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Some of the direct and indirect environmental impacts are related to the construction of fish farms (FFs) and small hydropower plants (SHPs) around the world. Diatom communities are one of the best bioindicators of various pressures like eutrophication, chemical and organic pollution. The main objective of this study was to examine the influence of SHP and FF on diatom community and water quality of the Prištavica River in Serbia. A total of 184 epilithic diatom taxa from 55 genera were identified. Sites after the FF and SHP are distinguished by the same dominant species in each season. Compared to the other sites, species diversity in summer was lower at site after SHP. In terms of spatial dynamics, four groups of taxa are distinguished. Some centric taxa were associated with sites downstream the FF and SHP. Altered physical and chemical parameters were documented at sites downstream of constructions. Water quality of the Prištavica River ranged from high to bad depending on diatom index, season, and sampling site. A greater difference in diatom index values was found at sites upstream and downstream of the FF, than at sites upstream and downstream of the SHP. [ABSTRACT FROM AUTHOR]

The investigation of the Despotovica River was carried out in April 2017 with the aim to provide an indicative ecological status assessment. Phytobenthos and aquatic macroinvertebrate communities were followed as well as physico-chemical parameters of water. Ecological status assessment is given based on biological (epilithic diatoms and macroinvertebrates) and supporting physico-chemical water quality elements, according to the Serbian National regulation on parameters of ecological and chemical status of surface waters and parameters of chemical and quantitative status of ground waters. The ecological status was determined by the worst evaluated water quality element. Based on the analysis of investigated parameters of biological and physico-chemical water quality elements, the indicative ecological status of the Despotovica River could be assessed as bad (class V), which is the result of the river's load of organic and inorganic origin but also of heavy metals. [ABSTRACT FROM AUTHOR]