Photo-enhanced toxicity of two weathered Macondo crude oils to early life stages of the eastern oyster (Crassostrea virginica). Issue 1 (15th December 2016) - Finch, Bryson E.
Abstract: Polycyclic aromatic hydrocarbons (PAHs) have been reported to absorb ultraviolet (UV) light, resulting in enhanced toxicity. Early developmental stages of bivalves may be particularly susceptible to photo-enhanced toxicity during oil spills. In the current study, toxicity tests were conducted with sperm and three larval ages of the eastern oyster ( Crassostrea virginica ) to evaluate the photo-enhanced toxicity of low-energy water-accommodated fractions (WAFs) of two weathered Macondo crude oils collected from the Deepwater Horizon incident. Larvae exposed to oil WAFs under UV-filtered light demonstrated consistently higher survival and normal development than larvae exposed to WAFs under UV light. The phototoxicity of weathered Macondo oil increased as a function of increasing UV light intensity and dose. Early developing oyster larvae were the most sensitive to photo-enhanced toxicity, whereas later shelled prodissoconch larvae were insensitive. Comparisons between two weathered crude oils demonstrated that toxicity was dependent on phototoxic PAH concentration and UV light intensity. Highlights: Weathered Macondo crude oil was phototoxic to early larvae stages of eastern oysters. Photo-enhanced toxicity was dependent on eastern oyster life stage. Shelled veliger stage eastern oysters were not sensitive to phototoxicity. Photo-enhanced toxicity was dependent on phototoxic PAHs and UV light.