Ocean chemist John Kessler of Texas A&M University says he and a group of oceanographers made measurements of methane levels 10,000 to 100,000 times above normal and in some places "we saw them approaching 1 million times above" what would be normal, USA Today reported Wednesday.
The researchers spent 10 days sampling waters from 35 sites close to the ocean floor around the leak site, the newspaper said.
The gases are emanating from the same geological layer as the oil, Kessler says.
While the world focuses on the escaping oil, one scientist says he's worried about the "highly unusual situation" of the increased methane levels.
The methane is not going to go away anytime soon, Peter Brewer, an ocean chemist at the Monterey Bay Aquarium Research Institute in Monterey, Calif., says.
Bacteria consuming the methane could "run rampant," using up all the oxygen and possibly creating localized dead zones, Brewer says.