L. Forró szerk.: Miscellanea Zoologica Hungarica 7. 1992 (Budapest, 1992)
Gulyás, P.; Forró, L.: Composition and abundance of microcrustacean fauna in the Upper Reservoir (Hídvégi-tó) of the Kis-Balaton
Number of individuals did not even diminish during the green-algal blooms in summer and fall, or during the Diatoma bloom in spring. Compared to previous years, the amount of planktonic crustaceans greatly increased as shown by the number of individuals and biomass maxima for the various parts of the lake: - the River Zala at the inlet: 33 i/dm 3 , 88 m&'m 3 , - in the vicinity of sampling place 2: 92 i/dm , 1223.5 mg/m 3 , - in the vicinity of sampling places 4 and 5:197 i/dm 3 , 4106.4 mg/m 3 , - in the vicinity of sampling places 6 and 7: 239 i/dm 3 , 6889.2 mg/m 3 , - at the outlet of the Hídvégi-tó: 166 i/dm 3 , 4490.5 mg/m 3 . Epibenthic communities In July 1987, besides a few cladocerans (e.g. Bosmina longirostris, Moina micrura, Alona rectangula), only one copepod species Acanthocyclops robustus £ limnetica was found in great abundance in the samples collected with funnel traps in the northern part of the lake (Station I) (Fig. 1). In contrast, at Station II Moina micrura dominated among the few cladocerans, but the individuals of A robustus £ limnetica constituted the greatest part of the sample. It is interesting that in that sample Iliocryptus sordidus was also represented by one specimen. The sample collected at Station III had an entirely different species composition, also containing such cladoceran species as Ceriodaphnia quadrangula, Chydorus sphaericus. Besides the unvariably dominant^, robustus £ limnetica, individuals of Megacyclops viridis and Thermocyclops crassus were also recorded. The samples collected in October 1987 slightly differed from the summer ones, since fewer species were found in the traps. The greatest number of species occurred at Station III. During the summer 1988, collections were made on three occasions. In July collections were made at Stations I and II. The species compositions of cladoceran assemblages were similar, Moina micrura, Alona rectangula and Alona affinis occurring most frequently. Of the Copepoda, Acanthocyclops robustus £ limnetica was dominant at both stations, but at Station II besides Cyclops vicinus two other species (Eucyclops serrulatus, Megacyclops viridis) also occurred. In July, samples were taken at all of the three stations, and in them Acanthocyclops robustus I limnetica was the dominant species, and of the very few cladocerans Moina micrura was the most frequent. During August collections were made at Stations I and III. Species richness was higher at Station III. At both stations the massive dominance of Acanthocyclops robustus £ limnetica was characteristic. In the course of the series of studies 16 Cladocera and 9 Copepoda species were found in the funnel traps (Table 1). The number of crustacean species ranged from 2 and 8 in the samples. The results obtained in 1988 showed that species number was the greatest in June, ranging from 6 to 7 and 4 to 5 at Stations I and II respectively. In July species numbers decreased, in the samples collected at Stations I, II and III 3-4, 2 and 2-3 species were found respectively. In August, the individuals of 2-3 species made up the cladoceran and copepod assemblages at Station I and III.
