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Deepwater Horizon Oil Spill Revisited: The Role of Microbes
03/25/2011 | Medea Steinman, (Ocean Systems)
Tags: 03.23.11 webinar, Deepwater Horizon, oil spill, Gulf of Mexico, microbes, biological pump

The Macondo oil well exploded in the Gulf of Mexico in April 2010 and was finally sealed in September. Many methods have been used to mitigate the affects and amounts of oil present in Gulf waters, including dispersants, containment, burning, oil removal, and even erecting barrier islands.

Meanwhile, microbes have played an important remediating role as well. Ever heard of “the biological pump?” In this process, largely driven by phytoplankton, carbon is incorporated via photosynthesis into marine foodwebs and is either respired back out into the atmosphere or sinks as fecal particles, dead organisms, and other organic material, into the ocean depths. There it may get buried in sediments and lithify. In that case we could call it “sequestered.” (Also see 10/6/10 webinar archive.) On their way to becoming “marine snow,” these organic particles are consumed or decomposed by bacteria.

Image of cartoon showing process of biological pump with Carbon dioxide entering ocean from atmosphere and being processed either back out to atmosphere or down into depths via planktonic and bacterial processes.
The Biological Pump moves carbon-based matter between the ocean surface and its depths.

When carbon enters the ocean as oil, either though natural seeps or as a result of human activities, it becomes part of this metabolic chain. In the Gulf of Mexico, there are many naturally occurring oil seeps and, as a result, the Gulf ecosystem fortunately has some natural mechanisms for processing crude oil and the harmful polycyclic aromatic hydrocarbons (PAH) it contains. Aided by warmer temperatures, some species of microbes living in the gulf are capable of breaking down those tough PAH molecules. What do they say about “one man’s trash…?” Well, three cheers for bacteria.

Karen and Kjell’s webinar presentation did an excellent job explaining all of this. We don’t know how much oil is left or exactly where it all is now. Nor do we know how much oil microbes have consumed. Even if we did, we might not be able to say that it all came from the Macondo well. But we know they are eating it. We also know that the dispersants, alas, make it more difficult for microbes to break down the PAHs because they attach to the hydrocarbons and make it harder for bacteria to attack the molecules. Karen and Kjell also surprised some of us with the historical record comparing the 2010 Gulf spill to other major spills. How big do you think this one was, relatively speaking?

Image showing cartoon of Loop Current as curving arrow moving through Gulf of Mexico, with eddies and gyres breaking off and remaining in Gulf.
The Loop Current connects Gulf of Mexico waters to the Caribbean Sea and the Gulf Stream, but it also causes eddies and gyres to develop within the gulf.

Check out the webinar archive (coming very soon!) and hear these two research scientists explaining all this and more. There you can also access their map containing many useful and informative educational assets.

Join us on April 13th for our next webinar featuring Dr. David Fields of Bigelow Laboratory for Ocean Sciences who will talk about “How Zooplankton Are Effected by Changes in the Marine Environment.”

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