Red List habitat classification > RL - Marine habitats > RLNEA - Atlantic > NEAA4.23 Communities on Atlantic soft circalittoral rock

Communities on Atlantic soft circalittoral rock

Quick facts

Red List habitat type code NEAA4.23
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 occurs on moderately wave-exposed, circalittoral soft rock such as soft chalk, clay or peat exposures, in areas subject to moderately strong tidal streams. As it is found in highly turbid water conditions it can be present in shallow water and sometimes even around the low water mark. The associated biotopes may therefore sometimes be present in the infralittoral and even the littoral zone. Soft chalk and firm clay are often too soft for sessile filter-feeding animals to attach and thrive in large numbers, so there is generally an extremely impoverished epifauna, particularly on upward-facing surfaces. The vertical rock faces may be somewhat richer. The rock is sufficiently soft to be bored by bivalves such as Pholas dactylus, and by polychaete worms Polydora sp. which may form a complete cover in highly turbid conditions. Carbonate cemented structures formed by methane seeps ('bubbling reefs') are also examples of this habitat. These have been reported from the northern Kattegat and the Skagerrak where they are present as slabs or pillars up to 4m high and are colonised by anthozoans Metridium senile, Alcyonium digitatum and Tealia felina as well as species which bore into the surfaces such as the
sponge Cliona celata, the polychaete Dodocaceria concharum and the bivalve Hiatella sp. The three dimensional structures also provides shelter for mobile species such as crabs and lobster, cod and pollack.

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 beendetermined 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 survey information reveals that it has a widespread distribution (e.g. sublittoral chalk habitat present on the south east and south coasts of the UK and the Channel coast of France and the island of Helgoland in the southern North Sea, and 'bubbling reefs' in the Kattegat). There is insufficient information to provide an overall estimate of historical, recent and possible future trends in quantity and 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 any trends in quantity and quality and the fact that its overall distribution is unknown.
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

  • Transportation and service corridors
    • Shipping lanes, ports, marine constructions
  • Biological resource use other than agriculture & forestry
    • Fishing and harvesting aquatic resources
    • Professional active fishing
    • Benthic or demersal trawling
  • Natural System modifications
    • Human induced changes in hydraulic conditions
    • Removal of sediments (mud...)
    • Modification of hydrographic functioning, general
    • Dykes, embankments, artificial beaches, general
    • Sea defense or coast protection works, tidal barrages
  • Climate change
    • Changes in abiotic conditions

Habitat restoration potential

Where the substrate is damaged this habitat is irreplaceable. Where the associated communities have been affected, timescales and ability to recover are 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

Examples of this habitat occur within Marine Protected Areas where there may be management measures to avoid damage. Useful measures would include limitations on activities which cause direct damage to the soft sediment, such as dredging or the use of towed demersal fishing gears.

List of conservation and management needs

  • Measures related to spatial planning
    • Establish protected areas/sites
  • Measures related to hunting, taking and fishing and species management
    • Regulation/Management of fishery in marine and brackish systems


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 597,111 63 Unknown EOO and AOO have been calculated on the available data. Although this data set is known to be incomplete the figures exceed the threshold for threatened status for EOO.
EU28+ 63 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)
Kongens Nytorv 6
1050 Copenhagen K
Phone: +45 3336 7100