Table 5. Comparison between IC10 and IC50 values and relevant ecological guidelines.
| Herbicide | IC10 | IC50 | ANZECC71 ETV 99%,95%,90% | Proposed ANZECC72 ETV 99%,95%,90% | GBRMPA18 ETV 99%,95%,90% |
|---|---|---|---|---|---|
| Diuron | 1.2 | 4.3 | 1.8, 1.8, 1.8 | 0.08, 0.3, 0.4 | 0.9, 1.6, 2.3 |
| Fluometuron | 17 | 132 | NA | NA | NA |
| Tebuthiuron | 3.9 | 28 | 0.02, 2.2, 20 | 4.3, 8.8, 12.0 | 0.02, 2, 20 |
| Atrazine | 3.4 | 22 | 0.7, 13, 45 | 2.8, 3.8, 4.6 | 0.6, 1.4, 2.5 |
| Ametryn* | 0.8 | 3.5 | NA | 0.02, 0.1, 0.3 | 0.5, 1.0, 1.6 |
| Metribuzin* | 0.8 | 4.8 | NA | NA | NA |
| Simazine | 3.0 | 28 | NA | NA | 0.2, 3.2, 11 |
| Prometryn* | 1.6 | 6.7 | NA | NA | NA |
| Bromacil | 3.4 | 25 | NA | NA | NA |
| Hexazinone* | 2.5 | 11 | 75, 75, 75 | 0.9, 1.2, 1.5 | 1.2, 1.2, 1.2 |
All concentrations in μg l−1. Ecotoxicity threshold values (ETVs μg l−1) formulated to protect 99%, 95%, 90% of phototropic species. Current ANZECC guidelines are freshwater. NA not available. ETVs in bold are not protective of PSII activity in H. ovalis at the IC10 threshold. *indicates 48 h IC50 values.