Oscillations in density and diversity ofPisidium communities in two biotopes in Southern Poland

Abstract

From September 1979 to October 1980 in two types of biotopes (in the stream at Kaliś and in the Biaŀa Przemsza River near Jaroszowiec, southern Poland)P.amnicum, P.milium, P.subtruncatum, P.nitidum, P.personatum, P.casertanum andP. sp.non det. were found.P.amnicum was accepted as an indicator species for the river community, andP.milium for the stream. The irregular changes of species composition of the sphaeriid community in the stream at Kaliś are rather accidental and the only temporary occurrence ofP.nitidum, P.personatum andP. sp.non det. in the Biaŀa Przemsza River might be connected with seasonal migration.