Stone-dwelling leeches [Hirudinea, Clitellata] of Lake Hancza [Poland]: Different sampling methods determine different taxonomic structures

The work concerned the taxonomic structure and densities of assemblages of leeches inhabiting the stony littoral of oligotrophic Lake Hañcza in North-Eastern Poland. Samples collected manually from stone surfaces were compared with those found on artificial structures made of PVC. The differences between the assemblages sampled by these different methods were much greater than those between assemblages sampled manually from natural stones at most of sampling sites. Such differences make it clear that artificial substrates differ from a littoral stone surface in the way they are colonized by leeches to the extent that using artficial substrates did not prove to be a good method for study the leech community in a stony littoral.