Geoscience Reference
In-Depth Information
meaning “great shellfish bay.” At White Oak Point, on the lower Potomac River, an oyster shell midden is test-
ament to four thousand years of continuous harvests. Oysters became the source of a major fishery in colonial
times in areas such as Chesapeake Bay, Narragansett Bay, and Long Island Sound. In the 1880s, at the height
of local production, the Chesapeake was the greatest oyster-producing region in the world. Predictably, like the
blue crab and shad, the eastern oyster suffered from severe exploitation, and its numbers have been reduced a
hundredfold in the last 150 years. More recently, parasitic diseases have further ravaged surviving oyster beds.
Although this loss has had a direct economic impact, its effect on the ecosystem is perhaps more profound.
Chesapeake is an Algonquian word meaning “great shellfish bay,” named for the eastern oyster once so abundant
there.
The reproduction of the eastern oyster is heavily influenced by temperature. The ideal temperature is
between 18° and 25°C (64° and 77°F), one that occurs in the Mid-Atlantic region from late May to September.
Males are stimulated to spawn by temperature as well as food supply, and tend to spawn first. The presence of
spawn in the water then stimulates the females to release eggs, which are fertilized externally. The larval stage
lasts two to three weeks, again depending on food availability and temperature. During this time the larvae mi-
grate vertically, tending to concentrate near the bottom during the outgoing tide and rising in the water column
during the incoming tide, a behavior that increases their chances of being retained in the estuary. Eventually
the larvae must settle on a clean, solid surface, preferably the shells of other oysters. This gregarious behavior
enhances the larvae's ability to successfully reproduce and provides protection from predators and other phys-
ical stresses. It also results in the building of oyster reefs, which, in the past, carpeted acres of shallow water
habitats and sometimes grew to the truly impressive height of 4 meters (13 feet).
STRIPED BLENNY
