Neonicotinoid insecticides from a marine perspective: acute and chronic copepod testing and derivation of environmental quality standards
Moeris, S.; Vanryckeghem, F.; Demeestere, K.; De Schamphelaere, K.A.C. (2021). Neonicotinoid insecticides from a marine perspective: acute and chronic copepod testing and derivation of environmental quality standards. Environ. Toxicol. Chem. 40(5): 1353-1367. https://hdl.handle.net/10.1002/etc.4986 In: Environmental Toxicology and Chemistry. Setac Press: New York. ISSN 0730-7268; e-ISSN 1552-8618, more |  |
| Keywords | Copepoda [WoRMS]
Marine/Coastal | | Author keywords | Neonicotinoids; Marine ecotoxicology; Copepods; Immobilization; Acuteand chronic testing |
| Authors | | Top | - Moeris, S., more
- Vanryckeghem, F., more
- Demeestere, K., more
- De Schamphelaere, K.A.C., more
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| Abstract | Neonicotinoid insecticides have become of global concern for the aquatic environment. Harpacticoid copepods are among the organisms most sensitive to neonicotinoids. We exposed the brackish copepod Nitocra spinipes to 4 neonicotinoid insecticides (clothianidin, imidacloprid, thiacloprid, and thiamethoxam) to investigate acute toxicity on adults (96-h exposure) and effects on larval development (7-d exposure). We used these results in combination with publicly available ecotoxicity data to derive environmental quality standards (EQS). These EQS were ultimately used in a single-substance and mixture risk assessment for the Belgian part of the North Sea. Acute toxicity testing revealed that immobilization is a more sensitive endpoint than mortality, with 96-h median effect concentration (EC50) values of 6.9, 7.2, 25, and 120 µg L–1 for clothianidin, thiacloprid, imidacloprid, and thiamethoxam, respectively. In addition, the larval development tests resulted in 7-d no-observed-effect concentrations (NOECs) of 2.5, 2.7, 4.2, and >99 µg L–1 for clothianidin, thiacloprid, imidacloprid, and thiamethoxam, respectively. The derived saltwater annual average (AA-)EQS were 0.05, 0.0048, 0.002, and 0.016 µg L–1 for clothianidin, thiacloprid, imidacloprid, and thiamethoxam, respectively. Finally, the risk characterization revealed some exceedances of the AA-EQS in Belgian harbors for imidacloprid (number of exceedances, n = 2/4), for thiacloprid (n = 1/4), for thiamethoxam (n = 1/4), and for the mixture of the 4 neonicotinoids (n = 4/4), but not at the open sea. At the open sea site, the toxic unit sums relative to the AA-EQS were 0.72 and 0.22, suggesting no mixture risk, albeit with a relatively small margin of safety. Including short-term EC10 (96-h) values of N. spinipes for the AA-EQS derivation led to a refinement of the AA-EQS for clothianidin and thiamethoxam, suggesting their use for the AA-EQS derivation because one of the overarching goals of the definition of EQS is to protect species at the population level. |
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