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
LAKE HIDEGSÉGI flower plants ( Phragmites communis , Typha angustifolia, Schoenoplectus litoralis ) located in Lake Hidegségi (Fig. 1). From each substrate plant type 15 repetition were collected to obtain statistically reliable results. In the case of Phragmites and Schoenoplectus the abovewater parts were cut off, then a glass tube (13 mm diameter, 0.2 in in length) was pulled over the underwater stump and cut off at end the tube. The lower end of the tube was closed and the section of the stem thus transvered to a collecting jar. In this way the samples contained the loosely attached layer too (LAZAREK 1982). Sections of Typha an gustifolia were collected without the use of tube, because the diameter of Typha is larger then 13 mm. The periphyton was thoroughly SC raped off from the sections of stem within 48 hours, and then the samples of periphyton were fixed in formaldehyde solution (2-4 %). The permanent diatom slides were prepared with the H 2 0 2 method of HORVÁTH(1975).Four hundred individuals were counted in eacn sample to yield a counting accuracy of - 10 % (LUND et al. 1958). The Shannon diversity index were calculated for each sample (SHANNON 1948). Floristical data were analyzed using cluster analysis based on Jaccard' s measure (JACC ARD 1908), and WPGMA fusion algorithy (SNEATH & SOKAL 1973). For the calculations the BP programme package was used (RAJCZY & HAJDU 1981). RESULTS Fig. Location of sampling position One hundred and five taxa were identified during the study (Cyanophyta 3, Chrysophyta-Bacillariophyceae 98, Chlorophyta 4). These are listed in Table T. The high percentage of diatoms is remarkable because of the total number of individuals (92.5 %). Diatoms are practically fully dominant on Phragmites and Schoenoplectus (99.7 % and 99.9 % respectively), while on Typha the relative frequency of individuals of blue-green and green algae is 13 % (Fig. 2). The most prevalent diatom throughout the study was Achnanthes minutissima occurring on every macrophyte stem section studied. On Schoenoplectus and Phragmites it gave 70 % of the total number of individuals on the average, while 48 % of the algae living on Typha belonged to this algae of minute size. In addition, the following taxa of considerable quantity were found (averages): Diatoma elongatum 14 %, Oscillatoria sp . 4.6 °k Cocconeis pediculus 2.4 %, Bacillaria paradoxa 2.1 %, Synedra acus 1.6 %, Gomphonema sp . 1.2% Rhoicosphenia curvata 1.1 %. These taxa were found on all the three kinds of substrate. The number of taxa found only on one substrate is the following: on Phragmites 11, on Schoenoplectus 17, on Typha 24. I found a total of 54 taxa on Phragmites. 57 taxa on Schoenoplectus and 74 taxa on Typha . Cluster dendrogram of samples based on Jaccard' s measure is shown in Fig. 3. Two large groups are separated. One contains samples mainly from Schoenoplectus and Typha, and the other contains all the samples from Phragmites , three samples from Schoenoplectus and two samples from Typha . The two samples joining supplementarily are from Typha and Schoenoplectus , respec-
