Red List habitat classification > RL - Marine habitats > RLNEA - Atlantic > NEAA5.45 Atlantic lower circalittoral mixed sediment

Atlantic lower circalittoral mixed sediment

Quick facts

Red List habitat type code NEAA5.45
Threat status
Europe Vulnerable
EU Vulnerable
Relation to
Source European Red List habitat factsheet
European Red List of habitats reports
European Red List of habitats (Excel table)


This habitat comprises offshore (deep) fully saline circalittoral habitats with slightly muddy, mixed gravelly sand and stones or shell. It may cover large areas of the offshore continental shelf in depths ranging from 20-150m although there are relatively little data available on its precise extent. This and similar habitats are known to often be highly diverse supporting large numbers of infaunal polychaete and bivalve species. Epibenthos include sea anemones, sponges and sea urchins.

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 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.


Characteristic species
For full habitat description, please download the habitat factsheet.

Threat status

Synthesis of Red List assessment

This habitat has a large natural range in the North East Atlantic. A combination of survey data and modelling indicates that it does not have a restricted geographical distribution nor occur in only a few locations in the North East Atlantic and therefore qualifies as Least Concern under criterion B.
Most sedimentary benthic systems on the continental shelf of Europe have been modified by fishing activities, particularly bottom trawls and dredging, in the last 100 years and this habitat remains under fishing pressure. Disturbance of the substratum due to intensive fishing activities using bottom trawls or dredges can damage or modify infaunal communities, with burrowing echinoderms and bivalves being particularly vulnerable and therefore affect habitat quality. Data for 2103/2014 year has revealed that more than 70% of this habitat in the North Sea and Celtic Sea was subject to fishing pressure by bottom otter, beam and mid-water trawls. Given that this is based on a single year of data, and that this type of pressure has been taking place for decades, it is likely to be an underestimate of the total area of this habitat which has been subject to such pressure. Cumulative impacts are therefore also likely to have occurred.
Expert opinion is that there has been a substantial reduction in quality of this habitat, most likely an intermediate decline affecting more than 50% of its extent although it is clear that in some locations there has also been a severe decline. The severity will depend on factors such as the intensity and frequency of disturbance. This habitat has therefore been assessed as Vulnerable for both the EU 28 and EU 28+ because of both past and likely continuing declines in quality.
Red List Category Red List Criteria
Vulnerable C/D1
Red List Category Red List Criteria
Vulnerable C/D1

Confidence in the assessment

Red List of habitat categories and criteria descriptions

Pressures and threats

  • Biological resource use other than agriculture & forestry
    • Fishing and harvesting aquatic resources
    • Professional active fishing
    • Benthic or demersal trawling
    • Benthic dredging
  • Pollution
    • Marine water pollution
    • Oil spills in the sea
    • Toxic chemical discharge from material dumped at sea
    • Non-synthetic compound contamination
    • Synthetic compound contamination
    • Radionucleide contamination
    • Introduction of other substances (e.g. liquid, gas)

Habitat restoration potential

The capacity for this habitat to recover once severly damaged is unknown.

Trends in extent

Average current trend in quantity

Unknown Unknown
EU28 EU28+

Trends in quality

Average current trend in quality

Decreasing Decreasing
EU28 EU28+

Conservation and management needs

Beneficial management measures for this habitat include the regulation of fishing methods and the control of other types of activities such as sand and gravel extraction which damage or disturb seabed communities. In addition, the control of chemical contaminants from discharges and spills may be important, particularly when this habitat occurs close to coasts and river/estuarine catchments.

List of conservation and management needs

  • Measures related to wetland, freshwater and coastal habitats
    • Restoring/Improving water quality
  • Measures related to marine habitats
    • Restoring marine habitats
  • 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
  • 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 Decreasing 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 5,109,391 1,232 >31,057 The area estimate for this habitat has been derived from a synthesis of EUNIS seabed habitat geospatial information for the European Seas but is recognised as being an underestimate.
EU28+ >1,232 >31,057 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