Evaluation of Triploid Oysters as a Tool to assess Short- and Long-term Seafood Contamination of Oil Spill-impacted Areas

Abstract

The objective of this field and laboratory study was to evaluate the use of triploid Eastern oysters, Crassostrea virginica, as a bioindicator of polynuclear aromatic hydrocarbon (PAH) contamination in oil spill-impacted areas. Bivalve mollusks have shown to be valuable tools for assessing the short-term (weeks to months) bioavailability and impact of hydrophobic contaminants following oil and chemical spills. Approximately 1-year after the initial Deepwater Horizon spill, PAH concentrations were measured in sediment and caged oysters at sites within the Northern Barataria Bay. Two (2) seven-week large-scale mesocosm studies were conducted with diploid and triploid oysters to assess the effects of multiple whole South Louisiana crude (SLC) oil concentrations and seasonal water temperature variation on the PAH bioaccumulation and depuration rates within the test populations. Tissue analyses from the mesocosm study showed that PAH concentrations were generally higher and less variable in triploids than diploids. The studies showed that triploid Crassostrea virginica can be an appropriate organism to serve as a bioindicator of PAH contamination as they are abundant, stationary filter-feeders that provide ample tissue for analysis, and accumulate PAHs in response to contamination. Although diploid oysters are more representative of ecological impacts, triploid oysters are the only ploidy to have the capability to accurately assess oil and chemical spill impacts during oyster breeding season.