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(066) Application of Leslie Matrix and Bootstrap methodologies to estimate chemical effects on aquatic populations and communities. Grist, Eric1, Crane, Mark1, Whitehouse, Paul2, Sorokin, Neal2, Wilkinson, Helen3, 1 2 3 ABSTRACT- Toxicity to aquatic organisms is usually expressed in terms of effects on individuals (for example, mortality, reproduction, growth) and these summary statistics are the basis for risk assessment and derivation of water quality standards. However, toxicity expressed at the level of the population may be more relevant to such regulatory applications. In this presentation, the influence of toxicity is explored through evaluating effects of a range of toxins on population intrinsic growth rate and structure. Using data gathered on different freshwater species, and in some cases re-analysing raw data, life tables are constructed and population level effects are assessed. Sensitivity analyses and confidence intervals for the intrinsic growth rate are obtained by a computer intensive 'bootstrap' approach. By developing a double bootstrap method to resample the set of all test endpoints, species sensitivity distributions describing the effect of a particular toxin on a given multispecies assemblage are generated. Key words: demography, resampling, species sensitivity distributions |
