The diversity of annelids in subterranean waters: a case study from Poland

Not all invertebrate groups commonly occur in subterranean waters but annelids live in surface and underground habitats. The annelid species' richness in various underground waters (wells and interstitial and cave waters) and surface streams of Poland was compared, and the habitat preferences for the most frequent species were determined. Until now, 111 annelid taxa (mainly oligochaetes) had been identified in underground waters in Poland, with higher numbers (71) in the interstitial habitat than in stream bottoms (62). The number of species identified in the caves and wells was distinctly lower (54 and 29, respectively). The Correspondence Analysis did not separate the samples from various underground water types into distinct groups, and the distribution of well fauna was especially scattered (in the ordination diagram) because abiotic parameters differ strongly in studied wells. Only three stygobiontic species (Cernosvitoviella parviseta, Enchytraeus dominicae and Trichodrilus moravicus) were related to some caves. The analysis of the available data indicate that to obtain a comprehensive picture of the aquatic fauna in a given country all types of subterranean aquatic habitats should be sampled and taken into account. Moreover, to ascertain the composition of benthic invertebrates in running waters, investigation of the interstitial habitat should also be performed.