Short description of Hemigrapsus sanguineus, Asian shore crab

A small crab with a square carapace (shell) up to 4.5 cm, variable in colour from orange-brown to greenish-black.  Three distinct ‘teeth’ on each side of the carapace and banding on the walking legs are distinguishing features, as is a fleshy bulb at the pincer base of larger males. The teeth on the carapace are more acute than those of H. takanoi a closely related species.

Impact summary: Hemigrapsus sanguineus, Asian shore crab

A voracious, opportunistic omnivore, this crab may significantly affect native crab, fish and shellfish populations by disrupting the food web.  Where it has established the crab competes with native shore crabs for food and space.  It could be potentially damaging to shellfish production as it may prey on commercially important species. 

Habitat summary: Hemigrapsus sanguineus, Asian shore crab

The Asian shore crab inhabits estuarine and marine habitats and occurs within the intertidal or shallow subtidal zones.  It is typically found on more exposed rocky shores but also occurs in soft sediments under the shelter of rocks or shells, artificial structures, mussel beds and oyster reefs. 

Overview table

Environment	Marine
Species status	Non-Native
Native range	Northwestern Pacific
Functional type	Predator
Status in England	Non-Native
Status in Scotland	Non-Native
Status in Wales	Non-Native
Location of first record	Barry South Wales
Date of first record	4

Origin

The Asian shore crab is native to the western Pacific Ocean from Russia along the Korean and Chinese coasts to Japan.  It is one of the most common crabs found intertidally along the Japanese shoreline. 

First Record

The Asian shore crab was first recorded in the British Isles on the north-west coast of Guernsey in April 2000; since then several more specimens have been positively identified on various shores in Guernsey and Jersey. 

In April and May 2014, specimens were found on the coast of South Wales (1 individual) and Kent (3 individuals)

Pathway and Method

Asian shore crab larvae are thought to have been introduced to European waters through discharge of ships’ ballast water.  The Asian shore crab has since extended its range through natural larval dispersal by water currents.  It is unclear how it reached the Channel Islands, but given the proximity of the abundant populations on the French coast, natural larval dispersal, hull fouling and association with oyster transportation are possibilities.  Pathway to GB mainland is unclear. natural dispersal to South Wales from known populations is unlikely.

Species Status

Since initial reports of the Asian shore crab in New Jersey in 1988, its spread has been rapid along the east coast of the USA,  covering over 1500 km from North Carolina to Maine.  Asian shore crab densities in rocky intertidal habitats are now extremely high and usually exceed those of the previously dominant green crab Carcinus maenas.  In France the Asian shore crab was first recorded in 1994 at La Rochelle, and is now present along an 1100 km stretch of the Atlantic coast from France to Germany, occurring abundantly in many areas.  Given the Asian shore crab’s relatively long planktonic larval phase; tolerance of a wide range of temperature and salinity; previous successful establishments in regions where it has been introduced and recent occurrence in the Channel Islands, its arrival in Great Britain had been anticipated. 

Dispersal Mechanisms

Asian shore crab larvae spend between 16 and 55 days in the water column before developing into juvenile crabs, during which time they may be transported considerable distances by currents.   Larvae may also be transported in ships’ ballast water, being released into harbours or bays.

Reproduction

Females typically copulate several times during the mating season and can store sperm to fertilize more than one brood.  They can produce up to 50,000 eggs several times during the spawning season and produce two broods within 40 days.  Once hatched larvae are planktonic for up to one month, and growth and maturation are rapid, with juveniles reaching a mean carapace width of 20 mm within two years.  The reproductive period may be longer than that of native crabs, and this combined with such high fecundity may contribute to the species’ invasive success.

Known Predators/Herbivores

Little is known about the Asian shore crab’s role as prey for native species, but it is likely that potential predators would include certain fishes, shore birds and other crabs. 

Resistant Stages

None known.

Habitat Occupied in GB

Limited records from rock pools on the lower shore in Guernsey and Jersey since 2009.  Specimens have been found in mid-upper shore rocky substrates similar to those already occupied on the European continent. Suitable habitats are, widespread throughout GB coastal waters. 

Native to the western Pacific Ocean from Russia along the Korean and Chinese coasts and Japanese archipelago.  In GB, individuals have been recorded in South Wales and Kent (England). The species has been found in Guernsey and Jersey since 2009.

Environmental Impact

Significant reductions in common shore crab abundance and mussel density have been reported where the Asian shore crab has achieved high densities in mainland Europe, and similar effects across the broader community may be expected.   Common shore crab is also reported to have been displaced by the Asian shore crab in rocky shore habitats in several places in North America, including New England and New Jersey.   Recruits and juveniles of other invertebrates including snails, barnacles and polychaetes may also be threatened due to increased predation.

Health and Social Impact

None known.

Economic Impact

It has been suggested that Asian shore crabs could pose a threat to mussel and oyster growing operations.  Potential competition with species of economic value which spend their juvenile phase in the intertidal zone, including the edible crab Cancer pagurus may also present a concern. 

Identification

Global Invasive Species Database. (2006) Factsheet for Hemigrapsus sanguineus. Available from: http:www.issg.orgdatabasespeciesecology.asp?si=756&fr=1&sts=&lang=EN

Biology, ecology, spread, vectors

Anderson, J.A., & Epifanio, C.E. (2010) Mating and sperm storage of the Asian shore crab Hemigrapsus sanguineus.  Journal of Shellfish Research, 29, (2), 497-501.

Breton, G., Faasse, M., Noel, P. & Vincent, T. (2002) A new alien crab in Europe: Hemigrapsus sanguineus (Decapoda: Brachyura: Grapsidae). Journal of Crustacean Biology, 22, (1), 184-189.

Dauvin, J.-C. (2009) Establishment of the invasive Asian shore crab Hemigrapsus sanguineus (De Haan, 1835) (Crustacea:Brachyura:Grapsoidea) from the Cotentin Peninsular, Normandy, France. Aquatic Invasions, 4, (3), 467-472.

Dauvin, J.-C., Tous Rius, A., & Ruellet, T. (2009) Recent expansion of two invasive crab species Hemigrapsus sanguineus (de Haan, 1835) and H. takanoi Asakura and Watanabe 2005 along the Opal Coast, France. Aquatic Invasions, 4, (3), 451-465.

Lord, R. (2010) Asian shore crab, Hemigrapsus sanguineus, reaches shores of Channel Islands. Sustainable Guernsey [online]. Available from: http:www.sustainableguernsey.infoblog201004asian-shore-crab-hemigrapsus-sanguineus-reaches-shores-of-channel-islands

Micu, D., Nita, V. & Todorova, V. (2010) First record of the Japanese shore crab Hemigrapsus sanguineus (de Haan, 1835) (Brachyura: Grapsoidea: Varunidae) from the Black Sea. Aquatic Invasions, 5, Supplement 1, S1-S4.

Management and impact

Jensen, G.C., McDonald, P.S., & Armstrong, D.A. (2002) East meets west: competitive interactions between green crab Carcinus maenus, and native and introduced shore crab Hemigrapsus spp. Marine Ecology Progress Series, 225, 251-262.

General

Anderson, J.A., & Epifanio, C.E. (2010) Mating and sperm storage of the Asian shore crab Hemigrapsus sanguineus. Journal of Shellfish Research, 29, (2), 497-501.

DAISIE European Invasive Alien Species Gateway (2006) Hemigrapsus sanguineus. Available from: http:www.issg.orgdatabasespeciesecology.asp?si=756&fr=1&sts=&lang=EN

Micu, D., Nita, V. & Todorova, V. (2010) First record of the Japanese shore crab Hemigrapsus sanguineus (de Haan, 1835) (Brachyura: Grapsoidea: Varunidae) from the Black Sea. Aquatic Invasions, 5, Supplement 1, S1-S4.

Seeley, B; Sewell, J; Clark, PF. 2015 First GB records of the invasive Asian shore crab, Hemigrapsus sanguineus from Glamorgan, Wales and Kent, England.. Marine Biodiversity Records, 8 (102)