The use of diatoms to assess the water quality in the Wisłoka River in the town of Dębica and the surrounding area

The objective of this work was to examine the water quality using three diatom indices SPI, GDI and TDI. The material for the study was collected during four seasons from autumn 2010 to summer 2011, from four sampling sites located on the Wisłoka River, in the town of Dębica and the surrounding area. The Wisłoka at all selected sites was characterized by alkaline or close to neutral pH (pH 6.5-7.7). Electrolytic conductivity ranged from 364 to 480 µS cm^-1. The Wisłoka at the selected sites in the urban area and in the surrounding areas was characterized by high diatom species richness. The total of 238 taxa from 53 genera were recorded, of which the most numerous were: Nitzschia (44), Navicula (33) and Gomphonema (12). Achnanthidium minutissimum var. minutissimum, Amphora pediculus, Navicula gregaria, N. lanceolata, and Nitzschia dissipata ssp. dissipata were usually the dominant species. Chemical parameters indicated very good quality of water. However, the diatom indices used to assess the water quality, classified the studied water into a group corresponding to quality class III or IV.