Communities of microorganisms have been thriving in the Gulf of Mexico despite the presence of naturally-occurring oil seeps in the water surface, a new study says.
Some areas of the ocean floor are known to have deposits of natural oil and gas, which sometimes make their way to the surface in the form of seeps. When these substances accumulate in the water surface, they begin to form nutrient-rich bubbles.
In a study featured in the journal Nature Geoscience, researchers from Columbia University have discovered that algae-like organisms called phytoplankton tend to congregate near areas of the Gulf of Mexico where seeps of natural oil and gas can be found.
While the oil and gas does not appear to be particularly beneficial to the microorganisms, the researchers believe the nutrients in the bubbles are what draw them to the seep formations. The phenomenon can be compared to how the upwelling of currents brings nutrients from the ocean floor to the surface.
Phytoplankton communities gather in areas of the Gulf where these bubbles form to feed on the nutrients they bring.
"This is the beginning of evidence that some microbes in the Gulf may be preconditioned to survive with oil, at least at lower concentrations," oceanographer Ajit Subramaniam from Columbia's Lamont-Doherty Earth Observatory said.
He explained that the phytoplankton communities that they were able to observe did not suffer from low concentrations of oil, suggesting that the microorganisms may have a process that allows them to thrive in this environment.
However, Subramaniam said that this does not mean that long term exposure to oil at any concentration is beneficial to the phytoplankton.
Impact Of Natural Oil On Phytoplankton
Following a series of laboratory experiments, the researchers found that phytoplankton do not receive any benefit from any amount of oil, though the microorganisms seem capable of tolerating the presence of the substance at low concentrations in a marine setting.
Aquatic ecologist and study co-author Andy Juhl said that the direct impact of oil is often negative. However, there are cases where small amounts of the substance can be offset by the positive effect of the nutrients that oil often brings with it.
By using satellite radar data, the researchers were able to get a detailed picture of where the oil and gas seeps are formed across the Gulf of Mexico. This allowed them to produce a reading of how these substances impact the ocean surface.
The team discovered that parts of the Gulf where natural oil seeps can be found had microbial communities that were twice as dense as those in other areas.
The highest phytoplankton concentration was located several hundred feet below the water surface, where the microorganisms could thrive on the amount of rising nutrients and sunlight that penetrates from the above.
Subramaniam and his colleagues are now planning to explore how marine life in the Gulf interacts with the oil and gas seeps in the surface.
They wish to determine which specific phytoplankton types benefit most from the natural oil bubbles, as well as how exactly oil and gas are able to make their way from the ocean floor to the surface.
