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
These are among the Rotatoria and Crustacea as well. In saprobiological evaluation these species could serve for the indication of higher organic concentrations. 19. Nagymetszés trench Less polluted water than the previous one in spite of the fact that specific electric conductivity value is somewhat higher 820-1040 pS/cm, referring to alpha-oligohalobic-oligomesohalobic stage. On the basis of the inorganic ionic composition the water is within the beta-limno-type with ionic dominance of Ca - Mg - HC0 3 and Mg - Ca - HC0 3 . The parameters of oxygen budget also indicate better water quality as evidenced by the smaller fluctuations. On the basis of the measured COD values the water is moderately polluted. Among the nitrogen forms the ammonium and nitrate concentrations are lower, while the nitrite, orthophosphate phosphor and total phosphorus indicate worse water quality. Chlorophyll-ű content was found to be usually low (1.5-14.1 pg/1), with the exception of a November measurement when 61.0 pg/1 value was determined. Rotatoria and Crustacea communities are similar in species composition and abundance value to the Tetves creek. Altogether 34 species were found during the survey. Abundance value varied between 332-2984 ind./100 liter. The two largest and the two smallest value were found at identical sampling time. Dominant and rare species were also similar, of the latter category the Bosmina coregoni could be mentioned. Similarly to the previous creek species-rich Zooplankton communities were characteristic here. Predominately the abundance of organic pollution tolerant species was observed. 20. Kőrőshegyi creek Similarly to the previously described ones the water of the creek is heavily polluted. This is indicated by the high values of conductivity between 945-1170 pS/cm. This range corresponds to the alpha-oligohalobic-oligo-mesohalobic stages. On the basis of the inorganic ionic composition the water is within the beta-limno-type with ionic dominance of Ca - Mg - HC0 3 and Mg - Ca - HC0 3 . Among the oxygen budget parameters the oxygen saturation indicates the presence of organic pollutants which exceeded only at one occasion the 100% value. Similar water quality class is established on the basis of the dissolved oxygen content. COD values indicate tolerable pollution level. The elevated ammonium, nitrite and phosphorus characterize nutrient contents while the nitrate was less. All of these parameters indicate heavy pollution. Results of the water chemistry analyses indicate high organic pollutant levels. This is quite evident from the results of the Zooplankton community species composition and abundance values as well. Both the high taxon number (43), and the large populations and in presence of Copepoda (2) species all indicate the high trophic state of the creek Abundance values were measured between 1553-3173 ind./100 liter, but opposite to the previous creek this high value prevailed in each occasions. This also indicated planktonic eutrophication, characteristic of the eutrophic stage. Dominant species were represented by the Brachionusgenus with 10 species, while the Keratella with 5 species. Large amounts of the already mentioned Rotatoria and Crustacea species, tolerant to organic pollution, were found here. Rare species were represented by some new species (Keratella testudo, K. tropica, Mytilina bisulcata), not found in the previously described streams. On the basis of the results of the Zooplankton community investigations this creek is from moderately to heavily polluted, with high saprobic stage.
