The species sensivity distribution approach compared to a micrososm study: A case study with the fungicide fluazinam

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 EC10-based SSD gave a median HC5 value of 0.6 µg L-1 and a 90% confidence interval of 0.1–1.9 µg L-1. The EC50-based SSD gave a median HC5 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 (NOECmicrocosm). 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 EC10-based HC5 and the lower limit EC50-based HC5 were lower, and the median EC50-based HC5 was slightly higher than the NOECmicrocosm. This is consistent with other studies that compared SSDs with responses in model ecosystems that received repeated applications of pesticides