Sensitivity of fish embryos to weathered crude oil: Part II. Increased mortality of pink salmon (Oncorhynchus gorbuscha) embryos incubating downstream from weathered Exxon valdez crude oil

Abstract

Abstract-We incubated pink salmon embryos under three exposure conditions, direct contact with oil-coated gravel, effluent from oil-coated gravel, and direct contact with gravel coated with very weathered oil (VWO). Embryo mortalities and polynuclear aromatic hydrocarbon (PAH) accumulation in embryo tissues during the direct-contact and effluent exposure experiments were not significantly different, indicating that PAH accumulation was mediated by aqueous transport. Mortality rates for embryos exposed initially to a total PAH concentration (TPAH) of 1.0 ppb were significantly higher than controls when the PAH were derived from VWO. The same aqueous TPAH concentration failed to increase mortality rates when the PAH were derived from less weathered oil, indicating that toxicity of effluents from the VWO was primarily associated with the larger PAH. We conclude that water quality standards for TPAH above 1.0 ppb may fail to protect fish embryos. Further, pink salmon embryos incubating in Prince William Sound after the Exxon Valdez oil spill may have accumulated lethal concentrations of PAH from interstitial water that was contaminated when it percolated through oil reservoirs located upstream from salmon redds.

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“…Field and laboratory investigations demonstrated that there was a common syndrome of crude oil-induced developmental toxicity in a range of teleost fish. This was described by pericardial edema, body axis curvature, yolk edema and jaw reductions (Heintz et al, 1999;Carls et al, 1999;Pollino and Holdway, 2002;Couillard, 2002). These results of the studies were in agreement with the current study.…”

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“…Similarly, dolphinfish eggs and larvae exposed to mean (±95% CI) ΣPAH concentrations of 1.2 ± 0.6 to 30 ± 7 μg L −1 ΣPAHs exhibited reduced swimming performance and associated cardiac abnormalities, presumably leading to increased mortality . Findings of elevated mortalities from exposures in this range are documented among many taxa (e.g., Heintz et al, 1999). Thus, the first condition for population-level impacts owing to PAH exposure as noted above is met.…”

“…As with the Exxon Valdez spill, many of the effects of DWH may take a decade or more to become apparent. With respect to fish populations affected by Exxon Valdez in Prince William Sound, impacts have specifically focused on Pacific herring (Thorne and Thomas, 2008) and pink salmon (Heintz et al, 1999). In both fish species, unlike with DWH, a substantial fraction of the egg and larval production of the affected substocks occurred within the spill zone.…”

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“…PAHs are known to be highly toxic to larval herring, topsmelt, minnow, and salmon (Petersen and Kristensen, 1998;Heintz et al, 1999;Couillard et al, 2005). Toxic effects include hemorrhages, spinal deformities, growth retardation, and death (Billiard et al, 1999;Carls et al, 1999 (Kujawinski et al, 2011).…”