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(35-02) The predictive value of biodiversity indices and multivariate techniques in ecological risk assessment of chemicals. Van den Brink, Paul*,1, Smit, (Els)2, 1 Alterra Green World Research, Wageningen, The Netherlands2 National Institute for Public Health and the Environment, Bilthoven, The Netherlands ABSTRACT- In ecological risk assessment, effects of chemicals on biological diversity are normally evaluated in terms of integrative endpoints. For instance when using results of microcosm and mesocosm experiments in the assessment, effects of stressors are presented by showing the changes in biodiversity indices in time for the different treatments. Recent research, however, indicated that these indices are quite insensitive for detecting subtle effects of compounds. This may be due to the fact that only a part of a community is sensitive to the chemical (e.g. arthropods in case of the effects of an insecticide on macro-invertebrates). More important, information and statistical sensitivity is lost during the integration of underlying data into a single parameter or by applying a step-wise analysis. Additionally, the variability in experimental results decreases the chances of subtle effects being detected. The recently developed multivariate technique Principal Response Curves (PRC) overcomes these problems by a simultaneous analysis of all data on abundance of species per time and concentration, focussing on the changes in a treatment relative to those in the control. This technique has also the advantage that an interpretation back to the species level is allowed. In this paper critical threshold levels resulting from diversity indices and PRC will be compared using aquatic and terrestrial studies evaluating the effects of pesticides and heavy metals. The critical threshold levels of PRC will also be compared with the response of the most sensitive endpoint to estimate the protective power of PRC for changes at the species level and herewith the biological diversity of ecosystems. The possibilities and limitations of PRC to evaluate pollutant effects on biological diversity in field situations will also be discussed. Key words: Principal Response Curves, mesocosm, community level effects, biological diversity |
