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Species
Carcinus maenas Leach, 1814
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NCBI
EOL Text
The United States government is currently undergoing programs in which to slow the growth of green crab populations fearing a shift in biodiversity in many of the nations coastal regions. Several options are being discussed in which to achieve this. One of which includes introducing a barnacle that can sterilize female green crabs, and the egg predator, Carcinonemertes epialti, to limit the number of green crab offspring being produced.(Washington Dept. 1997)
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The shore crab feeds on invertebrates including worms, molluscs and crustaceans Small molluscs and barnacles are taken by young crabs (2). Breeding peaks in summer, and mating can only take place shortly after the female moults; the male finds a female before she is due to moult, and carries her around underneath his body for a number of days (2). After the moult, copulation occurs. The female creates a cavity by burrowing in the sand; she lays the eggs whilst positioned over this cavity, attaches them to her walking legs and carries them around for several months (2). After hatching, the larvae are planktonic for 2-3 years. They then settle as young crabs, and reach maturity after around a year (2).
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The green crab enjoys a variety of different foods. These foods include clams, oysters, mussels, and other small crabs. The green crab is very dexterous and has many ways in which to open up the shellfish on which it feeds. The green crab is known as a very vicious carnivore that will consume anything it can get its claws on.(Holden 1997, Washington Dept. 1997)
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Due to the number of shell fish the green crab eats, and the rate at which it is done, the green crab is seen as a large threat to the many of the nations commercial shellfisheries. It is estimated that millions of dollars could be spent and are spent each year to try and thwart the green crabs from destroying a very important industry, and helping to maintain biodiversity in areas poplutlated by the green crab. The green crab also carries a parasitic worm that can infect birds that prey on the crabs. This can have a potentially devastating effect by throwing off the food chain, and on the ecosystem as a whole in these areas. (Washington Sea 1998, Washington Dept.1997, Jaquette 1998, Holden 1997)
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Source | http://animaldiversity.ummz.umich.edu/accounts/Carcinus_maenas/ |
In Great Britain and/or Ireland:
Animal / parasite / endoparasite
Portunion meanadis endoparasitises visceral cavity of Carcinus maenas
Animal / parasite / endoparasite
adult of Sacculina carcini endoparasitises body of Carcinus maenas
The green crab serves no basic benefit to humans.
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Source | http://animaldiversity.ummz.umich.edu/accounts/Carcinus_maenas/ |
Carcinus maenas is prey of:
Conger conger
Trigla lucerna
Dicentrarchus labrax
Ciliata mustella
Based on studies in:
Portugal (Estuarine)
This list may not be complete but is based on published studies.
- L. Saldanha, Estudio Ambiental do Estuario do Tejo, Publ. no. 5(4) (CNA/Tejo, Lisbon, 1980).
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Rights holder/Author | Cynthia Sims Parr, Joel Sachs, SPIRE |
Source | http://spire.umbc.edu/fwc/ |
- "Shore crab" redirects here. This may also be used for crabs in the superfamily Grapsoidea.
Carcinus maenas is a common littoral crab, and an important invasive species, listed among the 100 "world's worst alien invasive species".[2] It is native to the north-east Atlantic Ocean and Baltic Sea, but has colonised similar habitats in Australia, South Africa, South America and both Atlantic and Pacific coasts of North America. It grows to a carapace width of 90 millimetres (3.5 in), and feeds on a variety of molluscs, worms and small crustaceans, potentially impacting a number of fisheries. Its successful dispersion has occurred via a variety of mechanisms, such as on ships' hulls, packing materials, bivalves moved for aquaculture, and rafting.
C. maenas is known by different names around the world. In the British Isles, it is generally referred to as the shore crab, or green shore crab. In North America and South Africa, it bears the name green crab or European green crab. In Australia and New Zealand, it is referred to as either the European green crab or European shore crab.
Contents
Description[edit]
C. maenas has a carapace up to 60 millimetres (2.4 in) long and 90 mm (3.5 in) wide,[3] but can be larger outside its native range, reaching 101 mm (4.0 in) wide in British Columbia.[4] The carapace has five short teeth along the rim behind each eye, and three undulations between the eyes. The undulations, which protrude beyond the eyes, are the simplest means of distinguishing C. maenas from the closely related C. aestuarii, which can also be an invasive species. In C. aestuarii, the carapace lacks any bumps and extends forward beyond the eyes. Another characteristic for distinguishing the two species is the form of the first and second pleopods (collectively the gonopods), which are straight and parallel in C. aestuarii, but curve outwards in C. maenas.[3]
The colour of C. maenas varies greatly, from green to brown, grey or red. This variation has a genetic component, but is largely due to local environmental factors.[5] In particular, individuals which delay moulting become red–coloured rather than green. Red individuals are stronger and more aggressive, but are less tolerant of environmental stresses, such as low salinity or hypoxia.[6]Juvenile crabs on average display greater patterning than adults.[7]
Native and introduced range[edit]
C. maenas is native to European and North African coasts as far as the Baltic Sea in the east, and Iceland and Central Norway in the north, and is one of the most common crabs throughout much of its range. In the Mediterranean Sea, it is replaced by the closely related species Carcinus aestuarii.
C. maenas was first observed on the east coast of North America in Massachusetts in 1817, and may now be found from South Carolina northwards;[8] by 2007, this species had extended its range northwards to Placentia Bay, Newfoundland.[9] In 1989, the species was found in San Francisco Bay, California, on the Pacific coast of the United States. Until 1993, it was not able to extend its range, but reached Oregon in 1997, the state of Washington in 1998 and British Columbia in 1999,[10][11] thus extending its range by 750 kilometres (470 mi) in ten years.[12] By 2003, C. maenas had extended to South America with specimens discovered in Patagonia.[13]
In Australia, C. maenas was first reported "in the late 1800s"[14] in Port Phillip Bay, Victoria, although the species was probably introduced as early as the 1850s.[15] It has since spread along the south-eastern and south-western seaboards, reaching New South Wales in 1971, South Australia in 1976 and Tasmania in 1993. One specimen was found in Western Australia in 1965, but there have been no further discoveries in the area since.[14]
C. maenas first reached South Africa in 1983, in the Table Docks area near Cape Town.[16] Since then, it has spread at least as far as Saldanha Bay in the north and Camps Bay in the south, over 100 kilometres (62 mi) apart.
There have been appearances of C. maenas recorded in Brazil, Panama, Hawaii, Madagascar, the Red Sea, Pakistan, Sri Lanka and Myanmar; however, these have not resulted in invasions, but remain isolated findings. Japan has been invaded by a related crab, either C. aestuarii or a hybrid of C. aestuarii and C. maenas.[17]
It is believed, based on the ecological conditions, that C. maenas could eventually extend its range to colonise the Pacific coast of North America from Baja California to Alaska.[10] Similar ecological conditions are to be found on many of the world's coasts, with the only large potential area not to have been invaded yet being New Zealand; the New Zealand government has taken action, including the release of a Marine Pest Guide[18] in an effort to prevent colonisation by C. maenas.
Ecology[edit]
C. maenas can live in all types of protected and semi-protected marine and estuarine habitats, including habitats with mud, sand, or rock substrates, submerged aquatic vegetation, and emergent marsh, although soft bottoms are preferred. C. maenas is euryhaline, meaning that it can tolerate a wide range of salinities (from 4 to 52 ‰), and survive in temperatures of 0 to 30 °C (32 to 86 °F).[19] The wide salinity range allows C. maenas to survive in the lower salinities found in estuaries. A molecular biological study using the COI gene found genetic differentiation between the North Sea and the Bay of Biscay, and even more strongly between the populations in Iceland and the Faroe Islands and those elsewhere. This suggests that C. maenas is unable to cross deeper water.[20]
Females can produce up to 185,000 eggs, and larvae develop offshore in several stages before their final moult to juvenile crabs in the intertidal zone.[21] Young crabs live among seaweeds and seagrasses, such as Posidonia oceanica, until they reach adulthood.[22]
C. maenas has the ability to disperse by a variety of mechanisms,[21] including ballast water, ships' hulls, packing materials (seaweeds) used to ship live marine organisms, bivalves moved for aquaculture, rafting, migration of crab larvae on ocean currents, and the movement of submerged aquatic vegetation for coastal zone management initiatives. Thresher et al.[14] found C. maenas dispersed in Australia mainly by rare long-distance events, possibly caused by human actions.
C. maenas is a predator, feeding on many organisms, particularly bivalve molluscs (such as clams, oysters, and mussels), polychaetes and small crustaceans.[23] They are primarily nocturnal, although activity also depends on the tide, and crabs can be active at any time of day.[24] In California, preferential predation of C. maenas on native clams (Nutricola spp.) resulted in the decline of the native clams and an increase of a previously introduced clam (the amethyst gem clam, Gemma gemma).[25]C. maenas has been implicated in the destruction of the soft-shell clam (Mya arenaria) fisheries on the east coast of the United States and Canada, and the reduction of populations of other commercially important bivalves (such as scallops, Argopecten irradians, and northern quahogs, Mercenaria mercenaria).[21] The prey of C. maenas includes the young of bivalves[26] and fish, although the effect of its predation on winter flounder, Pseudopleuronectes americanus is minimal.[27]C. maenas can, however, have substantial negative impacts on local commercial and recreational fisheries, by preying on the young of species, such as oysters and the Dungeness crab, or competing with them for resources.[28]
Control[edit]
Due to its potentially harmful effects on ecosystems, various efforts have been made to control introduced populations of C. maenas around the world. In Edgartown, Massachusetts, a bounty was levied in 1995 for catching C. maenas, to protect local shellfish, and 10 tons were caught.[29]
There is evidence that the native blue crab in eastern North America, Callinectes sapidus, is able to control populations of C. maenas; numbers of the two species are negatively correlated, and C. maenas is not found in the Chesapeake Bay, where Callinectes sapidus is most frequent.[30] On the west coast of North America, C. maenas appears to be limited to upper estuarine habitats, in part because of predation by native rock crabs (Romaleon antennarium and Cancer productus) and competition for shelter with a native shore crab, Hemigrapsus oregonensis.[31] Host specificity testing has recently been conducted on Sacculina carcini, a parasitic barnacle, as a potential biological control agent of C. maenas.[32] In the laboratory, Sacculina settled on, infected, and killed native California crabs, including the Dungeness crab, Metacarcinus magister (formerly Cancer magister), and the shore crabs Hemigrapsus nudus, Hemigrapsus oregonensis and Pachygrapsus crassipes. Dungeness crabs were the most vulnerable of the tested native species to settlement and infection by the parasite. Although Sacculina did not mature in any of the native crabs, developing reproductive sacs were observed inside a few Metacarcinus magister and Hemigrapsus oregonensis. Any potential benefits of using Sacculina to control C. maenas on the west coast of North America would need to be weighed against these potential non-target impacts.[32]
Use as a food[edit]
Legal Sea Foods, an East Coast of the United States restaurant chain has arranged to purchase green crabs in season from local fishermen, in the first known commercial use for the crabs in the US food industry. Legal plans to test crab and shrimp etouffee, crab risotto with spring vegetables, and crab minestrone, all made with green crab stock, in their test kitchen during the winter of 2015 and offer the dishes in their other restaurant locations during the crab season.[33]
Fishery[edit]
C. maenas is fished on a small scale in the north-east Atlantic Ocean, with approximately 1200 tonnes being caught annually, mostly in France and the United Kingdom. In the northwest Atlantic, C. maenas was the subject of fishery in the 1960s, and again since 1996, with up to 86 tonnes being caught annually.[34]
Taxonomic history[edit]
Carcinus maenas was first given a binomial name, Cancer maenas, by Carl Linnaeus in his 1758 10th edition of Systema Naturae.[35] An earlier description was published by Georg Eberhard Rumphius in his 1705 work De Amboinsche Rariteitkamer, calling the species Cancer marinus sulcatus, but this predates the starting point for zoological nomenclature.[35] A number of later synonyms have also been published:[35]
External identifiers for Carcinus maenas | |
---|---|
Encyclopedia of Life | 128502 |
ITIS | 98734 |
NCBI | 6759 |
WoRMS | 107381 |
Also found in: Wikispecies, ADW, MarLIN |
- Monoculus taurus Slabber, 1778
- Cancer granarius Herbst, 1783
- Cancer viridis Herbst, 1783
- Cancer pygmaeus Fabricius, 1787
- Cancer rhomboidalis Montagu, 1804
- Cancer granulatus Nicholls, 1943
- Megalopa montagui Leach, 1817
- Portunus menoides Rafinesque-Schmaltz, 1817
- Portunus carcinoides Kinahan, 1857
The lectotype chosen for the species came from Marstrand, Sweden, but it is assumed to have been lost.[35] In 1814, writing for The Edinburgh Encyclopaedia, William Elford Leach erected a new genus, Carcinus to hold this species alone (making it the type species of the genus, by monotypy).[35] In 1847, Nardo described a distinct subspecies occurring in the Mediterranean Sea, which is now recognised as a distinct species, Carcinus aestuarii.[1]
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Rights holder/Author | Wikipedia |
Source | http://en.wikipedia.org/w/index.php?title=Carcinus_maenas&oldid=653291244 |
Shore crabs, also known as green crabs, are the crabs you find the most along Dutch shores. They are native to the North Sea, but have managed to spread throughout the world in a very short time. Due to the invasion of European shore crabs in American waters, this species is listed number 18 out of the 100 most damaging intruders in the world. You don't have to search for long to find one if you're by the sea. Birds don't have to wait long either; during low tide, lots of crabs are eaten. The crab itself thinks it can handle its enemies and will courageously try to pinch your fingers or toes should you encounter one. Shore crabs are the 'garbage collectors of the sea'; they eat whatever is dead or sick. On the tidal flats, they eat all sorts of benthic animals.
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Rights holder/Author | Ecomare |
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Carcinus maenas preys on:
detritus
Mytilus galloprovincialis
Based on studies in:
Portugal (Estuarine)
This list may not be complete but is based on published studies.
- L. Saldanha, Estudio Ambiental do Estuario do Tejo, Publ. no. 5(4) (CNA/Tejo, Lisbon, 1980).
License | http://creativecommons.org/licenses/by/3.0/ |
Rights holder/Author | Cynthia Sims Parr, Joel Sachs, SPIRE |
Source | http://spire.umbc.edu/fwc/ |