Red List habitat classification > RL - Marine habitats > RLNEA - Atlantic > NEAA4.21 Echinoderms and crustose communities on moderate energy Atlantic upper circalittoral rock

Echinoderms and crustose communities on moderate energy Atlantic upper circalittoral rock

Quick facts

Red List habitat type code NEAA4.21
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 occurs on wave-exposed, moderately strong to weakly tide-swept, circalittoral bedrock and boulders. Echinoderms, faunal and algal crusts (red encrusting algae) dominate, giving a sparse appearance. It occurs from depths, where the light becomes insufficient for macroalgae down to about 100 meters although occasionally also encountered in deeper water.

On vertical faces there may be dense aggregations of the cup coral Caryophyllia smithii, large expanses of encrusting red algae or, in conditions of moderate exposure, the soft coral Alcyonium digitatum. The sea fan Swiftia pallida can be present on silty substratum and the anemone Urticina feline and the sponge Ciocalypta penicillus at the sand-rock interface. The polychaete Pomatoceros triqueter can be locally abundant, and may in some cases cover far more rock surface than A. digitatum, especially on vertical faces. Clumps of robust hydroids such as Abietinaria abietina and Nemertesia antennina occur occasionally.

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

There are a lack of quantitative data on extent and condition of this habitat. Although it is known to be widespread, exceeding thresholds of EOO and AOO for Red Listing, there is insufficient information to provide an overall estimate of historical, recent and possible future trends in quantity and quality.
This habitat has a large EOO and AOO, and therefore qualifies as Least Concern under criterion B. However the habitat is assessed as Data Deficient both at the EU 28 and EU 28+ levels because of the lack of information on area and any 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
    • Fishing and harvesting aquatic resources
    • Professional active fishing
  • Pollution
    • Marine water pollution
  • Natural System modifications
    • Human induced changes in hydraulic conditions
    • Removal of sediments (mud...)
    • Siltation rate changes, dumping, depositing of dredged deposits
    • Sea defense or coast protection works, tidal barrages

Habitat restoration potential

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

Trends in extent

Average current trend in quantity

Unknown Unknown
EU28 EU28+

Trends in quality

Average current trend in quality

Unknown Unknown
EU28 EU28+

Conservation and management needs

Beneficial management measures for this habitat would include regulation of fishing methods to reduce physical damage and incidental siltation, coastal development, and dredging and dumping of dredge spoils. This may be promoted in management schemes for Marine Protected Areas or integrated coastal management schemes. Measures to maintain water quality would also be beneficial.

List of conservation and management needs

  • Measures related to marine habitats
    • Other marine-related measures
  • Measures related to spatial planning
    • Establish protected areas/sites
  • Measures related to hunting, taking and fishing and species management
    • Regulation/Management of fishery in marine and brackish systems


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)
Bay of Biscay and the Iberian Coast Present Unknown Unknown Unknown
Celtic Seas
Greater North 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 604,383 324 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+ >324 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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1050 Copenhagen K
Phone: +45 3336 7100