Shellfish ‘hot zones’ hit hard by acidic oceans

"Acidification will harm more than ocean creatures; it will have real impacts on people's lives," says Lisa Suatoni. "It will pinch pocketbooks, it will put livelihoods at risk, and it will alter the fabric of communities all across the country." (Credit: Chesapeake Bay Program/Flickr)

Coastal communities in as many as 15 US states, which depend on the nation’s $1 billion shellfish industry, face long-term economic risk due to ocean acidification, experts warn.

A new study shows that vulnerable communities go far beyond the Pacific Northwest—long a primary focal point of attention and resources—and include Maine, the Chesapeake Bay, and the Louisiana bayou.

While Northern California has a strong economic dependency on shellfish and is highly exposed to ocean acidification, the area was not a large focus of the new report that is published in Nature Climate Change.

Lucrative mollusks

Researchers say the area is less vulnerable than other coastal regions in the United States due to the state’s early efforts to address ocean acidification and climate change. Lack of economic data also made assessing the impact to California and other West Coast regions more difficult.

“Ocean acidification has already cost the oyster industry in the Pacific Northwest nearly $110 million and jeopardized about 3,200 jobs,” says Julia Ekstrom, who was lead author of the research while a scientist with Natural Resources Defense Council and is now director of the climate adaptation program at the Policy Institute for Energy, Environment and the Economy at University of California, Davis.

“Our research shows, for the first time, that many communities around the US face similar risks.”

Ocean acidification happens when oceans absorb growing amounts of carbon dioxide produced by burning fossil fuels. Acidic waters make it more difficult for creatures with calcium carbonate shells or skeletons, including mollusks, crabs, and corals, to grow shells and survive.

Mollusks, known to be particularly sensitive to ocean acidification, are among the most lucrative and sustainable fisheries in the United States.

Livelihoods at risk

For the study, researchers integrated physical, economic and social data into an assessment of various regions’ overall vulnerability to ocean acidification. The findings show that risk factors are threefold:

  • Physical: Local factors, such as local nutrient pollution from agricultural runoff, amplify the global phenomenon acidification.
  • Economic: Industry factors, such as total revenues, influence the importance of shellfish to a community.
  • Social: Diversity of local employment decrease communities’ capacity to cope with change.

“Our analysis shows acidification will harm more than ocean creatures; it will have real impacts on people’s lives,” says Lisa Suatoni, NRDC Oceans Program senior scientist. “It will pinch pocketbooks, it will put livelihoods at risk, and it will alter the fabric of communities all across the country.”

Hot zones

Varying combinations of risk factors have created several unique “hot zones” around the country, researchers say:

  • New England: Productive ports of downeast Maine and southern Massachusetts, where poorly buffered rivers run into cold New England waters, which are especially enriched in “acidifying” carbon dioxide.
  • Mid-Atlantic: East Coast estuaries like Narragansett Bay, Chesapeake Bay, and Long Island Sound, where an abundance of nitrogen pollution exacerbates ocean acidification in shellfish-rich areas.
  • Gulf of Mexico: Terrebonne and Plaquemines Parishes of Louisiana—and other communities in the Gulf of Mexico —where the shelled-mollusk industry is limited to oysters, gives this region fewer options for alternative, potentially more resilient, mollusk fisheries in the short term.
  • Pacific Northwest: The Oregon and Washington coasts and estuaries, where a potent combination of risk factors converge, including cold waters, upwelling currents that bring corrosive waters closer to the surface, corrosive rivers, and nutrient pollution from land runoff.

Of particular concern are the study’s findings that many of the most economically dependent regions are currently the least prepared to respond.


States such as Massachusetts, New Jersey, Virginia, and Louisiana have minimal research and monitoring for ocean acidification and little government support at federal or state levels to reduce their risk.

Since the current assessment focused on mollusks, it offers only one slice of overall vulnerability within the ecosystem. Researchers say the analysis should also be applied to a broader set of at-risk species, such as crabs and coral, and the services they provide.

While reducing global carbon emissions is the ultimate solution, the researchers say localized solutions can be implemented:

  • Reduce local pollutants, such as agricultural runoff in the Chesapeake Bay.
  • Diversify fishing fleets and investment in aquaculture of high-value shellfish species in southern Massachusetts (raising shellfish away from souring waters).
  • Develop “early warning” systems for corrosive waters in the Pacific Northwest.
  • Cultivate acidification-resistant strains of oysters in the Gulf of Mexico.

“There is plenty we can do to help these at-risk communities while protecting our environment,” Suatoni says. “Tailored action plans should be developed for each ocean acidification hot zone. The time to act is now.”

Source: UC Davis