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.

   Codium spp. with red seaweeds and sparse Laminaria saccharina on shallow, heavily-silted, very sheltered infralittoral rock


Habitat (physical) description

Salinity Reduced (18-30ppt)
Wave exposure Sheltered, Very sheltered, Extremely sheltered
Tidal streams Weak (>1 kn), Very weak (negligible)
Substratum Boulders, cobbles, bedrock
Zone Infralittoral
Depth Band 0-5 m, 5-10 m
Other Features Heavy siltation

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.KVS.Cod <I>Codium</I> spp. with red seaweeds and sparse <I>Laminaria saccharina</I> on shallow, heavily-silted, very sheltered 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

Very shallow, heavily-silted infralittoral rock characterised by dense stands of Codium spp., together with silt-tolerant red seaweeds, the green seaweed Ulva spp. and often only a sparse covering of the kelp Laminaria saccharina. This biotope appears to have a restricted distribution, being known at present only from the sheltered voes of Shetland, some Scottish lagoons and from the harbours of south-west England. These locations suggest the habitat is likely to be subject to reduced salinity conditions (although the habitat data indicate mostly fully marine records). Dense Codium spp. can occur at very sheltered sites, on cobbles or boulders, often in dense patches interspersed with filamentous red seaweeds Bonnemaisonia hamifera, Antithamnionella spirographidis and Ceramium spp. Where sediment is present the red seaweed Polyides rotundus is commonly found along the rock-sediment interface, and the sponge Dysidea fragilis often occurs on the rock. Other red seaweeds that may be present include Chondrus crispus, Callophyllis laciniata, Gelidium latifolium, Corallina officinalis and coralline crusts. The brown seaweeds Halidrys siliquosa, Desmarestia viridis or Chorda filum may be present in high abundance and although kelp L. saccharina may occur, it is usually sparse. There are no conspicuous fauna that typify this biotope, though polychaetes such as terebellids and spirorbids may occur. The opisthobranch Elysia viridis may be locally abundant on the seaweeds and is known to favour Codium fragilis in particular. Large stands of Codium sp. (generally Common abundance) are accompanied by red seaweeds such as G. latifolium, C. laciniata and A. spirographidis on the rock beneath. Cod has been reported to occur in the shallows of The Fleet, Bembridge Ledges, Pagham Harbour and Jersey (Tittley et al. 1985). In Ireland, species-poor shallow, silted bedrock in the North Water of Mulroy Bay, Co. Donegal, is characterised by Griffithsia corallinoides (Common) and Codium tomentosum (Frequent) forming a narrow band below the kelp zone (Lsac.Ft). Cod has not been described from any other sites in Ireland. If Codium spp. is less than Common amongst dense L. saccharina and Chorda filum, it should not be recorded as Cod.

Situation

This biotope occurs on bedrock below a sublittoral fringe of mixed kelp L. saccharina and Laminaria digitata (Lsac.Ldig) or below a L. saccharina forest (Lsac.Ft) or else on isolated boulders on sediment. It appears to be most frequently found in lagoons. Further information on which species of Codium is present and on the associated fauna is required.

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
Terebellidae 2 Frequent 21-40 %
Spirorbidae 2 Occasional 21-40 %
Carcinus maenas 3 Occasional 41-60 %
Bonnemaisonia hamifera 9 Frequent 41-60 %
Gelidium latifolium 2 Frequent 21-40 %
Corallinaceae 4 Frequent 41-60 %
Corallina officinalis 2 Occasional 21-40 %
Chondrus crispus 1 Frequent 21-40 %
Callophyllis laciniata 2 Occasional 21-40 %
Polyides rotundus 1 Occasional 21-40 %
Antithamnionella spirographidis 1 Frequent 21-40 %
Ceramium 1 Common 21-40 %
Ceramium nodulosum 1 Occasional 21-40 %
Ectocarpaceae 1 Occasional 21-40 %
Desmarestia viridis 3 Frequent 21-40 %
Chorda filum 3 Frequent 41-60 %
Laminaria saccharina 4 Abundant 41-60 %
Halidrys siliquosa 1 Occasional 21-40 %
Ulva lactuca 3 Occasional 41-60 %
Cladophora 1 Occasional 21-40 %
Codium 32 Common 81-100 %

Similar biotopes

IR.LIR.K.Lsac.Ft
In Cod L. saccharina is replaced in abundance by Codium spp.

IR.LIR.KVS.LsacPsaVS
Lower diversity of red and brown seaweeds.

IR.LIR.KVS.LsacPhyVS
Reduced salinity and lower diversity of red and brown seaweeds.

IR.LIR.Lag.FChoG
Dense Codium spp. can occur in the saline lagoons of Scotland amongst fucoids and C. filum.

Biotope history

Classification Habitat code
96.7 SIR.Lsac.CodR

Photos

IR.LIR.K.Cod Codium spp. with red seaweeds and sparse Laminaria saccharina on shallow, heavily-silted, very sheltered infralittoral rock, W Kirk Taing, North Sanday. Sue Scott © JNCC
IR.LIR.K.Cod Codium spp. with red seaweeds and sparse Laminaria saccharina on shallow, heavily-silted, very sheltered infralittoral rock, W Kirk Taing, North Sanday. Sue Scott © JNCC

Back to top