For ocean acidification, think globally but act locally

The oyster industry in the Pacific Northwest region of the United States has already lost nearly $110 million in revenue and some 3,200 jobs due to climate change. Of all the carbon dioxide emissions that we pump into the atmosphere, about a quarter of it winds up becoming dissolved in the ocean. All that dissolved CO2 decreases the pH of seawater, and as a result, shelled mollusks, like clams and oysters, suffer. And when mollusks suffer, the fisheries that rely on those species suffer as well. Revenue is lost and people are fired.

Natural Resources Defense Council researcher Julia A. Ekstrom (who is now Director of the Climate Adaptation Program at the University of California, Davis Policy Institute) and colleagues point out that while real, measurable impacts from ocean acidification and climate change have spurred coastal communities to search for solutions (even while the globe works towards a reduction in CO2 emissions), there is little understanding about “which locations and people will be impacted by [ocean acidification], to what degree, and why, and what can be done to reduce the risks.”

Focusing on shelled mollusk fisheries in the United States, Ekstrom reported the first vulnerability assessment for an entire nation’s coastal regions this week in the journal Nature Climate Change. The assessment was comprised of three main dimensions: (1) the exposure of marine ecosystems to acidification, taking into account factors that could amplify acidification locally, such as agricultural runoff; (2) the social importance of shellfish for each coastal economy, based on factors like the value of shellfish, the proportional contribution of shellfish to commercial fisheries, the number of licenses for mollusk fishing given out each year, and so on; and (3) the capacity of those coastal economies to adapt to ocean acidification, which was based on whether local governments had climate- or acidification-related policies in place, whether there were employment alternatives, and whether there were relevant scientific laboratories or institutes nearby to assist local policymakers with trouble-shooting assistance or early warning information.

The analysis revealed that of 23 bioregions along the US coastline, 16 – nearly 70 percent – are expected to see rapid ocean acidification by the year 2050. Ecosystems around the Pacific Northwest and Southern Alaska will likely be affected soonest by acidified seawater; by contrast, the communities that appear least prepared for the coming changes are found along the eastern seaboard and in the Gulf of Mexico. However, the two regions are least adaptable for different reasons. On the east coast, it’s thanks to the overwhelming economic dependence on shellfish resources. Southern Massachusetts, for example, has the highest mollusk harvest revenue of any coastal area in the Unites States. The Gulf of Mexico, on the other hand, is at risk due to social factors such as low political engagement on matters of climate and oceans and a dearth of local scientific resources.

The researchers highlight the fact that their study is but a first step towards identifying possible solutions to the degradation of shelled mollusk fisheries. However, what they see as the most important finding is that the combination of exposure to acidified seawater, economic dependence, and social factors combine to “create a mosaic of vulnerability nationwide.” A nationwide solution, they argue, will likely be insufficient to address the problem. Instead, strategies must be developed at the regional and local levels, which can then be supported with scientific expertise, ecological monitoring, and coordination at the national level. – Jason G. Goldman | 25 February 2015

Source: Ekstrom J.A., et al. (2015). Vulnerability and adaptation of US shellfisheries to ocean acidification, Nature Climate Change, DOI:

Header image: Eastern oysters, copyright Rick Friedman.