Creating a new niche with our own mistakes

bacteria by adonofrio

Bacteria rush in to gobble up oil plumes from Deepwater
[Via Ars Technica]

Researchers have discovered a large contingent of silent partners in the Deepwater oil spill cleanup—bacteria. Two samples of a deep-sea oil plume show that a high number of microbes have populated the oily area and are hacking away at the hydrocarbon concentration. The bacteria also seem to be using relatively little oxygen to metabolize parts of the oil, minimizing their own environmental impact.

The samples of water were taken inside and outside a large oil plume about 6 miles from the well site and three-quarters of a mile below the surface, and date from a month after the Deepwater Horizon rig explosion. The scientists compared the chemical composition of the waters, as well as their microbial cell populations.

Despite the hostile environment, they found that the density of microbial cells inside the plume was twice that of uncontaminated water. The population was diverse, but certain types known to metabolize hydrocarbons using ambient oxygen and thrive in the presence of oil in cold water were particularly plentiful.

The authors of the paper found that, on average, the microbes were consuming hydrocarbons fast enough to give the plume’s oil a half life of one to six days. The metabolization isn’t yet taxing the water too badly, either, as the oxygen concentration inside the plume is only eight percent lower than normal, a figure consistent with other recent results.

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It looks like we might have been a little lucky here in the short term. These newly isolated bacteria are not only able to digest the oil but to also do it in ways that do not use up large amounts of oxygen, which is what is seen with bacteria at shallower depths.

It may well turn out that the use of dispersants at such depths as Deepwater – something that had never been done before and was only really done to prevent oil from reaching the surface – may have been fortuitous.

A half-life of 1 to 6 days is totally unexpected.

We may have been lucky this time. Once the oil is gone, I would expect most of these bacteria to die and perhaps sequester much of the released carbon as new sediments.

But we should remain cautious. Putting new pressures on an environment with the results of our own mistakes may have ramifications that we can not anticipate.