B. Papp szerk.: Studia Botanica Hungarica 32. 2001 (Budapest, 2001)
Buczkó, Krisztina, Reskóné Nagy, Mária , Vinogradova, Oxana N.; Kiss, Gábor: The occurence of Aphanothece stagnina (Spreng.) A. Br. in Lake Velence, Western Hungary
shed area of 615 km 2 . Its average water depth is 1.2 m, which means that great winds may easily stir up the water affecting it down to the bottom. In the 70s, before the lake regulation, one of the main characteristics of the lake was its mosaic-like pattern, in which the quality of the different parts of the entire water body was clearly separable. Among the two streams providing water supply for the lake, the "Császár-víz", flowing through the western part of the lake, abundant in reeds, looses most of its organic matter in a natural way, while the other stream in the eastern part of the lake runs directly into it. Due to this, near the place called "Fürdető" the amount of organic matter is the largest in the lake, and the colour of the water is greener than elsewhere. The interior parts of the lake, surrounded with reeds, with their dark brownish water, have been habitats of swampy character. The third type of habitat is usually referred to as the waters of transitional features (BARTHA 1977, BARTHA and HAJDÚ 1979). LAKATOS (1976,1978), LAKATOS and BARTHA (1989) have provided details on the benthonic eutrophisation of Lake Velence. MATERIAL AND METHODS Macroscopic mucilaginous colonies were sampled from the water surface in August 1997. The material was partly fixed by formalin solution, and partly dried up, and placed into the Collectio Algarum of the herbarium at BP under the number 1997/47. Collecting the lake bottom samples was carried out by an Ekman-Birge sampling instrument, and each sample was taken from a bottom surface of 15 by 15 cm. The samples taken by this method are considered undisturbed, thus well representing the circumstances in the lake bottom. In the monitoring of the lake we have been using this method continuously since 1989. The first author identified the taxa using Felfóldy's guide (FELFÖLDY 1972), and it was confirmed by O. VINOGRADOVA. Her microscopic examination was made under an Olympus BX^tO light microscope. Identification was performed using "Siisswasserflora von Mitteleuropa" (KOMÁREK and ANAGNOSTIDIS 1999). RESULTS AND DISCUSSION As a result of macroscopic observation and microscopic investigation of the material collected in Lake Velence, it was identified as Aphanothece stagnina (Spreng.) A. Br. The species description is given below: Colonies macroscopic, gelatinous, irregularly spherical, up to 5-6 cm in diameter, dark grape-green, with loosely dispersed cells. Action on colonies by lactic acid testified the presence of calcite. Mucilage of the individual cell envelopes is confluent, invisible. Cells cylindrical with
