Dr. Fűköh Levente szerk.: Malakológiai Tájékoztató 12. (Eger, 1993.)

SZABÓ, S.: The effect of becoming waterless and experiments of livingplace reconstraction on Monusca living in the soid laces of Upper Kiskunság

All individuals of Lymnaea stagnalis decayed during the experiments in aquarium even if they dealt with the drought for a little while by touching the mud with their mouths. I also didn't succeed in observing the survival on dry ground. There is a flowing across canal between the water storage number I and the lake signed "A" and in the 2-3 cm deep water of its bowe these individuals assembled in large numbers during the dry period. Return - settlement At the beginning of the experimental period the occurence of species was mosaic-like on both territories. In the last three years I was able to observe the return and settlement of mollusca well with the help of colouring experiments and •network-coenological maping on the livingplace reconstructional territories. National Park of Kiskunság, number III. The reason for 67% increase of species number is double. On the one hand the Lymnaea stagnalis - not as animite but fresh subfossile condition - existed earlier in all probability. The colouring experiments show their definite moving between the deeper parts of reeds and the open water. The egg piles settled on many specimen's shell moving in the open water are unusual experience (in case of Lymnaea peregra as well!) They drag along these piles of eggs but in normal case they take them on the flora. Settlement of Gyraulus albus, Hippeutis complanatus and Segmnetina nitida from the alimentary canal can be definitely observed by the network - coenological mapping. The reason for appearance of Armiger crista and Lymnaea palustris still unexplained. National Park of Kiskunság, territory number II. In the examined period I experienced settlement only once on territory Apaj. The appearance of Perforatella rubiginosa in autumn 1991 was not longlasting because I did not find any individual of them since then in spite of the accurate research. The settlement of mollusca has definitely positive tendency at Apaj. The Anisus spirorbis seems to go into latent condition there, where it is touched by negative effects of the oecological elements. The direction of migration is definitely radial in case of this species. Now it is widely spreaded in the whole lake signed „A" and its caracteristics are influenced only by the pH value and Na2C3 amount of water. Now more generation live together. In case of prosperous waterlevel we can expect the pullulation of these individuals in large numbers, wich has significant effect on biomassa. There are definite oecological refugiums in case of other species, for example the Segmentina nitida, Planorbarius corneus in the north-west reeds of lake signed „A" , the Lymnaea peregra in more digged hole next to the dams, the Lymnaea stagnalis and the Planorbis planorbis at the enviroment of the waterstorage outlet. The fishponds - mentioned before - deserve attention. They are not linked to the reconstructional watersystem but are linked to each other by the smaller linking canals. The ponds - although they are separated pieces - show balanced picture comparing to other territories. On basis of the picture showing by malacocoenosis we can conclude that, there was water here - it is a relatively deeper part in one or two period of the year before the reconstructional period. On basis of researches the pond signed 3/a" plays central role there, where the characteristics of species are the most favourable. Moving off anywhere