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2I - High-tiered Studies (MO7/1) Comparsion of results from short and longterm bioassays with Gammarus fossarum regarding pesticides and pharmaceuticals. Zenker, Armin1, Böhmer, Jürgen1, 1 University of Hohenheim, Institute of Zoology - Aquatic Ecology, Stuttgart, Baden-Württemberg, Germany ABSTRACT- Considering the problems in translating bioassay results to community effects, it was proposed to try the opposite approach by viewing from top down. In the field, effects on macrobenthon biocoenosis were observed under measured toxic stress. In laboratory, bioassays were conducted with a single organism or a population of one species, testing wether the effects were really dependent on the measured toxicants. As in former investigations we chose G. fossarum as a test organism, because it is relatively sensitive to toxic stress and often found in our reference streams. The aim of the present study was to compare results of the different levels of biota and pick out the most sensitive but also practicable one for possible risk assessment. The laboratory tests were short exposure bioassays of about 12 hours in the Multispecies Freshwater Biomonitor (MFB) or 48 hours in small aquaria with the endpoints behaviour and mortality, and longterm effects were studied in 40 days tests in the laboratory or over 9 months in semi-field experiments with the endpoints reproduction and mortality. The concentrations of toxicants were the environmental relevant concentration (e.g. Pirimicarb 10.8 Key words: top down view, behaviour, pesticides, effect translation |
g/l) up to a concentration were clear impacts had appeared. By the shortest test over 12 hours we observed effects only with a concentration 100 times higher the field concentration, but in the semi-field experiment over 9 months we obtained significant effects by the environmental relevant concentration. For risk assessment 9 months biomonitoring experiments are not feasible, but the 40 days experiment revealed also significant results at concentrations 10 times higher than the environmental relevant dose.