Az Alpokalja természeti képe közlemények 12. (Praenorica - Folia historico-naturalia Szombathely, 2012)
7. Summary
Praenorica Folia historico-naturalia, XII (2012) 7. SUMMARY The range of algae and concentration of chlorophyll-a in Stages I and II of the KisBalaton Water Protection System, designed to reduce pollution in Lake Balaton, were followed from the outset with a view to learning how the waters of the Zala become standing water, about the eutrophication processes there, and about the system's effect on water quality in the Keszthely Bay of Lake Balaton. The planktonic and filamentous algae of the still uncompleted system were examined over three periods (1985-88, 1991-1994 and 1999-2000). Under Stage I, the waters of the river Zala in the upper part of the storage system turned over one year into standing water, and in 1987 developed a strong presence of planktonic lake algae as far as the outflow. The total number of taxa in 1985-88 was 601, of 218 were identified in 1985, 337 in 1986, 446 in 1987, and 397 in 1988. A detailed list oftaxa appears in Table 1.1. To sum up: 618 taxa were found in four years. The breakdown of the alga taxa was as follows: Cyanobacteria 70, Xanthophyceae 9, Chrysophyceae 27, Bacillariophyceae 131, Cryptophyta, Dinophyta 14, Euglenophyta 122, Chlamydomonadales 20, Volvocales 9, Chlorococcales 184. Ulotrichales 3, Desmidiales 23. The greatest number of species (Monoraphidium , Scenedesmus spp., Pediastrum spp.) was found in the Chlorococcales group of green algae, followed by diatoms. The planktonic Aulacoseira distans, Cyclotella meneghiniana, Nitzschia acicularis, Skeletonema potamos, Stephanodiscus hantzschii and Thalassiosira weisflogii dominated in the early storage period, followed by the green algae in the summer. There appeared several flagellate alga taxa (the third largest group) which prefer shallow, marshy waters. From 1987, cyanobacteria caused algal blooming (Microcystis aeruginosa, Microcystis flos-aquae , Aphanizomenon flos-aquae), which led to very high chlorophyll-a concentrations (up to 1287 mg/m 3). The commonest taxa in most samples were Lyngbya limnetica, Merismopedia minima, Aulacoseira subarctica, Cyclotella meneghiniana, Stephanodiscus hantzschii, Nitzschia acicularis, Monoraphidium contortum, Scenedesmus spinosus. Only one species. Stephanodiscus hantzschii, featured in more than 80 per cent of the samples constancy. New recorded occurrences in Hungary appeared mainly in the Trachelomonas and Kephyrion taxa. Based on its alga associations, the reservoir could be divided into four surface areas initially, then three, and later only two. In Stage 2 the composition of the algae was measured in drawn plankton samples and in the coating of weed. The total number of taxa was 317. A detailed list of the taxa appears in Table 2.1. The yearly breakdown was 114 in 1991, 134 in 1992, 160 in 1993, and 141 in 1994. By group they broke down into 60 Cyanobacteria, 107 Bacillariophyceae, 10 Dinophyta and Chryptophyta, 32 Euglenophyta, 64 Chlorococcales, 29 Zygnematales, and 16 others. Compared with Stage 1, there were 118 newly occurring taxa, most of them diatomic algae and cyanobacteria. Nitzschia capitellata, Nitzschia linearis and Amphora ova/is featured on a mass scale in the alga coatings of Ceratophyllum and Stratiotes. The richest in taxa (58) was the alga coating of Ceratophyllum demersum in the Vörsi-víz. The taxa common to all the weeds amounted to 31 per cent of the total. The constant alga were Cyclotella meneghiniana, Fragilaria ulna and Nitzschia acicularis. It was 132
