Effects of Deepwater Horizon oil and dispersants on various life stages of oysters Crassostrea virginica.

The 2010 Deepwater Horizon Oil Spill released oil into the Gulf of Mexico.  Many of the polycyclic aromatic hydrocarbons and other oil constituents found in oil are toxic. The oil spill, which continued for three months and which resulted in extensive exposure of nearshore habitats well beyond the period when oil was being discharged from the wellhead, coincided with the spawning season of the Eastern oyster (Crassostrea virginica), an environmentally and commercially important shellfish species in the Gulf of Mexico. The long planktonic nature (14 to 21 days) of oyster larvae, sedentary nature of adult oysters, high filtration rates and their micro algal/particulate diet make them vulnerable to acute exposure to contaminants both in solution and bound to suspended sediment, and adsorbed onto algal and other particles.

We conducted a series of experiments to examine the effects of the Deepwater Horizon (DWH) oil and dispersants on various life stages of oysters ranging from gametes to adults. Oysters were exposed to water accommodated fractions of oil (with and without dispersant), sediment elutriates, contaminated sediment, and contaminated algae. Fertilization success, morphological development, growth, survival and settlement success after these exposures were measured. Fertilization success decreased, developmental abnormalities increased, and larval growth, survival and settlement, and reproductive development of adults decreased in a dose-dependent manner relative to oil exposure and exposure duration.

Results suggest that exposure of various life stages of oysters to oil and/or dispersants will have a negative impact on overall growth and survival and may have implications on the population structure.