L. Hably szerk.: Studia Botanica Hungarica 19. 1986 (Budapest, 1986)
Buczkó, Krisztina: A comparative study of the periphytic algae on three different flower plant species in Lake Hidegségi Fertő, Hungary
tively. Hence the periphyton of Phragmites and Schoenoplectus are well separated, while the periphyton of Typha is mixed with them, Fig. 4 shows the diversity of the 3 x 15 samples in increasing order. Looking at the diversity values between 2 and 3 we can notice that there are 10 samples in this interval from Typha, while from Phragmites and Schoenoplectus only 3 and 1, respectively. That is to say, the diversity of the samples from Typha is greater than that of the other samples. DISCUSSION Considering the abundance of the taxa my results are well in coincidence with the data of previous periphyton analyses made on Lake Fertő. PADISÁK (19821 found 68 taxa on Phragmites and 76 on Typha in Lake Herlakni this is another small brownwater inner lake of the Ferto. The dissimilarity in the distribution according to phyla is remarkable. She found 34 diatoms on Phragmites an 29 on Typha. Presumably the reason for the considerable difference is seasonal succession. Padisák elaborated samples from July, while the present sampling was in November. The temperature optimum of diatoms is considerably lower than that of algae of other phyla (PADISÁK 19851, sp this can be the reason for the strong diatom dominance in late autumn. There are very few studies on seasonal changes of periphyton communities on natural substrates, mainly due to a large number of methodological difficulties. The results of colonization studies on artificial substrate just because of host-specificity cannot be applied. A further problem is that in many studies only the seasonal changes of diatoms are analyzed (e.g. BLINN et al 1980, MILLIE et al 1983). Since we only planned such studied on Fertő, we are mainly reduced to conjectures. The result of cluster analysis shows that Phragmites and Schoenoplectus are well separated from each other so there is a considerable difference between them. The periphyton of Typha is mixed with both of them. The two supplementarily joining samples contain very few taxa (their diversity is less than 1), one contains 10, the other 4 taxa only. However, these taxa are common so these are not separated from the other samples. Considering diversities, the periphyton of Phragmites and Schoenoplectus seems to be similar while the diversity of algae living on Typha is greater. Comparing the lists oi taxa it is clear that Achn anthes minutissima can be found on Typha in considerably smaller number than on the two other substrates. Thus most prevalent taxa is responsible for the dissimilarity of diversities. We can state that the periphytons of all the three substrates are different. The periphytonn of Phragmites and Schoenoplectus are different floristically, while the periphyton of Typha differs from the other two in its diversity. The purpose of further studies is to calrify distribution and colonization patterns of periphytic algae on these three macrophyte hosts after which the dissimilarities found in this study can probably be explained. Fig. 2. Percentage contribution of periphytic diatoms and other algae relative to total number of individuals, upon three aquatic flower plants in Lake Hidegségi. (1 = Phragmites communis, 2 = Schoenoplectus litoralis, 3 = Typha angustifolia)
