The eastern oyster…

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“River and creek mouths are so favored by oysters because the murk they carry is actually micro-algae–swarms of phytoplankton thriving on the nitrogen- and phosphorous-based wastes brought down from the land upstream. When these nutrients enter a bay, they fertilize the water and promote phytoplankton blooms. This phytoplankton is the oyster’s principal food. Too much of it and the water will become choked and life will slip away. But when oysters are present, they gobble the phytoplankton down, cleaning and clearing the water in the process. A single oyster will filter as much as fifty gallons of water a day. Multiply that by several trillion–the historical oyster population of greater New York–and you can understand why the visibility in New York waters was once much better…

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When a healthy oyster population filters and clears the water, sunlight is able to penetrate into the depths, in turn spurring the growth of several species of amphibious grass. This partnership of oyster and grasses turns out to be a foundational element of bountiful seafood in estuary environments. Oysters and marsh grasses stabilize the shoreline and create protective pockets of shallow water–essential for the sensitive lives of juvenile fish. This biological arrangement is known as a salt marsh, and its importance cannot be overstated. Salt marshes produce more basic food energy per acre than any other known ecosystem in the world–even more than tropical rainforests. They sequester more carbon than any other known ecosystem and can absorb as much as a foot of tidal storm surge. But where salt marshes really are worth their salt is in seafood production. Three-quarters of all the commercial fish species we eat rely on salt marshes for all or part of their life cycles. So it is in large part because of the oyster and the salt marshes they enabled that Dutch settlers arriving in New Amsterdam in the seventeenth century found vast schools of fish in New York waters…

An oyster reef in the Baruch Marine Field Laboratory on the South Carolina coast. Jonathan Wilker, an associate professor of chemistry at Purdue, has shown that oysters produce a unique adhesive material to form these complex reefs. (Photo courtesy of Jonathan Wilker/Purdue University)

[Today] wild oyster reefs rank among the most endangered ecosystems in America, with 80 percent of the wild reefs now gone. Along with them have also gone the fish-producing salt marshes. By some estimates, the United States has lost 70 percent of its historical salt marsh, much of it in the last fifty years. Is it any wonder that the American catch is impaired by so much loss?”

-American Catch