Eco-Assessment of Streams of Konya Closed River Basin (Turkey) Using Various Ecoregional Diatom Indices
Abstract Ecological assessments of freshwater ecosystems based on diatom metrics are an important issue to attain environmental sustainability. The present study aimed to evaluate differences in the diatom-stressors relationship in relatively least disturbed streams in the Konya closed river basin using multivariate analyses and to bio-assess streams by application of different ecoregional diatom indices. Cocconeis euglypta, Cymbella excisa, Cocconeis placentula, and Achnanthidium minutissimum are the most contributing species to the dissimilarity of sampling stations between rainy and dry seasons and also between altitude (A2 800-<1600 m and A3 ≥1600 m) groups. A strong (82.8%) correlation between diatom species and stressors was expressed by the first two axes of canonical correspondence analysis. Diatom species displayed distinct responses to environmental variables (electrical conductivity, Ni, Cu, B, and altitude) playing important roles on the distribution of diatom species. Diatom indices indicated different ecological statuses of stations from a bad to a high. European diatom indices except Duero Diatom Index-DDI and Trophic Diatom Index-TDI showed well responses to the eco-assessment of streams and indicated high ecological status for the least disturbed sampling stations symbolized as S16, S20, S24, S25, S27-29, S37, and 39. These results were also supported by abiotic evaluation. Among diatom indices, although TIT was more competitive in the bio-assessment of streams, it is necessary to increase its species list by determining their trophic weights in future studies. This indicates that the revision of ecoregional specific diatom metrics with the enhancement of diatom species numbers according to their ecological preferences is needed to correctly interpret the water quality.