Structure and production of the metazoan zooplankton in Lake Balaton (Hungary) in summer

Taxonomical diversity, numerical density, biomass, production, and biomass turnover of the metazoan zooplankton of Lake Balaton were compared between two different open water areas with different primary production, in the summers 1998, 1999, and 2000. Density of the zooplankton showed 1.1 to 3.2 fold differences between the less and more trophic areas. Density of the crustaceans, add up to the total density of rotifers and veligers. Net production of the primary consumers (filter-feeders and sedimentators) in the more trophic area exceeded 2 to 4 times of that in the less trophic area. In secondary consumer (predatory) level, such a difference had not been observed. The ratio between the net production of the primary and secondary consumers changed in the range of 4.7 to 5.9 and 14.5 to 30.3 in the less and the more trophic areas, respectively. Gross production of the zooplankton exceeded 8.5 to 9.1 and 5.1 to 5.9 times of the net production in the less and the more trophic areas, respectively. Biomass turnover time of the zooplankton was 8.41 and 7.79 days, in the less and the more trophic area, if net production was considered. Considering the gross production, that was 2.5 and 2.2 days, respectively.