Acidic Ocean Water Is Dissolving Sea Snail's Shells
Increasing acidity of the ocean is dissolving the shells of tiny marine snails called pteropods, according to a new study by the National Oceanic and Atmospheric Administration. The pteropod is a free-swimming snail found in oceans around the world that grows to a size of about one-eighth to one-half inch.
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The evidence of corrosive waters impacting the snails, which provide food for pink salmon, mackerel, and herring, was discovered by a research team at NOAA's Pacific Marine Environmental Laboratory in Seattle, Wash.
"Our findings are the first evidence that a large fraction of the West Coast pteropod population is being affected by ocean acidification," said Nina Bednarsek, NOAA's lead researcher on the project. "Dissolving coastal pteropod shells point to the need to study how acidification may be affecting the larger marine ecosystem. These near shore waters provide essential habitat to a great diversity of marine species, including many economically important fish that support coastal economies and provide us with food."
The percentage of pteropods with dissolving shells has doubled since the pre-industrial era and is expected to triple by 2050, when coastal waters become 70 percent more corrosive than in the period before the industrial age impacted ocean acidity, researchers said.
The highest percentage of the tiny snails with dissolving shells were found along a portion of the continental shelf from northern Washington to central California. In that region, 53 percent of the pteropods' shells were impacted by ocean acidity. Scientists from NOAA's Northwest Fisheries Science Center and Oregon State University were part of the research team.
"We did not expect to see pteropods being affected to this extent in our coastal region for several decades," said William Peterson, an oceanographer at the Northwest Fisheries Science Center. "This study will help us as we compare these results with future observations to analyze how the chemical and physical processes of ocean acidification are affecting marine organisms," Peterson said in a NOAA report on the study.
Peterson is co-author of the study, "Limacina helicina shell dissolution as an indicator of declining habitat suitability owing to ocean acidification in the California current ecosystem," published April 30 in Proceedings of the Royal Society B.
The researchers studied one kind of pteropod, which is a planktonic snail, known as the sea butterfly because of the winglike body parts that allow them to glide through the water, according to Science magazine.
The findings suggests that sea life is already being affected by changes in the ocean's chemistry caused by rising carbon dioxide levels in the atmosphere.
"It really changes the game" by demonstrating that acidification is having a noticeable impact, said biological oceanographer Jan Newton, co-director of the Washington Ocean Acidification Center at the University of Washington in Seattle, according to Science. Newton was not involved in the study.
Like other shellfish, pteropods use dissolved carbonate in seawater to build their shells, according to Science. Laboratory studies have shown that the process can be disrupted and shells can dissolve as seawater becomes more acidic.
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