Vodní měkkýši Sázavy a vybraných přítoků se zaměřením na ohrožené a nepůvodní druhy

Abstract

This paper presents the results of a malacological survey of the Sázava River and its tributaries conducted over the last 20 years. The Sázava River (Czech Republic, Central and Eastern Bohemia) is one of the major tributaries of the Vltava River. Altogether 45 species of aquatic molluscs were found at 221 sites located at the Sázava River and its tributaries. More than 60% of recorded species of the Sázava River and its tributaries are common and widespread. The population of critically endangered Margaritifera margaritifera in the Jankovský potok is near extinction. Other threatened bivalves Pseudanodonta complanata, Unio crassus and Sphaerium rivicola were recorded in the Sázava River. Populations of U. crassus were also found in several tributaries (Blanice, Hejlovka, Martinický potok) while in the Sázavka Brook and the Želivka River only a few individuals were found. Gyraulus acronicus, a rare gastropod in the Czech Republic, was recorded in the Blanice River and several dam reservoirs. Four non-native species (Potamopyrgus antipodarum, Physa acuta, Gyraulus parvus, Dreissena polymorpha) were found in the monitored streams and reservoirs but usually in a relatively small number of localities. Most of these were located in the lower section of the Sázava River, Švihov dam reservoir and some tributaries.

Keywords

• mollusca
• sázava river
• threatened species
• faunistics