Red List habitat classification > RL - Marine habitats > RLBAL - Baltic > BAL42 Epifaunal communities on Baltic circalittoral rock and mixed substrata (predominantly hard)

Epifaunal communities on Baltic circalittoral rock and mixed substrata (predominantly hard)

Quick facts

Red List habitat type code BAL42
Threat status
Europe Near Threatened
EU Near Threatened
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 aphotic zone where at least 90% of the substrate is rock, boulders or stones as well as on mixed (predominantly hard) substrates where the percentage of rock is between 10-90% according to the HELCOM HUB classification. The HELCOM HUB identifies 14 different biotopes associated with the habitat. In each case the dominate species or species group (in the biotope title) constitutes at least 50% of the biomass. These are: epibenthic bivalves, chordates, cnidarians, bryozoans, crustaceans and sponges. 

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 been determined and applied on a location-specific basis. The amount of sediment covering the hard surfaces and the diversity, abundance and biomass of associated fauna are potential quality indicators for this habitat. 

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

Threat status

Synthesis of Red List assessment

There have been significant declines (up to 30%) in the extent of many of the associated biotopes and predicted future declines. Some decline in quality (up to an estimated 10%) has also been reported for some of the associated biotopes but the overall trend is uncertain. The lack of quantitative data means precise figures cannot be given at the present time.
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 eight of the associated biotopes as Near Threatened (A1), and eight as Least Concern (A1). Two were not evaluated. Given the past and predicted future declines in extent of this habitat, current expert assessment is that it should be assessed as Near Threatened (A1) for both the EU 28 and EU 28+.
Red List Category Red List Criteria
Near Threatened A1
Red List Category Red List Criteria
Near Threatened A1

Confidence in the assessment

Red List of habitat categories and criteria descriptions

Pressures and threats

  • Mining, extraction of materials and energy production
    • Mining and quarrying
    • Sand and gravel extraction
    • Exploration and extraction of oil or gas
  • Biological resource use other than agriculture & forestry
    • Fishing and harvesting aquatic resources
    • Professional active fishing
    • Benthic dredging
  • Pollution
    • Pollution to surface waters (limnic, terrestrial, marine & brackish)
    • Nutrient enrichment (N, P, organic matter)
    • Input of contaminants (synthetic substances, non-synthetic substances, radionuclides) - diffuse sources, point sources, acute events

Habitat restoration potential

The associated biotopes dominated by bryozoans have the potential to fairly quickly recolonise destroyed areas after the pressure/threat has been removed and the environmental conditions restored. Recovery rates are unknown for the other biotopes.

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

All actions which aim to reduce physical disturbance of aphotic stony bottoms in the Baltic Sea are important for the conservation of epifaunal turf communities on rock and mixed substrates. In addition, appointing protected areas where the habitat is known to occur and restricting bottom trawling, offshore construction work and gravel extraction in these areas would constitute an effective conservation measure. Further mapping activities should be carried out to better delineate the area of occurrence.

List of conservation and management needs

  • Measures related to wetland, freshwater and coastal habitats
    • Restoring/Improving water quality
  • Measures related to spatial planning
    • Establish protected areas/sites
  • 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)
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

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