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

from this pond the values are getting worse except Planorbis planorbis and Anisus spirorbis. I have to mention the pond number I, which east part is open watered (pelagic), and its west part has got similar conditions to the other ponds. At the east part of the pond the degradation occurs always earlier then at the other places because of the faster increase of the pH value and the Na2C03 amount of water. The biomassa of snailspecies in sodic waters Morphology - and sometimes colour - of mollusca living in sodic waters differs from the molluscs' living in other waters (Richnovszky, A. 1993). It is the same in case of snailbiomassa. Against the common literary measure facts (Soós, L. 1943) in the sodic waters of Upper Kiskunság the mature specimen of watersnails reach only 40-80% of the average size. The Lymnaea stagnalis reach the average size in the reeds. The Lymnaea palustris can be found in capital size around Apaj. The size of Anisus spirorbis is between 80100% depending on the chemical conditions of water. The Hippeutis complanatus show the smallest size (38%) Biomassa of snailcoenosis in the sodic lakes From the examined lakes "Fehérszék" and "Pozsáros" have the largest biomassa and the biomassa of lake "Kisréti" and fishpond of Apaj is not negligible. "Kelemenszék", "Zabszék", "Pipásszék" have insignificant snailbiomassa. Apaj: Fishpond (livingplace reconstruction) In the reeds found at north-east part of the lake the value of biomassa is the largest. By the way the oecological refugium of Lymnaea stagnalis is here. Moving off the snailbiomassa may decrease in opened waters even one seventieth. Lake Háromszögi, Pozsáros, lake Gyékény These small lakes are similar to each other in biomassa, coenological characteristics and species combination. They can get watersupply - in case of high water level - from the canal number XXXI apart from the precipitation. Fehérszék (livingplace reconstruction) Due to the reconstructional work lasting more than 3 years there are 67% more species here with increasingly better conditions. There were species - with big bodies - in the opened water only here in large numbers because this lake gets the fresh water from the alimentary canal from the direction of the opened water. Here, in the opened water the value of snailbiomassa was much higher than in the reeds.