Nivní malakofauna povodí Úštěckého potoka a její vývoj během holocénu [The floodplain mollusc fauna of the Úštěcký Brook catchment basin and its development during the Holocene (North Bohemia, Czech Republic)]

Abstract

This paper presents a research of floodplain mollusc assemblages of the Úštěcký Brook catchment basin (Elbe tributary, North Bohemia, Czech Republic). Altogether, 71 mollusc species (69 species of Gastropoda, 2 species of Bivalvia) were recorded in the study sites between 2007 and 2011, representing 29% of the total Czech malacofauna. The common forest species dominated (41% of all recorded species) and included some rare woodland species as Daudebardia rufa, Discus perspectivus, Macrogastra ventricosa, and Sphyradium doliolum. Rare wetland species protected by the NATURA system Vertigo angustior and endangered wetland species Vallonia enniensis were also found. The richest assemblages occurred on the upper part of the brook, while the lower part was very species poor due to agriculture land use in this fertile floodplain. A small calcareous moorland, situated in the northeastern vicinity of Úštěk Town (north Bohemia) includes a Holocene mollusc succession that was subdivided into three local mollusc zones: I – basal zone with marked numbers of Discus ruderatus, Vertigo geyeri and numerous aquatic taxa, II – with forest species including Platyla polita and III – dominated by open-ground and catholic species. Despite the specific conditions of the moorland habitat the succession largely corresponds with the standard developmental pattern of the mollusc fauna in the zone of mid-European uplands. Of particular interest is the developmental break reflected by the poor fauna in the layer 3. The malacofauna of the Úštěcký Brook can be used as a model of alluvial mollusc assemblages of the brook floodplain that is situated in the warm area of Central Europe with long-term history of agriculture land use.