Shellfish are a good source of nutrition, and many people enjoy harvesting and eating them. Oysters, razor clams, and mussels have long been food sources for Washingtonians. They’re an integral part of local traditions and livelihoods. Many shellfish are also filter-feeders, which means they help keep water clean.
But these animals are in trouble. Carbon pollution from human activities is turning their home — the ocean — into a hostile environment because of ocean acidification. To help communities adapt, we created an ocean acidification indicator to visualize changing marine water conditions in Washington state. An “indicator” is a simply presented data reference tool used by scientists to communicate complex information.
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Tracking ocean acidification
Our long-term ocean acidification monitoring program, established in 2019, tracks how carbon pollution affects marine waters. We measure water conditions monthly at 28 locations in Puget Sound and along the coast. For each location, we sample water at the surface and at 100 feet, which tells us how acidification conditions change with depth.
Our measurements let us estimate a water property called aragonite saturation state. Aragonite is a form of calcium carbonate that many marine organisms produce to build their skeletons and shells. The lower the saturation state, the more difficult it is for shellfish and salmon to build and maintain their protective skeletons and shells. This effect will worsen as ocean acidification shifts the ocean’s chemistry.
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Making an invisible problem visible
Using over four years of monitoring data, we created the Ocean Acidification Indicator to visualize annual ocean acidification conditions and to track the long-term effects of carbon pollution in greater Puget Sound. The indicator represents the number of days in each year when water conditions are favorable for sensitive marine animals. Think of it as a window of opportunity for oysters, crabs, and young salmon to grow and thrive.
Our research helps us pinpoint two annual timeframes:
- The range of days when water conditions are favorable, which is the ocean acidification indicator
- The range of days when water conditions are corrosive, making it more difficult for shellfish and salmon to thrive
Ocean chemistry is shifting because of carbon emissions. Our data show seasonal changes in greater Puget Sound. Water conditions are favorable for shellfish and salmon from spring to summer, and unfavorable from fall to winter. Favorable conditions have declined since the early 1800s.
What have we learned by tracking and studying ocean acidification in Washington? Puget Sound and the coastal environment are changing rapidly because of carbon pollution.
- There are seasonal changes in Puget Sound when favorable conditions for shellfish and salmon begin in spring and continue through most of the summer.
- Water in deep parts of Puget Sound and the coast is more corrosive than water in shallow areas, increasing stress for organisms near the seafloor like Dungeness crabs and oysters.
- Some regions of Puget Sound are more at risk because ocean acidification is worsening naturally occurring corrosive conditions.
The more we learn, the more we can share with our partners to help them adapt and adjust management practices. We’re sharing our data with Tribes, shellfish farmers, resource managers, policymakers, and scientists throughout the state and the west coast.
Shellfish farmers can use the indicator to track months when water conditions are better for growing shellfish. Resource managers and policymakers can evaluate whether they need to adjust management practices. Scientists and research partners can build on our data to develop new tools or studies to better understand ocean acidification and forecast future conditions.
We strive to support thriving shellfish communities and healthy ocean habitats by sharing this information and coordinating with our partners.
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Washington State Department of Ecology, 10 December 2024. Full Article.
