Suppression of Cyanobacterial Blooms by Zooplankton: Experiments in Natural Water Bodies with the Use of Flow-Through Ecosystems

Abstract

—In a pond, the trophic press of fish suppresses the development of large-size filter-feeders (Daphnia longispina and Simocephalus vetulus). Large-size cladoceran species are replaced by smaller species. The Micro-cystis aeruginosa blooms and the trophic press of fish are accompanied by a loss of the species diversity of filter-ing zooplankton and by a drop in its biomass to minimal levels. Flow-through experimental ecosystems separate zooplankton-consuming fish, thereby causing abrupt increases in zooplankton abundance and biomass. Water flow in the experimental ecosystem destroys cyanobacterial colonies and increases the proportion of their fractions with a size making them edible. This favors increases in zooplankton abundance, size, and fertility.