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Natural oil seeps encourage microbial life in Gulf of Mexico

"This is the beginning of evidence that some microbes in the Gulf may be preconditioned to survive with oil," said researcher Ajit Subramaniam.

By Brooks Hays
Natural oil seeps encourage microbial life in Gulf of Mexico
Natural oil and gas seeps produce oil and gas bubbles on the surface of the Gulf of Mexico. Microbial communities seem to thrive nearby. Photo by Ajit Subramaniam/Columbia

NEW YORK, Jan. 25 (UPI) -- Scientists from Columbia University's Earth Institute have discovered a new biological phenomenon in the Gulf of Mexico. Phytoplankton communities are thriving above natural oil seeps.

There's oil and gas trapped in the rocks and sediment of the ocean floor. Sometimes, some of that oil and gas makes its way to the surface. Natural oil seeps can be found scattered across the Gulf of Mexico, with natural gas sometimes rising as much as a mile, forming bubbles at the surface.

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Researchers found the tiny algae-like microorganisms known as phytoplankton -- the foundation of the marine food web -- congregating near where these natural oil seeps surface.

Scientists say the oil and gas itself is not beneficial, but the nutrients the bubbles bring with them are. Like the upwelling of ocean currents, the rising bubbles draw deep-dwelling nutrients to the surface. As a result, pytoplankton congregate to feed on the nutrients.

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"This is the beginning of evidence that some microbes in the Gulf may be preconditioned to survive with oil, at least at lower concentrations," Ajit Subramaniam, an oceanographer at Columbia University's Lamont-Doherty Earth Observatory. said in a press release.

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Subramaniam is the co-author of a new study on the phenomenon, published this week in the journal Nature Geoscience.

"In this case, we clearly see these phytoplankton are not negatively affected at low concentrations of oil, and there is an accompanying process that helps them thrive," Subramaniam said. "This does not mean that exposure to oil at all concentrations for prolonged lengths of time is good for phytoplankton."

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In a series of lab experiments, study co-author Andy Juhl, an aquatic ecologist at Lamont, determined that at no amount of oil on its own is a boon to phytoplankton. But in a marine setting, it can be tolerated at low concentrations.

"The direct effect of oil is usually negative, but in some cases small amounts of oil can be outweighed by the positive effect of the nutrients that are tagging along," Juhl explained.

Juhl, Subramaniam and their colleagues found the microbial communities surrounding natural oil seems in the Gulf were about twice as dense as those found a few miles away. The highest concentration of phytoplankton was found a couple hundred feet beneath the surface, where the microbes could benefit from both the rising nutrients and sunlight penetrating from above.

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The scientists plan to continue their research into the interactions between oil and marine life. Next, they plan to study which types of phyotplankton benefit the most from rising oil and gas bubbles. They also want to better understand the path of oil and gas from the ocean floor to the ocean surface.

RELATED NASA: Oceans' phytoplankton numbers are trending downwards

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