L. Hably szerk.: Studia Botanica Hungarica 23. 1992 (Budapest, 1992)

Buczkó, Krisztina; Ács, Éva: Preliminary studies on the periphytic algae in the branch-system of the Danube at Cikolasziget (Hungary)

minutissima was found in "flowing water form" (without stalk) but in "standing water amount" (it was predominant). Another phenomenon confirming the "flowing water" character of the site is the dominancy of Achnanthes lanceolata. Achnanthes lanceolata is a typical, dominant and constant taxon of flowing water periphyton in the Danube (ÁCS and KISS 1991). It was completely absent from the samples before the flood but it became predominant after it. The result of the cluster analysis (using CZEKANOWSKI's resemblance measure - Fig. 3) show that the sample collected from twig after the flood is separated from the others. However, its species composition is also significantly different from that of the other samples. (Relative abundance of Achnanthes minutissima was found to be only 1.5 % - similar to the summer samples in the main branch at Göd (ÁCS and KISS 1991). Perhaps the flood brought this twig from the main branch. The sampling points are quite well separated from each other (Fig. 3). Within this, the samples collected from Carex acutiformis differ from the other samples collected from the 2nd sampling point. This is caused by Characium ensiforme whose dominance was as high as 67.42, while on other hosts it was only 9.5 and 5.0 Sampling points Fig. 4. Abundance of periphyton in the 4 sampling points. For abbreviations see Fig. 3.