Aerobic bacteria could produce the greenhouse gas methane in the surface waters of the world’s oceans, suggests a study published online this week in Nature Geoscience. The research indicates that marine methane production may increase in response to climate change, releasing more methane into the atmosphere in a positive feedback loop.
David Karl and colleagues measured methane production in seawater samples collected off the coast of Hawaii. They found that marine bacteria break down a phosphate-containing compound in oxygenated seawater, producing methane as a by-product. They found that methane production was greatest in phosphate-depleted waters.
The upper oceans are known to be rich in methane, relative to the atmosphere, but the precise source of this methane has perplexed researchers. Production of the gas was previously thought to be limited to oxygen-free environments unlike the sea surface.