Blogs / 80beats

The Chesapeake Bay was once carpeted with oysters, but that was before centuries of overfishing, pollution, and disease took their toll: Today the oyster population has been reduced to less than 1 percent of its historical population. But a new restoration effort has shown unprecedented progress in bringing the bivalves back. In the Great Wicomico River, a tributary of the Bay, researchers have created a 87-acre oyster colony that contains about 185 million oysters.

The Chesapeake’s oyster reefs were destroyed by centuries of watermen towing rakelike metal “dredges” and silted over by dirt flowing from the mid-Atlantic’s farms and growing cities. The final blow came in the mid-20th century: A pair of new diseases killed oysters by the millions. Now, in many places, the bay bottom is a flat expanse of green mud. “Just picture, you know, a clear-cut forest,” said Kennedy Paynter, a biology professor [Washington Post].

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The French oyster industry has been devastated by the abrupt die-off of juvenile oysters; this summer, oyster farmers watched in dismay as between 40 and 100 percent of their young oysters were wiped out. Now researchers say they’ve found the cause of the mysterious blight: The oysters have been infected with a herpes virus for which there is no known cure.

A warm winter and wet spring left the young oysters especially vulnerable to Oyster Herpesvirus type 1, they say. They matured too fast, feeding on abundant plankton, the scientists say. [French oyster expert Tristan Renault says] that “the animal has been using up a lot of energy developing its genitalia and using a lot less to defend itself” [BBC News].

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