Rising acidity puts Pacific Coast shellfish in peril

A panel of marine scientists is warning that the Pacific Coast’s increasing acidity could disrupt food chains and threaten the Pacific Northwest’s shellfish industry.

The increasingly corrosive water threatens the survival of many organisms, from microscopic plants and animals at the base of the food chain to shellfish, corals and the young of some marine species, the researchers told a congressional field hearing.

The data indicate that acidic water is appearing along the Pacific Coast decades earlier than expected. The acidified water does not pose a threat to humans, but it could dissolve the shells of clams, oysters and other shellfish.

The acidic seawater is moving closer to shallow waters containing the bulk of marine life, according to a recent article in the journal Science.

One of the article’s authors, Christopher Sabine, said he watched small marine snails placed in water of similar acidity to that recorded last summer off the northern California coast.

“We actually saw the shells dissolving off these living organisms. They were dissolving off the terapods as they were ‘swimming’ around,” Sabine said. Such creatures make up as much as 40 percent of the Pacific king salmon’s diet.

Global ocean currents make the Pacific Northwest’s coastal ecosystems particularly vulnerable to acidification’s effects, Sabine said.

A worldwide “conveyor belt” very slowly carries colder water from the North Atlantic to the North Pacific. Along the way, the water accumulates carbon dioxide from dead organisms, so it naturally has a higher carbon dioxide concentration before man-made carbon dioxide is added. A process known as “up-welling” drags this water into shallower, coastal areas.

“As long as CO{-2} continues to increase in the atmosphere, the oceans will continue to absorb that,” Sabine said. “What we’re seeing is only going to get worse.”

Corrosive water could be disastrous for Washington state’s shellfish industry, noted one panel member, Brian Bishop, owner of Little Skookum Shellfish Growers in Shelton, Wash. Washington state produces 85 percent of all shellfish on the West Coast, Bishop said.

“This acidity dissolves calcium carbonate, which is the thing that shells are made out of. If diatoms, corals, clams and oysters succumb to this, it not only wipes out the shellfish industry but potentially the entire marine food chain,” said Bishop, a fifth-generation shellfish harvester.

The panel members said they did not know exactly how acidification will affect Puget Sound and other Northwest coastal waters.

“We know very little about the biological effects of acidification on the West Coast,” said Terrie Klinger, of the University of Washington’s School of Marine Affairs. However, research has demonstrated that there will be early and strong effects in Northwest coastal ecosystems, she added.

“We won’t see a total collapse in food chains, but we will see substitutions,” Klinger said. “We may end up with food chains or food webs that are highly undesirable and not productive for the means that we use them today.”

Dan Catchpole, Associated Press, Courier-Journal , 7 July 2008. Article.

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