Turkish Journal of Botany




Bioassessment of surface waters is one of the most important approaches to predict the deterioration of ecosystems and achieve environmental sustainability according to the application of the European Water Framework Directive. The present review emphasizes the importance of the bioassessment of freshwater quality especially running waters based on diatom metrics. Nutrient enrichment and hydromorphological alternation driven by human activities are the main factors for the ecological compromise of freshwater ecosystems. Currently, the bioassessment of the ecological condition of inland water bodies is adopted worldwide. Bioassessment is complementary to physicochemical and hydromorphological data for evaluating the ecological conditions of rivers; however, measuring all the physical and chemical changes is expensive and impractical. Therefore, monitoring biota helps to determine the changes occurring in ecosystems. Thus, diatoms are used as bioindicators to assess environmental conditions of the ecosystems, but their use requires great taxonomic knowledge, otherwise, the results will be biased. Many diatom indices have been developed based on the trophic weight and indicator values of diatoms in different ecoregions in the last decades. This review highlights the importance and advantages of using diatom metrics in the bioassessment of the ecological status of surface waters in the different ecoregions, especially running water. To analyze the complex response of diatom communities to environmental gradients and assess the quality of the ecosystem, multivariate statistical approaches are needed. The challenge here is how to define criteria for classes of water bodies in a biologically meaningful way. For this reason, biological condition gradient is suggested as an appropriate and effective approach to develop trophic criteria based on the relationships between nutrient concentrations and biological indicators of ecological conditions


Biological condition gradient, diatom metrics, ecoregion, water quality evaluation

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