title: Toxic effects of chemical dispersant Corexit 9500 on water flea Daphnia magna.
abstract: In 2010, approximately 2.1 million gallons of chemical dispersants, mainly Corexit 9500, were applied in the Gulf of Mexico to prevent the oil slick from reaching shorelines and to accelerate biodegradation of oil during the Deepwater Horizon oil spill. Recent studies have revealed toxic effects of Corexit 9500 on marine microzooplankton that play important roles in food chains in marine ecosystems. However, there is still little known about the toxic effects of Corexit 9500 on freshwater zooplankton, even though oil spills do occur in freshwater and chemical dispersants may be used in response to these spills. The cladoceran crustacean, water flea Daphnia magna, is a well-established model species for various toxicological tests, including detection of juvenile hormone-like activity in test compounds. In this study, we conducted laboratory experiments to investigate the acute and chronic toxicity of Corexit 9500 using D. magna. The acute toxicity test was conducted according to OECD TG202 and the 48 h EC50was 1.31 ppm (CIs 0.99-1.64 ppm). The reproductive chronic toxicity test was performed following OECD TG211 ANNEX 7 and 21 days LOEC and NOEC values were 4.0 and 2.0 ppm, respectively. These results indicate that Corexit 9500 has toxic effects on daphnids, particularly during the neonatal developmental stage, which is consistent with marine zooplankton results, whereas juvenile hormone-like activity was not identified. Therefore, our findings of the adverse effects of Corexit 9500 on daphnids suggest that application of this type of chemical dispersant may have catastrophic impacts on freshwater ecosystems by disrupting the key food chain network. Copyright © 2016 John Wiley & Sons, Ltd.
authors.affiliation: Department of Basic Biology, Okazaki Institute for Integrative Bioscience, National Institute for Basic Biology, National Institutes of Natural Sciences, Faculty of Life Science, SOKENDAI (Graduate University for Advanced Studies), 5-1 Higashiyama, Okazaki, Aichi, 444-8787, Japan.|Environmental Genomics Group, School of Biosciences, University of Birmingham, Birmingham, B15 2TT, UK.
authors.forename: Kenji
authors.initials: K
authors.lastname: Toyota
authors.affiliation: Graduate Program in Marine Biology, The University of Charleston at the College of Charleston, Charleston, SC, 29412, USA.|Marine Biomedicine and Environmental Science Center, Hollings Marine Laboratory, Charleston, SC, 29412, USA.
authors.forename: Nicole A
authors.initials: NA
authors.lastname: McNabb
authors.affiliation: Marine Biomedicine and Environmental Science Center, Hollings Marine Laboratory, Charleston, SC, 29412, USA.|Department of Pathology and Laboratory Medicine, Medical University of South Carolina, Charleston, SC, 29412, USA.
authors.forename: Demetri D
authors.initials: DD
authors.lastname: Spyropoulos
authors.affiliation: Department of Basic Biology, Okazaki Institute for Integrative Bioscience, National Institute for Basic Biology, National Institutes of Natural Sciences, Faculty of Life Science, SOKENDAI (Graduate University for Advanced Studies), 5-1 Higashiyama, Okazaki, Aichi, 444-8787, Japan.
authors.forename: Taisen
authors.initials: T
authors.lastname: Iguchi
authors.affiliation: Marine Biomedicine and Environmental Science Center, Hollings Marine Laboratory, Charleston, SC, 29412, USA.|Department of Obstetrics and Gynecology, Medical University of South Carolina, Charleston, SC, 29412, USA.
authors.forename: Satomi
authors.identifier: 0000-0001-6184-3616
authors.initials: S
authors.lastname: Kohno
mesh_terms: D000818:Animals; D003621:Daphnia / Q000187:drug effects* / Q000502:physiology; D017753:Ecosystem; D005618:Fresh Water / Q000737:chemistry; D007928:Lethal Dose 50; D008055:Lipids / Q000633:toxicity*; D012098:Reproduction / Q000187:drug effects; D013501:Surface-Active Agents / Q000633:toxicity*; D023382:Toxicity Tests, Acute; D036401:Toxicity Tests, Chronic; D014874:Water Pollutants, Chemical / Q000633:toxicity*
chemical_list: D008055:Lipids; D013501:Surface-Active Agents; D014874:Water Pollutants, Chemical; C470995:corexit 9500
keywords: Chemical dispersant; Corexit EC9500A; Daphnia magna; OECD TG202; OECD TG211; Short-term screening assay