Crude Oil in the Bile of Fish: BP Horizon Oil Spill

Since the 2010 BP oil spill, marine scientists at the University of South Florida (USF) have sampled more than 2,500 individual fish representing 91 species from 359 locations across the Gulf of Mexico and found evidence of oil exposure in all of them, including some of the most popular types of seafood. The highest levels were detected in yellowfin tuna, golden tilefish and red drum. The study represents the first comprehensive, Gulf-wide survey of oil pollution launched in response to the Deepwater Horizon spill.

Over the last decade have examined the levels of polycyclic aromatic hydrocarbons (PAHs), the most toxic chemical component of crude oil, in the bile of the fish. Bile is produced by the liver to aid in digestion, but it also acts as storage for waste products.

“We were quite surprised that among the most contaminated species was the fast-swimming yellowfin tuna as they are not found at the bottom of the ocean where most oil pollution in the Gulf occurs,” said lead author Erin Pulster…Pulster says it makes sense that tilefish have higher concentrations of PAH because they live their entire adult lives in and around burrows they excavate on the seafloor and PAHs are routinely found in Gulf sediment. However, their exposure has been increasing over time, as well as in other species, including groupers, some of Florida’s most economically important fish. …

Oil pollution hot spots were also found off major population centers, such as Tampa Bay, suggesting that runoff from urbanized coasts may play a role in the higher concentrations of PAHs. Other sources include chornic low-level releases from oil and gas platforms, fuel from boats and airplanes and even natural oil seeps — fractures on the seafloor that can ooze the equivalent of millions of barrels of oil per year.

Excerpts from Firste Gulf of Mexico-wide survey of oil pollution completed 10 years after Deepwater Horizon, Science Daily, Apr. 15, 2020

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