Increasing Ocean Acidity Threatens Marine Food Web in Circumpolar Waters

Nov 13, 2015

Ocean acidity threatening the marine food web …  


All the carbon humans are spewing into the atmosphere through smokestacks and tailpipes is increasing the acidity of the world’s oceans. And that’s harming species that must form protective shells to survive – like microscopic mollusks known as pterapods.

“Pterapods make shells out of calcium carbonate minerals,” says University of Alaska-Fairbanks researcher Claudine Hauri. “And in order for these organisms to build these shells, they need carbonate ions. The concentration of carbonate ions decreases because of ocean acidification.”

Claudine Hauri, a researcher with UAF's International Arctic Research Center, tests a carbon-dioxide sensor at the Alaska SeaLife Center in Seward, Alaska.
Credit Andrew McDonnell/UAF

Hauri says that’s a huge concern, because creatures like pterapods are at the base of the food pyramid on which much marine life depends.

“They’re an important part of the food web,” she said. “Seabirds eat them. Whales eat them. Salmon eat them. So, they’re very important.”

Ocean acidity is increasing because the seas absorbing much of the carbon dioxide humanity is generating, hindering the ability of pterapods and other such life forms to fully develop shells. Hauri says the problem is even worse in circumpolar waters, because their acidity already is higher than seawater at mid- and lower latitudes.

Recent research by Hauri and two others shows elevated ocean acidity in southern circumpolar waters and the likelihood of increasing acidification in the coming decades.
Credit IARC/UAF

“If you add this anthropogenic or human-induced carbon dioxide, you push those systems at the poles closer to a threshold that is bad these for example, tiny little sea snails,” she said.

Research published last summer suggests that within 30 years the Bering Strait off Alaska’s western coast may reach that threshold. That could threaten Alaska’s highly productive fisheries that last year yielded 5.8 billion pounds of seafood, worth nearly $2 billion.

Hauri says ocean acidification threatens fisheries and the food web that sustains them.

“We don’t know what happens if we take out one species,” she said. “It could collapse, it could go on. We don’t know.”

The journal Nature Climate Change last week published new research by Hauri and two co-authors on ocean acidification in southern waters, near Antarctica.