Red List habitat classification > RL - Marine habitats > RLMED - Mediterranean > MEDA2.33 Communities of Mediterranean mediolittoral mud

Communities of Mediterranean mediolittoral mud

Quick facts

Red List habitat type code MEDA2.33
Threat status
Europe Vulnerable
EU Vulnerable
Relation to
Source European Red List habitat factsheet
European Red List of habitats reports
European Red List of habitats (Excel table)


This habitat is present in sheltered inlets and embayments which are not part of major estuarine systems. It may also form in areas that were previously rocky or cobble fields, but where pseudofaeces have accumulated from filter-feeding gastropods, leading to the presence of a thick layer of mud. Such a build up of pseudofaeces results in a bed that is very soft to walk on, and sediment which is anoxic to the surface.

Indicators of quality:

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

There are no commonly agreed indicators of quality for this habitat, although particular parameters may have been set in certain situations, e.g. protected features within Natura 2000 sites, where reference values 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

Approximately two-thirds of the Mediterranean coastline is currently urbanized and in the most industrial regions this increases to 75%. This urbanization has especially impacted deltas, estuaries and coastal lagoons, therefore it is reasonable to presume that these habitats have suffered declines in quantity and quality. It has not been possible to quantify this decline therefore this assessment is based on expert opinion.
This habitat has been assessed as Vulnerable for both the EU 28 and EU 28+ because of an estimated substantial reduction in quality. This is based on an intermediate decline affecting more than 50% of the habitat.
Red List Category Red List Criteria
Vulnerable C/D1
Red List Category Red List Criteria
Vulnerable C/D1

Confidence in the assessment

Red List of habitat categories and criteria descriptions

Pressures and threats

  • Urbanisation, residential and commercial development
    • Urbanised areas, human habitation
    • Industrial or commercial areas
    • Discharges
  • Pollution
    • Pollution to surface waters (limnic, terrestrial, marine & brackish)
    • Marine water pollution
    • Soil pollution and solid waste (excluding discharges)
  • Natural System modifications
    • Human induced changes in hydraulic conditions

Habitat restoration potential

The capacity for this habitat to recover once severely damaged is unknown.

Trends in extent

Average current trend in quantity

Decreasing Decreasing
EU28 EU28+

Trends in quality

Average current trend in quality

Decreasing Decreasing
EU28 EU28+

Conservation and management needs

There are various legal provisions and policies which relate to this habitat such as the ICZM Protocol of from Barcelona Convention. Beneficial measures include improving water quality and both direct and indirect effects of coastal development. Direct engagement of stakeholder in the planning of the management process, analysis of social and economic costs and benefits of different management options will be essential to the successful implementation of conservation actions. Other measures include better management of waste from industry and urbanisation, improving water quality and establishing marine protected areas and other spatial planning measures.

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
    • Legal protection of habitats and species
    • Manage landscape features
  • Measures related to urban areas, industry, energy and transport
    • Urban and industrial waste management
    • Specific management of traffic and energy transport systems
    • Managing marine traffic


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)
Adriatic Sea Present Unknown Decreasing Decreasing
Aegian-Levantine Sea
Ionian Sea and the Central Mediterranean Sea
Western Mediterranean 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 914,346 242 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+ >242 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

Not available

Vegetation types

Relation to vegetation types (syntaxa)

Not available

Other classifications

Not available
European Environment Agency (EEA)
Kongens Nytorv 6
1050 Copenhagen K
Phone: +45 3336 7100