Americans consume approximately 700 million farmed oysters per year. Despite our love for these briny bivalves, shellfish and the coastal communities that depend on them face serious threats.
In a recent piece, Eric Scigliano examines “The Great Oyster Crash” of 2007, in which oyster seed (larvae) off the coast of Oregon and Washington began dying by the millions, seemingly without cause. After taking aggressive measures to eliminate bacteria in the tanks, and failing to halt their losses, the owners began to suspect the problem was a more fundamental change in the makeup of the oceans. With the help of local scientists, they found that their losses were directly linked to a far more ominous phenomenon: ocean acidification.
As Scigliano explains, “the oceans are the world’s great carbon sink, holding about 50 times as much of the element as the air.” As carbon emissions from burning fossil fuels and other industrial processes rise, so too does the level of acidity in the oceans. Once it reaches a certain threshold, ocean acidification becomes lethal to many species, including clams and oysters, which become unable to build the shells or skeletons they need to survive.
The rise in acidity and subsequent oyster crash took a significant toll on coastal communities – from 2005 to 2009, West Coast production dropped from 93 million pounds to 73 million pounds, representing $11 million in lost sales. This case is among the earliest examples of ocean acidification imposing a direct effect on the economy. Unfortunately, we can safely say it is far from the last.
By installing new technology to carefully monitor ocean temperatures and chemistry, some west coast hatcheries were able to rebuild, but their bounty might be short-lived. While temporary mitigation measures have been successful, they are just that – temporary. Scientists from Mexico, Canada, and the United States found that upwellings of acidic water like those that wiped out the Pacific hatcheries operate on a delay of several decades – the water rising from the deep ocean today holds CO2 absorbed approximately 30 to 50 years ago. In the last 50 years, the levels of CO2 in the atmosphere have risen 25 percent – a terrifying presage for the health of the world’s oceans. Burke Hales, one of the scientists involved in the research, explains:
“We’ve mailed a package to ourselves … and it’s hard to call off delivery.”
Benoit Eudeline, chief hatchery scientist for Taylor Shellfish Farms, the largest US producer of farmed shellfish, likened the current situation to “sitting on a ticking time bomb.”
The threat of ocean acidification spreads far beyond the oyster industry and carries potentially catastrophic implications for the entire food chain. Basically any fish that might find its way onto your dinner plate relies on krill, plankton, snails or other shelled creatures that stand to be hit earliest and hardest by acidification. The chart below, for instance, shows that about half the annual catch by value in the U.S. comes from mollusks and crustaceans and another 24 percent are animals that directly feed upon these calcifiers – representing billions of dollars and millions of jobs at stake. (See chart above.)
The damaging effects of ocean acidification will likely be felt even more acutely beyond American shores. A recent study found that mollusk fisheries will decline most in poor countries that are already struggling with protein deficiencies. In Madagascar, one of the countries the study predicted would be hit hardest, fishing provides 7 percent of the GDP and generates nearly half a million jobs – and local officials confirm the effects of both climate change and ocean acidification are already being felt.
Though advancements in science and fisheries management can help provisionally assuage the blow of ocean acidification, ultimately, only significant measures to reduce carbon emissions in the atmosphere will prevent the oceans from becoming more acidic and threatening more species. The groundbreaking 2005 study on ocean acidification conducted by The Royal Society recommended “a major internationally coordinated effort” to stem the tide of acidification, unequivocally stating, “action needs to be taken now to reduce global emissions of CO2 to the atmosphere to avoid the risk of irreversible damage to the oceans.” Six years later, we’re still waiting.
— Kiley Kroh is associate director of Ocean Communications at the Center for American Progress
- Nature Geoscience study: Oceans are acidifying 10 times faster today than 55 million years ago when a mass extinction of marine species occurred
- Nature Geoscience study concludes ocean dead zones “devoid of fish and seafood” are poised to expand and “remain for thousands of years.”
- Geological Society: Acidifying oceans spell marine biological meltdown “by end of century” — Co-author: “Unless we curb carbon emissions we risk mass extinctions, degrading coastal waters and encouraging outbreaks of toxic jellyfish and algae.”