Red List habitat classification > RL - Marine habitats > RLMED - Mediterranean > MEDA5.6v Mediterranean infralittoral mussel beds

Mediterranean infralittoral mussel beds

Quick facts

Red List habitat type code MEDA5.6v
Threat status
Europe Endangered
EU Endangered
Relation to
Source European Red List habitat factsheet
European Red List of habitats reports
European Red List of habitats (Excel table)


Infralittoral mussel beds on rocky and soft bottoms comprised of either the horse mussel Modiolus barbatus or the common mussel Mytilus galloprovincialis/edulis. Attached by byssus threads to rocks and piers, within sheltered harbours and estuaries and on rocky shores of the open coast, sometimes living in dense masses on soft bottoms mixed with pebbles wherever there are suitable surfaces for attachment. The diet of mussels consists of phytoplankton and detritus filtered from the surrounding water. More frequently they can be found close to river mouth areas. There are three distinct habitat components; the interstices within the mussel matrix; the biodeposits beneath the bed; and the substratum afforded by the mussel shells themselves. A diverse range of epibiota and infauna often exists in these parts of the habitat.

Indicators of quality:

Both biotic and abiotic indicators have been used to describe marine habitat quality. These include the presence of particular species, water quality parameters, levels of exposure to a particular exposure as well as more integrated indices which describe habitat function and structure, such as trophic index, or successful stages of development in habitats that have a natural cycle of change over time.

There are no known commonly agreed indicators of quality for this habitat, although particular parameters may be set in certain situations, e.g. protected features with Natura 2000 sites, where reference values may have been determined and applied on a location-specific basis. 

Characteristic species
For full habitat description, please download the habitat factsheet.

Threat status

Synthesis of Red List assessment

In past centuries, natural mussel beds covered a large part of the infralittoral zone is suitable areas, especially the areas close to river mouths and sheltered bays. The intensive exploitation of the mussel beds along with the cultivation and the introduction of non-native species for cultivation has resulted in dramatic historical decline. There is a lack of information on past trends in quality but future decline is predicted in response to climate change, diseases and non-native species interaction.
Expert opinion is that this habitat should be assessed as Endangered because of its historical decline for both the EU 28 and EU 28+.
Red List Category Red List Criteria
Endangered A3
Red List Category Red List Criteria
Endangered A3

Confidence in the assessment

Red List of habitat categories and criteria descriptions

Pressures and threats

  • Biological resource use other than agriculture & forestry
    • Marine and Freshwater Aquaculture
    • Fishing and harvesting aquatic resources
  • Pollution
    • Pollution to surface waters (limnic, terrestrial, marine & brackish)
    • Marine water pollution
  • Invasive, other problematic species and genes
    • Invasive non-native species
  • Natural System modifications
    • Other ecosystem modifications
  • Natural biotic and abiotic processes (without catastrophes)
    • Biocenotic evolution, succession
    • Interspecific faunal relations
    • Reduced fecundity/ Genetic depression

Habitat restoration potential

This habitat has the capacity to recover its typical characteristics and functionality relatively rapidly (within 10 years) if the reasons for the degradation are addressed. Seeding of mussel beds can be considered as an intervention to enhance recovery rates.

Trends in extent

Average current trend in quantity

Decreasing Decreasing
EU28 EU28+

Trends in quality

Average current trend in quality

Unknown Unknown
EU28 EU28+

Conservation and management needs

The remaining natural beds are very few, scattered through the European Mediterranean countries. Whenever these are exploited, this has to be regulated through intervention measures (changes in the extent and amount of the extracted mussels per year). Also, a detailed mapping of the extent of the natural mussel beds is lacking and should be a priority for the countries that host this habitat.

List of conservation and management needs

  • Measures related to wetland, freshwater and coastal habitats
    • Restoring/Improving water quality
    • Restoring coastal areas
  • Measures related to marine habitats
    • Restoring marine habitats
  • Measures related to spatial planning
    • Establish protected areas/sites
    • Establishing wilderness areas/allowing succession
    • Legal protection of habitats and species
  • Measures related to hunting, taking and fishing and species management
    • Regulation/Management of fishery in marine and brackish systems
  • Measures related to urban areas, industry, energy and transport
    • Urban and industrial waste management
  • Measures related to special resouce use
    • Regulating/Managing exploitation of natural resources on sea


For each habitat a distribution map was produced from a wide variety of sources indicating known and potential occurrences of the habitat in 10x10 km grids within Europe. Occurrences in grid cells were given in two classes: actual distribution from relatively reliable sources (surveys, expert knowledge), and potential distribution based on models or less reliable indicators. Please download the fact sheet to see the map.

Geographic occurrence and trends

Seas Present or presence uncertain Current area of habitat (Km2) Recent trend in quantity (last 50 years) Recent trend in quality (last 50 years)
Gulf of Bothnia Present - Unknown
Greater North Sea
Aegian-Levantine Sea
Ionian Sea and the Central Mediterranean Sea
Western Mediterranean Sea
Baltic Proper
Black Sea

Extent of Occurrence, Area of Occupancy and habitat area

Extent of Occurrence (EOO) (Km2) Area of Occupancy (AOO) Current estimated Total Area Comment
EU28 1,031,556 73 Unknown EOO and AOO have been calculated on the available data. Although this data set is known to be incomplete the figures exceed the thresholds for threatened status.
EU28+ 73 Unknown EOO and AOO have been calculated on the available data. Although this data set is known to be incomplete the figures exceed the thresholds for threatened status.
AOO = the area occupied by a habitat measured in number of 10x10 km grid cells.
EOO = the area (km2) of the envelope around all occurrences of a habitat (calculated by a minimum convex polygon).

Characteristic species

The full list of characteristic species and genus are available above from the Summary. The species available in the EUNIS database are shown here.
Invertebrates Hexaplex trunculus
Invertebrates Modiolus barbatus
Invertebrates Mytilus galloprovincialis
Invertebrates Stramonita haemastoma
Species scientific name English common name Species group
Hexaplex trunculus Invertebrates
Modiolus barbatus Invertebrates
Mytilus galloprovincialis Invertebrates
Stramonita haemastoma Invertebrates

Vegetation types

Relation to vegetation types (syntaxa)

Not available

Other classifications

Not available
European Environment Agency (EEA)
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