Acidic ocean hits Pacific Northwest (article and video)

Changes in ocean chemistry threaten Washington state’s Makah tribe as well as the region’s shellfish industry

The path to Cape Flattery is a twisty, moss-carpeted tunnel underneath red cedar and Douglas fir trees that crowd Washington state’s rugged coastline. Micah McCarty scrambles down the forest trail to a shoreline below, leaping across tide pools and slippery rocks to a point where waves break on shellfish beds. We’ve reached the northwesternmost point of the U.S. mainland, a craggy tip of the Olympic Peninsula that belongs to the Makah tribe.

This group of Native Americans has been fishing and harvesting here for the past 2,000 years. McCarty, the tribe’s 42-year-old former chairman, pulls out a pocket knife and squats down to scrape a handful of mussels and barnacles into his hand. “We call them slippers and boots,” he says. “I’ll make them into a Makah paella tonight.”

McCarty and his family grew up picking these marine delights along the coast. Oysters, clams, cockles, barnacles, and other types of mollusks and shellfish have always been part of the Makah diet, as well as the tribe’s culture. The shells are used both as beads in ceremonial regalia and as musical instruments. But now, changes in the global climate have led to rising ocean acidification that has put in peril the future of the Makah harvest.

“It’s already starting to impact the way that the shellfish cling to the rocks,” says McCarty as he points to a group of “boots.” The gooseneck barnacles are a species with a flexible orange “neck” that attaches itself to the wave-tossed rocks. “They can’t hold on very well. When the waves hit, you see there’s very few left of that colony.”

McCarty isn’t a scientist, but his observations here at Cape Flattery confirm what marine biologists and chemists are finding across this region and the globe. Increasing levels of carbon dioxide in the atmosphere are reacting with seawater and lowering its pH. That increasing acidity is damaging shellfish, coral reefs, and other marine animals.

Over the past 250 years, the average upper-ocean pH has decreased by about 0.1 units, from about 8.2 to 8.1. This drop in pH corresponds to an increase in the acidity of about 30%. Unless things change, scientists predict the average acidity of the surface ocean will be more than double preindustrial levels by the end of this century, according to the federal 2013 National Climate Assessment.

When CO2 levels in seawater rise, the availability of carbonate ion decreases. That change makes it more difficult for marine organisms to build and maintain shells and other hard body parts from calcium carbonate. If the carbonate ion level drops too low, seawater corrodes the shells. The animals have higher mortality, and juveniles and larvae are most at risk. Any die-off could have devastating effects on Washington’s $270 million shellfish and aquaculture industry.

In the Pacific Northwest, the problem of ocean acidification is especially bad for several reasons. One reason is that prevailing winds push surface waters away from the coast, causing a local upwelling of carbon-rich water from the deeper ocean to the surface. This upwelled water is naturally rich in nutrients, is high in CO2, and has low pH. But now, the upwelled waters are also carrying an ever-growing load of human-generated CO2 picked up from the atmosphere 30 to 50 years ago when the water was last in contact with the atmosphere. As a result, deep water today is more corrosive than ever to shell-building organisms such as oysters, clams, scallops, mussels, crabs, abalone, and pteropods (small sea snails eaten by fish and other marine life).

A separate acidification process is under way in the vast expanse of Puget Sound, just as in other estuaries along the world’s coastlines. Runoff from farms, storm sewers, and urban pollution flushes organic carbon and other nutrients into estuaries that are nurseries to growing shellfish. These nutrients fuel blooms of marine algae, which then die, fall to the bottom, and during decomposition result in more CO2 being released to the water. In the air, emissions of nitrogen and sulfur oxides from factories, cars, and power plants are yet another source of nutrients that cause blooms that lead to more acidic waters.

The chemical soup resulting from all of these acidification processes has made both Puget Sound and the Washington coastal area among the most acidic water­ways on the planet, according to Jan Newton, senior principal oceanographer at the University of Washington’s Applied Physics Laboratory.

“Because we’re increasing the anthropogenic contribution of CO2, that pushes the concentrations in the ocean higher and higher,” Newton says. She explains the twin dilemmas of Washington shell fishers—upwelling along the coast and eutrophication in the estuaries—that are lowering the pH of both areas.

“The concern is, Will the biology be more susceptible and change, or is it possible that some of our outer coast species will be resilient?” Newton asks. “Are we at their threshold? Will we reach it in five or 50 years? Nobody knows that, but the risks are there.”

Newton is directing a network of ocean-monitoring buoys along parts of the Washington coast and Puget Sound that are giving researchers more information about hot spots of acidity. She’s also working with the Makah and three other Indian tribes to serve as eyes and ears to changes already under way. Some tribal members are helping deploy the massive buoys on oceanographic cruises, crunching numbers along with researchers and reporting their own data about abundance of the marine species they rely on.

Because the Makah and other tribes have long oral and written histories of the status of their surrounding environment, they have been able to fill in gaps for researchers such as Newton who are studying the ocean changes. Tribal members are providing scientists anecdotal, yet vital, data about the abundance of marine organisms like clams, mussels, and other shellfish that they have harvested for generations.

Eric Niiler, Chemical & Engineering News, 25 March 2013. Full article and video.


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