Deepwater Horizon: Microbial Life Acts as an Emergency Cleanup Crew

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Oil from the Deepwater Horizon spill – microbes helped in the cleanup! Image by Green Fire Productions / CC by 2.0

On April 20, 2010, the Deepwater Horizon oil rig exploded. The explosion was devastating. For several months, oil gushed from an underwater well, sending about 4.9 million barrels of oil into the Gulf of Mexico. A massive oil slick headed for sensitive wetland areas and spread throughout the water, and public concern was overwhelming. When it was all over, oil had covered 68,000 square miles of ocean, closing fisheries and contaminating underwater and coastal habitats.

But as people struggled to contain the spill, the ocean’s microbial life was already on alert. As people worked to prevent and contain the damage, underneath the water in the Gulf of Mexico, the cleanup crew was on already active: microbes that consume oil were growing in numbers, degrading the oil as it spewed from the well.

In research presented at a meeting of the American Chemical Society, Dr. Terry Hazen of the University of Tennessee in Knoxville described the changes that happened as the oil began to spill. In an interview with Decoded Science, Hazen discussed the ways in which the Gulf of Mexico’s microbes are able to clean up underwater oil.

The Gulf of Mexico Has a Natural Cleanup Crew

There’s no good place to have an oil spill, but the Gulf of Mexico is uniquely placed to degrade underwater oil. In the Gulf, there are natural oil seeps, and around these seeps there are oil-degrading microbes. Hazen estimates that every year, 400,000 to a million barrels of oil seep into the Gulf of Mexico’s waters, feeding the microbes that live there. The microbes have adapted to move toward the oil, and they can degrade it at very low temperatures – the very temperatures found in the deeper parts of the ocean.

After the Deepwater Horizon spill, Hazen and his colleagues had the opportunity to observe the changes in microbial communities in the areas around the spill. For nearly two months after the well was capped, the microbes kept on degrading the oil, removing it from the water column. Like any community of plants and animals, the community of organisms in the water column changes depending on what food is available.

First, there are the fast-food lovers: the bacteria that degrade the parts of the oil that are easiest to degrade, such as the alkanes. Once the bulk of the oil is gone, methane-oxidizing bacteria move in to degrade the methane.  By looking at the community of organisms that is in the water column, Hazen can see the signs of recent oil spills, even if the oil is no longer present.

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