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LR.HLR.MusB.Cht.Cht
Chthamalus spp. on exposed upper eulittoral rock

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Habitat (physical) description

Distribution

 Salinity: Full (30-35 ppt) 
 Wave exposure: Very exposed, Exposed, Moderately exposed 
 Tidal streams:  
 Substratum: Bedrock; large boulders 
 Zone: Eulittoral - mid, Eulittoral - upper 
 Depth Band: Mid shore, Upper shore 
 Other Features: Also on sheltered vertical rock 

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.

Previous code

This biotope occurred in previous versions of the classification as:
ELR.BPat.Cat in part - Version: 97.06
ELR.BPat.Cht in part - Version: 97.06

Distribution of habitat LR.HLR.MusB.Cht.Cht  Chthamalus spp. on exposed upper eulittoral rock
Distribution of habitat LR.HLR.MusB.Cht.Cht Chthamalus spp. on exposed upper eulittoral rock, based on records on the UK Marine Recorder database and EUSeaMap. Red dots represent records on which the biotope is based. Blue dots show other certain records, black dots show records tentatively assigned to this biotope. Yellow areas show level 2 and 3 sublittoral and deep-sea habitats prediced by EUSeaMap within UK waters.

Biotope description

Very exposed to moderately exposed upper and mid eulittoral bedrock and boulders characterised by a dense community of barnacles, including Chthamalus montagui, Chthamalus stellatus and Semibalanus balanoides, and the limpet Patella vulgata. Damp cracks and crevices in the rock provide a refuge for small individuals of the mussel Mytilus edulis, and the winkles Melarhaphe neritoides and Littorina saxatilis. These crevices can also be occupied by encrusting coralline algae and the anemone Actinia equina. Patches of the black lichen Verrucaria maura and the green seaweed Enteromorpha intestinalis may be present, though in low abundance (Occasional). Shaded vertical littoral fringe and upper eulittoral bedrock may be characterised by the shade-tolerant red seaweeds Catenella caespitosa, Bostrychia scorpioides and/or Lomentaria articulata. Where the turf of C. caespitosa is well established, barnacles are rare. Geographical variation: There is much regional variation in the distribution and zonation of Chthamalus spp. On the west coast Chthamalus spp. dominate the upper eulittoral, often forming a distinct white band above a darker band of S. balanoides in the mid eulittoral zone (Sem). C. montagui is better adapted to resist desiccation and, therefore, extends further up the shore. In the south-west Chthamalus spp. can be the dominant barnacles throughout the eulittoral zone.

Situation

Cht.Cht is found below the black lichen Verrucaria maura (Ver.B or Ver.Ver) on very exposed shores. It is found above the mussel Mytilus edulis and barnacles biotope (MytB). On slightly less exposed shores the wrack Fucus vesiculosus is able to survive and a mixed barnacle and F. vesiculosus biotope may occur (Sem.FvesR) beneath the Cht. On such moderately exposed shores Cht may still occur on steep and vertical faces, while fucoids dominate the flatter areas (Sem.FvesR or Fves), though these communities should not be confused with Sem.FvesR. Cht can also occur above Sem. On very sheltered sea lochs in Argyll, West Scotland Chthamalus spp. are unusually abundant in the upper eulittoral zone.

Temporal variation

Unknown.

Similar biotopes

LR.FLR.Lic.Ver.VerOccurs in the littoral fringe above the Cht.Cht biotope. The barnacles C. montagui and S. balanoides and limpets P. vulgata are sparse (all Occasional) while V. maura occurs at a higher abundance (Abundant).
LR.HLR.MusB.Cht.LpygFound especially in the south. Lichina pygmaea forms a distinct band, often with the bivalve Lasaea adasoni embedded in the thalli. The species composition is similar though red and green seaweeds such as Corallinaceae and Enteromorpha spp. are not present.
LR.HLR.MusB.Sem.FvesROccurs in the mid eulittoral zone on slightly less exposed shores. It notably lacks Chthamalus spp. and is dominated by a higher abundance of S. balanoides and the whelk Nucella lapillus. Usually, a sparse flora of seaweeds is present including the wrack Fucus vesiculosus and the green seaweed Enteromorpha spp.

Characterising Species

Taxa Frequency Typical Abundance % Contribution to similarity
Actinia equina O 2
Chthamalus montagui A 29
Chthamalus stellatus C 7
Semibalanus balanoides F 7
Patella vulgata C 19
Littorina C 2
Littorina saxatilis F 11
Melarhaphe neritoides C 3
Mytilus edulis O 6
Enteromorpha intestinalis F 2
Verrucaria maura F 2

Example photographs of biotope


Chthamalus montagui with small prosobranchs, Trebetherick, Keith Hiscock, © JNCC View over tilted bedrock strata dominated by barnacles,  into bay with village, Cornwall, Kate Northen, © JNCC
Click on an image for a larger view


Version 15.03 of the classification adds a deep-sea section to version 04.05; therefore superseding version 04.05, 97.06 and 03.02.

This online classification should be cited as:

JNCC (2015) The Marine Habitat Classification for Britain and Ireland Version 15.03 [Online]. [Date accessed]. Available from: jncc.defra.gov.uk/MarineHabitatClassification

Information from the shallower section (up to sublittoral sediment, taken from Version 04.05) be cited as the report accompanying Version 04.05, as follows:

CONNOR, D.W., J.H. ALLEN, N.GOLDING, K.L.HOWELL, L.M. LIEBERKNECHT, K.O. NORTHEN AND J.B. REKER (2004) The Marine Habitat Classification for Britain and Ireland Version 04.05. In: JNCC (2015) The Marine Habitat Classification for Britain and Ireland Version 15.03 [Online]. [Date accessed].
Available from: jncc.defra.gov.uk/MarineHabitatClassification
ISBN 1 861 07561 8


Information from the deep-sea section (added in March 2015) should be cited as the report accompanying the deep-sea section, as follows:

PARRY, M.E.V., K.L. HOWELL, B.E. NARAYANASWAMY, B.J. BETT, D.O.B. JONES, D.J. HUGHES, N. PIECHAUD, T.D. NICKELL, H. ELLWOOD, N. ASKEW, C. JENKINS and E. MANCA (2015) A Deep-sea Section for the Marine Habitat Classification of Britain and Ireland. JNCC report 530. In: JNCC (2015) The Marine Habitat Classification for Britain and Ireland Version 15.03 [Online]. [Date accessed].
Available from: jncc.defra.gov.uk/MarineHabitatClassification
ISSN 0963 8901