Red List habitat classification > RL - Marine habitats > RLMED - Mediterranean > MEDA5.47 Communities of Mediterranean lower circalittoral (shelf-edge) detritic bottoms or open-sea detritic bottoms

Communities of Mediterranean lower circalittoral (shelf-edge) detritic bottoms or open-sea detritic bottoms

Quick facts

Red List habitat type code MEDA5.47
Threat status
Europe Data Deficient
EU Data Deficient
Relation to
Source European Red List habitat factsheet
European Red List of habitats reports
European Red List of habitats (Excel table)


This habitat develops on a mixture of gravel sediments, sand and mud. The fine part of the mix appears in a greater proportion than in the sediments that support the coastal detritic biocenosis. The gravel, mainly organogenic, is largely formed by calcareous debris of quaternary thanatocenoses. The open-water detritic bottoms normally belong to the lower circalittoral and constitute the deepest layer of the circalittoral zone on soft bottoms. These communities are present in detritic bottoms with abundance of dead shells, bryozoans and coral skeletons. This habitat hosts a biocenosis of great diversity and abundance. The high production of plankton at the shelf break makes it an important feeding ground for large shoals of fish and cetaceans. Some facies of the edge of the platform, such as the one made by the crinoid Leptometra phalangium, increase the structural complexity of the habitat enhancing the abundance and species richness. They also host a high abundance of spawners of commercially important species, e.g. Red Mullet (Mullus barbatus), Hake (Merluccius merluccius), Blue Whiting (Micromesistius poutassou) and Trisopterus minutus capelanus. Thus, the conservation of shelf-edge habitat is also important with a view to reducing the fish mortality in the sensitive phases (recruitment, spawning, postspawning) of the life cycle of demersal fish species.


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

This is a very poorly studied habitat type and only few reports exist on its distribution, with only a description of the composing communities along some EU Mediterranean countries available. Moreover, data on quality or quantity is lacking and territorial data is not available for much of its distribution range. Several scientific reports highlighted however the impact due to demersal trawling activities. Althought this habitat has a large Extent of Occurrence (EOO) and Area of Occupancy (AOO), and therefore qualifies as Least Concern under criterion B, the habitat is assessed as Data Deficient both at the EU 28 and EU 28+ levels because of the lack of information on its trends in quantity and quality.
Red List Category Red List Criteria
Data Deficient -
Red List Category Red List Criteria
Data Deficient -

Confidence in the assessment

Red List of habitat categories and criteria descriptions

Pressures and threats

  • Biological resource use other than agriculture & forestry
    • Professional active fishing
    • Benthic or demersal trawling
    • Benthic dredging

Habitat restoration potential

Leptometra phalangium is typical of the most productive and species-rich shelf-edge environments and easily disturbed by trawling. Individuals are fragile and suffer a strong impact due to demersal trawling (by removal and death). Their reduction might also affect other components of the community and increase fish mortality rates in crucial life history stages of fishes, such as juveniles and spawners. It is unknown how easily these communities can recover, particularly if fishing activities do not stop.

Trends in extent

Average current trend in quantity

Unknown Unknown
EU28 EU28+

Trends in quality

Average current trend in quality

Decreasing Decreasing
EU28 EU28+

Conservation and management needs

Basic knowledge on the habitat and its distribution in the Mediterranean, its species assemblages, its species biology (distribution, abundance, habitat preferences, life cycles) and monitoring data on trends is needed to improve spatial planning in general, and strategic planning of particular human activities. Monitoring of spatial distribution of fishing effort is also recommended.
Designation of Marine Protected Areas (MPA) and Fisheries Restricted Areas (FRAs) in sites where this habitat occurs, particularly where Leptometra phalangium, Neolampas rostellata and Ophiacantha setosa occur, should be established to create a representative network of Mediterranean MPAs. This will also help to control the fishing effort, especially the establishment of closed areas over part of the distribution of this habitat to protect juvenile and spawning fish and fragile benthic communities.

List of conservation and management needs

  • Measures related to spatial planning
    • Establish protected areas/sites
    • 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 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)
Adriatic Sea Present Unknown Decreasing Unknown
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 1,038,660 1,242 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+ >1,242 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)
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