EUNIS habitat classification 2012 amended 2019 > A - Marine habitats > A2 - Littoral sediment > A2.7 - Littoral biogenic reefs > A2.72 - Littoral mussel beds on sediment > A2.721 - Mytilus edulis beds on littoral sediments

Mytilus edulis beds on littoral sediments

English name: Mussel beds on littoral sediments

Quick facts

EUNIS habitat type code A2.721
Bern Convention Included in a Resolution 4 habitat type at a higher level (A2.72)

Description (English)

Dense aggregations of Mytilus edulis on the mid and lower shore, on mixed substrata (mainly cobbles and pebbles on fine sediments), on sand, or on sheltered muddy shores. In high densities the mussels bind the substratum and provide a habitat for many infaunal and epifaunal species. The wrack Fucus vesiculosus is often found attached to either the mussels or cobbles and it can be abundant. The mussels are often encrusted with the barnacles Semibalanus balanoides, Elminius modestus or Balanus crenatus. Where boulders are present they can support the limpet Patella vulgata. The winkles Littorina littorea and L. saxatilis and small individuals of the crab Carcinus maenas are common amongst the mussels, whilst areas of sediment may contain the lugworm Arenicola marina, the sand mason Lanice conchilega, the cockle Cerastoderma edule, and other infaunal species. The characterising species list shown below is based on data from epifaunal sampling only. Three sub-biotopes are recognised for this biotope, distinguished principally on the basis of the sediment type associated with the mussel beds. The three types of intertidal mussel beds may be part of a continuum on an axis that is most strongly influenced by the amount of pseudofaeces that accumulate amongst the mussels. The differences may not always be directly connected to the underlying substratum on which the mussel bed may have started a long time ago. It should be noted that there are few data available for the muddy (A2.7213) and sandy (A2.7212) subunits, therefore there are no characterising species lists or comparative tables for these two sub-biotopes.
Situation: On more exposed, predominantly rocky shores this biotope can be found below a band of ephemeral green seaweeds (unit A2.821). On sheltered, predominantly rocky shores either a F. vesiculosus dominated biotope or a biotope dominated by the wrack Ascophyllum nodosum (A1.3132; A1.3142) can be found above or the barnacle dominated biotope (A1.1133). On mudflats and sandflats, this biotope may be found alongside Cerastoderma edule beds (A2.242) and other A2.2 and A2.3 biotopes. The intertidal A2.721 biotope can extend seamlessly into the subtidal.
Temporal variation: The temporal stability of mussel beds can vary a lot. Some beds are permanent, maintained by recruitment of spat in amongst adults. Other beds are ephemeral, an example of which are beds ocurring at South America Skear where large amounts of spat settle intermittently on a cobble basement. The mussels rapidly build up mud, and are unable to remain attached to the stable cobbles. They are then liable to be washed away during gales. A second example of ephemeral mussel dominated biotopes occurs when mussel spat ("mussel crumble") settles on the superficial shell of cockle beds, such as is known to occur in the Burry Inlet.

Source: EUNIS habitat classification

Vegetation types

Relation to vegetation types (syntaxa)

Not available

Species mentioned in habitat description

Algae Ascophyllum nodosum
Algae Fucus vesiculosus
Invertebrates Arenicola marina
Invertebrates Balanus crenatus
Invertebrates Carcinus maenas
Invertebrates Cerastoderma edule
Invertebrates Elminius modestus
Invertebrates Lanice conchilega
Invertebrates Littorina littorea
Invertebrates Mytilus edulis
Invertebrates Patella vulgata
Invertebrates Semibalanus balanoides
Species scientific name English common name Species group
Ascophyllum nodosum Algae
Fucus vesiculosus Algae
Arenicola marina Invertebrates
Balanus crenatus Invertebrates
Carcinus maenas Invertebrates
Cerastoderma edule Invertebrates
Elminius modestus Invertebrates
Lanice conchilega Invertebrates
Littorina littorea Invertebrates
Mytilus edulis Invertebrates
Patella vulgata Invertebrates
Semibalanus balanoides Invertebrates

Other classifications

Classification Code Habitat type name Relationship type
Marine Habitat Classification Britain/Ireland 0405 LS.LBR.LMus.Myt <I>Mytilus edulis</I> beds on littoral sediments 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 A2.721 Mytilus edulis beds on littoral sediments same
EUNIS Habitat Classification 200308 A1.331 Mytilus edulis beds on eulittoral mixed substrata same
EUNIS Habitat Classification 200202 A1.331 Mytilus edulis beds on eulittoral mixed substrata same
EUNIS Habitat Classification 199910 A1.331 Mytilus edulis beds on eulittoral mixed substrata same
MNCR BioMar 97.06 (Britain & Ireland) SLR.MX.Myt Mytilus edulis beds on eulittoral mixed substrata same
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