THE STONE CRAYFISH AUSTROPOTAMOBIUS TORRENTIUM (SCHRANK) IN THE CZECH REPUBLIC
Five species of crayfish, comprising two native species Austropotamobius torrentium and Astacus astacus, one introduced European species, Astacus leptodactylus and two alien American species, Orconectes limosus and Pacifastacus leniusculus, occur in open waters of the Czech Republic. The stone crayfish is highly endangered species in the country, known only from several recent records. Four localities have been confirmed for the presence of the stone crayfish in the Czech Republic. Basic characteristics of the following stone crayfish occurring localities are described: Míza and Upořský brook in Křivoklát protected area, Zubřina brook near Domažlice, Luční brook near Trutnov and Klabava brook in Brdy Military Training Area. The present localities have been investigated for chemical, structural and terrestrial environments. Properties of these waters (morphology, supply of substrate, current, aquatic and terrestrial environment) are compared with literature data. Strong conservation actions are necessary to save the endangered stone crayfish on most north-eastern limit of its distribution.