BIOTIC

BIOTIC Species Information for Mytilus edulis
All Taxonomy Biology Distribution Reproduction

Researched by	Lizzie Tyler	Data supplied by	University of Sheffield
Refereed by	This information is not refereed.
Distribution and Habitat
Distribution in Britain & Ireland	Very common all around the coast of the British Isles, with large commercial beds in the Wash, Morecambe Bay, Conway Bay and the estuaries of south-west England, north Wales, and west Scotland.
Global distribution	Occurs from the White Sea, south to southern France in the N.E. Atlantic. In the W. Atlantic it extends from the Canadian Maritimes south to North Carolina. It occurs on the coasts of Chile, Argentina, the Falkland Islands and the Kerguelen Isles.
Biogeographic range	Not researched	Depth range
Migratory	Non-migratory / Resident
Distribution Additional Information	Global distribution Previous records of Mytilus edulis on north African coasts, and in the Mediterranean were probably Mytilus galloprovincialis and Mytilus edulis is absent from the Pacific coast of North America (Gosling, 1992c; Seed, 1992). Previous records of Mytilus edulis from the Pacific coast of North America were probably Mytilus trossulus and/or Mytilus galloprovincialis (Seed, 1992; Seed pers comm.). Mytilus edulis has been reported from Iceland (Varvio et al., 1988). Mytilus edulis occurs on the east and west coasts of South America, and the Falkland Islands (Seed, 1992). Records of mussels form the Kerguelen Islands may be Mytilus edulis (MacDonald et al., 1992; Gosling, 1992c; Seed, 1992). Factors affecting zonation Although sometimes abundant in the subtidal Mytilus edulis is primarily an intertidal species. Mytilus edulis can withstand extreme wave exposure, maintaining byssal attachment in high energy environments (Seed & Suchanek, 1992). The upper limit of Mytilus edulis populations on rocky shores is determined by its tolerance of temperature and desiccation, which may be synergistic, i.e. sudden mass mortalities at the upper limit of intertidal mussel beds are often associated with prolonged periods of unusually high temperatures and desiccation stress (Seed & Suchanek, 1992). Recruitment or movement into cracks, crevices or pools provides some protection from extremes of temperature and desiccation as well as from storms. Mytilus edulis is relatively tolerant of extreme cold and freezing, surviving a drop in tissue temperature to minus 10 °C (Williams, 1970). However, Bourget (1983) noted that cyclic exposures to sublethal temperatures e.g. minus 8 °C every 12.4hrs resulted in death after 3-4 cycles. This suggests that Mytilus edulis can survive occasional, sharp frost events, but may succumb to consistent very low temperatures over a few days (see sensitivity to temperature change). Mytilus edulis is generally unable to maintain attachment to steep or vertical rock surfaces, where they are typically replaced by barnacles and fucoids. Cycles of loss and recruitment may result in a patchy distribution of clumps of mussels on the shore. The lower limit of distribution is strongly influenced by predation, primarily from starfish but also dog whelks and crabs. For example, on the east coast of England, the starfish Asterias rubens and the dog whelk Nucella lapillus eliminate mussels from the lower intertidal (Seed, 1969). In Ireland, however, the lower limit is probably controlled by the crabs Carcinus sp. and Liocarcinus sp., the dog whelk Nucella lapillus and the starfish Marthasterias glacialis (Kitching & Ebling, 1967). Daly & Mathieson (1977) reported that the lower limit of Mytilus edulis populations at Bound Rock, USA, was determined by burial or abrasion by shifting sands. Burial or abrasion is probably an additional controlling factor on British coasts where mobile sediment, such as sand, cobbles or boulders, occur (Holt et al., 1998). Subtidal populations often occur on sea mounts, dock pilings and offshore oil platforms, where they grow to a large size, probably due to the lack of predators (Seed & Suchanek, 1992).

Substratum preferences	Bedrock Large to very large boulders Sandy mud Muddy gravel Rockpools Biogenic reef Artificial (e.g. metal/wood/concrete) Mixed Muddy sand Small boulders Under boulders Caves Crevices / fissures	Physiographic preferences	Open coast Strait / sound Sealoch Ria / Voe Estuary Enclosed coast / Embayment
Biological zone	Upper Eulittoral Mid Eulittoral Lower Eulittoral Sublittoral Fringe Upper Infralittoral	Wave exposure	Very Exposed Exposed Moderately Exposed Sheltered Very Sheltered
Tidal stream strength/Water flow	Strong (3-6 kn) Moderately Strong (1-3 kn) Weak (<1 kn)	Salinity	Reduced (18-30 psu) Variable (18-40 psu) Full (30-40 psu)
Habitat Preferences Additional Information
Distribution References	Fish & Fish, 1996, Hayward & Ryland, 1990, Hayward et al., 1996, Tebble, 1976, Gosling, 1992(c), Varvio et al., 1988, MacDonald et al., 1992, Bayne, 1976b, Seed & Suchanek, 1992, Williams, 1970, Bourget, 1983, Almada-Villela et al., 1982, Seed, 1969b, Kitching & Ebling, 1967, Holt et al., 1998, Daly & Mathieson, 1977, Suchanek, 1978, Almada-Villela, 1984, Clay, 1967(d), Gosling, 1992(a), Seed, 1992, Seed, 1995, Gray et al., 1997, Carter & Seed, 1998, Suchanek, 1985, Hayward & Ryland, 1990,