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Researchers examine glaciers' effects on ocean acidification in Prince William Sound

Yereth RosenAlaska Dispatch News

Three unmanned vessels called "gliders" and a tour boat equipped with special scientific equipment will be cruising Prince William Sound this summer gathering data about acidification and the effects of glacial melt on it, organizers of the project said on Tuesday.

The project, funded mostly by the National Oceanic and Atmospheric Administration, is being led by two University of Alaska scientists who are experts in the issue -- Jeremy Mathis and Wiley Evans -- with help from the Alaska Ocean Observing System.

Two of the gliders look like yellow surfboards skimming the water's surface, said Mathis, who also works for NOAA's Pacific Marine Environmental Laboratory, along with Evans. They will be steered remotely and -- project organizers hope -- away from other ships operating in the Sound, he said. The third glider "looks like a torpedo that you would shoot out of a submarine," and it will move beneath the water's surface to gather data at various levels underwater, he said.

The tour ship, operating out of Whittier, will ferry sightseers to glaciers and other scenic spots as the onboard equipment takes additional measurements.

The gliders and tour ships will be deployed next week, Mathis said. They will operate in the Sound until the fall, gathering five months of data.

Ocean acidification occurs as carbon dioxide in the atmosphere is absorbed by the oceans, relieving some pressure on the climate due to the greenhouse effect but shifting that burden to the marine world.

"The oceans are doing a great service to the atmosphere by taking up some of that carbon dioxide," Mathis said. Without the oceans' absorption of that greenhouse gas, the world's climate would be even warmer than it is now, he said.

But the cost is more acidic marine water, and potential stress to marine life, especially any creatures that need calcium carbonate to build shells.

Scientists estimate that the oceans are 25 percent more acidic than they were 300 years ago, AOOS said in a statement.

Acidification is a particular problem in polar regions, where waters are colder and thus hold more carbon dioxide.

Alaska's relatively shallow seas and high abundance of marine life also contribute to the buildup of ocean carbon. And tidewater glaciers, like those tumbling into Prince William Sound, appear to be making the problem even worse for Alaska waters, according to research by Mathis, Evans and colleague Jessica Cross. One paper, published in January in the journal Biogeosciences, focuses on calcium carbonate levels in Prince William Sound, and more research on conditions in Glacier Bay will soon be published, Mathis said.

"Ocean acidification is all about reduction of the material in the water that's the building blocks of shells," he said. The fresh water that pours into the sound from melting glaciers does not contain any of those minerals, so when it mixes into the sound's salt water, the effects of acidification are exacerbated: "The more glacial melt you have, the more dilution you have of this carbonate material."

For Prince William Sound and similar northern waters with glaciers feeding into them, accelerated melt is a "double whammy," Mathis said. "While the glacial melt isn't ocean acidification, it's exacerbating or making acidification worse," he said.

The gliders and the equipment on the tour ship will capture information from the period when the glaciers start their spring melt through the period when that glacial fresh water pours into the Gulf of Alaska.

The glacial water usually accumulates in the sound through the summer because winds are light during that season, Mathis said. When fall arrives, the high winds usually return, he said, and "glacial water that has accumulated in Prince William Sound gets all flushed out into the Gulf of Alaska."

Earlier research by Mathis and Evans identifies the Gulf of Alaska as a major carbon-dioxide sink.

Contact Yereth Rosen at yereth@alaska dispatch.com.


By YERETH ROSEN
Alaska Dispatch