Tribal nations and other partners look for ways to reduce ocean acidity, which has increased 30% in 250 years

It was about 2006 and oyster growers in the Salish Sea were seeing a decline in the abundance and growth of their farmed bivalves. 

A decline in pH levels, tests revealed, had made local seawater corrosive enough to dissolve calcium carbonate in the water that oysters need for shell growth. 

Ocean acidification — the result of carbon dioxide released into the air that settles in the ocean — had reached growers’ shores in the inland coast of Washington state. And if nothing was done to address it, the shellfish growers told then-Gov. Christine Gregoire and their district legislator, they would have to move their operations to more pH-balanced waters in Hawai’i.

The issue didn’t gain traction out of the gate with Washington state lawmakers — who were grappling with crime and mental health issues and teacher pay in their districts — didn’t gain traction, that is, until lawmakers recognized how ocean acidification might affect the state’s economy. 

“Back then, we were barely figuring out what ocean acidification was,” said former state Sen. Kevin Ranker (D-Orcas Island), who wrote the state’s first legislation dealing with ocean acidification.

“All we knew was that a whole bunch of oysters were dying. It wasn’t because it was a big climate issue or a big ocean issue that I was able to get legislation passed. It’s because I walked onto the Senate floor and said, ‘We just lost 300 jobs to the state of Hawai’i because our waters are polluted and we need to figure it out.’ And everyone was like, ‘Holy s***, we’d better do something.’”

Shellfish aquaculture in Washington state contributes $270 million to the annual economy and 2,700 local jobs, according to the Nature Conservancy. The value of state crab landings — nontribal and tribal — during the 2022–23 season was $64.6 million, according to the state Department of Fish and Wildlife. That value, however, grows in terms of jobs and money generated as the crab moves from boat to market. 

But ocean acidification is growing and there’s more at stake than the economy. Marine scientists and environmental advocates say ocean acidification is harming the ecosystem and is threatening traditional foods and treaty rights. Tribal nations that share geography with the Lower 48 and Alaska are employing new tools to track acidification and adapt to changes in waters that have helped sustain them since time immemorial. 

Scientists say carbon dioxide produced by the burning of coal, oil and gas has increased the amount of carbon in ocean water, upsetting the ocean’s pH balance. About 25% of carbon dioxide, or CO₂, released into the air dissolves into the ocean, according to the Smithsonian National Museum of Natural History. 

“When carbon dioxide dissolves in seawater, the water becomes more acidic and the ocean’s pH drops,” the Smithsonian reports. “Even though the ocean is immense, enough carbon dioxide can have a major impact. … Since the beginning of the industrial era, the ocean has absorbed some 525 billion tons of CO₂ from the atmosphere, presently around 22 million tons per day.”

As a result, the ocean is 30% more acidic today than it was at the start of the industrial era 250 years ago, according to the National Oceanic and Atmospheric Administration, (NOAA), the Smithsonian, National Resources Defense Council and others. 

pH is a measurement of how acidic or basic a substance is, on a scale of 0 to 14. Neutral pH is 7.0; anything less than that is considered to be acidic. Human blood has a pH of 7.35; black coffee, between 4 and 5; vinegar and soda, 3; stomach acid and lemon juice, 2; and battery acid, less than 1. According to the U.S. Geological Survey, each number represents a tenfold change in acidity. That means water with a pH of 7 is 10 times less basic [more acidic] than water having a pH of 8. 

The average upper-ocean pH is 8.1, according to NOAA. But pH varies by location. The University of Washington reported in 2015 that the pH in seawater at its labs in Friday Harbor on San Juan Island in the middle of the Salish Sea was 7.8. In Puget Sound, home of Seattle and Tacoma, seawater pH as low as 7.6 was recorded. Along the ocean coast, pH drops even more when upwelling brings deeper water to the surface — water that is rich in nutrients as well as carbon that long ago settled there.

Those drops in ocean pH are enough to erode the minerals that corals need to grow their skeletons and form the foundation for coral reefs, the research nonprofit Coral Reef Alliance reported. “Research shows that when exposed to high levels of CO₂, corals stop being productive and their risk of bleaching increases by up to 50%,” the nonprofit reported. Coral reefs provide habitat for clams, crabs, oysters, sea stars, sea urchins, sponges and many species of fish.

A 2016 NOAA study of Dungeness crabs in Northwest U.S. waters with low pH showed damage to the upper shell of numerous larval crabs, as well as the loss of hair-like sensory structures that crabs use to orient themselves to their surroundings. 

On the Makah Nation island of Tatoosh, in the extreme northwest corner of what is now Washington state, crustaceans have shown signs of weakening during periods of upwelling. 

Richard Arlin Walker, Salish Current, 27 June 2024. Article.

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