Ocean clams, worms release surprisingly large amounts of greenhouse gas

"It sounds funny but small animals in the seafloor may act like cows in a stable," said researcher Stefano Bonaglia.
By Brooks Hays  |  Oct. 13, 2017 at 9:41 AM
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Oct. 13 (UPI) -- Scientists have measured the amounts of greenhouse gas released by worms and clams in the Baltic Sea and the results are surprising.

Researchers estimate polychaetes and bivalves account for 10 percent of the Baltic Sea's methane emissions -- roughly the amount of methane released by 20,000 dairy cows.

Though not as ubiquitous as carbon dioxide in the atmosphere, methane's heat-trapping greenhouse effect is 28 times more potent than that of CO2.

Policy makers around the world have considered encouraging the farming of bivalves in the ocean as a way to meet the world's growing demand for protein and to ease pressure on fishing stocks. But the latest findings -- published this week in the journal Scientific Reports -- suggest policy makers take a closer look at the impacts of such decisions on greenhouse gas emissions.

"What is puzzling is that the Baltic Sea makes up only about 0.1 percent of Earth's oceans, implying that globally, apparently harmless bivalve animals at the bottom of the world's oceans may in fact be contributing ridiculous amounts of greenhouse gases to the atmosphere that is unaccounted for," Ernest Chi Fru, a researcher at Cardiff University in Wales, said in a news release.

Researchers measured trace gas, isotopes and molecules in ocean sediments, some samples containing worms and clams and others devoid of microfauna. Their analysis showed the polychaetes and bivalves were responsible for an eight-fold increase in methane emissions.

Scientists believe the methane released by worms and bivalves is a byproduct of their digestive process.

"It sounds funny but small animals in the seafloor may act like cows in a stable, both groups being important contributors of methane due to the bacteria in their gut," said lead author Stefano Bonaglia, a researcher at Stockholm University. "These small yet very abundant animals may play an important, but so far neglected, role in regulating the emissions of greenhouse gases in the sea."

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