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.

   Mixed fucoids, Chorda filum and green seaweeds on reduced salinity infralittoral rock


Habitat (physical) description

Salinity Reduced (18-30ppt), Low (<18ppt)
Wave exposure Extremely sheltered
Tidal streams Very weak (negligible)
Substratum Bedrock; boulders, cobbles and pebbles
Zone Infralittoral
Depth Band 0-5 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 IR.LIR.Lag.FChoG Mixed fucoids, <I>Chorda filum</I> and green seaweeds on reduced salinity infralittoral 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

Permanently submerged mixed fucoids on rock in lagoons. The main species are the wracks Fucus serratus and Fucus vesiculosus, but the brown seaweeds Chorda filum, Ascophyllum nodosum and Ectocarpaceae can be present as well. Red seaweeds are normally present and include Mastocarpus stellatus, Polyides rotundus, Chondrus crispus, Ceramium spp. and coralline crusts. A variety of green seaweeds is also present and include Enteromorpha spp., while dense patches of Cladophora rupestris may occur on vertical rock faces. The faunal component is restricted to the mussel Mytilus edulis, the polychaete Arenicola marina and the crab Carcinus maenas. Opossum shrimps Mysidae can be present as well. The kelp Laminaria saccharina is absent, possibly due to the low salinity conditions.

Situation

Nearby rock often supports similar biotopes of submerged fucoids (AscSpAs and FcerEnt) or where salinity is further reduced ProtFur can occur. Slightly deeper rock often supports Laminaria saccharina (Lsac.Ft), usually surrounded by more extensive areas of sediment. Seagrass beds thrive well in the muddy sediments of the lagoons and often cover large areas. They include both Ruppia spp. and Zostera marina and some locations in the Outer Hebrides support dense beds of the nationally rare stonewort Lamprothamnion papulosum (Rup and Zmar). The sublittoral mud, which abuts most of the submerged rock, can become anoxic and covered by a bacterial mat of Beggiatoa spp. (Beg).

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
Arenicola marina 2 Occasional 21-40 %
Mysidae 3 Frequent 21-40 %
Carcinus maenas 3 Occasional 21-40 %
Littorina littorea 6 Frequent 41-60 %
Mytilus edulis 3 Occasional 21-40 %
Corallinaceae 2 Occasional 21-40 %
Chondrus crispus 1 Occasional 21-40 %
Mastocarpus stellatus 2 Occasional 21-40 %
Polyides rotundus 2 Occasional 21-40 %
Ectocarpaceae 9 Frequent 41-60 %
Chorda filum 3 Occasional 21-40 %
Ascophyllum nodosum 3 Occasional 21-40 %
Fucus serratus 30 Common 61-80 %
Fucus vesiculosus 12 Frequent 41-60 %
Enteromorpha 2 Occasional 21-40 %
Enteromorpha intestinalis 3 Frequent 21-40 %
Cladophora rupestris 3 Frequent 21-40 %

Similar biotopes

Not applicable or unknown.

Photos

IR.LIR.LAG.FChoG Mixed fucoids, Chorda filum and green seaweeds on reduced salinity infralittoral rock, Loch an Strumore, Loch an Strumore, North Uist. Sue Scott © JNCC
IR.LIR.LAG.FChoG Mixed fucoids, Chorda filum and green seaweeds on reduced salinity infralittoral rock, Loch an Strumore, Loch an Strumore, North Uist. Sue Scott © JNCC

Back to top