Ocean acidification is a complex global problem because of increasing atmospheric carbon dioxide, but there also are a number of local acidification "hotspots" plaguing coastal communities that don't require international attention - and which can be addressed now.
A regulatory framework already is in place to begin mitigating these local hotspots, according to a team of scientists who outline their case in a forum article in the journal Science.
"Certainly, ocean acidification on a global level continues to be a challenge, but for local, non-fossil fuel-related events, community leaders don't have to sit back and wait for a solution," said George Waldbusser, an Oregon State University ecologist and co-author of the paper. "Many of these local contributions to acidity can be addressed through existing regulations."
A number of existing federal environmental laws - including the Clean Air Act, the Clean Water Act, and the Coastal Zone Management Act - provide different layers of protection for local marine waters and offer officials avenues for mitigating the causes of local acidity.
"The localized events might be nutrient-loading or eutrophication issues that can be addressed," said Waldbusser, an assistant professor in OSU's College of Oceanic and Atmospheric Sciences. "Communities don't have to wait for a global solution."
The commentary article in Science, "Mitigating Local Causes of Ocean Acidification with Existing Laws," was inspired in part by some of Waldbusser's work in Chesapeake Bay, which highlighted how increasing acidity in sections of the Chesapeake were exceeding rates that could be explained by increasing carbon dioxide from fossil fuel emission.
Lead authors on the Science forum paper were Ryan Kelly and Melissa Foley of the Stanford University Center for Ocean Solutions.
The scientists point to a recent lawsuit that resulted in a U.S. Environmental Protection Agency memorandum outlining the responsibility of individual states to apply federal environmental laws to combat acidification in state waters. As a result, EPA now encourages states to list "pH-impaired" coastal waters where such data exist.
One such example, Waldbusser says, is in Puget Sound, where nutrient-loading from sewage treatment plants has created large plankton blooms that eventually die and contribute to greater acidification.
"When these blooms die and sink to the bottom, they suck the oxygen out of the water," Waldbusser said. "Low oxygen is the flip side of high CO2. People in the Northwest are starting to become aware of hypoxia and its impacts, but there hasn't been the same awareness of ocean acidification on a local level."
Awareness of acidification may be growing. Waldbusser points to work at Whiskey Creek Shellfish Hatchery in Oregon's Netarts Bay, which monitors ocean water daily for acidification. The northwest oyster industry has been plagued by larval die-offs and ocean acidification may be to blame. The hatchery now takes water from the bay only at certain times of the day when acidification levels are lowest.
The OSU ecologist is also studying naturally occurring counter-balances to acidification, including the role of oyster and clam shells. Commercial oyster shells are typically removed from the water and native oyster populations have plummeted, so there are may be fewer shells in Oregon estuaries than ever before.
"Calcium carbonate shells help neutralize the effects of acidification," Waldbusser said. "In essence, they are akin to giving the estuary a dose of Tums. We're trying to determine how much of an impact shells may have and when conditions are corrosive enough to release the alkalinity from those shells back into the water."