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)
respectively. A more detailed study is necessary to clarify the reasons (perhaps Carex releases chemicals which inhibit diatoms?). Abundance (Fig. 4) on the old reeds was much higher (2.05 * 10 6 ind/cm 2 ) than on the green reeds (0.65 * 10 6 ind/cm 2 ). It is not too surprising, because there is more time to develop periphyton on old reed. Before the flood, the average abundance was lower in the 2nd sampling point than on the 1st and the 3rd point. It may have been caused by the lower water temperature and shadiness (Table 1). Abundance in the 4th point was low, as this sampling point was shaded by high trees. Table 1. Water temperature, total hardness and conductivity in the 4 sampling point in Cikolasziget, on 13 July, 1991 sampling points 1 2 3 4 water temperature (°C) 23.50 20 25 24.50 total hardness (°d) 11 13 11 12 conductivity (u,S) 63 63 63 64 SUMMARY Species composition, number of taxa and structure of the periphyton samples collected from the Danube's side branch-system at Cikolasziget show transitional characters between the periphyton of standing and flowing waters. Samples draw from the same sampling point resemble each other more than samples collected from the same hosts. This result was also found by STEVENSON and HASHIM (1989) in the branches of Maple river. It seems that the most important factor in the development of periphyton is water discharge. Under similar flowing conditions similar coats develop on the same host. Nevertheless further investigations are necessary to test these hypotheses, with more samples from different locations under various circumstances (seasons, water discharge, etc.). Acknowledgement: We gratefully acknowledge the help from Keve T. KISS in identification of the Centrales taxa, Miklós RAJCZY and Keve T. KISS for critical comments on the manuscript, from Peter CARENKO who confirmed on identification of some Chlorococcales taxa and from Ljudmilla BUHTIJAROVA who helped us in SEM identification. REFERENCES ÁCS, É., BUCZKÓ, K. and LAKATOS, GY. (1992): A Velencei-tó és a Fertő nádbevonatának összehasonlító algológiai elővizsgálata. (Comparative algological
