Red List habitat classification > RL - Marine habitats > RLNEA - Atlantic > NEAA1.44 Communities of Atlantic littoral caves and overhangs

Communities of Atlantic littoral caves and overhangs

Quick facts

Red List habitat type code NEAA1.44
Threat status
Europe Least Concern
EU Least Concern
Relation to
Source European Red List habitat factsheet
European Red List of habitats reports
European Red List of habitats (Excel table)


Where caves and overhangs occur on rocky shores, the shaded nature of the habitat diminishes the amount of desiccation suffered by biota during periods of low tides, allowing certain species to proliferate. In addition, the amount of scour, wave surge, sea spray and penetrating light determines the unique community assemblages found in upper-, mid- and lower-shore caves and overhangs.

Intertidal cave systems may be a few meters long or may extend considerable distances inland, while supporting fully marine biological communities. The flooded lava tube of Cueva de los Verdes – Jameos del on Lanzarote, in the Canary Islands penetrates some 2 km into the island. Biotopes from the surrounding shore or any of the fucoid communities occasionally extend into cave entrances and sometimes some distance beyond. Other open shore biotopes may also be found within caves, such as the that characterised by the green seaweed Prasiola stipitata on cave roofs favoured by roosting  birds, and localised patches of green algae where freshwater seepage influences the rock. Rockpools containing encrusting coralline algae, fucoids and kelp and hydroids and littorinid molluscs may occur also on the floor of cave entrances.

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

The presence of this habitat type in the North East Atlantic is well known. It is widespread and present in many locations. Although the geographical areas in which it occurs are known in general terms (cliffed coastlines) there is a lack of quantitative data on extent and quality. Threats and pressures on this habitat have been identified but the extent is considered to have been mostly stable over the last 50 years, with no substantial reduction in quality. The potential for future change due to changes in erosive processes, for example as a result of increased storminess associated with climate change is unknown.
The current Red List assessment is that this habitat qualifies as Least Concern in the EU 28 and EU 28+. This is because although changes will have taken place no significant trends in extent have been identified. The habitat also does not have a narrow geographical range and its distribution is such that the identified threats are unlikely to affect all localities at once.
Red List Category Red List Criteria
Least Concern -
Red List Category Red List Criteria
Least Concern -

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
    • Professional passive fishing
    • Leisure fishing
  • Human intrusions and disturbances
    • Outdoor sports and leisure activities, recreational activities
    • Nautical sports
    • Recreational cave visits
    • Scubadiving, snorkelling
    • Disturbance of species
  • Pollution
    • Marine water pollution
    • Oil spills in the sea

Habitat restoration potential

This is a naturally dynamic habitat with associated communities able to recover relatively rapidly if the cave structure remains present.

Trends in extent

Average current trend in quantity

Stable Stable
EU28 EU28+

Trends in quality

Average current trend in quality

Stable Stable
EU28 EU28+

Conservation and management needs

Intertidal cave habitats are present within some coastal and marine protected areas. Conservation and management measures include codes of conduct on access (e.g. to avoid disturbance to seals), regulation of coast protection works and coastal development. Oil spill contingency plans may specify actions to be taken in the event of intertidal cave habitats being affected.

List of conservation and management needs

  • Measures related to marine habitats
    • Other marine-related measures
  • Measures related to spatial planning
    • Establish protected areas/sites
    • Legal protection of habitats and species
  • 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 Stable Stable
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 2,173,829 672 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+ >672 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

The full list of characteristic species and genus are available above from the Summary. The species available in the EUNIS database are shown here.
Algae Cladophora rupestris
Algae Hildenbrandia rubra
Algae Prasiola stipitata
Invertebrates Munidopsis polymorpha
Species scientific name English common name Species group
Cladophora rupestris Algae
Hildenbrandia rubra Algae
Prasiola stipitata Algae
Munidopsis polymorpha Invertebrates

Vegetation types

Relation to vegetation types (syntaxa)

Not available

Other classifications

Not available
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