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(T/FF228) HERBEST, a model describing the effects and recovery of populations in stressed aquatic ecosystems. Van den Brink, Paul1, Kuyper, Marjolijn1, 1 ABSTRACT- To protect aquatic life from pesticide stress, the EU has set criteria for the registration procedure of pesticides (Uniform Principles). The first tier in the risk assessment consists of the calculation of the TER (Toxicity Exposure Ration). The actual ecological risk, however, not only depends on the exposure regime and the susceptibility of species, but also on factors like their life-cycle characteristics and the abilities of affected populations to recover. In this paper we will present the model HERBEST, which estimates direct effects and recovery of aquatic field populations from the predicted or measured exposure concentration, their laboratory toxicity and life-cycle characteristics. The life-cycle characteristics that are taken into account are the number of emergence-periods per year, the ability to migrate and the reproduction rate. The model is integrated in a user friendly user interface and its first version will be presented on this meeting. The scientific background of the model, its strengths and limitations will be presented. The predicted response by the model will be compared with real response data obtained from a number of semi-field experiments. Key words: effect model, recovery, risk assessment, pesticides |
