Red List habitat classification > RL - Marine habitats > RLNEA - Atlantic > NEAA3.21 Kelp and red seaweeds on moderate energy Atlantic infralittoral rock

Kelp and red seaweeds on moderate energy Atlantic infralittoral rock

Quick facts

Red List habitat type code NEAA3.21
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 is found on infralittoral rock in areas subject to moderate wave exposure, or on more sheltered coasts in areas subject to moderately strong tidal streams. Kelp forests develop in these situations and both the rock surfaces and kelp holdfasts and stipes are typically colonised by other algae. These are predominantly red algae with  good variety of delicate filamentous types. The most conspicuous sessile fauna include ascidians, bryozoans, echinoderms, crustaceans, and bryozoans.

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. The depth limit of kelp and/or red seaweeds is used in some countries as a Water Framework Directive parameter for assessing ecological status.

Characteristic species:

On bedrock and stable boulders there is typically a narrow band of kelp Laminaria digitata in the sublittoral fringe which lies above a Laminaria hyperborea forest and park. Other seaweeds typically present include Saccharina latissima, Delesseria sanguinea, Plocamium cartilagineum, Phycodrys rubens, Corallinaceae and Dictyota dichotoma. Characteristic fauna include Halichondria panacea, Urticina felina, Pomatoceros triqueter, Gibbula cineraria, Asterias rubens, and, Echinus esculentus as well as bryozoans Membranipora membranacea and Electra pilosa.


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

Threat status

Synthesis of Red List assessment

Survey information confirms that this habitat has a widespread distribution in the North East Atlantic. It has been studied in detail in some localities however there is insufficient information to determine whether there have been any historical, recent and possible future trends in quantity or 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 its 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

  • Urbanisation, residential and commercial development
    • Urbanised areas, human habitation
  • Biological resource use other than agriculture & forestry
    • Fishing and harvesting aquatic resources
  • Pollution
    • Pollution to surface waters (limnic, terrestrial, marine & brackish)
    • Nutrient enrichment (N, P, organic matter)
    • Marine water pollution
    • Oil spills in the sea
    • Toxic chemical discharge from material dumped at sea
  • Natural System modifications
    • Human induced changes in hydraulic conditions
  • Climate change
    • Changes in abiotic conditions
    • Temperature changes (e.g. rise of temperature & extremes)

Habitat restoration potential

The capacity for this habitat to recover once severely 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

The main approaches to the conservation and management of this habitat could be through control of seaweed harvesting, the management of activities that damage or disturb seabed communities, or that change the hydrological regime, such coastal development and the construction of hard coastal defence structures. In addition, the maintenance of controls of chemical discharges from outfalls to reduce the risk of contamination effects should also be considered. Such measures may be introduced within the framework of Marine Protected Areas.

List of conservation and management needs

  • Measures related to wetland, freshwater and coastal habitats
    • Restoring/Improving water quality
  • Measures related to marine habitats
    • Other marine-related measures
  • Measures related to spatial planning
    • Establish protected areas/sites
  • 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)
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 1,825,638 579 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+ >579 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