BIOMASS OF PLANKTONIC CRUSTACEANS AND THE FOOD OF YOUNG CYPRINIDS IN THE LITTORAL-ZONE OF LAKE BALATON

The littoral zone of Lake Balaton and its periphyton-zooplankton-fish communities have been investigated intensively in recent years. Total average number of crustacean plankton varied from 36 to 126 ind 1(-1), their biomass from 0.49 to 1.86 mg ww 1(-1) month (-1) at different a reas of the littoral zone. In general these values for the above param eters were higher in hypertrophic areas. 23 fish species occurred in t he littoral zone with cyprinids dominating. The seasonal food spectra of Y-O-Y roach (Rutilus rutilus), white bream (Blicca bjoerkna) and br eam (Abramis brama) were based mainly on planktonic crustaceans and be nthic/periphytic invertebrates. According to the frequency of occurren ce of crustaceans and other invertebrates, the food composition of you ng cyprinids differed significantly in the NE and SW-basins of the lak e.