Structural and functional changes in the taxocoenosis of caddis fly (Trichoptera) Cierny Vah River

The structural and functional changes in caddis flies taxocoenosis in the river Cierny Vah The river is impacted by the pumped-storage hydropower plant Cierny Vah. The impact of the Cierny Vah reservoir on caddis flies communities and theirs life history was examined at four sites of the Cierny Vah River. Site above the dam represents an undisturbed section, while the other sites represent affected sites. Quantitative samplings were conducted monthly from September 2012 to august 2013. There were 10 939 caddis fly larvae determined. The data were processed by the ASTERICS software. Length-frequency histograms were used for life cycle identification. Secondary production of an abundant species was evaluated by size-frequency method. The dominant species of the un-impacted site was Ecclisopteryx dalecarlica while the below-darn section was dominated by a species Hydropsyche incognita. The results show that Ecclisopteryx dalecarlica is very sensitive to regulation, which has been proved by life cycle histograms and rare occurrence at site immediately below dam. The dam is the reason for sensitive species reduction and enable more tolerant species to develop. (authors)