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

Fig. 8. Changes of relative abundance of Chaetoceros muelleri in the four years examined other samples are getting more and more similar (Figs 4-5). On the basis of the analyses of the periphyton samples it seems that the lake has lost its former mosaic-like character, except the natural protection area where the original water quality was more or less preserved, though the composition of its algal coating has been also transformed, by the immigration of certain blue-green algae originally characteristic of the basement regions. CONCLUSIONS By our days the Lake Velence has almost completely lost the former mosaic-like character of its water quality. Traces of the original water quality is maintained only by the protected western parts of the lake. Due to artificial interference, by the clearing of the remaining reed fields the water of formerly distinct regions have been mixed. Formerly, the unwelcome effects of local deterioration of water quality were isolated (local) effects (e.g. mass fish decay due to temporary decrease of oxigen), but lately the disadvantageous effects could spread almost without obstacles throughout the whole lake (e.g. the mass spread of the