Evaluation of the Toxicity of the Deepwater Horizon Oil and Associated Dispersant on Early Life Stages of the Eastern Oyster, Crassostrea virginica

Abstract The explosion of the Deepwater Horizon (DWH) drilling unit in April 2010 led to the largest marine oil spill in US history. For 87 days, unprecedented amounts of crude oil and dispersant were released into the Gulf of Mexico (GoM), coincident with the spawning and recruitment season of the oyster, Crassostrea virginica . Effects of acute exposures to surface-collected DWH oil (HEWAF), dispersed oil (CEWAF) and dispersant alone (Corexit 9500A®) on various life stages (gamete, embryo, larvae, or spat) of oysters were evaluated in the laboratory. Oil and dispersant adversely affected all life stages tested from sublethal responses, ranging from depressed fertilization, abnormal embryo development, inhibited larval growth and settlement, and feeding disruption of spat, to lethality. Detrimental effect of oil and associated dispersant on the reproduction and early development of C. virginica could impact the recruitment and consequently decimate the oyster natural populations in the affected areas.