Modiolus modiolus beds

Habitat: Modiolus modiolus beds

Description: The horse mussel Modiolus modiolus forms dense beds, at depths up to 70m (but may extend onto the lower shore), mostly in fully saline conditions and often in tide-swept areas. Although M. modiolus is a widespread and common species, horse mussel beds (with typically 30% cover or more) are more limited in their distribution. Modiolus beds are found on a range of substrata, from cobbles through to muddy gravels and sands, where they tend to have a stabilising effect, due to the production of byssal threads. Communities associated with Modiolus beds are diverse, with a wide range of epibiota and infauna being recorded, including hydroids, red seaweeds, solitary ascidians and bivalves such as Aequipecten opercularis and Chlamys varia. As M. modiolus is an Arctic-Boreal species, its distribution ranges from the seas around Scandinavia (including Skagerrak & Kattegat) and Iceland south to the Bay of Biscay.

OSPAR Regions where it occurs: I, II, III, IV, V

OSPAR Regions where under threat and/or in decline: I, II, III, IV, V

What is the latest status of the feature?

The status assessment describes the latest changes in distribution, abundance and range of the feature, as well as any changes in the threats and pressures impacting the feature. The status assessments are updated regularly and inform OSPAR’s consideration of the effectiveness of the measures and actions that have been adopted and implemented by Contracting Parties.