The Eastern oyster, Atlantic oyster, or the Virginia oyster, Crassostrea virginica, is a species of oyster that is native to the eastern seaboard and Gulf of Mexico coast of North America. It is also farmed in Puget Sound, Washington, where it is known as the Totten Inlet Virginica. ^[1] Eastern oysters are and have been very popular commercially. Today it is thought that less than 1% of the original population that existed in the Chesapeake Bay and its tributaries when the original colonists arrived in the seventeenth century remains^[2], although population estimates from any era are uncertain. The Eastern oyster is the state shellfish of Connecticut,^[3] and its shell is the state shell of Virginia and Mississippi.

Description

Like all oysters, Crassostrea virginica is a bivalve mollusk with a hard calcium-carbonaceous shell. Its shell provides protection from predation.

This particular type of oyster has an important environmental value. Like all oysters, Crassostrea virginica is a filter feeder. They suck in water and filter out the plankton and detritus to swallow, then spit the water back out, thus cleaning the water around them. One oyster can filter up to 48 gallons of water in 24 hours.

The Eastern oyster, like all members of the family Ostreidae, can make small pearls to surround particles that enter the shell. However these pearls are insignificant in size and of no value; the pearl oyster, from which commercial pearls are harvested, is of a different family.

Commercial value

The Eastern oyster used to be of great commercial value. Due to the steep decline in the number of oysters in various traditionally harvested areas primarily because of overfishing and diseases^[4], the annual catch has declined significantly. In Maryland, the 2006-2007 catch was 165,059 bushels (~7600 m³) of oysters ^[5]. Other regions of the east coast of the United States have successful oyster farms, including most notably Cotuit and Wellfleet on Cape Cod, in Massachusetts.

Diseases

"Dermo" (Perkinsus marinus) is a marine disease of oysters, caused by a protozoan parasite. It is a prevalent pathogen of oysters, causing massive mortality in oyster populations and poses a significant economic threat to the oyster industry.

"MSX" (Haplosporidium nelsoni) was first described along the mid-Atlantic coast in 1957^[6]. Mortalities can reach 90% to 95% of the oyster population within 2 to 3 years of being seeded^[7]. MSX slows the feeding rates of infected oysters leading to a reduction in the amount of stored carbohydrates. The reduction in stored carbohydrates inhibits normal gametogenesis during spawning, resulting in reduced fecundity.

See also

• Oyster

References