Can the oyster industry survive ocean acidification?

  • Jeremy Coleman, left, and James Roberts, right, harvest mussels for Taylor Shellfish Farms near Shelton, Washington, in 2011.

    AP Photo/Ted S. Warren
  • Discarded oyster shells at Taylor Shellfish Inc. The hatchery now treats its water to raise pH levels when needed, with mixed results.

    Sarah Gilman
 

For four frustrating months in 2007, Mark Wiegardt and his wife, Sue Cudd, witnessed something unsettling at their Oregon oyster hatchery: tank bottoms littered with dead baby oysters. Usually, the larvae are grown until they're three weeks old and a quarter of a millimeter in size -- 10 million bunched together are roughly the size of a tennis ball. Then they are shipped to 50-some growers in the U.S., Canada and Mexico. But that summer, the oysters died before they were ready to ship. Whiskey Creek Shellfish Hatchery struggled to fill a third of its orders.

"You have good and bad weeks, but this was a blanket kill on everything we tried to do," recalls Wiegardt. "We thought we were going out of business because we couldn't make the larvae grow."

It turned out that "corrosive" seawater, which makes it harder for young oysters to build shells, was largely to blame. Like the atmosphere, the world's seas are burdened by our fossil fuel use and deforestation. The ocean has sponged up a quarter of the carbon dioxide humans have produced since the Industrial Revolution, steadily lowering its pH. Today's seas are 30 percent more acidic than their pre-industrial ancestors. By the turn of the century, scientists anticipate they will be 150 percent more so -- a trend that led National Oceanic and Atmospheric Administration (NOAA) chief Jane Lubchenco to call ocean acidification climate change's "equally evil twin."

Even if manmade carbon emissions ceased tomorrow, the West Coast would face decades of increasingly corrosive water because the ocean is laden with CO2 from decades past and will continue to absorb the CO2 already in the air, slowly changing its chemistry. "The train has already left the station," says Richard Feely, a senior fellow at NOAA's Pacific Marine Environmental Laboratory in Seattle. "If we don't reduce carbon dioxide emissions, we'll (see) conditions that will be corrosive to more species."

Creatures that build shells from calcium carbonate -- pteropods, for example, tiny sea snails that swim with dainty "wings" and nourish the pink salmon that sustain Alaska's fishing industry -- are particularly vulnerable. In water, CO2 becomes carbonic acid, which releases hydrogen ions when it breaks down. The hydrogen ions bond with carbonate ions, stealing them from animals that use them to form calciferous homes. Experiments with non-shelled species have also yielded disturbing results. Clownfish -- the orange-and-white-striped reef dwellers immortalized in Finding Nemo -- seem to go deaf when raised in seawater with CO2 levels predicted to be present by 2050 and 2100.

But for Northwest oyster growers, ocean acidification is no distant threat. The Whiskey Creek die-offs, which continued in 2008, dealt the industry a serious blow, since the hatchery supplies the majority of independent West Coast growers. Production also slumped at Washington's Taylor Shellfish Inc., another major producer, in 2008 and 2009, and acidic water probably played a role. These declines came at an especially vulnerable moment: Larvae growing naturally at Washington's Willapa Bay, a chief source of wild seed, had also been failing, because the water was too cold. Seed shortages contributed to the region's 22 percent drop in production between 2005 and 2009, according to a trade group. "Ocean acidification poses a serious threat to Washington's marine economy, cultures, and environment," concluded a recent report from Washington state, the West Coast oyster industry's hub.

Now, growers are attempting to adapt to the sea's new chemical reality. Experiments are under way at Whiskey Creek and at least one other hatchery, which, owing to their geography, have already experienced what's expected to become the West Coast's norm before too long. These experiments should help the industry answer a pressing question:  Can it survive the inevitable?

Whiskey Creek's three barn-like buildings sit on Netarts Bay, a shallow, tree-fringed estuary whose wide mouth opens onto the azure Pacific. At low tide, the bay drains into the ocean; at high tide it's replenished. Since the bay's water exchanges frequently, it's an almost direct chemical reflection of the adjacent sea. Water conditions vary drastically between April and October, when northwesterly winds push surface water offshore, allowing water 500 to 650 feet below the surface to flow upward into near-shore regions -- a process known as upwelling. When that water hugs the coastline, it surges into Netarts Bay.

The upwelling water is rich with dissolved CO2, thanks in part to microbes that feast on decaying plants and animals in the deep, releasing CO2 as they go. This is a natural process, but CO2 from human activities has increased gas concentrations in upwelled water by about 12 percent, says NOAA's Feely. Together, the manmade and natural CO2 make this water's chemistry similar to what scientists expect to become commonplace along the West Coast by 2050. That's particularly true when it comes to a low availability of carbonate ions, which oysters use to build shells.

Research suggests that in the first two days of their lives, oyster larvae in carbonate-deficient water burn through energy faster than usual because they have to work harder to build shells. This exhausts them, retarding their growth. The oysters' failure to thrive is akin to young children eating lead-paint chips and later, in their teens, scoring miserably on SAT tests, says Burke Hales, a professor of ocean ecology and biogeochemistry at Oregon State University.

Michael Lewis
Michael Lewis Subscriber
Dec 10, 2012 07:58 PM
Why are these articles on technical subjects such as ocean pH written by people such as Brendon Bosworth, "an independent South African journalist who’s currently in the U.S... recently finished a master’s degree at the University of Colorado Boulder and am now working as an intern at High Country News?" People who have no experience with the subject at hand, no scientific credentials, no reason why we would accept the conclusions of such an article, obviously lifted from a wire service or press release.

It's time for some journalistic credibility.
Cally Carswell
Cally Carswell Subscriber
Dec 11, 2012 08:07 AM
Hello Michael,

Are there specific aspects of the story you wish to comment on? Otherwise, we ask that you refrain from personal attacks on the authors of HCN stories and other commenters, per our comment policy. This story was thoroughly reported and fact checked with many scientists, a number of whom are quoted in the story. In our view, the fact that Brendon is not a scientist does not compromise his ability to report on this subject matter. In fact, most journalists are not credentialed experts in the subjects they report on.

Cally Carswell
Assistant Editor, High Country News
Joanna Kirkpatrick
Joanna Kirkpatrick
Dec 11, 2012 03:06 PM
The deeper but also more complex question is, can the planet withstand ocean acidification? Think of the consequences to climate and the food chains of ocean as well as earth and air animals that live in and around it.
Jim Vance
Jim Vance
Dec 11, 2012 06:18 PM
It's a basic fact of chemistry and physics that colder water can absorb more CO2 than warmer water (the effect of a cold soft drink not fizzing so much when opened unlike a hot one explosively decompressing), and the CO2 absorbed by the oceans becomes more heavily concentrated in the colder, generally deeper ocean currents. Much is made by climate skeptics or denialists of the limited amount of warming measured by the UK Met, whose HADCRUT models are generally well-accepted as among the current leaders in climatology. A big problem is that the HADCRUT models only incorporate sea surface temperatures to a very limited depth, and not temperatures at lower depths where the heat absorbed from the atmospheric surface interface is being distributed via the Global Conveyor (linked currents) throughout all the planet's oceans. Where these upwellings of cold-current waters exist, the lowering pH trend is becoming well-documented and not simply in Oregon.

Other researchers have begun focusing more attention on the oceanic component of what is essentially a closely-coupled, dynamically interactive atmospheric-oceanic system which comprises the Earth's biosphere, and the findings are in stark contrast to the claim of skeptics (who frequently attempt to argue that acidification isn't a problem either):

Research shows humans are primary cause of global ocean warming over past 50 years

http://www.llnl.gov/[…]/NR-12-06-04.html
ilma Sixthirty
ilma Sixthirty
Dec 17, 2012 07:36 AM
A few slight problems with the article!! Oceans are NOT acidic, they are alkaline. Also, as they absorb CO2, they get MORE alkaline; they can NEVER be acidic. Ocean alkalinity is also temperature dependent, as they cool they absorb CO2, and as they warm the release it.

To say the oceans are corrosive, and that the pH lowers as it absorbs CO2 are just plain factually wrong! Mr. Bosworth needs to take a chemistry lesson.

The use of the term "ocean acidification" is designed to mislead, and the impression is that the oceans are turning to acid and destroying all life. This is so far from the truth, it is beyond comprehension. Using the word "acidification" is like saying "reversing" when slowing down going forwards. "Acidification" is used in the scientific community to mean a direction and not a state, and when used outside of that community, i.e. in public communication such as this, the understanding is the state of "being acid" and not the direction of "becoming less alkaline" or "becoming more neutral". Good journalism should understand this, and phrase accordingly.

This is from a retired scientist...

"Most of the earth's rocks and seabed sediment is essentially CaCO3 (limestone, chalk etc.).

CaCO3 is insoluble in water, but when attacked by acid such as carbonic acid H2CO3 (ie CO2 + H2O) then the following reaction takes place:

CaCO3 + H2CO3 = Ca(HCO3)2 otherwise known as Calcium bicarbonate.

Ca(HCO3)2 is soluble in water and is alkaline (strong base + weak acid = weak alkaline solution).

So the *more* CO2 dissolves in the oceans the more alkaline the oceans are likely to become! In crude terms the oceans are what is called a buffer solution. Ocean pH hovers at around 8 i.e. slightly alkaline.

To summarise. Unless the earth's crust *completely runs out of limestone and other carbonates of Calcium* (and Magnesium; Magnesium Carbonate = dolomite) the oceans can never become acidic.

Local variations can occur of course where there is no limestone present, but even silicate rocks can be slowly attacked by CO2 with a somewhat similar result."

Ms. Carswell, Mr. Lewis was not making a "personal attack", but pointing out, as I have done, that Mr. Bosworth should have undertaken some basic scientific learning before writing such an article, and editors such as yourself should have checked the (so-called) 'facts' for accuracy. To print such an article laden with fundamental errors is either just sloppy journalism, or reveals an pre-disposed bias towards climate alarmism.
Cally Carswell
Cally Carswell Subscriber
Dec 17, 2012 01:15 PM
The story, which focuses on the impacts on a particular region, does not claim the ocean is acidic, but that its pH is slowly declining, a broadly recognized phenomenon widely referred to as "ocean acidification."

Cally Carswell
HCN assistant editor
earl klug
earl klug
Jan 21, 2013 10:00 AM
Ilma (and Michael):
Ocean acidification is not some nebulous phenomena dreamed up by Mr. Bosworth (great article btw); a quick Web search for the term would have revealed scores of entries on the subject, e.g.:
http://en.wikipedia.org/wiki/Ocean_acidification

http://www.pmel.noaa.gov/co2/story/Ocean+Acidification

Ilma, I suspect your "scientist" may have retired some time back.