Classification

Description

GB distribution

Compiled by: Leigh Jones, Joint Nature Conservation Committee, Monkstone House, City Road, Peterborough PE1 IJY, UK.

Derived, in part, from: the UK marine biotope classification (Connor et al. 1997b) and a review undertaken for the UK Marine SACs Project (Holt et al. 1998).

SCR.Mod. Circalittoral mixed substrata, not influenced by significant tidal streams, with clumps or more extensive beds of Modiolus modiolus.

MCR.ModT. Modiolus beds on mixed substrata (cobbles, pebbles and coarse muddy sediments) in moderately strong currents, typically on the open coast but also in tide-swept channels of marine inlets. Often with sponges such as Hemimycale columella, hydroids such as Sertularia argentea, Hydrallmania and Abietinaria abietina, Alcyonium digitatum, barnacles, Alcyonium digitatum, bryozoans such as Alcyonidium mytili and ascidians Dendrodoa grossularia. This biotope is typified by examples off the north-west Lleyn Peninsula in North Wales and off Co. Down, Northern Ireland.

CMX.ModMx. Muddy gravels and coarse sands in deeper water of continental seas may contain venerid bivalves with beds of Modiolus modiolus. The clumping of the byssus threads of the M. modiolus creates a stable habitat that attracts a very rich infaunal community. Brittlestars such as Ophiothrix fragilis may also occur with this community. This biotope is very similar to the 'boreal off-shore gravel association' and the 'deep Venus community' described by previous workers (Ford 1923; Jones 1951). Similar Modiolus beds on open coast stable boulders, cobbles and sediment are described under MCR.ModT.

(from MNCR database March 1999)

Habitat requirements

Species composition and biodiversity

Ecological relationships

Sensitivity to human activities

Conservation and protection status

References