The Plight of the Dungeness Crab

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According to new research by NOAA Fisheries’ Northwest Fisheries Science Center, the Pacific Ocean is becoming more acidic and dissolving the shells of Dungeness crab larvae. The corrosion drastically reduces the crabs’ life expectancy; according to Jason Miller, lead author of the research, crab larvae are three times more likely to die when exposed to the lower pH levels currently found in Puget Sound.

Ocean acidification is the result of increased carbon dioxide in the atmosphere, according to NOAA. It is estimated by the NOAA that a quarter to a third of all carbon dioxide released into the atmosphere by fossil fuel consumption is absorbed by the ocean, causing the pH levels in the water to lower. The carbonate ions on which crustaceans and coral rely is less abundant in the acidic water, and they cannot build their shells or skeletons as effectively. As a result, crabs are more susceptible to predators and cannot effectively regulate their buoyancy. The low pH has also damaged the hair-like structures on which they rely for navigation, and it may cause developmental delays.

Dungeness crabs are an important part of the coastal economy; they are the highest revenue fishery in Washington and Oregon, and the second highest in California. While the crabs are the first species to be noticeably impacted by ocean acidification, oysters, clams and plankton all rely on the same carbonate ion and may be affected in the future.

Scientists were not expecting to see the impacts of acidification on the crabs until much later in the century. The only way to decrease the concentration of carbon dioxide in the ocean is to decrease the concentration in the atmosphere, and (according to NOAA Fisheries) these results will force the Pacific Northwest to consider the future of its commercial fishing industry. 



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