Assessment of the effects of the pesticide imidacloprid on the behaviour of the aquatic oligochaete Lumbriculus variegatus.

Contaminants, such as pesticides, can cause direct toxic effects when released into aquatic environments. Suitably sensitive species can help us understand and predict the impacts of such pollutants. Automated sediment toxicity testing and biomonitoring has grown rapidly, and biomonitoring instruments have proven appropriate for studying the effects of pollutants. A new approach in online biomonitoring, using the multispecies freshwater biomonitor was developed in the present study, using whole-sediment toxicity tests and behavioural responses of the freshwater oligochaete Lumbriculus variegatus. Endpoints, such as mortality and growth, were used to study the effects of the pesticide imidacloprid and to achieve a gradient of responses; exposures to contaminated sediments were performed over 10 days' duration (short-term tests). High mortality was observed in the three highest concentrations of imidacloprid, and inhibition of behaviour was monitored along a gradient of pesticide concentration. Exposure to imidacloprid-contaminated sediments affected growth, behaviour, and avoidance in L. variegatus.