Impacts of Deepwater Horizon oil and associated dispersant on early development of the Eastern oyster Crassostrea virginica J. Vignier a,b , L. Donaghy a , P. Soudant b , F.L.E. Chu c , J.M. Morris d , M.W. Carney d , C. Lay d , M. Krasnec d , R. Robert e , A.K. Volety a, ⁎ a Department of Marine and Ecological Sciences, College of Arts and Sciences, Florida Gulf Coast University, Fort Myers, FL 33965, USA b Laboratoire des Sciences de l'Environnement Marin (UMR 6539-LEMAR), IUEM-UBO, Technopole Brest Iroise, 29280 Plouzané, France c Virginia Institute of Marine Science (VIMS), College of William and Mary, Department of Aquatic Health Sciences, Gloucester Point, VA 23062, USA d Abt Associates, Boulder, CO 80302, USA e Ifremer, Unité Littoral, Centre Bretagne - ZI de la Pointe du Diable - CS, 10070-29280 Plouzané, France abstract article info Article history: Received 1 April 2015 Received in revised form 27 July 2015 Accepted 2 August 2015 Available online xxxx Keywords: Deepwater Horizon oil Oyster Fertilization CEWAF Corexit PAH The explosion of the Deepwater Horizon (DWH) oil platform resulted in large amounts of crude oil and dispersant Corexit 9500A® released into the Gulf of Mexico and coincided with the spawning season of the oyster, Crassostrea virginica. The effects of exposing gametes and embryos of C. virginica to dispersant alone (Corexit), mechanically (HEWAF) and chemically dispersed (CEWAF) DWH oil were evaluated. Fertilization success and the morphological development, growth, and survival of larvae were assessed. Gamete exposure reduced fertilization (HEWAF: EC20 1h = 1650 μg tPAH50 L -1 ; CEWAF: EC20 1h = 19.4 μg tPAH50 L -1 ; Corexit: EC20 1h = 6.9 mg L -1 ). CEWAF and Corexit showed a similar toxicity on early life stages at equivalent nominal concentrations. Oysters exposed from gametes to CEWAF and Corexit experienced more deleterious effects than oysters exposed from embryos. Results suggest the presence of oil and dispersant during oyster spawning season may interfere with larval development and subsequent recruitment. © 2015 Published by Elsevier Ltd. 1. Introduction The Eastern oyster, Crassostrea virginica (Gmelin, 1791), is one of the most commercially and ecologically important shellfish species propa- gating along the East Coast of the United States, from Maine to the Gulf of Mexico (Galtsoff, 1964; Volety et al., 2014). In 2012, total land- ings of C. virginica represented a value of $104 million in the United States from which $74 million originated in coastal regions of the north- ern Gulf of Mexico (National Marine Fisheries Service, 2012). In addition to its economic value, C. virginica is also an ecologically vital species. Oyster reefs, which have been built through successive reproduction and settlement of larvae onto existing reef structure, provide food, shel- ter, and habitat for many fish and shellfish species; improve water qual- ity; stabilize bottom areas; and influence water circulation patterns within estuaries (Coen et al., 2007; Newell, 2004; Peterson et al., 2003; Volety et al., 2014; Wells, 1961). In the northern part of the Gulf of Mexico, the oyster spawning season typically occurs from mid- spring through late fall (Ingle, 1951). On April 20, 2010, the explosion of the Deepwater Horizon (DWH) oil platform in the Gulf of Mexico led to the release of millions of barrels of crude oil 80 km off the coast of Louisiana (McNutt et al., 2012). The oil leak was discovered two days after the incident at a depth of 1544 m. After almost three months and several attempts to stop the leak, the well was finally cemented on July 15, 2010 (Crone and Tolstoy, 2010). Approximately 7 million L of the chemical dispersant Corexit 9500A® was used directly at the well- head and at the surface to disperse the oil slicks (Kujawinski et al., 2011). The DWH oil contaminated first the Louisiana coast and then the Mississippi, Alabama, and Florida coasts (Rosenbauer et al., 2010). Petroleum hydrocarbon contaminants pose a severe ecological risk to marine organisms. They can affect organisms by physical action (light reduction, asphyxia), by modification of habitat [change in pH (Neff, 1987), decrease of dissolved oxygen, decrease in food availabili- ty], and by toxic effects. Crude oil constituents are of particular concern because of their high chemical stability, low degradation, and lipophilic nature. Most toxic effects of crude oil are typically attributed to the aro- matic fraction, particularly polycyclic aromatic hydrocarbons (PAHs); PAHs are known to be persistent in the environment and are potentially mutagenic, genotoxic, and carcinogenic to organisms (Albers and Loughlin, 2003; Neff, 1985; Roesijadi et al., 1978). Chemical dispersants are complex mixtures, primarily containing surfactants (dioctyl sodium sulfosuccinate, also known as DOSS) and solvents (propylene glycol), which reduce the interfacial tension at the oil–water interface, and therefore facilitate the mixing of oil into the water (Canevari, 1973; Li and Garrett, 1998). Therefore, oil slicks Marine Pollution Bulletin xxx (2015) xxx–xxx ⁎ Corresponding author at: University of North Carolina Wilmington, 601 S. College Road, Wilmington, NC 28403, USA. E-mail address: voletya@uncw.edu (A.K. Volety). MPB-07117; No of Pages 12 http://dx.doi.org/10.1016/j.marpolbul.2015.08.011 0025-326X/© 2015 Published by Elsevier Ltd. Contents lists available at ScienceDirect Marine Pollution Bulletin journal homepage: www.elsevier.com/locate/marpolbul Please cite this article as: Vignier, J., et al., Impacts of Deepwater Horizon oil and associated dispersant on early development of the Eastern oyster Crassostrea virginica, Marine Pollution Bulletin (2015), http://dx.doi.org/10.1016/j.marpolbul.2015.08.011