Worms Create Methane Release in Oceans

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CORVALLIS, Ore. — Scientists say methane levels are high in waters near New Zealand, likely because of a worm habitat, creating tunnels that release the gas from below the ocean floor.

Off the coast of New Zealand, scientists have discovered a new methane seep habitat, where methane is being released. Andrew Thurber, a post doctoral fellow doing research at Oregon State University’s College of Earth, Ocean, and Atmospheric Sciences, is one of the primary researchers of the study. Thurber says methane seeps are found all over the world, but the one near New Zealand is different.

“It was dominated by this kind of worm called the ampharetidae,” Thurber said. “What was happening there was much more methane being released out of the sea floor than we expected, and much more than almost any other location on the planet.” 

Thurber says the ampharetidae worm is releasing more methane from the ocean’s floor for two reasons. 

“They live in tubes, which are burrows that go down into the sediment, and they create this type of chimney,” Thurber said.

The chimney-like tunnel allows the methane to seep out into the water columns, Thurber says. But researchers say the worms aren’t just creating burrows. They are also eating bacteria that usually would consume much of the methane.

“Another thing we think they’re doing is they’re actually eating the bacteria and potentially the archaea – these two microorganisms that normally consume all the methane,” Thurber said, “So it’s essentially eating the filter that normally keeps the methane consumed and trapped within the sediment.”

Usually, when methane is released into the water, Thurber says it dissolves or comes out as bubbles. Bacteria in the water columns usually consume the methane before the bubbles release into the atmosphere. In New Zealand, even though the worms are consuming these types of bacteria, scientists say the high methane levels are not worrisome yet.

“Currently, we’re not seeing bubbles being released into the atmosphere,” Thurber said. “But it’s something that we need to understand to find out if that could happen in the future.”

Scientists say the methane also provides as non-toxic food for different species, which actually increases the biodiversity where methane exists. So why should anyone care?

“Methane’s a greenhouse gas,” Thurber said. “It’s much more efficient at warming the atmosphere than CO2.”

Thurber says with rising amounts of carbon dioxide in the Earth’s atmosphere, the ocean temperatures are also rising. He says he’s not worried yet, but if there is an increase in water temperature at low ocean depths, he says that could mean a much higher chance of methane being released into the atmosphere. More than anything, Thurber stresses the importance of global methane research – something scientists say they have a limited understanding of.

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