L. Forró szerk.: Miscellanea Zoologica Hungarica 10. 1995 (Budapest, 1995)
Gulyás, P., Bancsi, I.; Zsuga, V.: Rotatoria and Crustacea fauna of the Hungarian watercourses
weather conditions one species was able to establish large populations (e.g. Bosmina coregoni 2.90 g/m 3 , Brachionus spp. and Notholca acuminata 1.42 g/m 3 ). The second stretch is in between the cooling lakes of the power stations and the Tatai Öreg-Lake, it has more stable water regime, and is richer in species (35 Rotatoria, 12 Cladocera 5 Copepoda). Biomass varied between 0.04 - 14.32 g/m . In the fall of 1993 and the spring of 1994, for example large populations were formed almost entirely of Bosmina coregoni, Daphnia longispina, and larvae of copepods. The communities were formed by taxa characteristic to eutrophic waters. In the water of the third section, downstream of the Tatai Öreg-Lake, Zooplankton communities characteristic to fishponds were found, dominated by species typically occurring in eutrophic and polytrophic stagnant waters. Accordingly, biomass values varied between 9.73 -110.05 g/m in almost every season. 35. Séd-Nádor-catorna Sampling was earned out downstream of Székesfehérvár. The communities were characterized by dominant Rotatoria and Crustacea species living in eutrophic and polytrophic waters. Almost all of the 48 Rotatoria, 9 Cladocera and 5 Copepoda species found are indicators of waters rich in organic matter and plant nutrients. Biomass was gradually increasing downstream and varied in the range of 0.12 - 13.61 g/m 3 . Among the investigated streams water quality of this canal is one of the worst. 36. Sió Sampling on the Sió was undertaken when no water outflow from Lake Balaton was conducted. On the basis of the Zooplankton community investigations the stream can be divided into two sections. In the Siófok region communities are richer, indicated by the occurrence of 54 Rotatoria, 10 Cladocera and 4 Copepoda species. Biomass at this section in general was low (0.12 - 0.91 g/m 3 ). In warm summer period however, when no water flow is encountered, a few eutrophic species of Brachionus, Euchlanis, Keratella and Lecane formed large populations (max. biomass value was 5.18 g/m 3 ). Downstream the composition of the community showed species number decrease and abundance increase. Dominance of taxa characteristic to nutrient rich waters is evident in almost every season. Biomass varied between 0.79 - 10.67 g/m , but during the vegetation period its value was near to maximum. On the basis of its Zooplankton community the Sió belongs to the eutrophic category. 37. Kapos 55 Rotatoria, 14 Cladocera and 2 Copepoda species were found in the river. Species composition of Zooplankton community until Dombóvár is relatively poor, due to the high amounts of filamentous algae and macrovegetation in the river bed and in the littoral zone. As a result of benthic eutrophication the biomass is low (0.04 -1.23 g/m 3 ). For this particular river section the occurrence of non-planktonic species is characteristic: Colurella colurus, Euchlanis pyriformis, Lecane closterocerca, Lepadella patella, Lophocharis oxysternon, Mytilina ventralis, Alona spp, Macrothryx laticornis, Eucyclops serrulatus. At river sections upstream of Dombóvár the species composition changed, as indicated by
