Oyster reefs are regulators of atmospheric CO2

Harmful fishing practices and high sediment pollution are disturbing the world's oyster reefs, and these disturbances could significantly impact levels of carbon dioxide in our atmosphere, according to a new study. Researchers at the University of North Carolina at Chapel Hill studied the carbon buried in 22 different reefs and found that, when disrupted, the reefs become sources of atmospheric carbon dioxide.

Why it matters: Higher levels of CO2 in the atmosphere can accelerate the effects of climate change, and oyster reefs may have a role in that process.

What they found: Reefs contain both organic carbon and inorganic carbon, which lives in shells. The organic carbon takes CO2 out of the atmosphere, while shell carbon feeds CO2 back into it. Whether a given reef is a source or sink of carbon depends on the ratio of carbon types buried. But "when you disturb a reef … you create a bigger source," says Joel Fodrie, one of the researchers. This is because while shell carbon is largely inert, organic carbon can be metabolized and start to vent CO2 if it is disturbed.

The limitations:

"We work in one place on the planet," Fodrie said. The scientists measured effects in the oyster reefs of North Carolina's temperate waters. Another study might test colder or warmer waters or consider mussel beds instead of oyster reefs, Fodrie said.