Leeches (Clitellata: Hirudinida) of an upland stream: taxonomic composition in relation to habitat conditions

Hirudinida comprise a constant component of benthofauna in running waters and their taxonomic composition is often analyzed to evaluate the environmental quality. However, the indicatory role of particular species is still arguable. Thus, it is very important to provide more detailed information on the impact of environmental parameters on the species structure within this group of invertebrates. Representatives of nine species were found in the investigated upland stream including mainly Erpobdella vilnensis and E. octoculata. The research has demonstrated that the hydromorphological conditions and feeding behavior are the main factors determining the taxonomic composition of leeches in particular sections of a watercourse.