Biological assessment of Demirci Stream in Gediz River Basin (West Anatolia of Turkey) and comparative performance of benthic macroinvertebrate-based metrics

Conserving freshwaters in West Anatolia requires biomonitoring tools to assess the ecological status of surface water bodies threatened by anthropogenic pollution. This study was carried out to determine water quality of Demirci Stream based on biotic indices. In this seasonal study, a total of seven sampling stations were determined. Asterics software was used to determine biotic and diversity index scores. Pearson's based correlations were applied in order to determine the proper biotic indices. Relationships between macrobenthic orders and physicochemical variables were revealed by Redundancy Analysis (RDA). Eleven taxonomic groups were found in Demirci Stream consisting of Hygrophlia, Arhynchobdellida, Isopoda, Tubificida, Amphipoda, Ephemeroptera, Plecoptera, Trichoptera, Diptera, Coleoptera and Hemiptera. As a result of this research, the sampling pints 1, 2, 3 and 4 were of good water quality class while sampling points 5, 6 and 7 were polluted. Arhynchobdellida, Tubificida and Diptera orders showed positive correlations with BOI5, EC, Cl-, TDS, (TC)-C-o, NH4-N, NO2-N and NO3-N variables, while negatively correlated with DO, Sat-O-2 and pH. SI, BMWP, ASPT and BBI were more proper than the FBI index to determine the water quality of Demirci Stream.