EUNIS habitat classification 2012 amended 2019 > A - Marine habitats > A2 - Littoral sediment > A2.8 - Features of littoral sediment > A2.82 - Ephemeral green or red seaweeds (freshwater or sand-influenced) on mobile substrata > A2.821 - Ephemeral green and red seaweeds on variable salinity and/or disturbed eulittoral mixed substrata

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

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

Quick facts

EUNIS habitat type code A2.821

Description (English)

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 unit A1.1133), 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. (unit A2.431). 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 (units A1.3152; A1.3132) or by M. edulis (A1.111) or by the polychaete Hediste diversicolor and the tellin Macoma balthica (A2.312) 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 A2.431, in which ephemeral algal growth has exceeded the capacity of the grazing molluscs.

Source: EUNIS habitat classification

Vegetation types

Relation to vegetation types (syntaxa)

Not available

Species mentioned in habitat description

Algae Enteromorpha intestinalis
Algae Fucus serratus
Algae Fucus vesiculosus
Algae Ulva lactuca
Invertebrates Arenicola marina
Invertebrates Carcinus maenas
Invertebrates Cerastoderma edule
Invertebrates Elminius modestus
Invertebrates Lanice conchilega
Invertebrates Littorina littorea
Invertebrates Macoma balthica
Invertebrates Mytilus edulis
Invertebrates Semibalanus balanoides
Species scientific name English common name Species group
Enteromorpha intestinalis Algae
Fucus serratus Algae
Fucus vesiculosus Algae
Ulva lactuca Algae
Arenicola marina Invertebrates
Carcinus maenas Invertebrates
Cerastoderma edule Invertebrates
Elminius modestus Invertebrates
Lanice conchilega Invertebrates
Littorina littorea Invertebrates
Macoma balthica Invertebrates
Mytilus edulis Invertebrates
Semibalanus balanoides Invertebrates

Other classifications

Classification Code Habitat type name Relationship type
Marine Habitat Classification Britain/Ireland 0405 LR.FLR.Eph.EphX Ephemeral green and red seaweeds on variable salinity and/or disturbed eulittoral mixed substrata source
CORINE Land Cover 4.2.3. Intertidal flats n/a
For relation to plant communities (syntaxa), see Vegetation types

History

Classification Code Habitat type name Relationship type
EUNIS Habitat Classification 200410 A2.821 Ephemeral green and red seaweeds on variable salinity and/or disturbed eulittoral mixed substrata same
EUNIS Habitat Classification 200308 A1.325 Ephemeral green and red seaweeds on variable salinity and/or disturbed eulittoral mixed substrata same
EUNIS Habitat Classification 200202 A1.325 Ephemeral green and red seaweeds on variable salinity or disturbed eulittoral mixed substrata same
EUNIS Habitat Classification 199910 A1.325 Ephemeral green and red seaweeds on variable salinity or disturbed eulittoral mixed substrata same
MNCR BioMar 97.06 (Britain & Ireland) SLR.FX.EphX Ephemeral green and red seaweeds on variable salinity or disturbed eulittoral mixed substrata same
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