A novel protocol for assessing aquatic pollution, based on the feeding inhibition of Daphnia magna

Abstract

In this study, sensitivity of a novel acute bioassay based on the feeding activity of Daphnia magna was assessed, using 2 and 4 h of exposure. For calibration purposes, results were compared with those of the standard immobility test as described by the ISO 6341:1996 standard. Using potassium dichromate as the reference chemical, after 4 h of exposure the proposed protocol showed similar sensitivity in comparison with the standard, as the EC 50 of the immobility test was 1.093 ± 0.098 mg•L -1, whereas the EC 50 of the feeding inhibition bioassay was 1.742 ± 0.133 mg•L -1. In order to test the sensitivity of the bioassay, toxicity of two other contaminants, copper and wastewater, was estimated and the results were compared with those of the standard immobility test. For both cases, the feeding inhibition test showed higher sensitivity, as in the case of copper the EC 50s were 0.0952 ± 0.0087 and 0.0753 ± 0.0152 mg•L -1, whilst the EC 50 recorded for the 24-h immobility test was 0.2407 ± 0.0159 mg•L -1. In the case of the effluent, EC 50 values after 2 and 4 h of exposure were 15.698 ± 2.681 and 12.557 ± 2.358 expressed as % of the wastewater, respectively, whereas the EC 50 of the immobility test was calculated to be 36.4688 ± 5.4887. © 2012 ONEMA.