Red List habitat classification > RL - Marine habitats > RLBLS - Black Sea > BLSA4.24 Invertebrate-dominated Pontic circalittoral rock

Invertebrate-dominated Pontic circalittoral rock

Quick facts

Red List habitat type code BLSA4.24
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)


Circalittoral rock starts at the lower limit of distribution of photophilic plants and ends where the circalittoral rocky substrate gives way to sediments. On the Northwestern Black Sea shelf the habitat occurs on rocky coasts in depths between 10-15 m (depending on local conditions of light penetration, the upper limit of the habitat is defined as the lower limit of photophilic plants) down to 30-70m (depending on how deep rocky reefs occur at the location). The fauna is highly diverse, including many invertebrate and fish species which occur only in this habitat, some of them rare or protected. The habitat is very important due to the crucial ecological role of mussels in the self-cleansing capacity of the ecosystem and in benthic- pelagic coupling. One square meter of mussel-covered circalittoral rock has a clearance rate of 1.3 to 7.1 m3 m-2  h-1  and is able to filter 31-170 m3 of seawater per day. Biological production of this habitat is usually around 6 kg m-2  but can exceed 10 kg m-2  in favourable conditions, with complex foodweb linking it to other habitats. Also, it is an important feeding ground, nursery and refuge for many commercially valuable fish species and it provides the biofiltering capacity essential for maintaining the quality of nearshore waters.

Indicators of quality:

The following parameters and thresholds have been established for Romania:

1. Cover of Mytilus galloprovincialis (in the habitat subtype where it is dominant) ≥ 50%

2. Cover of invertebrate crusts, turfs and canopies (in the habitat subtype where they dominate) ≥ 80%

3. Median shell length of Mytilus galloprovincialis ≥ 50 mm SL

4. Live biomass of Mytilus galloprovincialis where dominant ≥ 6kg m-2

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

Threat status

Synthesis of Red List assessment

In the EU 28 the habitat type is assessed as Vulnerable under Criterion C/D1. There has been an intermediate decline affecting >50%. There is no data to support this. It is based on expert opinion.
In the EU 28+ the habitat type is assessed as Vulnerable under Criterion C/D1. There has been an intermediate decline affecting >50%. This is based on quantitative data for localities in Crimea. The results have been extrapolated for the rest of the Black Sea.
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
    • Professional active fishing
  • Pollution
    • Nutrient enrichment (N, P, organic matter)
  • Invasive, other problematic species and genes
    • Invasive non-native species
  • Natural System modifications
    • Siltation rate changes, dumping, depositing of dredged deposits

Habitat restoration potential

Recovery through intervention cannot be achieved for this habitat. The habitat can recover naturally providing there is a sufficient sources of propagules and the abiotic conditions are appropriate.

Trends in extent

Average current trend in quantity

Stable Decreasing
EU28 EU28+

Trends in quality

Average current trend in quality

Stable Decreasing
EU28 EU28+

Conservation and management needs

The habitat is currently protected by some MPAs in some Black Sea states. In EU states eutrophication is now being managed by the Water Framework Directive (WFD). Trawling is not prohibited in EU states, protection measures are needed in this respect. Future management should include the designation of additional MPAs, improvement of water quality management outside EU member states, enhanced legal protection for occurrences of the habitat and key species (e.g. additions to the EU Habitats Directive), prohibiting of bottom trawling.

List of conservation and management needs

  • Measures related to marine habitats
    • Other marine-related measures
  • Measures related to spatial planning
    • Establish protected areas/sites
    • Legal protection of habitats and species
  • 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)
Black Sea Present Unknown Decreasing Decreasing

Extent of Occurrence, Area of Occupancy and habitat area

Extent of Occurrence (EOO) (Km2) Area of Occupancy (AOO) Current estimated Total Area Comment
EU28 11041 32 Unknown EOO and AOO have been calculated on the available data.
EU28+ 181 Unknown EOO and AOO have been calculated on the available data.
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