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(347) Characterisation of effect patterns on earthworm Eisenia andrei from binary metal mixtures - descriptive modelling. Svendsen, Claus 1, Hankard, Peter1, Spurgeon, David1, Jonker, Martijs2, Kammenga, Jan2, Weeks, Jason3, 1 2 3 ABSTRACT- Results from detailed experiments addressing mixture toxicity of binary metal mixtures to earthworm Eisenia andrei will be presented. Effects on adult survival and weight change were determined after 4 weeks of adult exposure, while cocoon and juvenile production were assessed after a further 4 week cocoon incubation period. Data has been analysed against both the similar (additive) and independent action reference model. This data analysis has been undertaken using the framework developed by Jonker M. J. et al., who will be presenting it for the first time at this conference. The initial experiment addressed the interactions of Zn and Cd and was designed so that data would allow identification not only of absolute synergism or antagonism, but also more detailed effects (i.e. effect level and ratio dependent deviations from the reference models). Although the data were variable, the initial analysis of survival data has identified subtle effect level dependent deviations from the reference models that would not have been identified without the new framework. Analyses of the sublethal data are currently being elaborated. Preliminary data from a further experiment of similar design, but comparing the mixture effects of all binary combinations of Cu, Cd, Zn and Pb are promising and will be included in the presentation. Some pitfalls of and recommendations for, the experimental design of mixture toxicity studies using earthworm will be highlighted. The overall complexity in the response patterns of different earthworm parameters caused by binary metal mixtures will be characterised in detail and discussed. Key words: Mixture toxicity, Earthworms, Metals, Descriptive models |
