Red List habitat classification > RL - Marine habitats > RLBAL - Baltic > BAL47 Infaunal communities in Baltic upper circalittoral coarse sediment and shell gravel not dominated by bivalves

Infaunal communities in Baltic upper circalittoral coarse sediment and shell gravel not dominated by bivalves

Quick facts

Red List habitat type code BAL47
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)


This is a Baltic Sea benthic habitat in the upper circalittoral where at least 90% of the substrate is coarse sediment or shell gravel according to the HELCOM HUB classification. Four associated biotopes have been described characterised by mixed infaunal macrocommunities with substrates ranging from coarse and well sorted shells and shell fragments (AB.E3X) to fine shell fragments (AB.E3Y), and also areas where the substrate is predominantly coarse and the biotope characterised by infaunal polychaetes (AB.I3M) or infaunal crustaceans (AB.I3N). In the latter case a sub-habitat identified by a large representation of Bathyporeia pilosa, which constitutes at least 50% of the biomass of the infaunal crustacean has also been described.

The habitat occurs in high energy areas, typically below 20m and for the coase sediments more usually below 30m. The community composition of macroinfauna is presumed to be different in the sand like shell gravel sand compared to coarser shell gravel of mainly semi-intact shells. These substrates support many different animals including non-burrowing animals but where the interstitial space is smaller burrowing polychaetes and amphipods can build tunnels using the small grains. The biotopes on shell gravel have a restricted distribution in the Baltic, especially where the substrate is comprised of  fine sand-like shell fragments as this has only been reported from The Belt Sea.

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 havebeen determined and applied on a location-specific basis. Diversity, abundance and biomass of the dominant. species and associated fauna are potential indicators of quality of this habitat

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

Threat status

Synthesis of Red List assessment

This habitat is present in all the Baltic Sea sub-basins sub-basins.There has been a decline in quantity of the associated biotope which occurs on fine sand-like shell fragments but quantitative data are lacking. One other biotope is considered to be stable and the remaining two have not been evaluated. There is insufficient data on which to base a historic trend assessment and estimates of future trends in quantity or quality.
The overall assessment for this EUNIS level 4 habitat has been based on the HELCOM (2013) assessments for the associated HELCOM HUB biotopes. Draft assessments were derived using a weighted approach whereby the HELCOM assessment outcomes were assigned a score. This was averaged across the relevant biotopes. The outcomes were reviewed by Baltic experts to reach a final conclusion. HELCOM (2013) assessed AB.E3Y as Near Threatened (B1a(ii)) and AB.I3N3 as Least Concern (A1). Biotopes AB.E3X and AB.I3M were not evaluated. Current expert opinion is that as the associated biotope which has shown some decline is small in extent compared to the other components of the habitat the assessment is Least Concern (A1) for both the EU 28 and EU 28+.
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

  • Pollution
    • Pollution to surface waters (limnic, terrestrial, marine & brackish)
    • Nutrient enrichment (N, P, organic matter)
  • Climate change
    • Changes in abiotic conditions
    • pH-changes

Habitat restoration potential


Trends in extent

Average current trend in quantity

Decreasing Decreasing
EU28 EU28+

Trends in quality

Average current trend in quality

Unknown Unknown
EU28 EU28+

Conservation and management needs

The extent and occurrence of the biotope needs to be mapped in more detail to determine its environmental requirements. Measures to reduce eutrophication will benefit this habitat type.

List of conservation and management needs

  • Measures related to wetland, freshwater and coastal habitats
    • Restoring/Improving water quality
  • Measures related to marine habitats
    • Other marine-related measures


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)
Baltic Proper Present Unknown Unknown Decreasing
Belt Sea
Gulf of Bothnia
Gulf of Finland
Gulf of Riga
The Sound

Extent of Occurrence, Area of Occupancy and habitat area

Extent of Occurrence (EOO) (Km2) Area of Occupancy (AOO) Current estimated Total Area Comment
EU28 >50,000 Unknown Unknown This habitat is present in all the Baltic sub-basins however there is insufficient information for accurate calculation of EOO and AOO.
EU28+ Unknown Unknown This habitat is present in all the Baltic sub-basins however there is insufficient information for accurate calculation of EOO and AOO.
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.
Invertebrates Bathyporeia pilosa
Invertebrates Pygospio elegans
Species scientific name English common name Species group
Bathyporeia pilosa Invertebrates
Pygospio elegans Invertebrates

Vegetation types

Relation to vegetation types (syntaxa)

Not available

Other classifications

Not available
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