A lot has been said, written, and discussed about the recent Oil Spill in the Gulf of Mexico. The spill has been capped but the damage remains. The Gulf of Mexico has now become the feedstock of several battles, fierce and feeble, in the legal, political and scientific realm. What battles you say? It’s what on your mind as well – What will happen of the Gulf of Mexico? What do we need to do to save the physical, chemical and biological environment? And the worst of all – Is the damage irreversible?


Sadly, we don’t have any answers yet. And let’s face it – there is no right answer. What we do have are cues from the environment itself. Scientists from the Lawrence Berkeley National Laboratory, University of Oklahoma, Pacific University, and The Lawrence Livermore National Laboratory have taken the proverbial stethoscope and are listening intently to the heartbeat of the deep underwater plume near the wellhead…and they have good news for us. In a recent paper, published in the journal Science, these scientists report some of their latest findings on the microscopic life that is abuzz in the hydrocarbon plume near the wellhead where the oil spill occurred.

Why is an oil spill an environmental hazard in the first place? Crude oil, as you may know, is a cocktail of high molecular weight aromatic hydrocarbons such as isopropyl benzene, n-propylbenzene, and naphthalene. These hydrocarbons are extremely persistent in the environment, which means that most organisms cannot use them as a substrate for growth or energy, nor do they get degraded by physical or chemical processes. Add to that, the fact that some of these chemicals are highly toxic and a few of them carcinogenic. So when oil spills occur, especially in such large quantities in such a small amount of time, it leads to a sudden loss of flora and fauna and a major imbalance in the prevalent ecosystem. These large opaque clumps of crude oil emanating from the Earth’s interior can be reduced to tiny droplets that can disperse in the water column by adding chemicals known as dispersants. If the sudden insurgence of crude oil in the marine ecosystem wasn’t hard to deal with, the organisms in the deep sea near the hydrocarbon plume in the Gulf had to also deal with the added toxicity of Corexit 9500 – the dispersant that was added in copious quantities soon after the spill.

Did anyone survive this massive onslaught? Surprisingly, yes! The authors of this study took samples from the deep sea up to 10 kms( 6.2 miles) away from the wellhead and saw that around the depth where the oil spill occurred there was a slight reduction in the amount of oxygen. This reduction in oxygen levels, usually indicative of respiration by living beings, was the first clue that led them to think that life is prospering in these toxic waters. They knew, from previous studies, that these living beings had to be microorganisms especially bacteria. With an a priori hypothesis that bacteria are living in this hydrocarbon plume, the authors went on to measure the density of bacteria in the water column in the Gulf and their hypothesis was proved right — the cell density was especially high just at the depth where the oil spill occurred. With these exciting preliminary results, the authors decided to take water samples near the plume and peer at them under the microscope and there was living proof – their paper has a few pictures of big, fat bacteria happily chomping down the hydrocarbons.

Where did these bacteria come from? How can they survive? Further analysis showed that there is a wide diversity of bacteria in the deep sea waters of the Gulf. Samples that the authors extracted from parts of the deep sea that were not affected by the oil spill showed up to 951 different bacterial taxa. Only 16 of them were found in the hydrocarbon plume. Did these 16 taxa just get lucky? No way, luck rarely works in the natural environment. These 16 taxa of bacteria, not surprisingly, have representatives, that have previously been reported to eat up hydrocarbons especially at low temperatures (as observed in the deep sea). How did these 16 taxa get to the plume? They didn’t happen to get there by luck either, they were already present in the deep sea water before the oil spill but were not as abundant because they were competing with many other taxa for food and resources. When there was a sudden insurgence of oil into their ecosystem, whilst most other bacteria perished, they survived because they could eat up the oil. Their numbers increased rapidly. Selecting for certain taxa that can degrade persistent compounds in the natural environment is termed by environmental engineers as ‘enrichment’. The authors analyzed the phospholipid fatty acids – components of the bacterial cell membrane, used as a signature for identifying different taxa – of bacteria in the plume to further deduce that there were two distinct groups of a taxa known as Oceanospiralles. Oceanospiralles have been found in hydrocarbon-enriched environments commonly and some of them are also known to be psychrophiles (cold-loving). Oceanospiralles are capable of surviving an oil spill because they contain genes for hydrocarbon utilization, such as the phdCI gene that is needed for naphthalene degradation.

These results show that the microbial community in the deep sea hydrocarbon plume in the Gulf of Mexico has already undergone a rapid adaptive shift. Selection has led to the formation of a new-fangled community that is not as diverse but highly specialized to degrade the oil. Apart from marveling at the rapid, dynamic response of the microscopic super heroes we must realize that these results imply that there is an intrinsic potential for bioremediation (removal of contaminants by microbes plants etc.) of oil contamination in the Gulf. We must devise our clean-up plans keeping them in mind.

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Comments

  1. #1 Lyle
    November 2, 2010

    It helps a lot that there are natural seeps in the Gulf, so that the bacteria always have some oil to feed on. Thus there are always some present, and give them a feast to end all feasts and they will do as bacteria do, be fruitful and multiply. This is the key difference with Prince William Sound the water temp is so much higher in the gulf and some oil is naturally present, so the bacteria are around. If one takes a 10+ year time frame I suspect an aweful lot of the damage will be gone.
    Trying to measure the Gulf versus Prince William Sound does not take these factors into account.

  2. #2 sinz54
    November 3, 2010

    There was a science fiction novel, “Mutant 59,” that tried to show what would happen if bacteria evolved that could eat plastic. Our modern civilization uses so many forms of plastic–it’s now ubiquitous–that bacteria that could disintegrate all that plastic would threaten our civilization.

  3. #3 natural cynic
    November 4, 2010

    Lyle:

    …the water temp is so much higher in the gulf and some oil is naturally present

    Some oil might be naturally in Prince William Sound since there is oil on the other side of the Kenai Peninsula in Cook Inlet. The temperature of the surface waters in the Gulf of Mexico are certainly warmer, but the deep waters of the gulf are just as cold.

  4. #4 Douglas Watts
    November 4, 2010

    What will happen of the Gulf of Mexico? What do we need to do to save the physical, chemical and biological environment? And the worst of all – Is the damage irreversible? Sadly, we don’t have any answers yet. And let’s face it – there is no right answer.

    Well yes, there actually is a ‘right’ answer. If the damage is irreversible, then the damage is irreversible. That’s called science, or at least math. If the spill causes a species, say a sea turtle, to become extinct, then that damage is ‘irreversible’ since extinction, by definition, is irreversible.

    There is a ‘right’ answer — and a wrong one.

  5. #5 Dipti Nayak
    November 4, 2010

    @Doug : Thanks for your comment but I request you to consider a few things before making conclusions on what ‘science’ really is!

    Firstly, let me clarify, what I meant when I wrote that there is no right answer. My statement implied that we don’t know what to do/what not to do in order to “clean-up” the oil spill. There is no right measure because scientists are still trying to understand even the most basic parameters in order to make models the open ocean ( for example, take biogeochemical cycles, or even microbial diversity… we’ve barely scratched the surface). Did you know that the a group of microbes called ammonia-oxidizing archaea were found to be major role-players in nitrogen cycling in the open ocean just 5 years ago? With such little knowledge how can we make conclusive statements. We can only try to do what we can based on the resources we have. How right or wrong it is, is highly contentious.

    Another point I’d like to raise is about species extinction. The Earth has always had a dynamic environment, the rise and fall of species is inevitable. Instead of belaboring my point I’d request you to read some of Stephen Jay Gould’s work… Let’s just take the case of sea turtles. As far as I know, there are some species that breed only in the Gulf of Mexico and they were endangered even before the oil spill happened. So the hypothesized extinction of your sea turtles would include many more factors than just the oil spill.

    I am sure you agree that the oil spill should have never happened in the first place and that it’s probably going to be one of the ugliest man-made disasters of our time (I was born right after Chernobyl!). It’s effects are wide-spread but the point of the article was to emphasize the role of microbes in helping the cleanup process. I hope you are convinced that microbes do play an important ecological role in contaminant cleanup..

  6. #6 Anjali
    November 5, 2010

    When the golf oil spill occurred I thought of how much of a negative environmental impact it would have. Then, when I heard for weeks and weeks that the spill hadn’t been capped I was sure there would be no way to repair the ecosystem of the Gulf. It is great to hear that these bacteria are cleaning up after us. I read about these bacteria that sound like magic before, but at that time scientists were still unsure if they actually worked. It’s great to hear that these bacteria can help up clean up the Gulf, but my question is how long will it take these bacteria to clean up this spill that released thousands of gallons? Also, are there animals that face extinction due this spill? When the spill was actually still going on I heard so much about how horrible it would be. Lately, I haven’t heard anything on the news about the real impact and what kinds of efforts our being made to clean it up. At least we know that if humans aren’t acting these bacteria are working to clean their homes.

  7. #7 Dipti Nayak
    November 6, 2010

    @Anjali : Those are some really good questions. About, how long it’ll take for bacteria to clean up the oil spill, I am not aware if there have been any estimates thus far. The Science page in NYTimes has an article on the impact of the spill on corals. Things don’t look too optimistic at that end sadly!

  8. #8 Alec
    November 7, 2010

    Like most people in the U.S., I was disgusted and appalled as the oil spill continued to reek havoc on the ecosystem of the Gulf. I cringed every time the tiny box with a video of the oil spill showed up on my TV screen. When the spill was stopped, I was relieved, but I also began to question how long this would take to clean up and the affect this would have on the environment. Until this article, I haven’t heard of any solution or clean-up plan for this tragedy. I find it interesting, and sort of ironic that bacteria, which we usually think of as harmful, are actually improving the ecosystem of the Gulf. I am fascinated that nature is working to solve our own problems. But we shouldn’t be relieved just yet because these bacteria will not be our saviors. I have a few questions related to this article and the oil spill. First of all, when scientists discovered these bacteria, how did they come to the conclusion that the lack of oxygen indicates life? I would usually think the opposite. Also, could these bacteria solve the problem by themselves eventually or will we need to interfere? I think that it would be great if they could do it alone or with other microorganisms over time because I feel like we always mess things up when we try and interfere. Another worry I have refers to the amount of bacteria. Will these bacteria be too abundant in the Gulf after the oil spill is cleaned up and possibly harm the balance of the ecosystem? And lastly, is anyone else successfully helping to clean up the spill or at least attempting to? I haven’t really heard anything lately about the effort to solve this problem.

  9. #9 Jon D
    November 9, 2010

    Hooray for those plucky little Prokaryotes!

    I find it really inspiring how nature always finds a way.. of course we dont know how long it’ll take for things to settle down, nor what effects this huge change in the competitive environment will have on the ecosystem but life will prevail in one way or another!

    Thanks for the writeup

  10. #10 Mayank
    May 26, 2012

    Thanks for such a wonderful post. It was a great read.

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