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Marine Habitat Classification


Description of biotope or habitat type

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   Ephemeral green and red seaweeds on variable salinity and/or disturbed eulittoral mixed substrata


Habitat (physical) description

Salinity Variable (18-35 ppt)
Wave exposure Sheltered, Very sheltered, Extremely sheltered
Tidal streams
Substratum Pebbles & cobbles on mud and sand
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.

Distribution of habitat LR.FLR.Eph.EphX Ephemeral green and red seaweeds on variable salinity and/or disturbed eulittoral mixed substrata

  • 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'

Point data based on records in the UK Marine Recorder Snapshot.

Description

Eulittoral mixed substrata (pebbles and cobbles overlying sand or mud) that are subject to variations in salinity and/or siltation, characterised by dense blankets of ephemeral green and red seaweeds. The main species present are Enteromorpha intestinalis, Ulva lactuca and Porphyra spp., along with colonial diatoms covering the surface of the substratum. Small numbers of other species such as barnacles Semibalanus balanoides and Elminius modestus are confined to any larger cobbles and pebbles or on the shells of larger individuals of the mussel Mytilus edulis. The crab Carcinus maenas and the winkle Littorina littorea can be present among the boulders, cobbles and seaweeds, while gammarids can be found in patches underneath the cobbles. In common with the other biotopes found on mixed substrata, patches of sediment are typically characterised by infaunal species including bivalves, for example, Cerastoderma edule and the polychaete Arenicola marina and the polychaete Lanice conchilega.

Situation

This biotope is found primarily on enclosed (estuarine) stony shores sheltered from wave action (compare with Sem.LlitX), with weak to moderate tidal streams and often subject to variable levels of salinity. It is found predominately in the mid shore zone above or at the same level as the biotope dominated by the barnacles S. balanoides and/or E. modestus and Littorina spp. (BLitX). If it is found in the upper shore region it can be backed by saltmarsh species such as Salicornia sp. and Spartina sp. Below are biotopes dominated by the wracks Fucus serratus or Fucus vesiculosus (Fserr.X; Fves.X) or by M. edulis (Myt.Myt) or by the polychaete Hediste diversicolor and the tellin Macoma balthica (HedMac) depending on the substratum. This is a biotope with a low species diversity and the 'high' number of species in the characterising species list is due to a variation in the species composition from site to site, not to high species richness at individual sites.

Temporal variation

This biotope may be a summer variation of BLitX, in which ephemeral algal growth has exceeded the capacity of the grazing molluscs.

Characterising Species

Taxon Relative importance of taxon for defining this community (%) Typical abundance - SACFOR scale % of core records where taxon was recorded
Elminius modestus 4 Occasional 21-40 %
Semibalanus balanoides 4 Occasional 21-40 %
Gammaridea 3 Occasional 21-40 %
Carcinus maenas 3 Occasional 21-40 %
Littorina littorea 2 Occasional 21-40 %
Mytilus edulis 5 Occasional 21-40 %
Porphyra 4 Occasional 21-40 %
Enteromorpha 56 Frequent 61-80 %
Enteromorpha intestinalis 2 21-40 %
Ulva lactuca 6 Frequent 21-40 %

Similar biotopes

LR.HLR.MusB.Sem.LitX
Occurs on boulders and cobbles on moderately exposed shores. It has a high abundance of S. balanoides, the limpet Patella vulgata and the whelk Gibbula cineraria and it has a higher diversity of red seaweeds.

LR.FLR.Eph.BLitX
Occurs on similar substrata and in similar wave exposure. It has a similar species composition, but a higher species diversity and abundance of the individual species. The winkles L. littorea and Littorina saxatilis are normally present along with the barnacles S. balanoides and E. modestus. See also temporal variation.

Biotope history

Classification Habitat code
6.95 LMXD.EPH

Photos

LR.FLR.EPH.EphX Ephemeral green and red seaweeds on variable salinity and/or disturbed eulittoral mixed substrata, Salum, Tiree. ANON © JNCC
LR.FLR.EPH.EphX Ephemeral green and red seaweeds on variable salinity and/or disturbed eulittoral mixed substrata, Salum, Tiree. ANON © JNCC
LR.FLR.EPH.EphX Ephemeral green and red seaweeds on variable salinity and/or disturbed eulittoral mixed substrata, Ryton Island, Tyne Estuary. Eleanor Murray © JNCC
LR.FLR.EPH.EphX Ephemeral green and red seaweeds on variable salinity and/or disturbed eulittoral mixed substrata, Ryton Island, Tyne Estuary. Eleanor Murray © JNCC
LR.FLR.EPH.EphX Ephemeral green and red seaweeds on variable salinity and/or disturbed eulittoral mixed substrata, Unspecified location. Tim Hill © JNCC
LR.FLR.EPH.EphX Ephemeral green and red seaweeds on variable salinity and/or disturbed eulittoral mixed substrata, Unspecified location. Tim Hill © JNCC

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