L. Forró szerk.: Miscellanea Zoologica Hungarica 7. 1992 (Budapest, 1992)

Gulyás, P.; Forró, L.: Composition and abundance of microcrustacean fauna in the Upper Reservoir (Hídvégi-tó) of the Kis-Balaton

On the basis of species found in the water samples taken at about 30 sampling points, the lake could be divided into well separable water quality regions. Using the similarity dendograms obtained by cluster analyses, the following water quality regions could be distinquished (Fig. 2): - the inlet section of the River Zala, and the River Zala at the bridge of Zalavár, - the section of the lake between the Zalavár road and the millstream at Rada, - the cassette, - the southern part of the lake and the surroundings at the outlet, - the area of the islet "Kányavári-sziget", - the River Zala at the bridge of Balatonhídvég (Fig. 3). 2 Fig. 2. 15 10 7 11 Sampling sites Clusters of sampling sites based on the coexistential pattern of planktonic crustaceans (Sorensen-index) The analysis of the regional distribution of planktonic crustaceans showed that the central parts of the lake (the brook "Szabari patak", the mill-stream of Rada) were most rich in cladoceran species, while in the southern part of the lake the number of copepod species was great. On the basis of results obtained during phyto- and Zooplankton studies and water chemical analyses performed in 1985,11 sampling places were allocated, at which in the following years systematic studies were carried out. In 1986, the dominance of rotifers was characteristic in the whole area of the lake. Cladocerans were sporadical on each occasion and at each place. In the southern parts overgrown with vegetation and in the vicinity of the islet "Kányavári sziget" the diversity of Zooplankton was the greatest (sampling places 6 and 7).