mostly along the main stream of the river Morava and around its larger tributaries. Natural stands are often changed and endangered by human activities (regulation of water streams, agriculture, amelioration, etc.): Hygrophilous species such as Succinea putris, Perforatella bidentata, P. rubiginosa live here. A different malacocoenosis can be in hard floodplain forests with elm, oak, maple and ash trees. It appears only in places occasionally overflown by water where floodplain forests of the association Fraxino pannonicae-Ulmetum appear. They are conserved on the higher terraces of the river Morava from the Vysoká pri Morave village to the village of Kuty. Due to their relatively damaged structure these areas have been declared state natural reserves (Horny les, Dolny les). Here e.g. Cochlodina laminata, Lehmannia marginata, Macrogastra ventricosa can be found sporadically. Marshes in different stages of succession belong to the most valuable biotopes. They are better conserved in the southern part of the alluvium, where the malacocoenoses are better developed, too. Species belonging to those critically endangered in Europe live here: Euconulus alderi, Bithynia leachi, Planorbis carinatus, Anisus vorticulus, A. spirorbis, Gyraulus riparius. Marsh depressions are covered by stands of Molinion caerulae. At present the suffer very much from human activities: they are being dried by intensive drainages and areas prepared like this are changed to arable land by ploughing. Only small fragments conserved on the wettest stands bear witness to the floristic richness of the area. Vertigo antivertigo, V. pygmaea, and V. angustior are the most important molluscs living here. Stands of the Phragmiti-Magnocaricetea class overflown several times a year by water cover the partly filled up dead arms of the river Morava. Seasonally a rich water malacofauna with species like Valvata cristata, Viviparus contectus, Bithynia tentaculata, Planorbis planorbis, Anisus leucostomus, Physa fontinalis is developed here. In the lowest, permanently and significantly wet parts of undrained terrain depressions the stands of alder-bog forest associations of the alliance Alnion glutinnosae appear here. They are wet depressions filled up with natural peat-moss (Sphagnum sp.). Here heavy acid mesotrophic-oligotrophic soils with thicker layers of bog (above 40-50 cm), or of peat-bog can be found. Today the form only a fragment of the original distribution. They are preserved in the inundation area of the river Morava and its larger confluents (Rudava, Myjava). Elsewhere they are driven back to most wet marshes. They are very poor in malacofauna. Due to hydromeliorative interferences the occurrence of associations of water surfaces was influenced very much, too. In rudiments associations of water plants of the Hydrocharietalia and Potametalia classes (Ofahelová, H. et al., 1994) can be found here. In the