Oyster growers fret about ocean acidification, Oregon State University study shows

Posted on The Register Guard: 29 Aug 2015 — By Diane Dietz


Just as there are few atheists in fox holes, you’d be hard pressed to find many Pacific Northwest oyster growers disbelieving in climate change — and the related ocean acidification, according to an Oregon State University study.

Three-quarters of oyster growers surveyed said they were either “extremely” or “very” concerned about ocean acidification, according to the study published this week in Journal of Shellfish Research.

Only 1 percent said they were “not at all concerned” about the process that turns seawater corrosive to shellfish.

“We got in big trouble with that” in the mid-2000s said Oregon grower Lilli Clausen. “We bought two years worth of larvae that didn’t make it after we paid for (them).”

One section of Clausen’s 635 acres of leased oyster flats in Coos Bay produced 50 baskets of oysters where there should have been 500, Clausen said.

“Those were really difficult years to get over,” she said. “This is beginning to be our first normal year.”

The U.S. public compared with the oyster growers, by and large, isn’t sweating ocean acidification, according to the OSU study.

 While 20 percent of the U.S. public answered “yes” that ocean acidification is having consequences today, 80 percent of those in the shellfish industry agreed, said Becky Mabardy, who conducted the study as a master’s student in marine resources at OSU.

“The growers’ answers were deeply felt,” she said.

“Many of them said that they are stressed out. They are having economic losses — and all of that is weighing on how concerned they are,” Mabardy said.

A minority of the general public — 40 percent — allowed ocean acidification might be something for future generations to worry about.

“They acknowledge the trend and they can see the direction, but it still is not that relevant to their life,” Mabardy said.

Mabardy surveyed oyster growers — and also clam, geoduck, mussel and abalone producers — in Washington, Oregon and California; 185 of them answered her 44-question online survey from January to March 2013.

The ocean’s acidity increases when the water takes up additional carbon dioxide from the atmosphere.

The average surface ocean acidity has risen 30 percent since 1750, according to Mabardy’s research.

But there are acidification “hot spots” such as off the coast of Oregon, where April-to-September upwellings of sunken carbon-dioxin-laden waters rise to the surface.

In the mid-2000s, acidification savaged the northwest shellfish industry. Oyster larvae — grown in big vats in sea water — began dying. Mortality reached 80 percent, according to the study.

Eventually, a pair of OSU researchers determined that elevated acidity in the water was preventing the larvae from forming a sufficient protective shell.

The lost of these seed crops dropped oyster production to 73 million pounds in 2009, down from 94 million pounds in 2005 — and cost growers millions of dollars, according to the study.

“We’re on a pathway that will have numerous ugly outcomes in the future,” one grower wrote in reply to an open ended question in the survey.

Acidification is hurting other northwest sea fauna. It’s dissolving the shells of tiny free-swimming marine snails, called pteropods, which provide food for pink salmon, mackerel and herring, according to research published by OSU.

Shellfish growers will discuss ocean acidification during the Pacific Coast Shellfish Growers Association’s 69th annual conference and trade show Sept. 22-24 in Hood River.

The panel is called: Ocean Conditions, Climate Change and Ocean Chemistry, said Mabardy, who was hired by the trade group to do outreach and project coordination.

Larvae growers have learned to buffer their tanks with sodium carbonate, basically Tums, to reduce acidity and stem larval deaths.

They’ve installed monitors to track the acidity or alkalinity in their tanks, and they’re learning to grow larvae when water conditions are optimal, Mabardy said.

The major solution to ocean acidification, however, is for nations to stop emitting so much carbon dioxide in the air. That means burning less fossil fuel. And that’s a tall order.

Oyster growers are the canary in the coal mine, Mabardy said.

“They are an indicator, really. They are seeing changes and they’re having to address them head on. They’re really being forced to action,” she said.

Clausen, who says she should have been retired from her oyster business by now, is ready to talk about change.

 “Most (carbon dioxide) probably comes from cars and maybe some factories. It wouldn’t hurt to start thinking about it and maybe modify some of the motors so there would be less,” she said.

Read this article on The Register Guard.