Red List habitat classification > RL - Marine habitats > RLNEA - Atlantic > NEAA5.43 Marine Atlantic infralittoral mixed sediments

Marine Atlantic infralittoral mixed sediments

Quick facts

Red List habitat type code NEAA5.43
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 comprises mixed (heterogeneous) sediments in fully marine or near fully marine conditions, supporting various animal-dominated communities, with relatively low proportions of seaweeds even though it is an infralittoral habitat. The sediment  may include well-mixed muddy gravelly sands or very poorly sorted mosaics of shell, cobbles and pebbles embedded in mud, sand or gravel. Due to the range of the sediment types that support this habitat, the  communities may vary considerably, including those characterised by bivalves, polychaetes and file shells. The very varied sediment composition also means  that the species diversity and biomass can be high. This has resulted in many species being described as characteristic of this habitat type, but most, in general contribute only a small proportion of the overall similarity.  Where the sediment is unstable, most of the fauna are mobile such as hermit crabs, netted dogwhelks and gobies. However, there may also be the dahlia anemones partially buried in the sediments  as well as cobbles or pebble with encrustations of keelworrns.

Indicators of Quality:

Both biotic and abiotic indicators have been used to describe marine habitat quality. These include; the presence of particular species, water quality parameters, levels of exposure to particular pressure as well as 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

Survey information confirms that this habitat has a widespread distribution in the North East Atlantic. There are documented changes in the quality of this habitat and some of the associated biotopes are known to have suffered substantial declines in quality and quantity. Nevertheless there is insufficient information to determine the overall trend for the North East Atlantic.
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 lack of information on its 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

  • Biological resource use other than agriculture & forestry
    • Fishing and harvesting aquatic resources
    • Professional active fishing
    • Benthic or demersal trawling
  • Pollution
    • Marine water pollution
    • Toxic chemical discharge from material dumped at sea
    • Synthetic compound contamination
    • Radionucleide contamination
  • 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 biotic conditions
    • Migration of species (natural newcomers)

Habitat restoration potential

Timescale between incidents of damaging activity, the type of damaging activity and the predominant species, influences recovery. Studies have shown that recovery times following dredging were significantly shorter for short-lived species (<1 – 3 years), free-living and tube-dwelling species and for scavenging or opportunistic species, than for medium-lived species (3 – 10 years), burrow-dwelling species and suspension feeders. Free living species are also likely to recolonise areas more quicky that those that grow attached to the substratum and have an erect or stalked body form such as seapens. Differences in therecoverability of different species groups following fishing may result in changes in community composition and ecosystem functioning over the long term.

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

Beneficial management measures for this habitat include the regulation of fishing activities which damage or disturb seabed communities, the regulation and control of coastal developments and of the construction of hard coastal defence structures. In some instances such measures are part of the mangement of Marine Protected Areas. In addition, the regulation of chemical discharges from outfalls, measures to reduce and mitigate against climate change and sea level rise, and and strategies to prevent the introduction of invasive species may also benefit this habitat.

List of conservation and management needs

  • Measures related to wetland, freshwater and coastal habitats
    • Restoring/Improving water quality
    • Restoring/Improving the hydrological regime
  • 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 5,014,877 1,015 >15,885 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+ >1,015 >15,885 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