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 digitata, ascidians and bryozoans on tide-swept sublittoral fringe rock


Habitat (physical) description

Salinity Full (30-35 ppt)
Wave exposure Sheltered, Very sheltered, Extremely sheltered
Tidal streams Very strong (>6 kn), Strong (3-6 kn), Moderately strong (1-3 kn)
Substratum Bedrock; boulders and cobbles
Zone Sublittoral fringe
Depth Band 0-5 m, Lower shore
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 IR.MIR.KT.LdigT <I>Laminaria digitata</I>, ascidians and bryozoans on tide-swept sublittoral fringe rock

  • 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

Sheltered bedrock, boulders and cobbles that are subject to moderate to strong tidal water movement characterised by dense Laminaria digitata, coralline crusts and sponges such as Halichondria panicea. Other seaweeds present include the foliose red seaweeds Chondrus crispus, Palmaria palmata, Cryptopleura ramosa and Mastocarpus stellatus as well as the calcareous Corallina officinalis. Green seaweeds present include Ulva lactuca, Enteromorpha intestinalis and Cladophora rupestris. The increased water movement encourages several filter-feeding faunal groups to occur. The sponges Leucosolenia spp., Scypha ciliata and Hymeniacidon perleve frequently occur on steep and overhanging rock faces. The bryozoans Electra pilosa, Membranoptera membranipora and Alcyonidium hirsutum encrust the kelp and other foliose seaweeds. In addition, ascidians such as Ascidiella scabra, Dendrodoa grossularia and colonial ascidians Botryllus byssoides and Botryllus leachi often thrive in this environment encrusting both the rock and the seaweeds. The tube-building polychaete Pomatoceros triqueter can be found on the rock and on the kelp holdfasts along with the barnacle Balanus crenatus. More mobile species such as the gastropods Gibbula cineraria and Calliostoma zizyphinum, the crab Carcinus maenas and the starfish Asterias rubens are also common. Areas where increased tidal movement influences this community can be found in the narrows and/or intertidal sills of sealochs.

Situation

This biotope often occurs immediately below the tide-swept Fucus serratus biotope (SLR.Fserr.T) consequently, some F. serratus may occur in this biotope (typically only Occasional). The sublittoral fringe of similarly sheltered shores that are not tide-swept are generally characterised by mixed Laminaria saccharina and L. digitata (Lsac.Ldig) or L. saccharina (Lsac). Below LdigT, at these sheltered, tide-swept sites, a canopy of mixed kelp species often occurs (see XKT and XKTX).

Temporal variation

Unknown.

Characterising Species

Taxon Relative importance of taxon for defining this community (%) Typical abundance - SACFOR scale % of core records where taxon was recorded
Halichondria panicea 5 Frequent 61-80 %
Dynamena pumila 2 Occasional 41-60 %
Pomatoceros triqueter 3 Occasional 61-80 %
Spirorbidae 2 Frequent 41-60 %
Balanus crenatus 1 Occasional 21-40 %
Carcinus maenas 2 Rare 61-80 %
Gibbula cineraria 2 Occasional 41-60 %
Calliostoma zizyphinum 1 Rare 41-60 %
Alcyonidium hirsutum 2 Frequent 41-60 %
Membranipora membranacea 2 Occasional 41-60 %
Bryozoa indet crusts 2 Frequent 41-60 %
Asterias rubens 1 Occasional 41-60 %
Ascidiella scabra 1 Frequent 21-40 %
Dendrodoa grossularia 1 Occasional 41-60 %
Botryllus schlosseri 3 Occasional 61-80 %
Botrylloides leachi 1 Rare 21-40 %
Palmaria palmata 3 Occasional 41-60 %
Corallinaceae 8 Common 61-80 %
Corallina officinalis 2 Occasional 41-60 %
Chondrus crispus 3 Occasional 41-60 %
Mastocarpus stellatus 1 Occasional 21-40 %
Cryptopleura ramosa 1 Occasional 41-60 %
Laminaria digitata 20 Abundant 81-100 %
Fucus serratus 3 Occasional 41-60 %
Enteromorpha 1 Occasional 41-60 %
Ulva lactuca 3 Occasional 61-80 %
Cladophora rupestris 1 Frequent 21-40 %

Similar biotopes

IR.MIR.KR.Ldig
Occur in non tide-swept areas and lacks the characteristic community of filter-feeders, though the individual species may be present.

Biotope history

Classification Habitat code
6.95 LRK.LDIG.T

Photos

IR.MIR.KT.LdigT Laminaria digitata, ascidians and bryozoans on tide-swept sublittoral fringe rock, Pool Roag, Loch Bracadale, Skye. Ian Fuller © JNCC
IR.MIR.KT.LdigT Laminaria digitata, ascidians and bryozoans on tide-swept sublittoral fringe rock, Pool Roag, Loch Bracadale, Skye. Ian Fuller © JNCC
IR.MIR.KT.LdigT Laminaria digitata, ascidians and bryozoans on tide-swept sublittoral fringe rock, Pool Roag, Loch Bracadale, Skye. Ian Fuller © JNCC
IR.MIR.KT.LdigT Laminaria digitata, ascidians and bryozoans on tide-swept sublittoral fringe rock, Pool Roag, Loch Bracadale, Skye. Ian Fuller © JNCC

Back to top