A New Multi-cell Exposure System for Continuous Tracking of Daphnia Behavior for Toxicity Assessments

Abstract

For several years, video tracking systems have been developed to analyze alterations in the swimming behavior of daphnia to provide early signals of chemical stress. However, these systems have limited testing abilities that do not allow for a systematic analysis of the robustness of behavioral endpoints. With recent advances in behavior tracking technology, we were able to develop a new behavioral analysis multi-cell exposure system named “Multi-DaphTrack” with a high-throughput testing capacity for assessing the behavioral response of Daphnia magna. The insecticide esfenvalerate was chosen as chemical model and tested on daphnid neonates at several concentrations for 48 h to (i) evaluate the performance of this new system and (ii) compare the sensitivity of our new multi-cell system with the standard immobilization assay and the Bbe®Daphnia Toximeter. Overall, the results demonstrated that our new “Multi- DaphTrack” system can detect significant behavioral effects of esfenvalerate at concentrations as low as 0.14 μg/L from a minimum of 1 h of exposure. Similar rapid behavioral effect trends were observed with the Bbe®Daphnia Toximeter. The behavior proved to be more sensitive than the standard immobilization endpoint. Significant behavioral changes were observed at the esfenvalerate concentrations that occur in contaminated rivers from agricultural areas in Europe and North America. Our results indicate that the “Multi-DaphTrack” system represents a powerful and convenient tool for the assessment of c and water quality