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

MISCELLANEA ZOOLOGICA HUNGARICA Tomus 13. 2TJ00 p. 59-75 Rotatoria and Crustacea plankton communities of the feed-water streams of the Lake Balaton by P. Gulyás (Received June 12,1999) Abstract: The paper deals with the Rotatoria, Cladocera and Copepoda plankton of the 21 streams feeding the Lake Balaton in the period of 1997-1998. Zooplankton studies were completed with detailed water chemical analyses from which only the water quality indices are evaluated herein. Occurrence data are given in an attached list of species according to streams, additionally water quality, faunistic and ecological characteristics are also assessed. Occurrence of 75 Rotatoria, 34 Cladocera and 13 Copepoda, altogether 122 species were recorded during the study. Keywords: feed-water of the Lake Balaton, water quality, Rotatoria, Cladocera, Copepoda plankton Introduction The Hydrobiological Department of the Water Resources Research Center during 1997-1998 conducted a detailed hydrobiological and water chemistry study of 21 small streams feeding the Lake Balaton. The primary aim of the study was to analyze the ecological state of the streams, collection of floristic and faunistic data and the methodological harmonization of the biological water quality assessment methods with the ones applied in the Member States of the EU. Preliminary studies were carried out between 1992 and 1997, a biomonitoring system was developed that is compatible with that applied in the European Community and takes into account the national monitoring and biodiversity surveys. In this earlier period we have conducted investigations at 48 larger rivers in Hungary when trophic and saprobic parameters, community structure of fito- and Zooplankton, as well as the survey of the aquatic macroscopic invertebrate were assessed in this integrated system (Gulyás 1992, 1993, 1997). No previous survey was ever conducted on the feed-waters of the Lake Balaton from this special respect. The present series of investigations is in harmony with the previous national survey and will represent a solid scientific background for the baseline ecological assessment of these streams to forecast long-term ecological changes. Results of water chemistry and biological investigations were evaluated according to the Hungarian Standards (MSZ 12749). Classification to water quality classes was also based on the principles as prescribed by the Hungarian Standards. This paper is particularly devoted to the assessment of the results of the investigation on the Rotatoria and Crustacea plankton. On the basis of the results a biological water quality monitoring system can be developed, which can be applied for the monitoring of the future ecological changes of the small streams around the Lake Balaton. Results are indicative of those water quality problems that effect at the present the ecological state of the lake. One of the most important factors amongst these is the nutrient load that enters to the lake via these streams causing eutrophication in the water body. In order to improve the ecological state of the Lake Balaton it is indispensable to have solid background information on the ecological state and biological water quality of the feed-waters of the lake.