Red List habitat classification > RL - Marine habitats > RLNEA - Atlantic > NEAA3.12 Kelp and seaweed communities on sediment-affected or disturbed Atlantic infralittoral rock

Kelp and seaweed communities on sediment-affected or disturbed Atlantic infralittoral rock

Quick facts

Red List habitat type code NEAA3.12
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)


Infralittoral rock habitat which is subject to disturbance through the mobility of the substratum (boulders or cobbles), abrasion/covering  by nearby coarse sediments, or suspended particulate matter (sand). The associated communities can be quite variable in character, depending on the particular conditions. Laminaria hyperborea and red seaweed communities typical of stable open coast rocky habitats are replaced by those which include more ephemeral species or which are tolerant of sand and gravel abrasion. As such Saccharina latissima, Saccorhiza polyschides or Halidrys siliquosa may be prominent components of the associated community. The foliose green seaweed Ulva spp. is fast to colonise newly cleared areas of rock and is often present, along with the foliose brown seaweed Dictyota dichotoma

Due to the disturbed nature of this habitat, fauna are generally sparse, being confined to encrusting bryozoans and/or sponges, such as Halichondria panacea and the gastropod Gibbula cineraria

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

Detailed information on the abundance and extent of this habitat is lacking, but it is known to have a widespread distribution. Data on the quantity and quality of this habitat, including any historical or recent, trends across the region are unknown.
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 given 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

  • Pollution
    • Marine water pollution
    • Oil spills in the sea
    • Toxic chemical discharge from material dumped at sea
    • Input of litter (solid waste matter)
  • Invasive, other problematic species and genes
    • Invasive non-native species
  • Natural System modifications
    • Human induced changes in hydraulic conditions
    • Modification of hydrographic functioning, general
    • Siltation rate changes, dumping, depositing of dredged deposits
    • Dykes, embankments, artificial beaches, general
  • Climate change
    • Changes in abiotic conditions
    • Temperature changes (e.g. rise of temperature & extremes)
    • Droughts and less precipitations
    • Flooding and rising precipitations
    • pH-changes
    • Water flow changes (limnic, tidal and oceanic)
    • Wave exposure changes
    • Sea-level changes
    • Changes in biotic conditions
    • Habitat shifting and alteration
    • Desynchronisation of processes
    • Decline or extinction of species
    • Migration of species (natural newcomers)

Habitat restoration potential


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 include the regulation of coastal developments that might affect adjacent areas of this habitat by altering sediment movement patterns and wave exposure. Also pollution control and regulation of discharges to the marine environment, the development of contingency plans to be followed in the event of a major pollution incident, and control on the potential introduction of non-native invasive species.

List of conservation and management needs

  • Measures related to wetland, freshwater and coastal habitats
    • Restoring/Improving water quality
  • Measures related to spatial planning
    • Other marine-related measures
    • Establish protected areas/sites


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 495,868 168 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+ >168 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