Sublethal Effects of Crude Oil and Chemical Dispersants on Multiple Life History Stages of the Eastern Oyster, Crassostrea virginica

The eastern oyster Crassostrea virginica is an ecologically and economically important species that is vulnerable to oil pollution. We assessed sublethal effects of soluble fractions of crude oil alone (WAF) and crude oil in combination with Corexit 9500 dispersant (CEWAF) on oysters at three life history stages. Veliger swimming, pediveliger settlement, and adult clearance rates were quantified after 24 h exposures to the contaminants. Veliger swimming speeds were not significantly impacted by 24 h exposures to WAF or CEWAF. A larger proportion of veligers were inactive following WAF and CEWAF exposure as compared to the control, but the effect was greater for pediveligers, and pediveliger settlement in the highest concentration CEWAF treatment decreased by 50% compared to controls. Thus, pediveligers may be particularly vulnerable to oil exposure. In the adults, we found significant clearance rates reductions that persisted 33 days after acute exposure to CEWAF. Knowledge of sublethal effects of oil and dispersant at multiple life history stages aids understanding of how this important species will respond to an oil spill.