Red List habitat classification > RL - Marine habitats > RLNEA - Atlantic > NEAA3.31 Atlantic silted kelp on marine low energy infralittoral rock

Atlantic silted kelp on marine low energy infralittoral rock

Quick facts

Red List habitat type code NEAA3.31
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 can be found in wave and tide-sheltered conditions with Laminaria hyperborea and/or Saccharina latissima on infralittoral bedrock and boulders.  It is typically subject to weak tidal streams and rather silty conditions. The associated seaweeds are silt-tolerant and include a high proportion of delicate filamentous types. Beneath the kelp canopy, the faunal component is generally less diverse than in kelp forests that develop in more exposed locations. Some areas, particularly in the lower infralittoral zone, are subject to intense grazing by urchins and chitons and subsequently may have poorly developed seaweed communities. In very sheltered conditions S.latissima may grow as a ‘cape form’ where there are often few associated seaweeds due to siltation, grazing or shading from the dense kelp canopy.

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 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

  • Pollution
    • Marine water pollution
    • Toxic chemical discharge from material dumped at sea
    • Non-synthetic compound contamination
    • Synthetic compound contamination
  • Natural System modifications
    • Human induced changes in hydraulic conditions
    • Modification of hydrographic functioning, general
    • Modification of water flow (tidal & marine currents)
    • Wave exposure changes
    • Dykes, embankments, artificial beaches, general
    • Sea defense or coast protection works, tidal barrages
    • Dykes and flooding defense in inland water systems
  • Climate change
    • Changes in abiotic conditions
    • Flooding and rising precipitations
    • Water flow changes (limnic, tidal and oceanic)
    • Wave exposure changes
    • Sea-level changes

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

Management of marine activities will be important to control factors leading to the decline in quantity and quality of this habitat. Integrated coastal zone management, which includes spatial planning measures and limits land claim and other activities that alter the tidal regime, are examples of beneficial measures. Others include the regulation of the construction of hard coastal defence structures, water quality improvement programmes to reduce the risk of toxic contamination, and measures to mitigate against climate change.

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
    • 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)
Celtic Seas Present Unknown Unknown Unknown
Greater North Sea
Bay of Biscay and the Iberian Coast

Extent of Occurrence, Area of Occupancy and habitat area

Extent of Occurrence (EOO) (Km2) Area of Occupancy (AOO) Current estimated Total Area Comment
EU28 1,210,154 584 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+ >584 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