Communities of Atlantic circalittoral caves and overhangs
|Red List habitat type||code NEAA4.71|
|Source||European Red List habitat factsheet|
|European Red List of habitats reports|
|European Red List of habitats (Excel table)|
Caves and overhanging rock in the circalittoral zone, away from significant influence of strong wave action. This habitat generally occurs in open coast waters or on wave sheltered coasts with moderate tidal flow. Caves and overhangs display a wide range of structural and ecological variation, depending on the prevailing physical and geological conditions. Those which have extensive areas of vertical and overhanging rock, and those that extend deeply into the rock, generally support the widest range and highest diversity of species. In the circalittoral zone these are characterised by sponges and anthozoans. Resident, seasonal and occasional species of fish are also present in sublittoral caves. Extensive cave systems, such as the flooded lava tubes in the Canary Islands, may become anchialine at their innermost extents because of the long residence time (months to years) of seawater. In such systems, the extent of saltwater intrusion, its stratification and the residence time of seawater (which can be from months to years) has resulted in a specialised fauna with pronounced morphological, physiological, biochemical and behavioural adaptations, such as the blind crab Munidopsis polymorpha.
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 ma yface; 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 overtime.
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.
Cave biotopes can be broadly divided into those characterised by long lived species and those characterised by ephemeral and scour tolerant species. Long lived species such as cup corals and sponges may be targeted as indicators that a cave system has remained undisturbed. Individuals or individual colonies of such species might represent suitable for monitoring change.
Synthesis of Red List assessment
|Red List Category||Red List Criteria|
|Red List Category||Red List Criteria|
Confidence in the assessment
Pressures and threats
- Human intrusions and disturbances
- Outdoor sports and leisure activities, recreational activities
- Scubadiving, snorkelling
- Natural System modifications
- Human induced changes in hydraulic conditions
- Siltation rate changes, dumping, depositing of dredged deposits
Habitat restoration potential
Several of the species typically present in this habitat appear to have short-lived benthic larvae, e.g. the soft coral Alcyonium hibernicum which broods planulae larvae that are released at a late development phase and so probably has a short planktonic life. Leptopsammia pruvoti also seems to have short-lived planulae larvae which may settle immediately or very soon after release. In the case of cup corals (Caryophyllia spp. Hoplangia spp.), growth rates are smaller compared to other zoanthids colonising cave walls and roofs.
Sponges are likely to have a longer lived larva and others species, such as the zoanthid anemones Parazoanthus axinellae and Parazoanthus dixoni, reproduce asexually to produce large colonies so may become restablished relatively rapidly if a source population is present and conditions are favourable.
Trends in extent
Average current trend in quantity
Trends in quality
Average current trend in quality
Conservation and management needs
List of conservation and management needs
- Measures related to marine habitats
- Other marine-related measures
- Measures related to spatial planning
- Establish protected areas/sites
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|
|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||unknown||unknown||Unknown||There is insufficient quantiative data to make an accurate estimate of EOO and AOO however this habitat is widespread.|
|EU28+||unknown||Unknown||here is insufficient quantiative data to make an accurate estimate of EOO and AOO however this habitat is widespread.|
EOO = the area (km2) of the envelope around all occurrences of a habitat (calculated by a minimum convex polygon).
Relation to other habitat types mentioned in legal instruments
|Legal text||Annex||Name in legal text||Code in legal text||
|Council Directive 92/43/EEC of 21 May 1992 on the conservation of natural habitats and of wild fauna and flora - consolidated version 01/01/2007||Annex I: natural habitat types of community interest whose conservation requires the designation of special areas of conservation||Submerged or partially submerged sea caves||8330||Narrower||http://ec.europa.eu/environm...rective/index_en.htm|