Rising acidity of seawater could disrupt NW food chains

Puget Sound faces an uncertain future due to the increasing acidity of seawater, a panel of marine scientists said Tuesday. The changes are coming more rapidly than expected, and could disrupt food chains and threaten Washington’s shellfish industry.

The acidic seawater is moving closer to shallow waters containing the bulk of marine life, according to an article this month in the journal Science. 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 latest research indicates acidic water is appearing along the Pacific Coast decades earlier than expected.

The research involved experts from Oregon, California and Canada.

The acidified water does not pose a threat to humans, but it could dissolve the shells of clams, oysters and other shellfish.

One of the article’s authors, Christopher Sabine, told Sen. Maria Cantwell, D-Wash., – who convened Tuesday’s hearing – and Rep. Jay Inslee, also D-Wash., about watching 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 comprise 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 CO2 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.”

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.”

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.

His family-owned farm has 27 year-round employees and around $2.8 million in annual sales.

“If we can’t grow our shellfish, the bank will foreclose on the mortgage. We’ll lose our farm, our homes,” Bishop said.

Jeff Koenings, director of Washington’s Department of Fish and Wildlife, called for “precautionary resource management,” such as the recently renegotiated Pacific Salmon Treaty. Current management schemes rely on historic trends that are not applicable, given changing climate conditions, Koenings said.

“In light of all this uncertainty we just need to cool; we need to cut the harvest on certain species down to a level that we think is sustainable,” Koenings said. Previous rates of harvest for some species, such as some salmon, are not sustainable now because of decreased productivity, he noted.

Inslee stressed that ocean acidification is different from climate change.

“There are people who still want to argue about climate change. Let them have that argument, but there’s no argument about ocean acidification,” Inslee said afterward.

Congress has taken small steps toward reducing carbon production, Inslee said. But a carbon cap-and-trade system – which allows companies or other groups to emit a certain amount of carbon and trade any excess allowance with other carbon producers – is Inslee’s goal.

“At least by next fall I believe we’ll have a cap and trade system in place,” he said.

Cantwell’s hearing was not part of any upcoming legislation, but rather designed to raise awareness of the issue in the Senate, said Ciaran Clayton, a Cantwell spokeswoman.

Dan Catchpole, examiner.com, 27 MAy 2008 . Article.

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