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Marine Habitat Classification

Description of biotope or habitat type

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   Laminaria saccharina, Gracilaria gracilis and brown seaweeds on full salinity infralittoral sediment

Physical habitat description

Salinity Full (30-35 ppt)
Wave exposure Moderately exposed, Sheltered, Very sheltered, Extremely sheltered
Tidal streams Moderately strong (1-3 kn), Weak (>1 kn)
Substratum Muddy sand and pebbles
Zone Infralittoral - upper, Sublittoral fringe
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.LsacGraFS <I>Laminaria saccharina</I>, <I>Gracilaria gracilis</I> and brown seaweeds on full 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 muddy sand, in moderately exposed or sheltered, fully marine conditions, with weak tidal currents. The community is characterised by a reasonable covering of Laminaria saccharina. Frequent Chorda filum may also form part of the canopy although not at the abundance in LsacCho. Beneath the canopy the community is characterised by the red algae Gracilaria gracilis, and various brown algal species particularly Dictyota dichotoma. Other members of the understory may include a variety of other filamentous and foliose red algae in particular Ceramium nodulosum and the green alga Ulva. The muddy sand substrate supports a variety of faunal species including polychaetes (Lanice conchilega) and gastropods (Hinia reticulata).


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
Cerianthus lloydii 1 Occasional 21-40 %
Lanice conchilega 4 Frequent 41-60 %
Pagurus bernhardus 1 Occasional 21-40 %
Carcinus maenas 4 Frequent 41-60 %
Hinia reticulata 2 Occasional 41-60 %
Corallinaceae 1 Occasional 21-40 %
Rhodophyllis divaricata 2 Occasional 21-40 %
Dudresnaya verticillata 1 Occasional 21-40 %
Halarachnion ligulatum 1 Occasional 21-40 %
Polyides rotundus 2 Occasional 21-40 %
Gracilaria gracilis 15 Frequent 81-100 %
Ceramium nodulosum 3 Frequent 41-60 %
Dictyota dichotoma 3 Occasional 41-60 %
Chorda filum 6 Frequent 41-60 %
Laminaria saccharina 11 Frequent 81-100 %
Ulva 8 Frequent 61-80 %

Similar biotopes or habitat types

LsacGraVS has a more sparse covering of L. saccharina, and a greater number of sponges and ascidians.

Chorda filum is much more prominant in LsacCho than in the present biotope.

Classification history of this biotope or habitat type

Classification version Code
96.7 MCR.PolCio

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