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Effect of dispersant on the composition of the water-accommodated fraction of crude oil and its toxicity to larval marine fish

Authors

  • Catherine M. Couillard,

    Corresponding author
    1. Environmental Sciences Branch, Department of Fisheries and Oceans, Maurice Lamontagne Institute, P.O. Box 1000, Mont-Joli, Quebec G5H 3Z4, Canada
    • Environmental Sciences Branch, Department of Fisheries and Oceans, Maurice Lamontagne Institute, P.O. Box 1000, Mont-Joli, Quebec G5H 3Z4, Canada
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  • Kenneth Lee,

    1. Centre for Offshore Oil and Gas Environmental Research, Bedford Institute of Oceanography, Fisheries and Oceans Canada, P.O. Box 1006, Dartmouth, Nova Scotia B2Y 4A2, Canada
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  • Benoît Légaré,

    1. Environmental Sciences Branch, Department of Fisheries and Oceans, Maurice Lamontagne Institute, P.O. Box 1000, Mont-Joli, Quebec G5H 3Z4, Canada
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  • Thomas L. King

    1. Centre for Offshore Oil and Gas Environmental Research, Bedford Institute of Oceanography, Fisheries and Oceans Canada, P.O. Box 1006, Dartmouth, Nova Scotia B2Y 4A2, Canada
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Abstract

Newly hatched mummichog (Fundulus heteroclitus) were exposed in a 96-h static renewal assay to water-accommodated fractions of dispersed crude oil (DWAF) or crude oil (WAF) to evaluate if the dispersant-induced changes in aqueous concentrations of polycyclic aromatic hydrocarbons (PAH) affected larval survival, body length, or ethoxyresorufin-O-deethylase (EROD) activity. Weathered Mesa light crude oil (0.05–1 g/L) and filtered seawater with or without the addition of Corexit 9500® were used to prepare DWAF and WAF. At 0.2 g/L, the addition of dispersant caused a two- and fivefold increase in the concentrations of total PAH (ΣPAH) and high-molecular-weight PAH (HMWPAH) with three or more benzene rings. Highest mortality rates (89%) were observed in larvae exposed to DWAF (0.5 g/L; ΣPAH, 479 ng/ml). A reduction in body length was correlated with increased levels of ΣPAH (r2 = 0.65, p = 0.02) and not with HMWPAH. The EROD activity increased linearly with HMWPAH (r2 = 0.99, p = 0.001) and not with ΣPAH. Thus, chemical dispersion increased both the ΣPAH concentrations and the proportion of HMWPAH in WAF. Dispersed HMWPAH were bioavailable, as indicated by a significantly increased EROD activity in exposed mummichog larvae, and this may represent a significant hazard for larval fish.

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