Vízügyi Közlemények, 2004 (86. évfolyam)

3-4. füzet - Gulyás Pál: A rotatoria és curstacea plankton biodiverzitás monitorozása a Tiszabercel Balsa közötti Tisza szakaszon és holtágban

510 Gulyás Pál As contrasted to this, the results of the investigations of 2001 indicated that the species composition of Rotatoria is the richest one, followed by that of the Cladocera and the Copepods. Some rare species were also registered but their number was less than before. No new rare species were registered. In the summer and fall of 2000, following the cyanide catastrophe, the number of individuals of Crustacea was slightly decreases. The reason was that in this period the water level was higher in the oxbow lakes and in the marshlands. On the basis of the results of the investigations the Crustacea stock can be grouped into four categories in respect to species composition and individual density: 1. Tisza (Tiszabercel, Balsa); 2. Wetlands (marshes), (Mocsolya and Lake János); Oxbow lakes (Szakadás, Oláh-Zúgi; Marótzúgi, Remete-Zúgi oxbows -dead-Tiszas—, and the Lake Kacsa); and the Canal Lónyai. Possessing these results one may state than in sluggish streams and standing water bodies Rotatoria and Crustacea are the planktons that are suitable for bio-monitoring and for the biological classification of these waters, and for assessing their trophic state. Knowing their population density one may suggest the timing of the need for water supplementation and the volume of water needed. In slowly flowing or medium flow velocity water courses and canals the data on the species composition and population density may also indicate the presence of polluting or toxic substances. The Rotatoria and Crustacea plankton of the River Tisza have changed in comparison of their state 10-15 years ago. It became a characteristic feature mainly in the periods after floding when the species-composition and density of individuals were, in the water volume of decreasing tendency, different from those in 2001.