Příspěvek k poznání vodních měkkýšů Vsetínské Bečvy a okolí (Česká republika)

Abstract

This paper brings a review of a malacological survey of the Vsetínská Bečva River, its tributaries, canals and other different aquatic habitats in surroundings (Eastern Moravia, Czech Republic). Vsetínská Bečva is a 58 km long river which rises in 870 m a.s.l. and joins Rožnovská Bečva River in Valašské Meziříčí at 288 m asl. Research was focused on endangered bivalve Unio crassus. Aquatic molluscs at 63 sites were studied in 2007. Altogether 19 species of aquatic molluscs (12 gastropods, 7 bivalves) were found. Three non-native species Potamopyrgus antipodarum, Physella acuta, and Gyraulus parvus, which are rare in Moravia, were found. Occurrence of vulnerable but in this region relatively common prosobranch Bythinella austriaca was confirmed in springs and rivulets. Research based on bivalves provided more interesting results. Existence of two large populations of Unio crassus were documented in two canals (mill races) in Hovězí and Vsetín. Populations of Unio crassus were estimated at 1500–2500 individuals in Hovězí and 1000–4000 individuals in Vsetín. Occurrence of young individuals of Unio crassus were confirmed in both cases. Rare bivalves Pisidium amnicum and P. moitessierianum were found at one site in Canal in Vsetín and also non-native Dreissena polymorpha was found at one site – the gravel pit near Nový Hrozenkov.

Keywords

• mollusca
• vsetínská bečva river
• faunistics
• unio crassus