L. Lőkös szerk.: Studia Botanica Hungarica 25. 1994 (Budapest, 1994)

Ács, Éva, Buczkó, Krisztina; Lakatos, Gyula: Changes in the mosaic-like water surfaces of the Lake Velence as reflected by reed periphyton studies

water surfaces with algae, while the riparian parts without reed was characterised by green water. The quality of certain water surfaces was changeable depending on the courses of the wind; these were of transitional character. In course of a restoration work in the eighties 4.1 km of reed fields were cleared, aiming at better recreation circumstances. The water chemical conditions of the lake are known from the works of FELFÖLDY (1972a, 1973, 1974, 1975, 1977) and GORZÓ (mscr.). Phytoplankton studies were performed by BARTHA (1977, 1979, 1980), BARTH A and HAJDU (1978), periphyton studies by LAKATOS (1975, 1976, 1978, 1983, 1986, 1989), LAKATOS and BARTHA (1989), LAKATOS and Ács (1990), LAKATOS et al. (1991), ÁCS and LAKATOS (1990), Ács et al. (1991). The present paper discusses the investigations of the reed cover of Lake Velence in 1989 and 1990. Studies in 1988 have already been published in details (ÁCS and LAKATOS 1990, ÁCS et al. 1991, LAKATOS and ÁCS 1991). For the evaluation of the formation of the mosaic-like character as well as for the interpretation of certain remarkable changes, data gathered in 1988 were also used, as well as the observations by LAKATOS and BARTHA (1989). MATERIALS AND METHODS Algal coating samples were collected in July 1988, 1989 and 1990 from the side of the reed-fields facing the open water surfaces, from the green reed stems just under the water surface level (5-35 cm below the surface). Sampling points coincided with those of LAKATOS and BARTHA (1989) who collected samples in 1978. Their points were originally selected with an eye based on the water Nagytó - Rigya Fig. 1. Sampling sites