While these (and many other) studies showed that bacteria were cleaning up the oil better than anyone expected, there was one nagging worry: what about the oil that was floating on the surface of the Gulf? Most of the studies dealing with bacterial decomposition in the Gulf concentrated on the oil that was deep underwater. The surface of the Gulf of Mexico is a much different environment from the deep waters, and it was feared that bacteria would not be as good at decomposing the oil that was floating on the surface.
Indeed, a 1995 study specifically looked at bacterial activity on the surface of the Gulf of Mexico near where the Deepwater Horizon disaster occurred. The researchers noted that the mix of chemicals in that region is not ideal for good bacterial activity. They even did experiments where they added excess glucose to the water and watched how the bacteria responded. While bacteria typically love to eat glucose, the researchers saw very little increase in bacterial activity. This led them to conclude that the surface waters were not very suitable for bacterial-led cleanup.1
The scientists at the Woods Hole Oceanographic Institution are, of course, familiar with the results of this study. So they thought that the oil on the surface of the Gulf would not be cleaned up nearly as quickly as the oil that was deep in the Gulf. Fortunately, they were wrong.
The scientists sampled oil at twelve different locations in the Gulf from June 19, 2010 to June 28, 2010. This was during the time period in which oil was still gushing out of the well. Five of the twelve locations were directly in the oil slick that was floating on top of the water, while the other seven were outside the slick. They then did a thorough analysis of the samples from all twelve locations, comparing the oil-slick samples to the non-oil-slick samples. The results were astounding:2
Our study shows that the dynamic microbial community of the Gulf of Mexico supported remarkable rates of oil respiration, despite a dearth of dissolved nutrients.
In other words, even though the surface waters of the Gulf should not support a lot of bacterial activity, the bacteria within the oil slick were eating the oil very quickly! So the cleanup crew that God designed to help keep the Gulf clean was a lot tougher than scientists expected it to be!
But wait a minute. Didn’t the scientists in 1995 show that even when you give the bacteria on the surface of the Gulf extra food, they just aren’t able to eat it because the other chemical they need aren’t present? Yes, but they did their test with a sugar (glucose), not a mixture of hydrocarbons like oil. In the end, the bacteria were able to utilize the products of the oil breakdown to fuel their activity. So the very activity of doing what they were designed to do actually allowed them to do more of it!
Now even though the bacteria were able to use the products of the oil breakdown, it was not ideal for them. The researchers noted the strong presence of a chemical that indicates “phosphate stress” in bacteria. In other words, the bacteria really could have used phosphate, but that wasn’t available in the surface waters of the Gulf, so they simply made due without it. The results weren’t ideal (for the bacteria), but the cleanup continued. As the authors note:
Microbes within the surface slick showed higher rates of alkaline phosphatase activity, indicating enhanced phosphate stress. Despite this, rates of microbial respiration and lipase activity were also higher within the slick, and the degradation of hydrocarbons was fairly rapid and supported the majority of respiration.
So even though they were stressed, the bacteria did their job effectively. I wonder how many of us can say the same thing when we are stressed out at work.
Not only did the bacteria show signs of stress, the scientists noticed one other very surprising thing: The bacteria didn’t reproduce much more than they would have without the oil. Why is this surprising? Remember, the bacteria ate the oil. That should have given them lots of extra energy. When organisms have a lot of extra energy, they tend to reproduce. So one would expect that if a lot of oil was being eaten, a lot of bacterial reproduction would take place. That didn’t seem to happen, however. The authors are planning follow-up experiments to try and determine exactly why the bacteria could eat all that oil but not reproduce very well. I will be interested to see what they find out.
Of course, the main conclusion of the report is that once again, nature performed better than anyone expected. God’s cleanup crew worked hard to clean up our mess, even under conditions that we thought would make it impossible for them to do their job effectively. This is even more evidence that the earth is anything but fragile. Instead, it is an incredibly well designed system that has all sorts of safety mechanisms built into it – safety mechanisms that work better than anyone expects.
This shouldn’t be surprising to any scientist who understands that earth and its inhabitants were built by an incredibly Intelligent Designer!
1. L. R. Pomeroy, et al., “Limits to Growth and Respiration of bacterioplankton in the Gulf of Mexico,” Marine Ecology Progress Series 117:259-268, 1995.
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2. Bethanie R. Edwards, et al., “Rapid microbial respiration of oil from the Deepwater Horizon spill in offshore surface waters of the Gulf of Mexico,” Environmental Research Letters 6, 2011 (available online)
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