Effects of three pesticides that differ in mode of action on the ecology of small indoor aquatic microcosms; an evaluation of the effects of the insecticide chlorpyrifos, the herbicide atrazine and the fungicide carbendazim

In the current study, the usefulness of an eight litre microcosm for the ecological risk assessment of pesticides is examined. Risk assessment studies were performed for three pesticides with different modes of action, viz. an insecticide (chlorpyrifos), fungicide (carbendazim) and herbicide (linuron) and compared with the results from other, larger scaled, experiments. When the recommendations workshops on the use of microcosm and mesocosm experiments in the ecological risk assessment of pesticides are used to evaluate the experimental design of the experiments, the test-system can be considered methodological correct. However, it should be noted that macrophytes and macroinvertebrates are absent (although snails were included in the three risk assessment studies) meaning that the test systems cannot be used if major effects are expected on these organisms. Moreover, possible unrealistic fate of the chemical due to the absence of sediment is a demerit of these microcosms.