Scientists link humans to ocean acidification, sea snail shells ‘dissolving’

Elevated carbon dioxide levels in the Pacific Ocean are connected to human activity, according to a study from the federal government, and that acidification is causing the shells of a key microscopic sea snail to dissolve, a phenomenon that could affect other species in the ecosystem.

Research from the National Oceanic and Atmospheric Administration released Tuesday linked elevated human-caused carbon dioxide levels along the waters off the West Coast to “shell dissolution” among the microscopic sea snail known as pteropods.

The NOAA-backed study builds on past research that found when sea snail shells are damaged, it could affect their ability to swim and evade predators. The pteropod, roughly the size of the head of a pin, is an important research subject because its shell is particularly susceptible to ocean acidification, which could have widespread implications for marine life.

“We estimate that since pre-industrial times, pteropod shell dissolution has increased 20 to 25 percent on average in waters along the U.S. West Coast,” Nina Bednaršek, a University of Washington scientist who conducted previous research on the snail, said in a statement.

“This new research suggests we need a better understanding of how changes in pteropods may be affecting other species in the food chain, especially commercially valuable species such as salmon, sablefish, and rock sole that feed on pteropods,” Bednaršek said.

Researchers analyzed carbon dioxide levels for several decades and were able to parse out how much of the emissions were human-caused versus levels that were naturally occurring in the ocean.

In shallow water, fossil fuel emissions comprised up to 60 percent of the carbon dioxide, researchers found. Those levels dropped as scientists looked at deeper waters, with just 21 percent of emissions coming from human activity at depths of 328 feet.

According to the study, more than 50 percent of pteropod shells collected in shallower waters were “severely dissolved.”

“This is the first time we’ve been able to tease out the percentage of human-caused carbon dioxide from natural carbon dioxide along a large portion of the West Coast and link it directly to pteropod shell dissolution,” Richard Feely, a NOAA senior scientist who led the research, said in a statement.

The research appears in Estuarine, Coastal and Shelf Science.

Contact: Andrew Theen, atheen(at), 503-294-4026, @andrewtheen

Andrew Thee, Oregon Live, 23 November 2016. Press release.

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