Breaking Waves

The shells of oysters – a commercially important shellfish whose reproduction and growth is threatened by climate-linked ocean acidification – may help counteract the effects of increased local acidity levels, according to a new study of New England’s Chesapeake Bay by a team of researchers led by Oregon State University’s George Waldbusser.

The study, published in the journal Ecology and reported this week in the New York Times , concludes that the buildup of old shells in undisturbed oyster beds – along with the oysters’ waste – can help restore alkalinity to waters that might otherwise be too acid for the shellfish to survive.

Like ocean waters around the world, the Chesapeake has become more and more acidic as a result of rising levels of carbon dioxide in the atmosphere. Now, by studying oyster populations in relation to acidity levels,Waldbusser’s team has concluded that oysters — particularly their shells — can play a significant role in reducing that acidity.

“Oyster shells are made out of calcium carbonate, so they’re sort of like an antacid pill,” said Waldbusser, an assistant professor of earth, ocean and atmospheric sciences at OSU and an author of the study. “In an undisturbed oyster reef, healthy oysters are generating a lot of biodeposits,” a genteel term for excrement, “which helps generate CO2 to help break down those shells, which helps to regenerate the alkalinity back into the environment.”

Ocean acidification is of great concern to commercial oyster growers. Additional  research by Waldbusser and colleague Burke Hales, conducted at an Oregon oyster hatchery, has shown that increasing acidity near commercial shellfish operations inhibits the larval oysters from developing shells and growing at a pace that makes oyster farming economically viable.

Waldbusser is also working on a Sea Grant-funded project to develop Web-based tools that would allow oyster growers and resource managers to better understand how acidification affects larval oysters so they can more effectively adapt, mitigate and adjust their operations to increase oyster survival and growth.

Learn more:

• Read the OSU news release
• Learn about Waldbusser’s current Sea Grant-supported research

The booklet Development of Live Shellfish Export Capacity in Oregon is available as a free download from Oregon Sea Grant.

There are many opportunities for seafood exporters to earn substantial profit in Asian markets. The trade in live shellfish exports to China could be especially lucrative. In many respects, Oregon’s shellfish industry is well positioned to meet this demand. However, due to certain impediments, interested parties remain largely unable to establish effective means of competing in the Chinese marketplace.

At the request of Oregon Sea Grant, a project was undertaken to provide stakeholders with recommendations for the continuing development of live shellfish export capacity in Oregon. The project was carried out by two investigators in three parts under the direction of Dr. Tim Miller-Morgan, Oregon Sea Grant Extension veterinarian at Oregon State University. Investigations consisted of reviews of literature on current live shellfish shipping practices, research of the prevailing export procedures and the economic and regulatory environments, and visits to sites of special interest and interviews with representative stakeholders.

Findings from this joint investigation formed the basis of this report.

Washington state, the leading US producer of farmed shellfish, this week launched a 42-step plan to reduce ocean acidification. The initiative — detailed in a report by a governor-appointed panel of scientists, policy-makers and shellfish industry representatives — marks the first US state-funded effort to tackle ocean acidification, a growing problem for both the region and the globe.

The state governor Christine Gregoire,  says she will allocate $3.3 million to back the panel’s priority recommendations.

“Washington is clearly in the lead with respect to ocean acidification,” says Jane Lubchenco, administrator of the US National Oceanic and Atmospheric Administration (NOAA).

As growing carbon dioxide gas emissions have dissolved into the world’s oceans, the average acidity of the waters has increased by 30% since 1750. Washington, which produces farmed oysters, clams and mussels, is particularly vulnerable to acidification, for two reasons: seasonal, wind-driven upwelling events bring low-pH waters from the deep ocean towards the shore, and land-based nutrient runoff from farming fuels algal growth, which also lowers pH.

Read the full story in Nature.

Learn more:

• Study: Our Oceans Are So Acidic They’re Dissolving Snails (The Atlantic)
• OSU researchers link acidification to oyster hatchery collapse (OSU News & Research Communications)
• Current Oregon Sea Grant research on ocean acidification and commercial shellfish
• Oregon Sea Video: An ocean acidification primer, featuring Dr. Richard Feely of NOAA’s Pacific Marine Environmental Laboratory

Could increases in ocean acidity be partly to blame for larval die-offs that have plagued Northwest oyster producers for much of the past decade? Scientists and growers believe that may be the case – and they’re struggling to help the region’s lucrative shellfish industry adapt to the risk.

In a recent blog post for the Sightline Institute, a Pacific Northwest sustainable policy center, former Seattle Post-Intelligencer reporter Jennifer Langston talks to growers and scientist who are concerned about ocean acidification and the threat it poses for oyster growers in the Pacific Northwest.

According to Langston, West Coast oyster production dropped from 94 million pounds in 2005 to 73 million pounds in 2009, resulting in an $11 million loss in sales for what had become a $72 million-a-year industry.

Langston interviewed researchers at Oregon State University who have embarked on a major, multi-year investigation of  the effects of ocean acidification on oyster production. Among that team is OSU researcher Chris Langdon, who has received Oregon Sea Grant support for his research on the health and production of oysters, abalone and other shellfish.

While Langdon and others have identified toxic organisms  such as Vibrio tubiashii as part of the problem, there are also signs that increasing ocean acidity is playing a role in the die-off of larval oysters, which appears to worsen when ocean temperatures and currents cause water that’s high in carbon dioxide and low in pH (acidic) to well up and mix with the “good” water normally found in the oyster breeding beds.

Using what researchers have learned from their ongoing study of the issue, two major oyster producers have been able to adapt their practices to ocean conditions. Using a monitoring buoy as an early alert to changes in seawater chemistry, they were able to schedule production for “good water” periods, resulting in a strong rebound in production in the 2010 season. But concern about the state of the oceans remains.

Read the entire article in Sightline Institute’s blog.

Read more about the NOAA research project and how it has helped growers adjust their aquaculture practices.

[Photo courtesy of OSU Extension Service]