Ecosystem risk analysis: A new methodology

Abstract

Abstract A method is presented for extrapolating laboratory toxicity data to aquatic ecosystem effects such as decreased productivity or reduction in game fish biomass. The extrapolation requires translating laboratory data into changes in the parameters of an ecosystem model, the Standard WAter COlumn Model (SWACOM). The translation is effected through knowledge of toxicological modes of action. The uncertainties associated with both laboratory measurements and extrapolations are explicitly retained, and risk estimates are given in the form of probabilities that an effect could occur. The approach is illustrated by scenarios in which effects of toxic substances are distributed across different trophic levels. Each scenario affects population interactions in different ways and alters both the level and the nature of the risks to ecosystem processes. Particular attention is paid to analyzing the interaction between toxicity and the uncertainties associated with extrapolation.