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4. Moving from the lab to the landscape: Extending the role of ecology in risk assessment (TU4/3) Scale dependency in pesticide side-effects creates problems for risk assessment and experimental design. Jepson, Paul1, 1 Oregon State University, Corvallis, U.S.A. ABSTRACT- The processes that govern the exposure, uptake, toxic effects and population recovery of terrestrial and aquatic invertebrates exposed to pesticides, evolve over a sequence of temporal and spatial scales. Pesticide effects can be divided into an initial stage, which is dominated by the intimate interactions between chemical and organism, and a later stage, which is dominated by population processes. As these stages evolve, discontinuities occur, across which shifts take place not only in temporal and spatial context, but also in the level of biological organization at which the underlying mechanisms and processes must be investigated. The parameters that govern the key processes underlying pesticide impact may only be quantified within particular spatial and temporal scales, and at specific levels of biological organization: they are both scale and level dependent. Progression through the various stages of the ecotoxicological process, and the transition through temporal and spatial scales may be logical on paper, but very few research projects have encompassed this breadth. There are consequences for this, particularly an excessive and perplexing focus on phenomena that take place at the micro scale. This paper explores the implications of scale dependency for the ecotoxicological interactions between pesticides and invertebrates (both terrestrial and aquatic), and examine the consequences for risk assessment and experimental design. Key words: pesticide, scale-dependency, risk assessment, aquatic macroinvertebrate |
