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Research identifies hot spots for addressing ocean acidification risks to US shellfisheries
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Research identifies hot spots for addressing ocean acidification risks to US shellfisheries

NOAA scientist explains value of first nationwide shellfish risk assessment for adaptation and resilience planning

We caught up with Dwight Gledhill, deputy director of NOAA’s Ocean Acidification Program, and one of the 17 authors of a perspective published today in Nature Climate Change on vulnerability of U.S. shellfisheries to ocean acidification.

Ruben van Hooidonk of NOAA’s Atlantic Oceanographic and Meteorological Laboratory, and Peter E.T. Edwards of NOAA’s Coral Reef Conservation Program, also contributed to the perspective. The lead authors were Julia Ekstrom and Lisa Suatoni of the Natural Resources Defense Council.

What is new in the perspective about the vulnerability of our shellfisheries to ocean acidification?

This is the first nationwide look at the vulnerability of our country’s $1 billion shellfish industry to the global, long-term problem of our oceans becoming more acidic due to the absorption of increasing amounts of carbon dioxide from the atmosphere. The piece draws from natural and social sciences to analyze which coastal communities in the continental United States are most vulnerable and why. This analysis looks at the physical effects of ocean acidification on shellfish, but also how other local effects such as upwelling currents rich in carbon dioxide, pollution from street runoff, fertilizers and sewage flowing into our rivers and bays, and economic dependency on particular shellfish species exacerbates the risks to some coastal communities. It also examines how much support there is from local governments and science communities to adapt to the changes ocean acidification may bring.

Will the public find any major surprises in this paper?

While within the scientific community there’s an understanding that ocean acidification will have long-term effects on communities around our coasts, this research may surprise many by highlighting the risks to shellfish and communities that depend on these fisheries in the Gulf of Mexico, along the Mid-Atlantic seacoast and in New England.

What are the main hot spots for ocean acidification, according to the Nature Climate Change perspective?

The research concludes that marine ecosystems and shellfish in the Pacific Northwest and southern Alaska are expected to be exposed soonest to rising ocean acidification, followed by the north and central West Coast and the Gulf of Maine on the East Coast. The risk analysis does not delve into Alaska but focuses on the continental United States. Recent NOAA-led research looked at the risk of ocean acidification to Alaska communities and fisheries. The Nature Climate Change perspective piece identifies four hotspots of rapid ocean acidification and notes that 16 of 23 bioregions that were studied are exposed to rapid ocean acidification.

The four main hot spots are:

  • Pacific Northwest coastal communities in Oregon and Washington are hot spots because of a combination of risk factors, including cold waters that absorb carbon dioxide more easily, thus increasing acidity, upwelling currents that bring carbon-dioxide rich waters closer to the surface, and rivers that empty fresh water into the coastal waters. Fresh water runoff dilutes seawater, making it less saturated with calcium carbonate, the element shellfish need to build shells.
  • Downeast Maine and southern Massachusetts are hot spots because rivers are bringing increasingly larger amounts of freshwater into the cold coastal waters that already absorb carbon dioxide at higher rates than warmer waters. Fresh water runoff dilutes seawater, making it less saturated with calcium carbonate, the element shellfish need to build shells.
  • New England and Mid-Atlantic estuaries including Narragansett Bay (Rhode Island and Massachusetts), Long Island Sound (New York and Connecticut) and Chesapeake Bay (Maryland and Virginia) are hot spots because fertilizer, sewage and street runoff flow into these estuaries, exacerbating ocean acidification. The runoff pollution generates more carbon dioxide in these waters, making them more acidic.
  • Gulf of Mexico areas such as Terrebonne and Plaquemines parishes in Louisiana are hot spots because the shellfish industry is focused on oysters here, and these communities have fewer options to switch to more resilient shellfish or fisheries.

What is NOAA’s strategy for addressing the risks of ocean acidification and will this research perspective help?

Ocean acidification is a global problem and its ultimate solution will require reducing carbon dioxide air emissions. But we cannot wait for this solution which will take strong global political actions. We can and are taking action at the national and local level to reduce the risks of ocean acidification and prepare communities to be more resilient in the face of this environmental change. Scientists, decision-makers and other stakeholders will need to work closely with fishing and aquaculture industries to develop tailored strategies that meet local needs.

The perspective in Nature Climate Change can help us prioritize important research needed to help communities adapt to ocean acidification. This analysis points out that we need more research and monitoring in coastal waters. And we need more research directed at how the most economically valuable species will be affected. The perspective notes that 95 percent of United States shellfish revenues come from only 10 species. Sea scallops and the eastern oysters account for 64 percent of our domestic shellfish revenues. We need to focus research on these species. The perspective shows that interdisciplinary research combining biological, physical, chemical and social science approaches can improve decision-making.

The perspective also provides models for action. Communities have already taken steps to adapt to ocean acidification, such as efforts in the Pacific Northwest to use real-time monitoring to adjust the timing of oyster production to avoid periods when water chemistry is less conducive to success. The states of Washington and Maine are actively raising the issue of ocean acidification, convening commissions of elected officials, scientists, fishing and aquaculture industry leaders and other stakeholders to craft strategies for adaptation and response.

The new research points to other coastal areas where adaptation strategies will be needed. NOAA is committed to working with states, industry, academic partners and environmental stewards to help provide the ocean observations and research on acidification that can help communities forecast these changes and develop the best strategies to mitigate the risks to shellfisheries and local economies, building more resilient communities for the future.

For more information, please contact Monica Allen, director of public affairs at NOAA Oceanic and Atmospheric Research at 301-734-1123 or by email at

The press release from the Natural Resources Defense Council on the perspective piece and other materials on the risk assessment can be read at the nrdc website.

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