Screening the Toxicity of Ni, Cd, Cu, Ivermectin, and Imidacloprid in a Short-Term Automated Behavioral Toxicity Test with<i>Tubifex tubifex</i>(Müller 1774) (Oligochaeta)

ABSTRACT A new automated online toxicity test for screening of short-term effects of chemicals is presented using the freshwater oligochaete Tubifex tubifex in the Multispecies Freshwater Biomonitor™ (MFB). Survival and locomotory behavior of the worms were observed during 24 h of exposure to metals (Cd, Cu, Ni), pesticides (Imidacloprid), and pharmaceuticals (Ivermectin). The LC50 values revealed increasing toxicity in the following order: Ni (> 100 mg/l) < Cu (15.2 mg/l) < Cd (4.9 mg/l) < Ivermectin (1.8 mg/l) < Imidacloprid (0.3 mg/l). The EC50 for locomotion showed a similar order of increasing toxicity: Ni (86 mg/l) < Cu (3.8 mg/l) < Ivermectin (2.0 mg/l) < Cd (1.1 mg/l) < Imidacloprid (0.09 mg/l). Toxicity was dependent on both concentration and exposure time. This could be demonstrated in 3d response models and proven in the statistical analysis showing a significant interaction term (C × T) for the experiments with Cu and Ni. T. tubifex proved to be very tolerant, but even then behavioral responses were more sensitive than mortality for Cu, Cd, and Imidacloprid. Key words: multispecies freshwater biomonitor™locomotionEC50 LC50 ACKNOWLEDGMENTS The study is part of the EU-Project NoMiracle (Novel Methods for Integrated Risk Assessment in Europe) and has been financially supported by the European Union, FP6, Contract No. 003956 to Dr. Almut Gerhardt. Antje Echterhoff and Petronella Závadská are gratefully acknowledged for practical assistance. Notes *p < .05 **p < .01 ***p < .001. *Including solvent, ns: not significant. *Least square fit: visual estimate ns: not significant.