Acidification of Pacific coast could disrupt entire marine food web


Clams (photo by J.-L. Teyssié)

Pacific Northwest shellfish producers are the first harbingers of a trend that may have wide ranging implications for the broader fishing industry: ocean acidification. By proactively seeking out adaptation solutions early on, the Northwest shellfish industry is attempting a self-rescue that may provide important lessons as other commercial species begin feeling the impacts of increasing acidification.

The general acidity of the oceans has risen 30 percent since the Industrial Revolution.1 The culprit is carbon, which is being released into the atmosphere through the burning of fossil fuels such as coal and oil. The oceans act like massive sponges soaking up airborne carbon. As carbon dissolves in seawater it forms carbonic acid, which lowers pH and increases acidity. This carbonic acid takes on a corrosive quality, eroding sea animal shells or skeletons, as well as robbing the water of important nutrients that allow these animals to grow shells in the first place. 2

The Pacific Coast of North America is being hit particularly hard because, due to a unique system of wind and currents, deep water rises to the surface along the West Coast. This older water has been absorbing carbon for a relatively long period of time and is therefore unusually acidic.

The West Coast shellfish industry, which contributes more than 100 million dollars a year to the economy and provides thousands of jobs, is in jeopardy. Acidity levels are already high enough to prevent oyster larvae from forming shells.

Whiskey Creek Shellfish in Netarts Bay, Oregon, was one of the first to identify acidity as the cause of high mortality rates in larval oysters. Owners Sue Cudd and Mike Wiegardt explain that the problem started in 2007. They experienced four straight months of zero production. Suspecting bacteria, they spent hundreds of thousands of dollars on treatment equipment, but it wasn’t effective.

Then hatchery manager Alan Barton, with a degree in oceanography, discovered the water coming into Netarts Bay had unusually low pH levels. The implications were monumental and treatment options only theoretical. “I was in despair. The problem was so big,” said Cudd. The ramifications were big indeed. Whiskey Creek produces 75 percent of all oyster seedlings used by West Coast oyster farmers.

Washington State shellfish growers tell a similar tale. Iconic Willapa Bay oysters haven’t self-reproduced since 2005. Every grower now relies on hatchery-produced larvae.

The Nisbets, of Goose Point Oysters, have been producing Willapa Bay oysters for nearly 40 years. When they realized the magnitude of the acidification problem they took drastic action, taking out a loan and building a new hatchery in Hawaii, where acidification is not yet a problem. The larvae are then shipped back to Willapa Bay once they are old enough to withstand the acidity.

Although the West Coast of North America is ground zero for acidification, other coastal areas including Maine and Virginia are also seeing rapid changes in ocean chemistry.

The harm done to oyster farmers is just the tip of the iceberg. “It hit us first but it’s just going to expand to other industries,” said Kathleen Nisbet. Acidification could in fact disrupt the entire marine food web. This is already happening with pteropods, tiny, snail-like creatures, that are a fundamental food source for a myriad of species, especially salmon stocks. Researchers had predicted pteropods could begin dissolving by mid-century, but Seattle scientists have recently discovered that acidifying seas are already damaging pteropods— decades earlier than expected.

Urgent action is needed to slow the pace of acidification by reducing global carbon dioxide emissions. If carbon emissions continue to rise at current rates, researchers estimate ocean acidity may double or triple (from pre-industrial levels)3 by the end of this century. Resulting pH levels would likely be lower with the rate of change being 10 times faster than what the oceans have experienced in 20 million years.

Recognizing the urgency, some states are beginning to take action. In 2011, former Washington Governor Christine Gregoire commissioned a groundbreaking Blue Ribbon Panel on Ocean Acidification. The panel identified 18 key early actions as essential in our effort to address ocean acidification.

Panel scientists found that in addition to carbon emissions local sources of pollution, such as wastewater and polluted runoff containing nitrates, exacerbate acidification. Panel co-chair Jay Manning noted, “We need to develop a better understanding of the magnitude of these sources and if they prove to be significant, act immediately to reduce loading from local sources.”

Oregon and California have formed a joint scientific panel to gain a clearer understanding of the effects of acidification in those jurisdictions. All three coastal states and British Columbia are developing a collaborative approach to addressing this pressing issue. In late 2013 Washington Governor Jay Inslee, Oregon Governor John Kitzhaber, California Governor Jerry Brown and British Columbia Premier Christy Clark signed an Energy and Climate Action Pact. This marks the first time that a coalition of states have identified ocean acidification as a key consideration in energy and carbon emission policies.

These are important first steps. Scientists can monitor ocean chemistry and work with industry, local communities and governments to identify and address the worst problems resulting from ocean acidity. In addition, developing adaptation strategies is essential, especially the expansion of monitoring capacity. With its state-of-the-art monitoring system, Whiskey Creek is now able to shutdown intake when acidity levels are dangerously high. To Wiegardt, installing the monitoring system was like, “…turning on the headlights.”

Shellfish farmers are the canaries in the coal mine. By closely following their proactive and successful quest for solutions, all fishing industry sectors will stand a better chance of overcoming what may be the greatest challenge of this century.

Cylvia Hayes, Environmental Leader, 15 January 2014. Article.

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