Zooplankton-phytoplankton interactions: a possible explanation of the seasonal succession in the Kuršiu Marios lagoon

The zooplankton-phytoplankton interactions in the Kuršiu Marios lagoon (southeastern Baltic Sea) were investigated in 1995. The objective was to evaluate the role of herbivores (crustacean zooplankton) in the seasonal succession of phytoplankton, as well as the influence of food conditions on structure and dynamics of zooplankton community. Our results demonstrated that the crustacean grazing pressure may restrict the development of small Chlorophyta and Diatomophyceae and, in turn, favouring growth of Cyanobacteria. Blooms of filamentous Cyanobacteria possibly has an inhibitory effect for Daphnia, decreasing their biomass as well possibly explaining the shift of dominant zooplankton species. The influence of planktivory on seasonal plankton succession remains unclear because of lack of fish data.