ABSTRACT
We are developing a simulation model of a plankton community in order to obtain a tool for causal analysis of experimental results from freshwater field tests and for prognosis of possible direct and indirect effects caused by a test substance. The model itself is a differential equation model, where the population dynamics are described via the processes of photosynthesis, consumption, assimilation, respiration, and mortality, depending on the forcing functions temperature, light, nutrient input, and toxicant concentration. After calibration using data from an untreated control microcosm the model was able to predict effects due to an insecticide application. On the basis of Monte-Carlo simulations the model can be used for risk assessment. This approach is demonstrated for different ecological endpoints by hypothetical examples.
