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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.

   Lithothamnion corallioides maerl beds on infralittoral muddy gravel

Physical habitat description

Salinity Full (30-35 ppt)
Wave exposure Sheltered, Very sheltered
Tidal streams Moderately strong (1-3 kn), Weak (>1 kn), Very weak (negligible)
Substratum Muddy maerl gravel
Zone Infralittoral
Depth Band 0-5 m, 5-10 m, 10-20 m
Other Features

Biotope origin

Derived using data from Various
Faunal group Epifauna

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.Mrl.Lcor <I>Lithothamnion corallioides</I> maerl beds on infralittoral muddy gravel

  • 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.


Live maerl beds in sheltered, silty conditions which are dominated by Lithothamnion corallioides with a variety of foliose and filamentous seaweeds. Live maerl is at least common but there may be noticeable amounts of dead maerl gravel and pebbles. Other species of maerl, such as Phymatolithon calcareum and Phymatolithon purpureum, may also occur as a less abundant component. Species of seaweed such as Dictyota dichotoma, Halarachnion ligulatum. and Ulva spp. are often present, although are not restricted to this biotope, whereas Dudresnaya verticillata tends not to occur on other types of maerl beds. The anemones Anemonia viridis and Cerianthus lloydii, the polychaetes Notomastus latericeus and Caulleriella alata, the isopod Janira maculosa and the bivalve Hiatella arctica are typically found in SS.SMp.Mrl.Lcor where as Echinus esculentus tends to occur more in other types of maerl. The seaweeds Saccharina latissima and Chorda filum may also be present in some habitats. SS.SMp.Mrl.Lcor has a south-western distribution in Britain and Ireland. Sheltered, stable, fully saline maerl beds in the north of Great Britain (where L. corallioides has not been confirmed to occur) may need to be described as an analogous biotope to SS.SMp.Mrl.Lcor (see SS.SMp.Mrl.Pcal).


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
Lithothamnion corallioides 28 Abundant 81-100%
Mediomastus fragilis 12 81-100%
Nematoda 11 81-100%
Asterias rubens 6 Frequent 61-80%
Caulleriella alata 6 61-80%
Hiatella arctica 6 81-100%
Janira maculosa 6 81-100%
Notomastus latericeus 6 81-100%
Polyplacophora 5 61-80%
Dictyota dichotoma 5 Common 41-60%
Gari tellinella 5 61-80%
Glycera lapidum 5 61-80%
Psamathe fusca 5 61-80%
Hilbigneris gracilis 5 61-80%
Sphaerosyllis bulbosa 5 61-80%
Anemonia viridis 4 Occasional 41-60%
Cerianthus lloydii 4 Frequent 41-60%
Halarachnion ligulatum 4 Frequent 41-60%
Amphipholis squamata 3 61-80%
Chorda filum 3 Frequent 41-60%
Dudresnaya verticillata 3 Frequent 41-60%
Gibbula magus 3 Occasional 41-60%
Liocarcinus depurator 3 Occasional 41-60%
Marthasterias glacialis 3 Occasional 41-60%
Pagurus bernhardus 3 Occasional 41-60%
Aonides paucibranchiata 2 61-80%
Caprella acanthifera 2 61-80%
Harmothoe impar 2 61-80%
Saccharina latissima 2 Occasional 21-40%
Microdeutopus versiculatus 2 61-80%
Kurtiella bidentata 2 61-80%
Nannonyx goesii 2 61-80%
Parvicardium scabrum 2 61-80%
Pholoe inornata 2 21-40%
Pisione remota 2 21-40%
Pista cristata 2 61-80%
Protodorvillea kefersteini 2 61-80%
Seraphsidae 2 Occasional 41-60%
Phymatolithon calcareum 2 Common 21-40%
Ulva 2 Frequent 41-60%
Lanice conchilega 1 Occasional 41-60%
Liocarcinus corrugatus 1 Occasional 21-40%
Pecten maximus 1 Occasional 21-40%

Similar biotopes or habitat types

SS.SMp.Mrl.Pcal.R occurs in less stable environments.

Classification history of this biotope or habitat type

Classification version Code Habitat name
2015 (15.03) SS.SMp.Mrl.Lcor Lithothamnion corallioides maerl beds on infralittoral muddy gravel
2004 (04.05) SS.SMp.Mrl.Lcor Lithothamnion corallioides maerl beds on infralittoral muddy gravel
1997 (97.06) SS.IMX.MrlMx.Lcor Lithothamnion corallioides maerl beds on infralittoral muddy gravel

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