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The World of Protozoa, Rotifera, Nematoda and Oligochaeta

Ref ID : 3504

Vera Opravilova; Microzoobenthos of the River Jihlava after the Construction of the Dalesice Waterworks. Limnologica (Berlin) 21(1):243-250, 1990

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To ascertain the impact of Dalesice Waterworks, changes in microzoobenthos were followed at the Hrubsice station on the river Jihlava. The first year of research, i.e. 1976-1977, was devoted to collecting baseline data before filling the reservoirs, the 2nd year - 1977-1978 - as a transitional period, and the 3rd year (= the 8th year since the beginning of this research), i.e. 1984-1985, reflects the changed due to the operation of the waterworks. Microzoobenthos was studied in 4 microhabitats: epilithic algal periphyton and detritus on submerged macrovegetation in the torrentile stretch; epilithic algal periphyton and detritus on macrovegetation near the bank in the fluviatile stretch. Microzoobenthos consisted mainly of the following groups of animals; Rhizopoda, Ciliophora, Nematoda, Rotatoria and Tardigrada. Abundance and biomass were studied. The latter was calculated from a volume of 0.1 ml of the sample sediment. Also the indices of diversity (H') and equitability (E) were determined. In the last year of research, i.e. when Dalesice Waterworks had been in operation for several years, the following changes in the composition of the microzoobenthos were found in comparison with the original situation: the number of taxa had decreased somewhat (Rhizopoda, Ciliophora, Rotatoria), the representation of Metazoa was lower (particularly in Rotatoria), and the values of the indices of diversity (H') and equitability (E) had decreased in all microhabitats. It can be judged that the reservoirs affected microzoobenthos above all by considerably reducing the supply of detritus and also by deepening the river and this effectively raising the water level. The character of river Jihlava at the station, which was originally that of the barbel zone, changed into that of the grayling zone.