Benthic Diatoms as Bioindicators: An Ecological Status Evaluation of the Gračanka River (Kosovo and Metohija)

Abstract

This research employs benthic diatom communities as bioindicators of the water quality of aquatic ecosystems. The study was conducted on a watercourse of the Gračanka River in Kosovo and Metohija that is exposed to different levels of anthropogenic pressure, including organic pollution, nutrient loading, and industrial mining impacts. Benthic diatom samples were collected from 10 locations. We assessed water quality using combined chemical and biological monitoring, including physicochemical parameters and diatom indices such as the IPS, CEE, and TDI. The diatom assemblage was composed of 93 species, dominated by the genera Navicula Bory, 1822 (14 spp.), Nitzschia Hassall, 1845 (13 spp.), and Gomphonema Ehrenberg, 1832 (9 spp.). Our study revealed that the combined effect of multiple pollutants significantly impacted diatom assemblages, as shown by spatial shifts in community structure that corresponded to anthropogenic water quality pressures at most investigated sites. Although diatom indices are useful for assessing ecological status, their reliability can be compromised in multi-stress environments. Consequently, integrating physicochemical data is essential for accurately interpreting the results of diatom-based bioassessments.