Application of an ecosystem model for aquatic ecological risk assessment of chemicals for a Japanese lake

The Lake Suwa version of the comprehensive aquatic systems model (CASM-SUWA ) was developed using field data from Lake Suwa, and evaluated to examine t he utility of CASM-SUWA for assessing the ecological risk of chemicals for aquatic ecosystems. The calibration of the parameters for the model provide d that the established reference model simulation could reproduce complex s easonal biomass behavior of populations that were not significantly differe nt from the general seasonal pattern for the Lake Suwa ecosystem. The sensi tivity analyses revealed the potential importance of indirect effects and d emonstrated that the parameter values of all the trophic levels were import ant in determining the biomass of each trophic level in the model. The risk estimation of linear alkylbenzene sulfonates (LAS) demonstrated that the m odel estimated the risks of direct toxic effects on each population and the indirect ecological effects that propagate through the food-web in the mod el ecosystem. The CASM-SUWA-derived benchmark levels were approximately one order of magnitude less than the field-derived NOECs in literature. The an alyses of the comparison implied that the model could provide a good basis in determining an ecological protective level of a chemical of concern in a quatic ecosystem. This modeling study demonstrated that the model can be us ed to provide additional information for the decision-making process in the management of the aquatic ecological risk of chemicals. (C) 2001 Elsevier Science Ltd. All rights reserved.