Folia Historico-Naturalia Musei Matraensis - A Mátra Múzeum Természetrajzi Közleményei 16. (1991)
Fűköh, L.: Examinations on faunal-history of the Hungarian holocene Mollusc fauna (Characterization of the succession phase)
2. FRESH-WATER FAUNA OF THE SUBSIDED ZONES In fresh-water faunas the successional processes- are accomplished more separable from the enviroment. The essential changes set in at that time when the quality of water (river, lake) changes (e.g. the first and second phase at Sárrét, Fejér county) or when in consequence of the oscillation nf the water-level we can observe the signs of periodical palaudal phase or dessication in the sediment (e.g. Fertô-lake: Fertőrákos, profile I., Lesence: fauna of the Nádaslake) . 2.1. River phase Generally we can conclude that the succession of the Hungarian fresh-water fauna starts with the appearance of species living in rivers ( Lithoglyphus naticoides ) , and beside them characteristic species is the Valvata piscinalis which requires prmanent water quality. After the disappearance of Lithoglyphus naticoides the dominance of Valvata piscinalis can be observed in the sediment. Valvata pulchella can be found mainly in the fluvial sediments of the older layers (e.g. Jászság, Kardoskút: Fehér-lake). This phase is the beginning of lime mud formation, which sediment with its peculiar fauna is illustrative of the lacustrian successions. 2.2. Lacustrian period The beginning or Lhe so called real lacustrian period is the formation of lime mud at the investigated territories. This phenomenon can be observed at Transdanubia (Fejér county, Sárrét, Lesence: Nádas-lake) as well as on the Great Plain (Danube - Tisza Interfluve) and in the Nyírség. This phase can be characterized by the frequency of Bithynia tentaculata , Gyraulus albus , and Lymnaea auricularia . The relatively deeper water of lakes is optimal for these species. 2.3. Fen and peat formation Beside the terrestrial species this type of sediment can be characterized by the presence of those species which are less sensitive to the chemical reaction, oxygen content, and temperature of the water: Anisus spirorbis and Physa fontinalis (can live in saliferous places), Lymnaea palustris (can live in all type of water), Lymnaea truncatula (can live in wet fields, too). This type of sediment contains, mainly in the initial phase, the Bithynia leachi which is the vicarious species of Bythinia tentaculata , the characteristic species of the previous phase. Its appearance is connected with the cange of temperature (cooling off). The species Valvata cristata and Gyraulus crista appear in large numbers. Rare, but significant the north-west spreading Gyraulus riparius . Its role in Hungarian fresh-water Mollusc fauna will be mentioned in a farther chapter. 3. COMPARING OF THE HUNCARIAN HOLOCENE MOLLUSC FAUNA SUCCESSION WITH FAUNAL SUCCESSIONS OF OTHER TERRITORIES During the investigation of the Mollusc fauna of Hungarian medium high mountain ranges we can consume the evolutionary data of the Holocene Mollusc fauna of Czech and Slovakian Republich the best. In Central-Europe malacologists use those oecological categories which writing up thanked to Lozek' s activity. It is why the published data can be used up well to out - line an Europaean evolutionary process in the different countries as well as in Hungary. Czech and Slovakian Republic In the Czech and Slovakian Republich, but mainly in Slovakia started a noteworthy faunal development on the Pleistocene-Holocene boundary. According to LOZEK (1965) 33,3 4 of the country's Holocene fauna lived at the end of the Pleistocene. During the Holocene there was remarkable enrichment from the point of view of species. The increase in the number of species was 9,6 \ in the PreBoreal phase. 17
