Fig. 4From: Detection of chemically induced ecotoxicological effects in rivers of the Nidda catchment (Hessen, Germany) and development of an ecotoxicological, Water Framework Directive–compliant assessment systemMicrotox assay. Mean and standard error of the mean of EC50 values (in mg sediment equivalents) for baseline toxicity of sediment samples from the rivers Nidda, Usa and Horloff. Reference sites N1, U1 and H1 are shaded. n = 6 with 8 pseudo-replicates eachBack to article page