L. Hably szerk.: Studia Botanica Hungarica 23. 1992 (Budapest, 1992)

Stollmayerné Boncz, Emilia: The alga species of the Csömör pool II.

importance of sampling points with one sample taken only (8, 9) or 3 samples (sampling point 6) is different. Taking all the algal groups into consideration, the highest number of species was found in point 4. It is immediately followed by, from the sampling points with considerable test number, point 3. Collating averages with reality, sampling point 2 is the poorest and 3 is the richest in algae. Evaluating the individual algal groups by sampling points, also points 3 and 4 turned out to be most productive in respect of algae. Most of the Cyanophyta were registered at sampling point 4, bulk of the Euglenophytons at sampling point 6, Xanthophyceae were mainly accumulated at point 3, while Bacillariophyceae reached their maximum at sampling point 6. Pyrrhophytons were found exclusively at sampling point 4, while Chlorophytons occurred at point 4 only. This is, of course, not exactly true for each month. E.g., the maximum of Cyanophyta took place in June at sampling point 3, that of Xanthophyceae at point 1 in May, Bacillariophyceae became most numerous at point 6 in August, Pyrrhophytons were occurring in June at sampling point 3, and Chlorophytons were observed in July at sampling point 3. Individual regions of the pool (the "island" and the "pool", respectively) were represented by different values of species/sample. Also, changes have been observed since 1984-85. In the course of the previous study, all the "lacustrine" values were higher (points 1, 2, 3, 8 and 9) than samples 4 and 7 of the island (sampling point 7 equivalent to recent sampling point 6). The group of Xanthophyceae did not even occur in the "island" samples of that series. By 1987-1990, the situation had changed. All groups (with the exception of Pyrrophytons present only in the lacustrine samples of sampling point 3) occurred in higher number on the two island sampling points (4, 6). Within the lake, the number of Cyanophytons generally decreased as compared to the values of 1984-85. In the other places, the average species number belonging to this taxon increased. As the flora of the lake became quite uniform as regards algal species, no specific tables are enclosed here. Rather, some characteristic features are stressed. E.g., species of Characium, Peridinium and Xanthopyceae (with two exceptions) were recovered only from lacustrine samples like Nitzschia heufleriana, e.g. samples from the island contained only Eunotia lunaris again; in single cases, the 1987-1990 samples contained Closteriococcus viernheimensis f. maior, Scenedesmus acutus f. altemans, Epithemia sp. (E. muelleri?) etc. As the main difference between the sampling points in the pool and on the island, i.e., pH value and the presence of Sphagnum species had disappeared, some local ecological factors are probably still at work. Even in the "island" samples of 1984-85, no species with definite preference for Sphagnum were found. There are more species in common between the "pool" and the island, respectively, than those typical of the pool only. This is understandable because the pool is small, and due to its sloping in S-N direction, the water can 'move' during higher water-levels; vegetation is not essentially different in any parts. The only exception is Lastrea thetypteris, occurring exclusively on the "island" and along the eastern shore. 27