The Eastern Oyster Notes “The abundance of oysters is incredible. There are whole banks of them so that the ships must avoid them … They surpass those in England by far in size, indeed, they are four times as large. I often cut them in two, before I could put them into my mouth. “ Swiss explorer Francis Louis Michel, 1701

1607 Oysters lived in mounds with their tips rising above the water surface. Capt. John Smith wrote in his logs about the trouble of navigating around these mounds. He also wrote that the water was so clear he could see 60 ft down.

Historically, oysters could live up to 30 years, growing 1” per year. Young oysters, called spat, attach to older oyster shells to grow. This layering is how oyster bars are formed.

Geographic Distribution The eastern oyster, Crassostrea virginica, is native to the East coast of Canada & US, Gulf of Mexico & Carribbean.

What Happened? -Dredging caused the loss of ALL mounds in the Bay. -We used 99% of all the oysters in 150 years. *It took 150,000 years to form these oysters. Photo credit: Chesapeake Bay Foundation

Early 1900’s -Oysters were harvested for their SHELLS for roads, calcium for chickens, construction, etc. -This picture is of 1 oyster house (we had 20 houses in VA).

What Happened? Oyster diseases – MSX & Dermo arrived in the 1980’s & kills young oysters. High sediment pollution smothers oysters since they don’t live in oyster bars anymore. New threat – acidification of ocean water b/c of excess CO2 in the atmosphere. This causes oyster shells to deteriorate in a chemical reaction.

1 week, planktonic and the size of a pin head, drifts with current Oyster Life Cycle 1 week, planktonic and the size of a pin head, drifts with current Larger Female 2 weeks, tries to sense chemical compounds in other oyster shells, settles & slithers “protandric hermaphrodites”

Filtration & Food Production Oysters are natural water purifiers. An adult oyster filters 60 gal of water/day! Filters Sediment Nutrients Toxins Bacteria BIODEPOSITION

Benthic-Pelagic Coupling Oysters consume algae & produces biodeposits Oysters are able to filter water and take pelagic food and turn it into benthic food to help support benthic animals (keystone species) Oysters consume algae & produces biodeposits Pelagic, predatory fish Nutrient rich deposits for worms

Before the bay’s decline, oysters could filter the ENTIRE bay in 3 days! Today it takes a year or more.

Biodiversity on Oyster Reefs

Oysters - a Keystone Species Habitat for fish & other organisms. Valuable link in food web & benthic-pelagic coupling. Control water quality by filtering phytoplankton. Once supported the most valuable shellfish fishery in the Chesapeake Bay.

Oyster Restoration began in 1994 Photo credit: Chesapeake Bay Foundation

#1 - Construct Reefs Photo credit: Chesapeake Bay Foundation

MRC Produced

#2 - Stock Reefs

A lot of oystermen now practice oyster farming.