L. Forró szerk.: Miscellanea Zoologica Hungarica 13. 2000 (Budapest, 2000)
Gulyás, P.: Rotatoria and Crustacea plankton communities of the feed-water streams of the Lake Balaton
values are characteristic to the eutrophic Hungarian waters. This was quite evidenced by the occurrence of the dominant species: Brachionus angularis, B. quadridentatus quadridentatus, B. quadridentatus brevispinus, Euchlanis dilatata, Keratella cochlearis cochlearis, K. c. tecta, Chydorus sphaericus, Pleuroxus aduncus, Acanthocyclops robustus f. limnetica, Eucyclops serrulatus, Macrocyclops albidus. Apart from the listed species some rare ones also occurred inhabiting the submersed vegetation and biotecton: Brachionus quadridentatus melheni, Lophocharis oxystemon, Mytilina ventralis, Paradicranophorus hudsoni, Testudinella parva, Eurycercus lamellatus, Oxyurella tenuicaudis, Eucyclops speratus. 9. Világos creek Specific electric conductivity values were extremely high in this creek in the range of 1480-1890 pS/cm. Minimal value corresponds to oligo-mesohalobic while the maximum value to the beta-mesohalobic stage. On the basis of the inorganic ionic composition the water is within the beta-limno-type with characteristic Ca - S0 4 , Ca - Mg - S0 4 and Ca - S0 4 - HC0 3 composition. The Világos creek is characterized by the specific electric conductivity value and sulfate content, which indicate high ionic strength of fresh and salt waters. Dissolved oxygen concentrations and COD values are all indicating even worse situation of high pollution. As far as the plant nutrients are concerned the amount of ammonium, nitrate and dissolved orthophosphate were all low and only the total phosphorus concentration was high, indicating polluted state. The chlorophyll-a concentrations varied widely in the range of 96.0-98.0 pg/1. Species composition of the Rotatoria and Crustacea communities was similar to the Kétöles creek, and the magnitude of abundance was almost identical (212-1156 ind./100 liter). Dominant species are characteristic to the slow flowing or stagnant eutrophic surface waters: Brachionus angularis, B. quadridentatus quadridentatus, Euchlanis dilatata, Lepadella patella, Lophocharis oxystemon, Ceriodaphnia quadrangula, Chydorus sphaericus, Acanthocyclops robustus f. limnetica, Eucyclops serrulatus. No rare species was found. On the basis of the Rotatoria and Crustacea results the water quality of the creek is moderately polluted, eutrophic. 10. Lesence creek Minimal value of specific electric conductivity indicate alpha-oligohalobic, and maximal value oligo-mesohalobic stage. On the basis of the inorganic ionic composition the water is within the beta-limno-type with characteristic Ca - HC0 3 -S0 4- or Ca - Mg - HC0 3 - S0 4 composition. The water quality of the creek is slightly worse than the Világos creek, as the result of the lower dissolved oxygen concentration and oxygen saturation. All of the measured other parameters are almost identical to the values measured on the previous creek. Chlorophyll-a contents of the water were showing similar fluctuations as the previously described stream. Number of Rotatoria and Crustacea taxa was 26, the presence of higher number of (6) Cladocera species is somewhat unexpected. Abundance values were measured to be low in every occasions, in the range of 70-238 ind./100 liters. The possible reason for this is the polluted water, the low oxygen content and lack of nutrients. Beside the already mentioned Rotatoria species the following ones are present in the biotecton: Cephalodella gibba, Trichocerca stylata, Trichotria pocillum and one Philodina species. Amongst the Crustacea species the following are aquatic plant surface dwelling: Alonella nana, Ceriodaphnia reticulata, Scapholeberis mucronata, Simocephalus vetulus and Acanthocyclops vernalis. On the basis of the Rotatoria and Crustacea plankton results this stream is polluted, with dense aquatic vegetation, and slow flow.
