Distribution of benthic diatoms in the Świnka River (Polesie Region) in relation to salinity

The River Świnka (Polesie Region, southeastern Poland) receives salty mine waters from the “Bogdanka“ SA coal mine. In April, July and October of 2005, investigations of benthic diatoms were conducted at four stations, two of which were located downstream of the entry point for canal mine waters, with the remaining two stations free from the influence of mine waters. Studies showed differentiation of diatom community species structure and relative abundance, as well as conductivity and Cl- concentrations at particular stations. Higher salinity (Cl- concentration reached 338.8 mg cm-3) and the appearance of saltwater diatom species (e.g. Navicula halophila, N. salinarum, Nitzschia commutata, N. constricta or Thalassiosira weissflogii) were observed in the part of the river influenced by mine waters.