The species sensitivity distribution approach compared to a microcosm study: a case study with the fungicide fluazinam.

Abstract We assessed the sensitivity of freshwater organisms (invertebrates and algae) to the fungicide Shirlan ® (active ingredient fluazinam) in single-species laboratory tests and in microcosms. Species sensitivity distribution (SSD) curves were constructed by means of acute toxicity data for 14 invertebrate species, since algae were much less sensitive. The EC 10 -based SSD gave a median HC 5 value of 0.6 μg L −1 and a 90% confidence interval of 0.1–1.9 μg L −1 . The EC 50 -based SSD gave a median HC 5 value of 3.9 μg L −1 (90% confidence interval: 0.9–9.9 μg L −1 ). The microcosms were treated four times with Shirlan ® (concentration range: 0.4–250 μg L −1 ). Responses of the microcosm communities were followed. The 2 μg L −1 treatment was the no-observed-effect concentration (NOEC microcosm ). The 10 μg L −1 treatment resulted in short-term effects on a few zooplankton taxa. Clear effects were observed at 50 and 250 μg L −1 . The responses in the microcosms were in line with the toxicity data for the tested lab species. The median EC 10 -based HC 5 and the lower limit EC 50 -based HC 5 were lower, and the median EC 50 -based HC 5 was slightly higher than the NOEC microcosm . This is consistent with other studies that compared SSDs with responses in model ecosystems that received repeated applications of pesticides.