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Shell Shock

The waters of Duxbury are changing, and not in a good way.

A commission formed by the State Legislature recently released a study warning that the level of acidification is rising in the waters of Massachusetts, posing a threat to the lo cal aquaculture industry. The commission included representatives from state agencies, conservation groups, industry leaders and legislators, including State Senator Patrick O’Connor, who represents Duxbury. O’Connor called acidification “an existential threat to our marine industry and our natural habitat.” 

In 2019, Duxbury growers harvested $5.7 million worth of oysters, according to the Division of Marine Fisheries. 

According to the report, as much as 30 percent of excess carbon dioxide in the atmosphere is absorbed by the ocean. In turn, that makes the water more acidic, which hinders the development of the shells of mollusks and lobsters. Calcium makes up the oysters’ shells and calcium “doesn’t react well to acidification,” Ben Lloyd, owner of Pangea Shellfish Company and Standish Shore Oyster Farms, said.

The 83-page report also cites nutrient pollution largely caused by runoff from septic systems, landfills and agricultural uses as another cause of increased acidification. Lo cal oyster farmers and others cited this as a more pressing threat than increased carbon dioxide in the atmosphere. “That’s been an ongoing problem,” Lloyd said. Ocean acidification is largely caused by changes in climate, but in the bay, it’s largely a result of water running off from the shore. “In Duxbury Bay, the more clear and present danger is nitrogen overloading,” Island Creek Oysters President Chris Sherman said. In the ocean, acidification happens on a much longer time scale, he noted. Acidification is just one of what Sherman called “a long list of negative externalities” that shellfish farmers deal with. In the short-term, it’s more of a problem in open water than in the bay, he not ed. 

Lloyd said that trees being illegally cut down in and near coastal wetlands also contribute to the problem. “These trees and vegetation are vital to the health of our coastal wetlands and marshes. This vegetation and the adjacent marshes are critical in absorption of excess nutrients from run off.”

A report recently released by the University of Vermont identified Southeastern Massachusetts, including Plymouth County, as one of 20 places in the United States where efforts should be made to reduce nitrogen runoff.  

“We are concerned about nitrogen in the bay and whether that affects the natural resources,” Duxbury Conservation Administrator Joe Grady said. “The biggest thing we can do is eliminate nutrient pollution,” O’Connor said. 

One way the town has tried to address the issue of bacterial pollution running  into the bay is through shared septic systems in the Bluefish river, Snug Harbor and Bay Road areas Grady said. The oysters themselves help cut down on that problem, since they filter out the excess nitrogen. It doesn’t have a negative effect on the oysters, but the mollusks can only filter so much, Lloyd noted. “They can’t take out all of the nitrogen.”

Right now, the rising acid levels aren’t affecting the oyster crop, Lloyd said. Grady, who farms his own shellfish beds in the bay, also said he hasn’t noticed an effect on his own crop yet. The big impact is on hatcheries, according to Lloyd. Some, he didn’t say which, condition their water to mitigate the effect.  Island Creek already has to account for the water’s increased acid level in their hatchery, which draws water from the bay, Sherman said. Data that’s been collected shows the change in acidity hinders the development of the larvae’s shells, he added.

One thing everyone seems to agree on is that more study of local conditions in the bay is needed. Money is needed to get more data on what the baselines conditions in the water, as well as to come up with ways to mitigate the problem, Sherman said. He said the ph level in the bay changes substantially because of the tides and weather.  “We’ve been trying to come up with a way to do some monitoring.”  Nitrogen is supposed to flush out with the tide, but “there are indicators that might not be the case,” Grady said. “That is a question that’s on the horizon,” Duxbury Bay Management Commission Chairman Joe Messina said. “What can the town do about water quality in the bay?” The commission has tried to get more formal water quality monitoring done in the bay, he said. Legislation has been introduced that would increase monitoring of the bay, reduce chemical runoff and carbon emissions, and restore wetlands that help keep that runoff from making it into the ocean, O’Connor said.

The report also calls for the establishment of a “Blue Communities” Program to encourage communities to start cost-effective green infrastructure projects, and incorporate conservation principles into local ordinances and zoning laws.

While the predictions in the report look to what appears to be far into the future, O’Connor said that taking action now will prevent damage in the future. The report estimates the economic damage could reach $100 million in the next 80 years. “Now is the time to act.”

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