Ocean acidification linked to larval oyster failure

Apr 11, 2012
Four to six month old "spat" or oyster seed at the Hatfield Marine Science Center in Newport,Oregon. © Oregon State University

Researchers at Oregon State University have definitively linked an increase in ocean acidification to the collapse of oyster seed production at a commercial oyster hatchery in Oregon, where larval growth had declined to a level considered by the owners to be "non-economically viable."

A study by the researchers found that elevated seawater carbon dioxide (CO2) levels, resulting in more corrosive ocean , inhibited the larval oysters from developing their shells and growing at a pace that would make commercial production cost-effective. As atmospheric CO2 levels continue to rise, this may serve as the proverbial canary in the for other ocean acidification impacts on shellfish, the scientists say.

Results of the research have just been published in the journal, .

"This is one of the first times that we have been able to show how affects oyster larval development at a critical life stage," said Burke Hales, an OSU chemical oceanographer and co-author on the study. "The predicted rise of atmospheric CO2 in the next two to three decades may push oyster larval growth past the break-even point in terms of production."

The owners of Whiskey Creek Shellfish Hatchery at Oregon's Netarts Bay began experiencing a decline in oyster several years ago, and looked at potential causes including low oxygen and . Alan Barton, who works at the hatchery and is an author on the journal article, was able to eliminate those potential causes and shifted his focus to acidification.

Barton sent samples to OSU and the National Oceanic and Atmospheric Administration's Pacific Marine Environmental Laboratory for analysis. Their ensuing study clearly linked the production failures to the CO2 levels in the water in which the larval oysters are spawned and spend the first 24 hours of their lives, the critical time when they develop from fertilized eggs to swimming larvae, and build their initial shells.

"The early growth stage for oysters is particularly sensitive to the carbonate chemistry of the water," said George Waldbusser, a benthic ecologist in OSU's College of Earth, Ocean, and Atmospheric Sciences. "As the water becomes more acidified, it affects the formation of calcium carbonate, the mineral of which the shell material consists. As the CO2 goes up, the mineral stability goes down, ultimately leading to reduced growth or mortality."

Commercial oyster production on the West Coast of North America generates more than $100 million in gross sales annually, generating economic activity of some $273 million. The industry has depended since the 1970s on oyster hatcheries for a steady supply of the seed used by growers. From 2007 to 2010, major hatcheries supplying the seed for West Coast oyster growers suffered persistent production failures.

The wild stocks of non-hatchery oysters simultaneously showed low recruitment, putting additional strain on limited seed supply.

Hales said Netarts Bay, where the Whiskey Creek hatchery is located, experiences a wide range of chemistry fluctuations. The OSU researchers say hatchery operators may be able to adapt their operations to take advantage of periods when water quality is at its highest.

"In addition to the impact of seasonal upwelling, the water chemistry changes with the tidal cycle, and with the time of day," Hales said. "Afternoon sunlight, for example, promotes photosynthesis in the bay and that production can absorb some of the carbon dioxide and lower the corrosiveness of the water."

A previous study co-authored by Hales found the water that is being upwelled in the Pacific Ocean off the Oregon coast has been kept at depth away from the surface for about 50 years – meaning it was last exposed to the atmosphere a half-century ago, when carbon dioxide levels were much lower. "Since have risen significantly in the past half-century, it means that the water that will be upwelled in the future will become increasingly be more corrosive," Hales said.

The OSU researchers also found that larval oysters showed delayed response to the water chemistry, which may cast new light on other experiments looking at the impacts of acidification on shellfish. In their study, they found that larval oysters raised in water that was acidic, but non-lethal, had significantly less growth in later stages of their life.

"The takeaway message here is that the response to poor water quality isn't always immediate," said Waldbusser. "In some cases, it took until three weeks after fertilization for the impact from the acidic water to become apparent. Short-term experiments of just a few days may not detect the damage."

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User comments : 5

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deatopmg
1 / 5 (3) Apr 11, 2012
So what are the pH changes? Did they measure them or just the HCO3-/CO2 conc.?? Or did they even do that?
Sounds to me like "OMG the oyster industry is suffering and it's due to that poison CO2, send money for further study".
Vendicar_Decarian
0.4 / 5 (37) Apr 11, 2012
Sean_W
1 / 5 (5) Apr 11, 2012
How can the author in good conscience omit the fact that the deep upwelling water which is supposed to contain less CO2 than future upwells will, is much higher in CO2 than current surface water because of the conditions it is was under? The oyster collapse is from the deep upwells and has nothing to do with wide-scale anthropogenic "ocean acidification" but that is what is stated at the beginning only to be back peddled to "water that will be upwelled in the future will become increasingly be more corrosive".

This article can be summarized as saying that human industry destroyed the present oyster fishery--or it will have done once the effects really get built up. These people have no conscience which answers my original question.
Dug
1 / 5 (4) Apr 11, 2012
Very badly written article and very lose to non-existent science. First - the title implies that ocean acidification is caused by failed oyster larvae.

Secondly, a local problem with high CO2, acidification and carbonate metabolism - which by the way is very common in areas of high runoff and pollution - doesn't prove or equate to global ocean acidification. Carbonate supersaturation and precipitation is occurring like it always has in the Bahamas - and it is just as meaningless to conclude this disproves ocean acidification as it is to suggest that local or regional shellfish problems proves it.
Howhot
5 / 5 (3) Apr 11, 2012
Actually Dug, it is a very clearly written article that makes several points. If you need numbers look them up in the journal, Limnology and Oceanography.

Basically the authors claim to have found that elevated seawater carbon dioxide (CO2) levels, resulting in more corrosive ocean water, inhibited the larval oysters from developing their shells"
Oyster shells are Calcium Carbonate and mixed with carbolic acids from CO2 H, so there isn't a surprise as to the damage elevate acidity could do to baby oyster seeds.

"This is one of the first times that we have been able to show how ocean acidification affects oyster larval development at a critical life stage," said Burke Hales
Co-author.

Do you see where this is going. The young oyster baby seeds are apparently very sensitive to lower PH levels (acidic) and the prediction is that given global CO2 level increases this will eventually be reflected in a decreasing population of oysters.