Biodiversity & Conservation

Mytilus edulis and Fucus vesiculosus on moderately exposed mid eulittoral rock



Image David Connor - Mytilus and fucoids. Image width ca 80 cm.
Image copyright information

Distribution map

LR.MLR.MusF.MytFves recorded (dark blue bullet) and expected (light blue bullet) distribution in Britain and Ireland (see below)

  • EC_Habitats

Recorded distribution in Britain and Ireland

Recorded from the Shetland Isles, the north east coast of England, isolated recordings on the Cornish and Welsh coasts, and almost continuously from the north Welsh coast to Luce Bay. Recorded at Rush Pier, Skerries to Malahide on the east coast of Ireland only. However, this biotope is probably under-recorded.

Habitat preferences

Temperature range preferences - Data deficient

Water clarity preferences - High clarity / Low turbidity
Medium clarity / Medium turbidity
Low clarity / High turbidity

Limiting Nutrients - Data deficient

Other preferences - Gentle slopes or horizontal platforms

Additional information

This biotope has been identified at locations with very different environmental conditions. It appears to occur in waters that are highly turbid (e.g. the east basin of the Irish Sea and north east England) and in waters with low turbidity (e.g. Shetland). It may be a predominantly turbid water biotope where mussels thrive as a result of high suspended sediment levels and fucoids survive due to moderate wave shelter.

The upper limit of the mussel bed is often clear cut (see Lewis, 1964) and determined by physical factors such as 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).

The lower limit of distribution is strongly influenced by predation, primarily from starfish but also dogwhelks and crabs. For example, on the east coast of England, the starfish Asterias rubens and the dogwhelk 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 dogwhelk Nucella lapillus and the starfish Marthasterias glacialis (Kitching & Ebling, 1967; Seed & Suchanek, 1992; Holt et al., 1998).

Mussels colonize areas denuded of barnacles by sediment scour, and are tolerant of a degree of sediment scour (Lewis, 1964). However, increased scour may also limit the lower extent of the mussel bed (Holt et al., 1998).

Connor et al. (1997) noted that sediment often occurs in the vicinity of this biotope, and the biotope may be silted. Tsuchiya & Nishihira (1985 & 1986) noted that increase sediment or silt build up within the mussel bed matrix, reduced the available space within the matrix, changing species composition, presumably in favour of infaunal invertebrates, and reduced species richness.

This review can be cited as follows:

Tyler-Walters, H. 2002. Mytilus edulis and Fucus vesiculosus on moderately exposed mid eulittoral rock. Marine Life Information Network: Biology and Sensitivity Key Information Sub-programme [on-line]. Plymouth: Marine Biological Association of the United Kingdom. [cited 27/11/2015]. Available from: <>