Ecological Risk Assessment (ERA) of GMO is basically identical to ERA of chemical substances, when it comes to assessing specific effects of the GMO plant material on the soil ecosystem. The tiered approach always includes the option of studying more complex but still realistic ecosystem level effects in 2nd tier caged experimental systems, cf. the new GMO ERA guidance: EFSA Journal 2010; 8(11):1879. We propose to perform a trophic structure analysis, TSA, and include the trophic structure as an ecological endpoint to gain more direct insight into the change in interactions between species, i.e. the food-web structure, instead of relying only on the indirect evidence from population abundances. The approach was applied for effect assessment in the agro-ecosystem where we combined factors of elevated CO2, viz. global climate change, and GMO plant effects. A multi-species (Collembola, Acari and Enchytraeidae) mesocosm factorial experiment was set up in a greenhouse at ambient CO2 and 450 ppm CO2 with a GM barley variety and conventional varieties. The GM barley differed concerning the composition of amino acids in the grain (antisense C-hordein line). The fungicide carbendazim acted as a positive control. After 5 and 11 weeks, data on populations, plants and soil organic matter decomposition were evaluated. Natural abundances of stable isotopes, 13C and 15N, of animals, soil, plants and added organic matter (crushed maize leaves) were used to describe the soil food web structure.
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SETAC Europe 21st Annual Meeting in the Milano Convention Centre, 2011