No Threat Found to Salmon Eggs Due to Exxon Valdez Oil Spill

Newswise — Since the Exxon Valdez oil spill in Prince William Sound 18 years ago, dozens of studies have looked at the wildlife in the area to assess its recovery from the spill. The latest study has determined that residual oil from local beaches poses an extremely low threat to pink eggs. The study is published in the latest issue of Environmental Toxicology and Chemistry.

The study tested two possible avenues for the long-term effects of the oil spill. Lead researcher Ernest Brannon of the Center for Salmonid and Freshwater Species at Risk and his team analyzed whether buried deposits of weathered Exxon Valdez oil on the shore dissolve into pore water at levels toxic to salmon embryos, and also whether toxic concentrations are being carried into adjacent intertidal salmon streams.

Salmon eggs were placed at the most heavily oiled sites and at control locations and were exposed naturally to oiled sediments for approximately 3 weeks. Eggs and sediment were then analyzed for polynuclear aromatic hydrocarbons (PAHs). No correlation was found between sediment PAH concentrations and egg PAH concentrations. Despite the fact that oil was visually observed at multiple sites, levels of PAHs in eggs were similar to concentrations observed at unoiled control sites.

Further, the chemical concentrations observed in the eggs suggest that concentrations of oil in the sediments of Prince William Sound are insufficient to pose a threat to salmon eggs. It appears that the residual oil at most sites has been weathered and the PAHs remaining are of a high molecular weight, making them unavailable for biological uptake.

To read the entire study, click here: http://www.allenpress.com/pdf/entc_26_418_780_786.pdf

Environmental Toxicology and Chemistry is the monthly journal of the Society of Environmental Toxicology and Chemistry (SETAC). For more information about the Society, visit http://www.setac.org.