Skip to Content

Marine Habitat Classification


Description of biotope or habitat type

To understand more about what this page is describing, see How to use the classification. See also How to cite.

   Modiolus modiolus beds with Mimachlamys varia, sponges, hydroids and bryozoans on slightly tide-swept very sheltered circalittoral mixed substrata


Physical habitat description

Salinity Full (30-35 ppt)
Wave exposure Moderately exposed, Sheltered, Very sheltered, Extremely sheltered
Tidal streams Weak (>1 kn), Very weak (negligible)
Substratum Boulders, cobbles and shells on muddy sediment
Zone Infralittoral - lower, Circalittoral
Depth Band 5-10 m, 10-20 m, 20-30 m
Other Features

Biotope origin

Derived using data from Various
Faunal group Epifauna

Download comparative physical and biological data. The comparative tables enable a rapid comparison of the species composition and principal physical characteristics between a given set of biotopes.

Distribution of habitat SS.SBR.SMus.ModMvar <I>Modiolus modiolus</I> beds with <I>Mimachlamys varia</I>, sponges, hydroids and bryozoans on slightly tide-swept very sheltered circalittoral mixed substrata

  • Records used to define the biotope (core records)
  • Other records assigned to this biotope, marked as 'certain'
  • Other records assigned to this biotope, marked as 'uncertain'
  • Predicted extent of the level 3 (for sublittoral rock & deep sea) or 4 (for sublittoral sediment) habitat

Point data based on records in the UK Marine Recorder Snapshot. Predicted habitat extent is from UKSeaMap.

Description

Dense Modiolus modiolus beds, covered by hydroids and bryozoans, on soft gravelly, shelly mud with pebbles in areas of slight or moderate tidal currents. The variable scallop (Mimachlamys varia) is frequently found in large numbers amongst the Modiolus shells. Hydroids such as Halecium spp. and Kirchenpaueria pinnata and ascidians such as Ascidiella aspersa, Corella parallelogramma and Ciona intestinalis may be found attached to pebbles or mussel shells. The echinoderms Ophiothrix fragilis and Antedon bifida are often frequent in this biotope as is the encrusting polychaete Spirobranchus triqueter. Similar communities have been found on cobble and pebble plains in stable, undisturbed conditions in some sea lochs, although not all these examples have Modiolus beds.

Situation

No situation data available.

Temporal variation

No temporal data available.

Characterising species

Taxon Relative importance of taxon for defining this community (%) Typical abundance - SACFOR scale % of core records where taxon was recorded
Modiolus modiolus 9 Common 81-100%
Ophiothrix fragilis 7 Frequent 81-100%
Spirobranchus triqueter 7 Frequent 81-100%
Antedon bifida 5 Frequent 61-80%
Asterias rubens 5 Frequent 81-100%
Echinus esculentus 5 Occasional 81-100%
Mimachlamys varia 4 Occasional 81-100%
Corallinaceae 3 Frequent 41-60%
Ascidiella aspersa 3 Frequent 41-60%
Buccinum undatum 3 Occasional 81-100%
Hyas araneus 3 Occasional 61-80%
Liocarcinus depurator 3 Occasional 61-80%
Urticina felina 3 Occasional 41-60%
Alcyonium digitatum 2 Occasional 61-80%
Balanus balanus 2 Occasional 41-60%
Cerianthus lloydii 2 Occasional 41-60%
Ciona intestinalis 2 Occasional 41-60%
Corella parallelogramma 2 Occasional 41-60%
Laminaria hyperborea 2 Common 41-60%
Ophiocomina nigra 2 Occasional 61-80%
Pagurus bernhardus 2 Occasional 41-60%
Protula tubularia 2 Frequent 41-60%
Aequipecten opercularis 1 Occasional 41-60%
Calliostoma zizyphinum 1 Occasional 41-60%
Crossaster papposus 1 Rare 41-60%
Steromphala cineraria 1 Occasional 41-60%
Halecium halecinum 1 Frequent 21-40%
Kirchenpaueria pinnata 1 Frequent 41-60%
Ophiura albida 1 Occasional 41-60%
Phycodrys rubens 1 Frequent 41-60%

Similar biotopes or habitat types

SS.SBR.SMus.ModHAs
SS.SBR.SMus.ModHAs is less species rich with far fewer sponges and hydroids growing on and amongst the Modiolus and few if any Mimachlamys varia.

Classification history of this biotope or habitat type

Classification version Code Habitat name
2015 (15.03) SS.SBR.SMus.ModCvar Modiolus modiolus beds with Chlamys varia, sponges, hydroids and bryozoans on slightly tide-swept very sheltered circalittoral mixed substrata
2004 (04.05) SS.SBR.SMus.ModCvar Modiolus modiolus beds with Chlamys varia, sponges, hydroids and bryozoans on slightly tide-swept very sheltered circalittoral mixed substrata
1997 (97.06) SS.CR.SCR.Mod.ModCvar Modiolus modiolus beds with Chlamys varia, sponges, hydroids and bryozoans on slightly tide-swept very sheltered circalittoral mixed substrata
1996 (6.95) SCR.ModSHBy

Back to top