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LR.FLR.Eph.BLitX
Barnacles and Littorina spp. on unstable eulittoral mixed substrata

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Habitat (physical) description

Distribution

 Salinity: Full (30-35 ppt), Variable (18-35 ppt) 
 Wave exposure: Sheltered, Very sheltered, Extremely sheltered 
 Tidal streams:  
 Substratum: Cobbles and pebbles on sand and gravel 
 Zone: Eulittoral 
 Depth Band: Mid 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.

Previous code

This biotope occurred in previous versions of the classification as:
BLit in part - Version: 97.06
LMXD.BLIT - Version: 6.95

Distribution of habitat LR.FLR.Eph.BLitX  Barnacles and Littorina spp. on unstable eulittoral mixed substrata
Distribution of habitat LR.FLR.Eph.BLitX Barnacles and Littorina spp. on unstable eulittoral mixed substrata, 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

The eulittoral zone, particularly the mid shore zone, of sheltered to extremely sheltered mixed substrata shores is often characterised by flat banks or scards of cobbles and pebbles (on sediment) which are either too small or unstable to support a seaweed community. The boulders and larger cobbles are usually colonised by the barnacles Semibalanus balanoides or in areas with variable salinity Elminius modestus and often dense aggregations of the winkles Littorina littorea and Littorina saxatilis are present as well. Between the cobbles and pebbles the mussel Mytilus edulis occasionally occurs, but always at low abundance. Juvenile crabs Carcinus maenas and gammarids may occur between and underneath the pebbles and cobbles. Brown seaweeds are rare, although the wrack Fucus vesiculosus may occasionally occur on larger cobbles and small boulders in the mid and upper shore zones. Ephemeral green seaweeds such as Enteromorpha intestinalis may also be present. Shallow pools and patches of standing water may occur in low-lying areas and may contain amphipods and filamentous green seaweeds. Due to the unstable nature of the substratum the diversity and density of flora and fauna is characteristically low.

Situation

This biotope is found primarily on enclosed (estuarine) stony shores in wave-sheltered conditions (compare with Sem.LlitX) and may be subject to variable levels of salinity. It is found predominately in the mid shore zone below or at the same level as the biotope dominated by ephemeral green seaweeds (EphX). If it is found in the upper shore region it can be backed by salt marsh species such as Salacornia and Spartina sp. Below are biotopes dominated by the wracks Fucus serratus or F. vesiculosus (Fserr.X; Fves.X).

Temporal variation

Unknown.

Similar biotopes

LR.HLR.MusB.Sem.LitXFound on more exposed, open coast sites, but with similar substrata. It is more species rich than BLitX, and red seaweeds including coralline crusts, Mastocarpus stellatus and Chondrus crispus are present. There is also a higher abundance of the limpet Patella vulgata and S. balanoides.
LR.FLR.Eph.EphXOccurs in a wider exposure range and similar physical conditions. It has a higher abundance of green seaweeds such as Enteromorpha spp. and Ulva lactuca and a lower abundance and frequency of occurrence of barnacles. Very low species diversity.

Characterising Species

Taxa Frequency Typical Abundance % Contribution to similarity
Elminius modestus F 15
Semibalanus balanoides F 18
Carcinus maenas O 7
Littorina littorea F 25
Littorina saxatilis F 15
Mytilus edulis O 6
Fucus vesiculosus O 3
Fucus vesiculosus O 3
Enteromorpha intestinalis O 3

Example photographs of biotope


Close view of cobbles with Littorina littorea, Blyth Power Station, Blyth Estuary., Eleanor Murray, © 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