Distribution data supplied by the Ocean Biodiversity Information System (OBIS). To interrogate UK data visit the NBN Atlas.Map Help
Researched by | Jacqueline Hill | Refereed by | This information is not refereed |
Authority | (Linnaeus, 1758) | ||
Other common names | - | Synonyms | - |
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.
Other common names include the 'swimming crab'.
- none -
Class | Malacostraca | Crabs, lobsters, sand hoppers and sea slaters |
Family | Polybiidae | |
Genus | Liocarcinus | |
Authority | (Linnaeus, 1758) | |
Recent Synonyms |
Typical abundance | Moderate density | ||
Male size range | Carapace width up to 56mm | ||
Male size at maturity | Carapace width 30mm | ||
Female size range | Carapace width 24mm | ||
Female size at maturity | |||
Growth form | Articulate | ||
Growth rate | |||
Body flexibility | None (less than 10 degrees) | ||
Mobility | |||
Characteristic feeding method | Predator, Scavenger | ||
Diet/food source | |||
Typically feeds on | Polychaetes, crustaceans, molluscs, ophiuroids and fishes constitute most of the diet (Freire, 1996). | ||
Sociability | |||
Environmental position | Demersal | ||
Dependency | Independent. None | ||
Supports | Host 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). |
Physiographic preferences | Open coast, Offshore seabed, Strait / sound, Ria / Voe |
Biological zone preferences | Circalittoral offshore, Lower circalittoral, Lower infralittoral, Sublittoral fringe, Upper circalittoral, Upper infralittoral |
Substratum / habitat preferences | Coarse clean sand, Fine clean sand, Muddy gravel, Muddy sand |
Tidal strength preferences | Moderately 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 preferences | Full (30-40 psu) |
Depth range | -5m to -300m+ |
Other preferences | No text entered |
Migration Pattern | No information found |
Reproductive type | Gonochoristic (dioecious) | |
Reproductive frequency | Annual protracted | |
Fecundity (number of eggs) | 100,000-1,000,000 | |
Generation time | ||
Age at maturity | 1 year | |
Season | See additional text | |
Life span | Insufficient information |
Larval/propagule type | - |
Larval/juvenile development | Planktotrophic |
Duration of larval stage | Not relevant |
Larval dispersal potential | - |
Larval settlement period | Insufficient information |
The MarLIN sensitivity assessment approach used below has been superseded by the MarESA (Marine Evidence-based Sensitivity Assessment) approach (see menu). The MarLIN approach was used for assessments from 1999-2010. The MarESA approach reflects the recent conservation imperatives and terminology and is used for sensitivity assessments from 2014 onwards.
Intolerance | Recoverability | Sensitivity | Evidence/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. |
Intolerance | Recoverability | Sensitivity | Evidence/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. | ||||
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. | ||||
No information | No information | No information | Not relevant | |
Insufficient information. | ||||
No information | No information | No information | Not relevant | |
Insufficient information. | ||||
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. |
Intolerance | Recoverability | Sensitivity | Evidence/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. |
- no data -
National (GB) importance | - | Global red list (IUCN) category | - |
Native | - | ||
Origin | - | Date Arrived | - |
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This review can be cited as:
Last Updated: 17/04/2008