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

Stands of Nuphar lutea, Sagittaria sagittifolia, Potamogeton natans, Nymphaea alba, Trapa natans the Moravian dead arms original malacofauna containg the species Viviparus acerosus, Planorbis carinatus, Anisus vortex, Bathyomphalus contortus, Gyraulus laevis, Anodonta anatina, A. cygnea, Unio tumidus is living. The main stream of the river Morava and its arms with gravely bottom are dominated by Unio crassus, U. pictorum, Valvata piscinalis, Sphaerium rivicola and others species. Results and discussion Preliminary research of 53 localities in the Morava river basin provides very interesting results. We have found 117 species of molluscs making 48% of molluscan species in Slovakia (Tab. 1). Species representation according to areotypes (Lisicky, M. J. 1991) is presented in Table 2. Large area species having broad zoogeographical distribution (45) and Eurosiberian species (33) are the most numerous. Three Carpathian areotypes bear witness to the Carpathian influence on this area. Southern species (Pontic, Meridional and Mediterranean) are represented by 16 species thus expressing their strong influence. The Balcanic species Amphimelania holandri was probably introduced by aquarists. The occurrence of three W European areotypes bears witness to the influence of the Subatlantic. From the viewpoint of the gene pool protection the occurrence of several species, belonging to the critically endangered ones not only in Europe, but also all over the world is important. For example Gyraulus riparius, Valvata pulchella, Bithynia leachi, Planorbis carinatus, Anisus vorticulus, Cochlicopa nitens, Euconulus alderi, Unio crassus, Pseudanodonta complanata and Pisidium amnicum belong to rare species in Slovakia. All these species have one thing in common - they live in water or in marshy biotopes. Out of further species the remarkable ones are those living at the borders of their area. From among the W-European species only Trichia striolata danubialis (known to live in the Danube river basin) and Balea perversa found on the castle rock of Devin can be found here. The species Monacha cartusiana, Tandonia rustica and Dreissena polymorpha have their northern distribution border in Slovakia, too. None of the species Sphaerium rivicola, Pseudanodonta complanata and Anodonta cygnea have been found more to the northern direction. We can find only a few Carpathian species, e.g. Chilostoma faustinum, Vestia turgida the border of which ends in the Little Carpathians. The occurrence of the Sudete - W-Carpathian species Deroceras praecox found only in the more northern areas of Slovakia, is surprising. After a more detailed research we can expect the occurrence of species such as e.g. Oxychilus inopinatus - in xerothermic localities, Discus rotundatus - in forest biotopes and Vallonia enniensis - in wet meadows. The presented paper summarizes the present state of knowledge on the malacofauna of the alluvium of the river Morava. During the research carried out between 1990-1994 117 molluscs species were determined. That is almost 48% of the total number of molluscs known in Slovakia. Similarly in different parts of Slovakia and Europe, many of marsh and water species are critically endangered, which, to a certain extent, is connected to human activity. One of the ways for this trend to cease would be to suggest within the new Law of nature protection No. 287/94 of the Code of Laws, for most important gene pool localities (areas) to become biocentres of territorial systems of ecological stability. This step max. provide some legislative protection.