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

10 Lim 0 cP°0 Fig. 1. The cells of Aphanothece stagnina. rounded ends, with homogeneous pale- to bright blue-green content, 3.8-4.4 x 7.6-8.4 um (Fig. 1). Occurs on the water surface and in sediments of Lake Velence. The size of the colonies in the sediment was quite variable. The samples collected near the "black waters" were relatively small (with diameters of 0.7-1 cm, like beans) while near the "brown waters" we sampled larger ones detached from the bottom. These have reached the size of 5-6 cm (like the dimensions of a peanut or walnut). The surface of the sample gathered in June 1997, with its greenish colour was in sharp contrast to the ochre-brown colour we had expected and had been accustomed to. Besides the colonies having homogeneous greenish colouration, we also detected some vivid green ones of the size of a bean. Thus, it was the first occasion of detecting such phenomenal occurrence of algae either in the water or on the sediment. In August 1997, besides the vicinity of "Német-tisztás", these mucilaginous colonies appeared in the "Mély víz" area, and by the end of the autumn, these were not only visible near the sediment surface, but also close to the water surface. Having reviewed the reports on Lake Velence we did not find any data or reference concerning the presence of Aphanothece stagnina. According to the fishermen who know these parts of the lake well, there is a massive occurrence of this cyanobacterium from time to time, however, depending on the weather conditions. There is a high probability that it is more widely distributed in the sediments. Based on our observations, the most probable occurrence of this species is in the areas illustrated in Figure 2.