Long-term analysis of fish assemblage structure in the middle section of the Sava River – The impact of pollution, flood protection and dam construction

• Published in: The Science of the total environment Vol. 651; no. Pt 1; pp. 143 - 153
• Main Authors: Piria, Marina, Simonović, Predrag, Zanella, Davor, Ćaleta, Marko, Šprem, Nikica, Paunović, Momir, Tomljanović, Tea, Gavrilović, Ana, Pecina, Marija, Špelić, Ivan, Matulić, Daniel, Rezić, Andrea, Aničić, Ivica, Safner, Roman, Treer, Tomislav
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 15.02.2019
• Subjects: Animals; Biota; Croatia; Environmental Monitoring; Fish diversity; Fishes; Floods - prevention & control; Hydromorphological alteration; Introduced Species; Large rivers; Longitudinal connectivity; Rivers; Stressor; Water Movements; Water Pollution, Chemical - adverse effects; Water Quality; Water Supply; Hydromorphological alteration; Longitudinal connectivity; Fish diversity; Large rivers; Stressor
• ISSN: 0048-9697; 1879-1026
• DOI: 10.1016/j.scitotenv.2018.09.149

At the beginning of the 20th century, the middle section of the Sava River in Croatia was unaffected by major human activities and rich in ichthyofauna. The Sava River was important for commercial and recreational fishing for the local population, which still remains today. However, the 1920s mining industry was established in Slovenia, which emitted carbon dust into the Sava River. At the same time, the construction of embankments to mitigate flooding started in the middle section. Furthermore, in the 1980s, the Krško nuclear power plant (NPP), and in the 2010s, the Krško hydropower plant (HPP) were built in Slovenia. These activities could have an impact on the composition of fish communities downstream from the major sources of disturbances. Therefore, the main aim of this paper were to analyze the changes in fish assemblages of the Sava River from 1978 to 2017, prior to and after the construction of Krško NPP and HPP at the Medsave site on the Sava River, 20 km downstream from the major construction operations. Collected data were divided into four sampling periods (SP): SP1, from 1978 to 1980; SP2, from 1991 to 1994; SP3, from 2001 to 2006, and SP4 from 2011 to 2017. Besides alien fish species, water quality and hydromorphological modifications were identified as significant stressors. In SP1 and SP2 limnophilic and eurytopic fish groups were predominant, and 26 different fish species were identified, but in SP3 and SP4 rheophilic fish groups become dominant, and the diversity has declined to 21 species. Threatened species blageon, Telestes souffia seems to be missing from the main course of the Sava River in last 20 years. It can be concluded that disturbances in the fish assemblage pattern have coincided with the presence of multiple stressors of human origin. [Display omitted] •Variations in fish assemblages of the Sava River from 1978 to 2017 were analyzed.•Limnophilic and eurytopic types of fish group were predominant from 1978 to 1980.•Four alien fish species recorded 1978–1991, of which three remained until today.•Changes in species composition and decline in diversity has been noted after 2001.•Threatened Telestes souffia appears to be missing from the Medsave site.