Biodiversity & Conservation

Mytilus edulis and Fucus vesiculosus on moderately exposed mid eulittoral rock



Image David Connor - Mytilus and fucoids. Image width ca 80 cm.
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Distribution map

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

  • EC_Habitats

For a list of 2004 characterising species please see the JNCC website.

Species indicative of sensitivity

To assess the sensitivity of the biotope, the sensitivity of component species is reviewed. Those species that are considered to be particularly indicative of the sensitivity of the biotope, and for which research has been undertaken in detail are shown below (see selection criteria). The biology of other component species of the biotope is also taken into account wherever information is known to the researcher.

Species found especially in this biotope

  • Ceramium shuttleworthianum
Community Importance Species name Common Name
Key structural Mytilus edulis Common mussel
Important structural Fucus vesiculosus Bladder wrack
Important functional Patella vulgata Common limpet
Important functional Littorina littorea Common periwinkle
Important functional Nucella lapillus Dog whelk


Holt et al. (1998) noted that the majority of the species associated with the mussels could probably colonize the rock surface in its absence. Therefore, the biotope and its species diversity is dependant on the presence of Mytilus edulis and has been included as key structuring. Fucus vesiculosus is characteristic of intertidal mussel beds in the middle eulittoral, provides additional habitat for mesoherbivores and may adversely affect the structure of the mussel bed and has been included as important structural. Grazing gastropods (e.g. Littorina littorea) may be important in the control of epifaunal and epifloral fouling of mussels, and hence the stability of the bed. Therefore, Littorina littorea has been included as important functional to represent the sensitivity of gastropods. Limpets may be excluded by the mussel patches which thus protect germling fucoids from grazing but are still important in the areas not dominated by mussels and Patella vulgata has been included to represent limpet sensitivity. Predators control the lower limit of the bed and influence the age structure and complexity of the mussel bed. Therefore, Nucella lapillus has been included as important functional. Where appropriate, the sensitivity of intertidal mesoherbivores has been assessed by reference to the gammarid Hyale prevosti.

Additional information

Long-lived, stable mussel beds on moderately exposed rocky shores (e.g. this biotope) develop diverse species communities with typically 50-100 species (Seed, 1996; Holt et al, 1998). Tsuchiya & Nishihira (1985 & 1986) give detailed species lists for intertidal Mytilus edulis patches in Japan, which demonstrate the potential species richness of similar habitats. The MNCR reported 128 species from this biotope, although not all species occur in all examples of the biotope (JNCC, 1999).

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 26/11/2015]. Available from: <>