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information on the biology of species and the ecology of habitats found around the coasts and seas of the British Isles

Harbour crab (Liocarcinus depurator)

Distribution data supplied by the Ocean Biogeographic Information System (OBIS). To interrogate UK data visit the NBN Atlas.

Summary

Description

The carapace of Liocarcinus depurator is wider than long, about 51 mm wide and 40 mm long. The species is immediately recognised by the violet-tinted paddle of the fifth leg in larger crabs. The rest of the body is pale reddish-brown with transverse rows of hairs on the carapace, most conspicuous towards the rear.

Recorded distribution in Britain and Ireland

All British and Irish coasts.

Global distribution

Distributed from Norway to West Africa including the Mediterranean.

Habitat

Found on the lower shore and sublittoral on fine, muddy sand and gravel.

Depth range

-5m to -300m+

Identifying features

  • Carapace broader than long, relatively flat, with numerous transverse, hairy, crenulations.
  • The antero-lateral margins of the carapace have 5 pointed teeth.
  • Wide orbits and three similar-sized rounded lobes between eyes.
  • Front of carapace with a median lobe slightly more prominent than two similar flanking lobes.
  • Chelipeds equal and stout.
  • Pereopods 2-4 of slight build, pereopod 5 with violet tinted strongly paddled dactylus.

Additional information

Other common names include the 'swimming crab'.

Listed by

- none -

Further information sources

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Biology review

Taxonomy

ClassMalacostraca
FamilyPolybiidae
GenusLiocarcinus
Authority(Linnaeus, 1758)
Recent Synonyms

Biology

Typical abundanceModerate density
Male size rangeCarapace width up to 56mm
Male size at maturityCarapace width 30mm
Female size rangeCarapace width 24mm
Female size at maturity
Growth formArticulate
Growth rate
Body flexibilityNone (less than 10 degrees)
Mobility
Characteristic feeding methodPredator, Scavenger
Diet/food source
Typically feeds onPolychaetes, crustaceans, molluscs, ophiuroids and fishes constitute most of the diet (Freire, 1996).
Sociability
Environmental positionDemersal
DependencyIndependent.
None
SupportsHost

The polychaete worm Iphitime cuenoti and the parasitic nemertean Carcinonemertes carcinophila that live in the branchial chambers of some individuals.

Is the species harmful?No

The species is edible. It is frequently found in fish markets in the Mediterranean (Mori & Zunino, 1987).

Biology information

  • Size range and size at maturity: values given are for Mediterranean individuals (Muino et al., 1999).
  • Feeding: Swimming crabs may exploit a wide range of dietary items including algae, sponges and many small invertebrates and may be considered omnivorous. However, Liocarcinus depurator is typically a scavenger and a carnivore. Freire et al. (1996) suggest the high diversity of food items in the diet of Liocarcinus depurator is due to the versatile functional structure of the chelipeds.
  • Host for: Abelló et al., (1988) found 5% of individuals in the northwestern Mediterranean infested with the polychaete Iphitime cuenoti. No evidence of disease in the branchial chamber was found and the authors suggest a commensal relationship between the crab and the polychaete. However, the relationship may involve some degree of parasitism. In the Firth of Lorne the parasitic nemertean Carcinonemertes carcinophila was found the gills of over 90% of Liocarcinus depurator sampled (Comely & Ansell, 1989(b)).

Habitat preferences

Physiographic preferencesOpen coast, Offshore seabed, Strait / sound, Ria / Voe
Biological zone preferencesCircalittoral offshore, Lower circalittoral, Lower infralittoral, Sublittoral fringe, Upper circalittoral, Upper infralittoral
Substratum / habitat preferencesCoarse clean sand, Fine clean sand, Muddy gravel, Muddy sand
Tidal strength preferencesModerately Strong 1 to 3 knots (0.5-1.5 m/sec.), Very Weak (negligible), Weak < 1 knot (<0.5 m/sec.)
Wave exposure preferences
Salinity preferencesFull (30-40 psu)
Depth range-5m to -300m+
Other preferencesNo text entered
Migration PatternNo information found

Habitat Information

Salinity: Liocarcinus depurator is essentially a marine species although a few individuals were found at the lower reaches of the Forth estuary where salinity varied between 24-35 psu (Mathieson & Berry, 1997).

Life history

Adult characteristics

Reproductive typeGonochoristic (dioecious)
Reproductive frequency Annual protracted
Fecundity (number of eggs)100,000-1,000,000
Generation time
Age at maturity1 year
SeasonSee additional text
Life spanInsufficient information

Larval characteristics

Larval/propagule type-
Larval/juvenile development Planktotrophic
Duration of larval stageNot relevant
Larval dispersal potential -
Larval settlement periodInsufficient information

Life history information

  • Time of gametes: In the northwestern Mediterranean female moult and copulation takes place between May and July (Abelló, 1989a).
  • Spawning: Females with eggs occur all year (Ingle, 1997) although a maximum proportion of ovigerous females has been observed indicating the existence of an annual reproductive cycle. In Plymouth, ovigerous females are reported from March to October, from April to May in Bristol, January to June in the Clyde and Argyll and from January to May in Galway (Ingle, 1997). In the warmer waters of the northwestern Mediterranean numbers of ovigerous females peak in the winter months from November to February and males were found to be sexually mature throughout the year (Abelló, 1989a). In Plymouth, Liocarcinus depurator was found to incubate three or more batches of eggs over the spring and summer breeding season (Wear, 1974).
  • Fecundity: The number of eggs carried by ovigerous females in the north western Mediterranean ranged from about 30,000 to 230,000 clearly increasing with the size of the female (Abelló, 1989a). However, a maximum of 140,000 eggs for the largest females was estimated in the Ligurian Sea (Mori & Zunino, 1987).
  • Age at maturity: In the Gulf of Genoa in the Ligurian Sea Liocarcinus depurator females attain sexual maturity, are fertilized and bear eggs within the first year (Mori & Zunino, 1987).
  • Larvae: in the plankton during spring and summer in British and North Sea waters (Ingle, 1980).

Sensitivity reviewHow is sensitivity assessed?

Physical pressures

 IntoleranceRecoverabilitySensitivityEvidence/Confidence
Intermediate High Low High
Although a swimming crab, Liocarcinus depurator normally crawls on the seabed. The species only really swims in extremis. Therefore, substratum loss, such as caused by dredging, is likely to result in the loss of some individuals whilst others may be able to escape. Intolerance is therefore, assessed as intermediate. Recovery should be good because Liocarcinus depurator has planktonic larvae and is able to reproduce several times a year (Wear, 1974).
Tolerant Not relevant Not sensitive High
Liocarcinus depurator is a mobile crab, able to crawl and also swim when necessary, and therefore unlikely to be affected by any smothering as it would be able to move up through the sediment or to an unaffected area.
Tolerant Not relevant Not sensitive Moderate
Liocarcinus depurator is tolerant of changes in suspended sediment because it is a demersal species and feeds by predation and scavenging. The species is also able to move to more suitable conditions if necessary.
No information
Not relevant Not relevant Not relevant High
Liocarcinus depurator is a sub-littoral species and so desiccation is not relevant.
Not relevant Not relevant Not relevant High
Emergence is not likely to occur in the species' preferred zone.
No information
Intermediate High Low Low
It is likely that the species is unable to keep its position on the benthos to feed and copulate in strong water flow and so intolerance has been assessed as intermediate. In laboratory experiments Liocarcinus depurator was unable to make progress towards bait in currents of 0.3m/s (0.6 knots) and 63% of animals were washed away (Nickell & Moore, 1992). However, the crab will drift in the water column or tumble along the seabed until quicker conditions occur.
No information
Intermediate High Low High
Liocarcinus depurator is likely to be tolerant of a range of temperatures consistent with a distribution north and south of Britain and Ireland populations and so will not be very intolerant of long term changes in temperature. Experiments with the species showed that a threefold decrease in egg incubation time of eggs can occur naturally in successive batches of eggs incubated during the early spring to mid-summer breeding season (Wear, 1974). At 13.1°C incubation time was 31.5 days and at 15.0 °C was 25.5 days. However, a rapid rise in water temperature of as little as 3°C can disrupt the natural sequence in the spawning and incubation of successive egg batches and also reduce fecundity by more than 90% (Wear, 1974) so that the viability of the population will be reduced. Intolerance is therefore assessed as intermediate. Very low water temperatures can cause mass mortalities of Liocarcinus spp.. During the severe winter of 1962-63 where water temperatures fell to 0°C for several weeks, many dead crabs were caught in research vessel trawls from the Dutch coast (Crisp, 1964). Recovery should be good because Liocarcinus depurator has planktonic larvae and is able to reproduce several times a year (Wear, 1974).
No information
Tolerant Not relevant Not sensitive Moderate
Liocarcinus depurator lives at depths of 300 m plus, is most active at night (Abelló et al., 1991), feeds by predation and scavenging on other invertebrates and is therefore, unlikely to be sensitive to changes in light brought about by increases in turbidity. The crab is commonly found in turbid conditions in harbours.
No information
Intermediate Very high Low Low
Liocarcinus depurator is a swimming crab and so is likely to be tolerant of some changes in wave exposure. However, it is likely that the species is unable to keep its position in areas of strong wave action so intolerance has been assessed as intermediate. The species also inhabits deep waters where wave action will have little impact.
No information
Tolerant Not relevant Not sensitive Moderate
Liocarcinus depurator is not likely to be sensitive to noise disturbance.
Tolerant Not relevant Not sensitive Moderate
Crabs have well developed visual acuity and are likely to respond to movement in order to avoid predators. However, it is likely that the species will be little affected by visual disturbance caused by the continuous presence for one month of moving objects not naturally found in the marine environment (e.g., boats, machinery, and humans). Therefore, the species is assessed as not sensitive.
High High Moderate High
Liocarcinus depurator was observed to be frequently injured and killed as a result of capture in a commercial 4m beam trawl (Kaiser & Spencer, 1995) and so an intolerance high has been recorded. Recovery should be good because Liocarcinus depurator has planktonic larvae and is able to reproduce several times a year (Wear, 1974).
Tolerant Not relevant Not sensitive High
The species is highly mobile and probably not sensitive to displacement to another area.

Chemical pressures

 IntoleranceRecoverabilitySensitivityEvidence/Confidence
No information Not relevant No information Not relevant
Bryan & Gibbs (1991) report that crabs appear to be relatively resistant to TBT although some deformity of regenerated limbs has been observed.
Heavy metal contamination
Intermediate High Low Moderate
Crompton (1997) reports that the concentrations above which mortality of crustaceans can occur is 0.01-0.1mg/l for mercury, copper and cadmium, 0.1-1mg/l for zinc, arsenic and nickel and 1-10mg/l for lead and chromium. Crustaceans are generally regarded as being more intolerant of cadmium than other groups (McLusky, 1986). However, crustaceans in general are less intolerant of most heavy metals than annelid worms and so intolerance has been assessed as intermediate. On return to normal conditions, recovery should be good because Liocarcinus depurator has planktonic larvae and reproduces several times a year.
Hydrocarbon contamination
No information No information No information Not relevant
Insufficient
information.
Radionuclide contamination
No information No information No information Not relevant
Insufficient
information.
Changes in nutrient levels
No information No information No information Not relevant
Insufficient
information.
Intermediate High Low Moderate
Liocarcinus depurator is essentially a marine species although a few individuals were found at the lower reaches of the Forth estuary where salinity varied between 24-35psu (Mathieson & Berry, 1997) and so intolerance is assessed as intermediate. Although the species is mobile and some individuals will be able to avoid unfavourable salinity changes, individuals are likely to be affected if salinity changes are widespread. On return to normal conditions, recovery should be good because Liocarcinus depurator has planktonic larvae and reproduces several times a year.
No information
High High Moderate Moderate
Cole et al. (1999) suggest possible adverse effects on marine species below 4 mg/l and probable adverse effects below 2mg/l. Crustaceans are generally less tolerant of hypoxia than polychaetes and bivalves and are rarely described from hypoxia stressed environments (Diaz & Rosenberg, 1995). Experiments looking at the resistance of marine invertebrates from the Baltic Sea, where temperature was 10°C and salinity 15psu, crustaceans had the shortest LD50 times (between 2 and 48 hours) at 0.15ml 02 (Theede et al., 1969). Therefore, a reduction in oxygen concentration to the benchmark level of 2mg/l for a week is expected to cause some individuals to die. Although the species is mobile and some individuals will be able to avoid hypoxic conditions changes individuals are likely to be affected if oxygen changes are widespread. On return to normal conditions recovery should be good because Liocarcinus depurator has planktonic larvae and reproduces several times a year.

Biological pressures

 IntoleranceRecoverabilitySensitivityEvidence/Confidence
Intermediate High Low Moderate
The incidence of black necrotic disease has been recorded for Liocarcinus depurator from sites on the west coast of Scotland (Comely & Ansell, 1989). The disease, which is believed to be caused by one or more of the chitinoclastic bacteria with secondary invasion by fungi, was found in the gills of almost 90% of Liocarcinus depurator. In the most extreme cases the gill lamellae were completely missing, only the blackened gill rachi being left. Intolerance has therefore, been assessed as intermediate. On return to normal conditions recovery should be good because the species has high fecundity and pelagic larvae.
Tolerant Not relevant Not sensitive High
There are no known non-native species competing with Liocarcinus depurator.
Intermediate High Low High
Liocarcinus depurator is often extracted as a by-catch species in benthic trawling. The species produces eggs several times a year which develop into planktonic larvae so recovery should be high.
Tolerant Not relevant Not sensitive Moderate
Liocarcinus depurator has no known obligate relationships.

Additional information

Importance review

Policy/legislation

- no data -

Status

Non-native

Importance information

  • Liocarcinus depurator is one of the most important by-catches of the Mediterranean demersal fishery (Abelló, 1989a).
  • Enclosure experiments in a sea loch in Ireland have shown that high densities of this decapod led to a significant decline in infaunal organisms (Thrush, 1986).

Bibliography

  1. Abelló, P., 1989. Reproduction and moulting in Liocarcinus depurator (Linnaeus, 1758) (Brachyura: Portunidae) in the Northwestern Mediterranean sea. Scientia Marina, 53, 127-134.

  2. Abelló, P., Reid, D.G. & Naylor, E., 1991. Comparative locomotor activity patterns in the portunid crabs Liocarcinus holsatus and L. depurator. Journal of the Marine Biological Association of the United Kingdom, 71, 1-10.

  3. Abelló, P., Sardá, R. & Masales, D., 1988. Infestation of some Mediterranean brachyuran crabs by the polychaete Iphitime cuenoti. Cahiers de Biologie Marine, 29, 149-162.

  4. Bryan, G.W. & Gibbs, P.E., 1991. Impact of low concentrations of tributyltin (TBT) on marine organisms: a review. In: Metal ecotoxicology: concepts and applications (ed. M.C. Newman & A.W. McIntosh), pp. 323-361. Boston: Lewis Publishers Inc.

  5. Comely, C.A. & Ansell, A.D., 1989. The incidence of Carcinonemertes carcinophila (Kolliker) on some decapod crustaceans from the Scottish west coast. Ophelia, 30, 225-233.

  6. Comely, C.A. & Ansell, A.D., 1989. The occurrence of black necrotic disease in crab species from the west of Scotland. Ophelia, 30, 95-112.

  7. Crisp, D.J. (ed.), 1964. The effects of the severe winter of 1962-63 on marine life in Britain. Journal of Animal Ecology, 33, 165-210.

  8. Crompton, T.R., 1997. Toxicants in the aqueous ecosystem. New York: John Wiley & Sons.

  9. Diaz, R.J. & Rosenberg, R., 1995. Marine benthic hypoxia: a review of its ecological effects and the behavioural responses of benthic macrofauna. Oceanography and Marine Biology: an Annual Review, 33, 245-303.

  10. Fish, J.D. & Fish, S., 1996. A student's guide to the seashore. Cambridge: Cambridge University Press.

  11. Freire, J., 1996. Feeding ecology of Liocarcinus depurator (Decapoda: Portunidae) in the Ría de Arousa (Galicia, north-west Spain): effects of habitat, season and life history. Marine Biology, 126, 297-311.

  12. Freire, J., Sampedro, M.P. & Gonzalez-Gurriaran, E., 1996. Influence of morphometry and biomechanics on diet selection in three portunid crabs Marine Ecology Progress Series , 137, 111-121.

  13. Hayward, P., Nelson-Smith, T. & Shields, C. 1996. Collins pocket guide. Sea shore of Britain and northern Europe. London: HarperCollins.

  14. Hayward, P.J. & Ryland, J.S. (ed.) 1995b. Handbook of the marine fauna of North-West Europe. Oxford: Oxford University Press.

  15. Howson, C.M. & Picton, B.E., 1997. The species directory of the marine fauna and flora of the British Isles and surrounding seas. Belfast: Ulster Museum. [Ulster Museum publication, no. 276.]

  16. Ingle, R., 1997. Crayfishes, lobsters and crabs of Europe. An illustrated guide to common and traded species. London: Chapman and Hall.

  17. Ingle, R.W., 1980. British Crabs. Oxford: British Museum (Natural History), Oxford University Press.

  18. Mathieson, S. & Berry, A.J., 1997. Spatial, temporal and tidal variation in crab populations in the Forth estuary, Scotland. Journal of the Marine Biological Association of the United Kingdom, 77, 167-183.

  19. McLusky, D.S., Bryant, V. & Campbell, R., 1986. The effects of temperature and salinity on the toxicity of heavy metals to marine and estuarine invertebrates. Oceanography and Marine Biology: an Annual Review, 24, 481-520.

  20. Mori, M. & Zunino, P., 1987. Aspects of the biology of Liocarcinus depurator (L.) in the Ligurian Sea. Investigacion Pesquera, 51(suppl. 1), 135-145

  21. Muino, R., Fernandez, L., Gonzalez-Gurriaran, E., Freire, J. & Vilar, J.A., 1999. Size at maturity of Liocarcinus depurator (Brachyura: Portunidae): a reproductive and morphometric study. Journal of the Marine Biological Association of the United Kingdom, 79, 295-303.

  22. Nickell, T.D. & Moore, P.G., 1992. The behavioural ecology of epibenthic scavenging invertebrates in the Clyde Sea area: laboratory experiments on attractions to bait in moving water, underwater TV observations in situ and general conclusions. Journal of Experimental Marine Biology and Ecology, 159, 15-35.

  23. Theede, H., Ponat, A., Hiroki, K. & Schlieper, C., 1969. Studies on the resistance of marine bottom invertebrates to oxygen-deficiency and hydrogen sulphide. Marine Biology, 2, 325-337.

  24. Thrush, S.F., 1986. Community structure on the floor of a sea-lough: are large epibenthic predators important? Journal of Experimental Marine Biology and Ecology, 104, 171-183.

  25. Wear, R.G., 1974. Incubation in British decapod crustacea, and the effects of temperature on the rate and success of embryonic development. Journal of the Marine Biological Association of the United Kingdom, 54, 745-762.

Citation

This review can be cited as:

Hill, J.M. 2008. Liocarcinus depurator Harbour crab. In Tyler-Walters H. and Hiscock K. (eds) Marine Life Information Network: Biology and Sensitivity Key Information Reviews, [on-line]. Plymouth: Marine Biological Association of the United Kingdom. Available from: http://www.marlin.ac.uk/species/detail/1175

Last Updated: 17/04/2008