Eco‐assessment of Değirmendere and Bulaklı streams using diatom indices from different ecoregions

Abstract

AbstractDiatom metrics are important tools for evaluating the environmental conditions of streams for the achievement of environmental sustainability. Aim of the present study was to assess the ecological status of Değirmendere and Bulaklı streams using diatom indices developed in different ecoregions and to elucidate responses of diatom assemblages to stressors using multivariate approaches. Analysis of similarity percentage indicated a 74% dissimilarity between Değirmendere and Bulaklı streams with the most contribution of Encyonopsis minuta, Achnanthidium minutissimum, Achnanthidium druartii, Amphora indistincta, and Gomphonema cuneolus species to this dissimilarity. The first two axes of canonical correspondence analysis exhibited a strong correlation (93.1%) between diatom assemblages and environment variables. Pollution‐tolerant species were associated with Bulaklı stream, whereas pollution‐sensitive species displayed relatedness to Değirmendere stream. Conductivity, salinity, oxidation–reduction potential, total phosphorus (TP), and orthophosphate were the significant effective environmental factors on the spatiotemporal distribution of diatom assemblages. Used diatom indices showed significantly positive and negative correlations with TP gradient. The results of bioassessment exhibited that diatom indices have different scores for the ecological status of the sampling stations. European diatom indices except Trophic Diatom Index and Duero Diatom Index mainly showed similar behavior in the bioassessment of ecological conditions of Değirmendere and Bulaklı streams. Among European diatom indices, Trophic Index Turkey was more competitive and could give better results in the bioassessment of streams. Results indicated that ecoregional specific diatom index could be used as a suitable tool to accurately evaluate the surface water quality.