A global-scale case of indigestion eats away at the organisms of the Earth's oceans, but delicious Chesapeake Bay oysters may be just the marine medicine people need to fight the devastating effects of ocean acidification.
Calcium carbonate in oyster shells matches the active ingredient in antacids that people crunch down when suffering indigestion or heartburn. Research published in Ecology examined how oyster populations, and the discarded shells humans return to the bay, serve a similar purpose in the Chesapeake Bay.
"Oyster shells are like slow-dissolving TUMS in the belly of Chesapeake Bay," study author Roger Mann of the Virginia Institute of Marine Science said in a press release. "As ocean water becomes more acidic, oyster shells begin to dissolve into the water, slowly releasing their calcium carbonate-an alkaline salt that buffers against acidity. An oyster reef is a reservoir of alkalinity waiting to happen."
Ocean acidification results from the one of the causes of global warming. Increased carbon dioxide concentrations in the atmosphere result in the ocean absorbing more of the gas. The dissolved carbon dioxide converts to carbonic acid and makes the oceans more acidic. Increasing acidity dissolves the hard structures of coral reefs and weakens some species' shells. It may also have serious consequences for some animals' reproductive cycles.
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However, now just when oyster shells' buffering powers are most needed, the Chesapeake Bay oyster beds can't fight acidity as well as in the past. Intensive harvesting and outbreaks of two diseases, known as Dermo and MSX, have decimated Chesapeake oyster numbers, according to NOAA. Oyster harvests have plummeted to less than one percent of 1880s levels. In the 1880s and 90s, fishermen harvested up to 120,000 pounds of oysters from the Bay each year.
One solution to oyster scarcity now floats tethered to the docks of many Chesapeake Bay residents. Dock owners grow oysters in floating bins that not only provide food, but also filter the bay's water and provide habitat for other species.
Chesapeake Bay oyster gardening started in the 1990s and grew to more than 2,000 gardeners by 2010, reported the Southside Sentinel.
"The idea was similar to having a few chickens," oyster garden pioneer Peter Perina told the Southside Sentinel. "I thought it could be something homeowners would do for the table or for some side income. All you need is a dock and the proper water salinity.
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"When you are getting your food and making your living from the water, you automatically become an environmentalist," Perina said. "If you are taking something from the water and eating it, you want to see the water be the cleanest place it can. There's an awareness that comes about as well, and you begin to see what an important role the oyster plays in the grand scheme of things."
IMAGE: Norfolk District Oceanographer Dave Schulte displays a cluster of oysters which were growing on the district's sanctuary reefs in the Great Wicomico River as part of the U.S. Army Corps of Engineers project to restore oysters in Chesapeake tributaries. (U.S. Army, Wikimedia Commons)