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Dispersants Have Some Gulf Fish Eating Oil

Jun 3, 2010 – 1:42 PM
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Dave Thier

Dave Thier Contributor

(June 3) -- BP's widespread use of chemical dispersants like Corexit 9500 to combat the oil spill in the Gulf of Mexico has already come under wide criticism, both for the chemical's toxicity and how -- while limiting the amount of oil that washes up on beaches -- it's merely disseminating it throughout the gulf ecosystem. Now comes a new cause for concern: As dispersants spread throughout the water column, the oil droplets they're creating are being mistaken as food by fish.

Susan Shaw, director of the Marine Environmental Research Institute, donned a wetsuit to explore the spill for a recent op-ed in The New York Times. She noted that a fish like herring would easily consume the small pieces of oil that dispersants have spread throughout the gulf, coating their food sources.

"The dispersants in the amounts they're using them are unprecedented," she told AOL News. "And the effects of marine life are unknown. This affects everything at the bottom of the food web, from little tiny shrimp-like creatures to exposing small fish themselves."

Dispersants work by breaking large oil slicks into small particles that can be processed by naturally occurring bacteria. Herring feed by opening their mouths and drifting through clouds of small organisms like phytoplankton. If globs of oil are either floating among the plankton or attached to it directly, the herring could end up eating the oil by accident.

What's more, small fish like herring form an essential piece of the gulf ecosystem. They're food for birds, dolphins, tuna, sharks and a range of larger -- and already stressed -- predators, which suffer most greatly from ocean contamination.

Eventually, the toxic concentrations can become especially dangerous to the animals at the very top of the food chain: humans.

Aside from herring, the dispersants may also be causing some of the ocean's deepest-dwelling denizens to consume oil. Many inhabitants of the oceanic abyss get their nourishment from what's called "marine snow": organic material that falls in a continuous shower from the upper levels of the ocean to the bottom. Smaller droplets of oil can attach to these particles, ensuring that caustic crude and toxic dispersants are distributed throughout the entire ocean population.

"With smaller and smaller droplets, it's more and more likely for that material to be carried into the deep sea," Doug Rader, chief ocean scientist for the Environmental Defense Fund, told AOL News. "This brings these ancient deepwater reefs oil-based pollution that you would otherwise only expect to find on the surface."

According to the EPA, BP has significantly reduced the amount of dispersants it is using in the gulf, but for some hungry fish, the damage may already be done: During her dive, Shaw says she saw herring eating small poisonous droplets of oil. Even as scientists have yet to grasp what the long-term effects of the spill on wildlife will be, these small forage fish indicate that these chemicals are only just beginning their journey through the gulf's food chain.

Filed under: Nation, Science
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