We're used to thinking of massive oil spills as a threat to birds and fish who get drenched. But new research shows that exposure to even tiny amounts of crude oil can cause brain deformities in Atlantic haddock embryos that kill the fish before they reach maturity.
The study, published in Nature Scientific Reports by team of scientists from Norway and NOAA Fisheries' Northwest Fisheries Science Center in Seattle, indicates that oil spills, particularly in northern latitudes, could devastate fisheries that are an important source of food for humans, the researchers warn.
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The findings build on previous research, which showed that polycyclic aromatic hydrocarbons (PAHs) in crude oil interfere with development in fish embryos. This 2004 study, for example, found that exposing zebrafish to PAHs caused defects that led cardiac dysfunction, as well as jaw deformities and spinal curvatures, and reduced the chance of survival.
The new study indicates that the chemicals cause genetic defects that lead to fatal craniofacial deformities as well.
The researchers say that Atlantic haddock are especially vulnerable to spills, because dispersed crude oil droplets attach to their eggs as they float in the ocean, most likely due to a protein in the eggshells that makes them especially sticky.
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Only 24 hours of exposure to low concentrations of dispersed oil led to severe head and facial deformities in haddock that scientists described as "bulldog," "jaw breaker," "Darth Vader" and "hunchback."
"The dispersed droplets of crude oil act like a kind of toxic time-release capsule that binds to the eggshells and leads to these extreme abnormalities," John Incardona, a NOAA research toxicologist, said in a press release. "That creates a unique and newly recognized pathway for crude oil to interfere in the reproduction and survival of these fish."
The damage occurs during a crucial 10- to 12-day period in embryonic development.
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Haddock belong to the gadiformes, a large order of fish that also include other ecologically and economically important species such as Arctic cod and pollock. More research needs to be done to determine the relative vulnerability of those species.
While only the biggest oil disasters tend to make the headlines, NOAA says there are thousands of oil and chemical spills of various sizes in U.S. coastal waters each year. The International Tanker Owners Pollution Federation a total of 7,000 tons of crude from reported leaks was released into the oceans worldwide in 2015.
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