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.

   Laminaria saccharina and Gracilaria gracilis with sponges and ascidians on variable salinity infralittoral sediment

Physical habitat description

Salinity Full (30-35 ppt), Variable (18-35 ppt)
Wave exposure Sheltered, Very sheltered, Extremely sheltered
Tidal streams Moderately strong (1-3 kn), Weak (>1 kn)
Substratum Stoney sediment
Zone Infralittoral
Depth Band 0-5 m, 5-10 m
Other Features

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.SMp.KSwSS.LsacGraVS <I>Laminaria saccharina</I> and <I>Gracilaria gracilis</I> with sponges and ascidians on variable salinity infralittoral sediment

  • 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.


Shallow kelp community found on stony sediment, in extremely sheltered, variable salinity conditions, with moderately strong tidal currents. The community is characterised by a more sparse covering of Laminaria saccharina, particularly when compared to the fully marine version of this sub biotope (SMP.LsacGraFS). Beneath the canopy the community is characterised by the red algae Gracilaria gracilis, and a variety of faunal species in particular sponges (Suberites ficus and Halichondria panacea) and ascidians (Ascidiella aspersa and Dendrodoa grossularia). The stony substrate provides a surface for attachment for these and many other filter and suspension feeding species, particularly barnacles (Balanus crenatus), hydroids (Urticina feline and Hydractinia echinata) and anemones. Other members of the understory may include a variety of filamentous and foliose red algae in particular Pterothamnion plumula, and the green alga Ulva.


No situation data available.

Temporal variation

No temporal variation data available.

Characterising species

Taxon Relative importance of taxon for defining this community (%) Typical abundance - SACFOR scale % of core records where taxon was recorded
Suberites ficus 3 Rare 41-60 %
Halichondria panicea 2 Occasional 41-60 %
Hydractinia echinata 1 Occasional 21-40 %
Urticina felina 2 Frequent 21-40 %
Cereus pedunculatus 5 Frequent 41-60 %
Terebellidae 2 Frequent 21-40 %
Lanice conchilega 2 Occasional 41-60 %
Pomatoceros 2 Occasional 41-60 %
Balanus crenatus 7 Frequent 61-80 %
Pagurus 2 Frequent 21-40 %
Carcinus maenas 8 Occasional 61-80 %
Gibbula cineraria 2 Occasional 41-60 %
Crepidula fornicata 2 Rare 41-60 %
Asterias rubens 1 Occasional 21-40 %
Ascidiella aspersa 2 Frequent 21-40 %
Dendrodoa grossularia 5 Frequent 41-60 %
Gracilaria gracilis 5 Frequent 41-60 %
Antithamnionella spirographidis 1 Occasional 21-40 %
Griffithsia corallinoides 1 Frequent 21-40 %
Pterothamnion plumula 3 Frequent 41-60 %
Laminaria saccharina 4 Occasional 41-60 %
Ulva 5 Occasional 61-80 %

Similar biotopes or habitat types

Not applicable or unknown.

Classification history of this biotope or habitat type

Classification version Code

Back to top