"A disturbing nationwide decline in oysters and the life-giving reefs that they build is particularly dramatic in California, where the once-abundant native species has been virtually wiped out, according to a recent scientific study."

"The report, published in the scientific journal Proceedings of the Royal Society B, said Olympia oysters, once an integral part of the Native American diet and a staple during the San Francisco Gold Rush, are functionally extinct.

"Essentially, today, the number of oyster reefs is zero," said Rob Brumbaugh, restoration director for the Nature Conservancy and co-author of the study. "It's the complete elimination of a key species and habitat on the West Coast."

The loss of native oysters - not to be confused with the farm-raised Japanese Pacific oysters - is a serious issue, he said, because oysters clean the water by filter feeding. A single oyster can filter up to 30 gallons of water a day, removing nitrogen and other pollutants, Brumbaugh said. The oyster beds, or reefs, they create provide habitat for myriad fish, crabs and other creatures. "

Peter Fimrite reports for the San Francisco Chronicle July 6, 2012. [2]