Mathematical modelling as a tool for predicting the intensity of eutrophication symptoms based on zooplankton and fish density

In temperate zones, algae biomass may be efficiently controlled by Daphnia sp., which is the most significant grazer among filter-feeding zooplankton. Daphnia population dynamics depends mostly on the trophic state of the ecosystem, which determines both fish community structure and food quality and availability. Relatively invariable water inflow to a reservoir with small amplitudes supports balanced biotic interactions. Here, we present simulations using the DALIS model that well characterised behaviour in a temperate ecosystem under stable abiotic conditions. The model results allowed us to predict the extent to which predation by fish would disturb the dynamics of Daphnia under different food conditions. Therefore, mathematical modelling may be an important tool for establishing appropriate recovery strategies in eutrophic water bodies. Although the model in this study characterised temperate zone conditions, its application to tropical lakes, where the dynamics of zooplankton and fish are substantially different, is discussed.