New York City's Billion Oyster Project is one of several restoration projects of that bivalve taking place in the United States. Restoring young oysters, or spats, to artificial reefs and by other methods has taken place in the Chesapeake Bay since 1997, with an accelerated focus since 2013. Here's a map of other oyster recovery projects nationwide. 

This effort is happening because oysters are a keystone species--they're considered integral to the ecosystems in which they appear. Forget Brita®--oysters are the original water filtration system. If we have had degrading water quality in New York Harbor, the Chesapeake Bay, the Gulf of Mexico, and the Pacific Coast, it is in part both a cause and an effect of the oyster decline, as NOAA has noted: "Fewer oysters means less filtration capacity." They consume phytoplankton, or free-swimming algae. But oysters, thought hardy and knotty in appearance, can be killed by long periods of low dissolved oxygen at the bottom of any bay or body of water. 

New York's project, which started in 2009 and involves planting young oysters (spats) on artificial reefs and including New York school children in raising the oysters before placing them in the Hudson estuary, aims to restore oysters, an original engineer of New York Harbor's ecosystem. In the past, places like Staten Island had a hearty oystering industry, as Mark Kurlansky's book The Big Oyster (Penguin 2006) noted.  

There is still work to be done. The Gulf Coast's active oyster industry was wiped out by Hurricane Katrina and the Deepwater Horizon oil spill. Also, the Chesapeake Bay is still estimated to have fewer than one percent of native oysters, and New York is not farther along. 

If you live near a coast, there are ways to contribute. In New Hampshire, for instance, authorities ask individuals to donate oyster shells for use in growing spats. Restoration centers in Maryland and Virginia note that they rely heavily on volunteer help in raising new oysters. How will you contribute in your area?

In the highly charged area of oysters in America, there's also the recent book The Oyster War (Counterpoint Press 2015) by Summer Brennan, about one oyster farm located within the Bay Area's Point Reyes National Seashore, which was accused of doing environmental harm and was involved in a major legal battle that went to the Department of Interior. 

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