The eastern oyster (Crassostrea virginica)—also called Wellfleet oyster, Atlantic oyster, Virginia oyster, or American oyster—is a species of true oyster 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. Eastern oysters are and have been very popular commercially. Today, less than 1% of the original 17th-century population (when the original colonists arrived) is thought to remain in the Chesapeake Bay and its tributaries, although population estimates from any era are uncertain. The eastern oyster is the state shellfish of Connecticut, its shell is the state shell of Virginia and Mississippi, and its shell in cabochon form is the state gem of Louisiana.
|Oyster bed on Cockspur Island, Georgia, USA|
This particular type of oyster has an important environmental value. Like all oysters, C. 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 more than 50 gallons of water in 24 hours. Eastern oysters also provide a key structural element within their ecosystem, making them a foundation species in many environments, and they serve as ecosystem engineers in western Atlantic estuaries. Similar to coral reefs, oyster beds provide key habitat for a variety of different species by creating hard substrate for attachment and habitation. Oyster beds have an estimated 50 times the surface area of an equally sized flat bottom. The beds also attract a high concentration of larger predators looking for food.
The eastern oyster, like all members of the family Ostreidae, can make small pearls to surround particles that enter the shell. These pearls, however, are insignificant in size and of no value; the pearl oyster, from which commercial pearls are harvested, is of a different family.
The lifecycle of C. virginica is: spawning, floating fertilized egg, trochophore, swimming straight-hinge veliger, swimming late veliger, swimming and crawling pediveliger, early spat, later spat, and adult oysters. Spawning of C. virginica is controlled by water temperatures and varies from north to south; northern oysters spawn at temperatures between 60 and 68 °F (15.5 and 20 °C), whereas southern oysters spawn at temperatures above 68 °F (20 °C). Spawning can also occur throughout the warm months.
Eastern oysters can reach sexual maturity at four months old. The eastern oyster has a complex reproductive cycle. The cycle begins during late summer and autumn months with the storage of glycogen energy reserves. This glycogen is then used to support gametogenesis during the next winter and early spring when food intake is at a minimum. The gametes begin to mature in late spring and then, from June to August they are spawned into the water column, where fertilization occurs. Each female produces from 75 to 150 million eggs, but only one in 1000 survive. Then, fertilized eggs develop into planktonic, free-swimming, trochophore larvae, also known as the early umbo stage, which have cilia and a small shell, in about six hours. The trochophore larvae depend on their internal yolk supply for energy. They then develop into a fully shelled veliger larvae, also known as the late umbo stage, which have a hinged side and a velum, formed within 12 to 24 hours. During this time, the shelled veliger larvae use their ciliated vela to capture food and swim. The larvae remain planktonic for about 2 to 3 weeks, depending on food and temperature conditions, and towards the end of this period, they develop into pediveliger larvae, also known as eyed larvae, which have an umbo, an eyespot, and a foot. During this time. the pediveliger larvae "settle to the bottom of the water column where they seek a hard substrate". Ideally, the pediveliger larvae try to locate an adult oyster shell to which they attach, but other hard surfaces will suffice. Lastly, "after careful selection of the proper attachment site, in or during relatively still water, the pediveliger larvae cement themselves to a firm clean surface and metamorphose to the adult form; these newly attached oysters are known as 'spat'". Upon being stimulated to settle, a larva cements its left valve to the substrate and metamorphoses into an oyster spat by discarding its velum, reabsorbing its foot, and enlarging its gills. During the first year of life, C. virginica oysters are protandric. Most spat are male, but once they reach sexual maturity, within four months in southern waters, some males change to females after the first or second spawning. Then, some females can even change back to males again.
The prodissoconch, the shell of the free-swimming veliger larval stage of C. virginica, is composed of aragonite, as opposed to the calcite composition of a postlarval adult oyster shell. The epithelium of the oyster's mantle secretes both the prodissoconch and the postlarval shells, but at different times. Tests were conducted to try to determine why larval and adult shells have different compositions. At the Biological Laboratory of the U.S. Bureau of Commercial Fisheries in Milford, Connecticut, larvae from the eastern oyster were reared in breeding tanks and were then collected, washed with distilled water, and dried as they died. The sample included a variety of larval stages, starting with the straight-hinge veliger larva with its shell, the protostracum, to the last stage of the umbo larva with its shell, the prodissoconch. Both of these larval stages have very thin, hyaline, and translucent shells. The study showed the specific gravity of aragonite is 2.95 and calcite is 2.72, so as far as weight is concerned, no advantage results for a larval oyster to have a shell made of one composition over the other. Then, oyster larval shells were compared not with adult shells, but instead with other bivalve larval shells. All, or almost all, bivalves have aragonitic larval shells because the majority of them have aragonitic adult shells, and C. virginica oyster larvae are assumed to have an aragonitic shell simply to conform to the general pattern in the bivalves. No adaptive need is seen for free-swimming larvae to have shells of a composition other than aragonite; they have that composition because their ancestors did. Adaptations for a thicker shell are required for defense against predators because the oysters are permanently immobilized and therefore live in different environments than those of the free-swimming larvae.
Before Columbus and the rise of industrial oyster operations, oysters abounded in the bay. Oysters first arrived in the Chesapeake 5,000 years ago, and shortly after, local Indians began eating them. Archaeologists found evidence the local Native Americans returned to the same place to collect oysters for 3,000 years. John Smith, on a voyage up the Chesapeake, stated oysters, "lay as thick as stones." In fact, the word Chesapeake derives from an Algonquian word meaning 'Great Shellfish Bay'. Because of the abundance of oysters filtering the waters of the Chesapeake, the water was much clearer than it is now. Visibility would sometimes reach 20 feet. When the English began settling the area, they evidently had a localized impact of the oyster population. One archaeological site measured oyster sizes near Maryland's old capital St. Mary's city from 1640 to 1710. In 1640, when the city was still small, oysters measured 80 mm, and in the city's maximum population in 1690, they measured to 40 mm. When the capital moved to Annapolis, the population moved with it, and by 1710, the oysters were back up to 80 mm. However, the effect of local overharvesting would remain local until after the Civil War, when a combination of new technologies led to the removal of nearly all the bay oysters.
During the industrial revolution, several new technologies were introduced to the Chesapeake Bay area, which allowed for more intensive oyster harvesting. First was the invention of canning. This allowed oysters to be preserved much longer, and created demand for oysters across the world. Secondly, the invention of the dredge enabled oyster harvesters to reach untouched depths of the Chesapeake. And finally, the proliferation of steam-powered ships and railroads made transportation more reliable, enabling merchants to sell oysters far and wide. Estimates for the harvest in 1839 give a figure of 700,000 bushels. After the Civil War, dredges were legalized, and harvesting exploded to 5 million bushels that year. By 1875, 17 million bushels were taken from the bay. The harvesting would reach its peak in the 1880s, with 20 million bushels being harvested from the bay each year. Not only were they being taken for food, but also oyster reefs, where oysters had built hills of their dead shells over thousands of generations, were being dredged out. Surplus oyster shells had many uses then. They were ground into mortar, used as filler in roads, and used as a source of lime in agricultural fertilizer. By the 1920s, harvests would be down to just 3–5 million bushels per year because of overharvesting.
Overharvesting would eventually deplete the remaining oyster population in the bay to just 1% of its historical level, where it stands today. Oyster harvests began to decline in the 1890s. They were being taken much faster than they could reproduce. Also, many of the shells and reefs were being taken and not being replaced. Oyster spat need a hard surface on which to attach, and these were vanishing because of the destruction of oyster reefs. By the 1920s, harvests were down to 3–5 million bushels per year, stabilized for a time by returning oyster shells back to the bay. But in the 1950s, the weakened oyster population had to deal with the diseases "dermo" and MSX. These decimated the remaining oyster population. The parasites which carried the disease are alien to eastern waters, and they were thought to have been brought to the Chesapeake by Asian oysters. Currently, oyster harvests average less than 200,000 bushels a year.
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, the annual catch has declined significantly. In Maryland, the 2006–2007 catch was 165,059 bushels (about 7600 m³) of oysters. Other regions of the East Coast of the United States have successful oyster farms, including most notably Cotuit and Wellfleet, Massachusetts, on Cape Cod.
Harvestable size of a C. virginica oyster is 75 mm, which can take from 12 to 36 months, depending on temperature, salinity of the water, and food supply. Salinity is a very important climatological variable that affects spatfall. Oysters do best where salinities range from 10 to 30 ppt; the range of 15 to 18 ppt is considered optimal. Typically, when salinity levels are less than 6 ppt, larvae will not settle and metamorphose into spat. In 2010, 665 miles of coastline were affected by the Deepwater Horizon oil spill. To keep the oil at bay and to spare the oystermen, the authorities of Louisiana made an unprecedented decision to maximize the fresh water flow through the region's canals to three times usual levels. At the mouth of the canals, salinity fell to almost zero, which was probably why most of the oysters died. Sujata Gupta ventured into the marshlands and Gulf of Mexico with Brad Robin, a man from a line of generations of oystermen in southeastern Louisiana. Robin and his crew threw a net over the side to haul in a catch. There were dozens of palm-sized oysters, but 75% of them were "boxes" or empty shells. However, as they traveled further towards the Gulf of Mexico, where the water was less salinity-stressed by the flush, only 20% of the haul came back as boxes, a promising sign the oysters are trying to come back. Gupta reported, "Now since there are so many empty shells scattered on the sea floor, the larvae have more to latch onto, improving their odds". However, salinity levels are not the only concern. Eastern oysters are filter feeders, so they are greatly affected by their surroundings since they are sessile organisms. This means if the water around them was contaminated with oil and the dispersant used to get rid of the oil, then these chemicals were collected by the oysters as they filtered the water. This is cause for great concern that the oysters are being killed by the toxins in the dispersant, as well. An added dilemma is oysters are in their weakest state after spawning season, which may have caused some of them to close their shells, resulting in death by suffocation within just a few days due to warm temperatures in the Gulf if the shells remain closed. The toxins in the oil and dispersants can also kill the larvae. To highlight the recovery of the state's oyster industry, the shell of C. virginica cut into cabochons was made Louisiana's official state gem in 2011.
"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.
Multinucleated sphere X (MSX) (Haplosporidium nelsoni), another protozoan, was first described along the mid-Atlantic coast in 1957. Mortalities can reach 90% to 95% of the oyster population within 2 to 3 years of being seeded. MSX slows the feeding rates of infected oysters, leading to a reduction in the amount of stored carbohydrates, which in turn inhibits normal gametogenesis during spawning, resulting in reduced fecundity.
Boonea bisuturalis (also known as the three-toothed odostome or the two-groove odostome) is a species of minute sea snail, a pyramidellid gastropod mollusk or micromollusk in the family Pyramidellidae, the pyrams and their allies. The species is one of eleven known species within the Boonea genus of gastropods.This species is ectoparasitic (an external parasite) on various bivalves and other gastropods. It is notorious as a pest on oyster beds. Its preferred hosts are the common periwinkle Littorina littorea, the mud snail Tritia obsoleta and the eastern oyster Crassostrea virginicaBoonea impressa
Boonea impressa, common name the impressed odostome, is a species of sea snail, a marine gastropod mollusk in the family Pyramidellidae, the pyrams and their allies. The species is one of twelve known species within the Boonea genus of gastropods.The preferred host of this ectoparasite is the eastern oyster Crassostrea virginicaCommon slipper shell
The common slipper shell, Crepidula fornicata, has many other common names, including common Atlantic slippersnail, boat shell, quarterdeck shell, fornicating slipper snail, Atlantic slipper limpet and it is known in Britain as the "common slipper limpet". This is a species of medium-sized sea snail, a marine gastropod mollusc in the family Calyptraeidae, the slipper snails and cup and saucer snails.Crassostrea
Crassostrea is a genus of true oysters (family Ostreidae) containing some of the most important oysters used for food. Some species in the genus have been moved to the genus Magallana.Fauna of Connecticut
The fauna of Connecticut comprise a variety of animal species.
The state bird is the American robin.
The state insect is the European mantis.
The state animal is the sperm whale.
The state shellfish is the eastern oyster.
The state fish is the American shad.
The state fossil is the Eubrontes giganteus.Haplosporidium nelsoni
Haplosporidium nelsoni is a pathogen of oysters, that originally caused oyster populations to experience high mortality rates in the 1950s, and still is quite prevalent today. The disease caused by H. nelsoni is also known as MSX (multi-nucleated unknown). MSX is thought to have been introduced by experimental transfers of the Pacific oyster (Crassostrea gigas), which is resistant to this disease.
MSX was first described in 1957, when it caused serious mortalities in Delaware Bay. Through extensive studies, an estimated 50% of oyster mortalities in lower Delaware Bay since the 1960s could be attributed to MSX infections, a devastating loss to the area.Mortalities are usually highest in the summer months, and also increase in higher salinity waters. MSX reduces the feeding rates of infected oysters, leading to a reduced amount of stored carbohydrates. The reduction in stored carbohydrates inhibits normal gametogenesis in the spring, with a reduction in fecundity.List of Connecticut state symbols
The following is a list of symbols of the U.S. state of Connecticut.List of Mississippi state symbols
The following is a list of state symbols of the U.S. state of Mississippi, as defined by state statutes.List of U.S. state shells
This is a list of official state shells for those states of the United States that have chosen to select one as part of their state insignia.These are seashells, the shells of various marine mollusks including both gastropod and bivalves. Each one was chosen to represent a maritime state, based on the fact that the species occurs in that state and was considered suitable to represent the state, either because of the species' commercial importance as a local seafood item, or because of its beauty, rarity, exceptional size, or other features.Oyster
Oyster is the common name for a number of different families of salt-water bivalve molluscs that live in marine or brackish habitats. In some species the valves are highly calcified, and many are somewhat irregular in shape. Many, but not all, oysters are in the superfamily Ostreoidea.
Some kinds of oysters are commonly consumed by humans, cooked or raw, and are regarded as a delicacy. Some kinds of pearl oysters are harvested for the pearl produced within the mantle. Windowpane oysters are harvested for their translucent shells, which are used to make various kinds of decorative objects.Oyster reef
The term oyster reef refers to dense aggregations of oysters that form large colonial communities. Because oyster larvae need to settle on hard substrates, new oyster reefs may form on stone or other hard marine debris. Eventually the oyster reef will propagate by spat settling on the shells of older or nonliving oysters. The dense aggregations of oysters are often referred to as an oyster reef, oyster bed, oyster bank, oyster bottom, or oyster bar interchangeably. These terms are not well defined and often regionally restricted.Oyster reef restoration
Oyster reef restoration refers to the process of rebuilding or restoring of oyster reefs all over the globe. Over time, oysters have been negatively affected by environmental change, such as harmful fishing techniques, over harvesting, water pollution, and other factors. The results of these factors have been disease and ultimately, a large decline in the global population of oysters and the prevalence and sustainability of oyster reefs. Apart from the ecological importance of oyster reefs, oyster farming is an important industry, particularly in coastal areas. Both artificial materials and natural components have been used to rebuild the reefs in an attempt to regenerate the oyster population thus fostering the reformation of reefs.Patchogue Bay
Patchogue Bay is a lagoon on the south-central shores of Long Island in the U.S. state of New York.
Part of the Great South Bay, Patchogue Bay is a cove between the points of land known as Blue Point and Howells Point, and across which ferries run south to Fire Island.Perkinsus
Perkinsus is a genus of alveolates in the phylum Perkinsozoa. The genus was erected in 1978 to better treat its type species, Perkinsus marinus, known formerly as Dermocystidium marinum. These are parasitic protozoans that infect molluscs, at least some of which cause disease and mass mortality. P. marinus is the most notorious, causing the disease perkinsosis, or dermo, in wild and farmed oysters.As of 2004 there were six valid species in the genus. At least two more have been described since then.Species and common hosts include:
Perkinsus andrewsi on Baltic clam (Macoma balthica)
Perkinsus beihaiensis on the oysters Magallana hongkongensis and M. ariakensis
Perkinsus chesapeaki on soft-shell clam (Mya arenaria)
Perkinsus honshuensis on Manila clam (Venerupis philippinarum)
Perkinsus marinus on eastern oyster (Crassostrea virginica)
Perkinsus mediterraneus on European flat oyster (Ostrea edulis)
Perkinsus olseni (syn. P. atlanticus) on blacklip abalone (Haliotis rubra) and grooved carpet shell (Ruditapes decussatus)
Perkinsus qugwadii on yesso scallop (Patinopecten yessoensis)P. andrewsi and P. chesapeaki might be the same species; because the latter was described first, the name P. andrewsi will be a synonym.Perkinsus marinus
Perkinsus marinus is a species of alveolates belonging to the phylum Perkinsozoa. It is similar to a dinoflagellate. It is known as a prevalent pathogen of oysters, causing massive mortality in oyster populations. The disease it causes is known as dermo or perkinsosis, and is characterized by the degradation of oyster tissues. The genome of this species has been sequenced.The species originally was named Dermocystidium marinum. It is responsible for the oyster disease perkinsosis, also known as dermo.Selander Bridge
Selander Bridge is a bridge in Dar es Salaam, Tanzania that connects the north west of Dar es Salaam's city centre to the south eastern Oyster Bay neighbourhood. It was constructed in 1929 and is named after John Einar Selander, Tanganyika's first Director of Public Works.The present bridge was funded by Japan International Cooperation Agency in 1980 and was its first road project in Tanzania. It lies along the Ali Hassan Mwinyi road.Selective breeding
Selective breeding (also called artificial selection) is the process by which humans use animal breeding and plant breeding to selectively develop particular phenotypic traits (characteristics) by choosing which typically animal or plant males and females will sexually reproduce and have offspring together. Domesticated animals are known as breeds, normally bred by a professional breeder, while domesticated plants are known as varieties, cultigens, or cultivars. Two purebred animals of different breeds produce a crossbreed, and crossbred plants are called hybrids. Flowers, vegetables and fruit-trees may be bred by amateurs and commercial or non-commercial professionals: major crops are usually the provenance of the professionals.
In animal breeding, techniques such as inbreeding, linebreeding, and outcrossing are utilized. In plant breeding, similar methods are used. Charles Darwin discussed how selective breeding had been successful in producing change over time in his 1859 book, On the Origin of Species. Its first chapter discusses selective breeding and domestication of such animals as pigeons, cats, cattle, and dogs. Darwin used artificial selection as a springboard to introduce and support the theory of natural selection.The deliberate exploitation of selective breeding to produce desired results has become very common in agriculture and experimental biology.
Selective breeding can be unintentional, e.g., resulting from the process of human cultivation; and it may also produce unintended – desirable or undesirable – results. For example, in some grains, an increase in seed size may have resulted from certain ploughing practices rather than from the intentional selection of larger seeds. Most likely, there has been an interdependence between natural and artificial factors that have resulted in plant domestication.Urosalpinx cinerea
Urosalpinx cinerea, common name the eastern or Atlantic oyster drill, is a species of small predatory sea snail, a marine gastropod mollusk in the family Muricidae, the murexes or rock snails.
They use chemoreception in their environment and are found to be sessile and encrusting organisms. Microscopic particles released by prey are carried through the sea water and captured by the Atlantic Oyster Drill. This animal is not physically able to close itself from its surrounding environment because of its siphonal canal.This species is a serious problem in commercial oyster beds, and it has been accidentally introduced well outside its natural range.Wellfleet
Wellfleet may refer to:
GeographyWellfleet, Massachusetts, a town in Massachusetts
Wellfleet Center Historic District
Wellfleet, Nebraska, a town in NebraskaOtherCamp Wellfleet, a former United States military training camp in Wellfleet, Massachusetts
Wellfleet Communications, a former Internet router company
Wellfleet Drive-In Theater, a drive-in cinema in Wellfleet, Massachusetts
Wellfleet oyster, a name for the eastern oyster (Crassostrea virginica)
Wellfleet Railroad Station, a former railroad station in Wellfleet, Massachusetts