The aim of this study was to determine the effect data for metoprolol as a model substance for beta-blockers in aquatic invertebrates. The results will be used as a basis for the validation of future mode of action-based in vitro test systems targeting this class of pharmaceuticals. Effects of metoprolol were investigated in two autochthonous species with high relevance in stream ecology: the amphipod Gammarus fossarum and the oligochaete Lumbriculus variegatus. Mortality in G. fossarum was not observed in acute toxicity testing (48 h), and a significant increase of mortality at 45 mg/L was found when amphipods were exposed chronically (40 days). The most sensitive population-relevant endpoints were the juvenile-adult ratio and number of egg-bearing females with NOEC/LOEC-values of 5/15 mg/L. No proteotoxic effects were identified in G. fossarum. The sediment toxicity test with L. variegatus according to the OECD Guideline 225 with an exposure time of 28 days resulted in EC10-values of 92.5 and 126.1 mg/kgdw for the endpoints reproduction and biomass, respectively. In L. variegatus the response kinetics of Hsp70 showed no significant difference between the treatments. A tendency for rising lipid peroxide concentrations was found between 0.03 and 10 mg/kgdw, which were significant between the treatments, but not to the control.
Keywords: Biomarker; Gammarus; Lumbriculus; metoprolol; pharmaceuticals.