Red List habitat classification > RL - Marine habitats > RLBLS - Black Sea > BLSA3.74 Caves, overhangs and surge gullies in Pontic infralittoral rock

Caves, overhangs and surge gullies in Pontic infralittoral rock

Quick facts

Red List habitat type code BLSA3.74
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)


Caves and overhangs in the infralittoral zone are completely submerged at all states of the tide. Light conditions are generally poor which influences the species that can occur in these situations. As a result communities of sciaphillic algae, sponges and mussels are commonly present. Information on the biodiversity of sublittoral caves in the Black Sea is extremely fragmentary but some studies have been undertaken. e.g. describing the dominating sponge communities  in the  shallow semi-submerged karst caves on the Tarhankut peninsula, Crimea.


The habitat includes a range of situations including: vertical walls under overhangs, semi-dark tunnels and walls and floors of semi dark tunnels. Each of these may contain its own unique diagnostic communities which are also influenced by the rock type and the size of the cave - most semi-submerged caves from the Tarkhankut peninsula are small (5-10m) but the longest Kapchik-2 is 250m in length. Studies of caves in the Tarkhankut peninsula indicate a faunal zonation with depth into the cave.

The habitat is dominated by filter feeders in the surge gullies, robust species able to cope with the heavy wave action.



Indicators of quality:


Both biotic and abiotic indicators have been used to describe marine habitat quality. These include; the presence of characteristic species and those which are sensitive to the pressures the habitat may face, 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

Detailed information on the abundance and extent of this habitat is lacking. Information on the quantity and quality of this habitat including historical or recent trends is unknown. For the purposes of Red List assessment this habitat is considered to be Data Deficient.
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

  • Pollution
    • Nutrient enrichment (N, P, organic matter)
    • Input of contaminants (synthetic substances, non-synthetic substances, radionuclides) - diffuse sources, point sources, acute events
    • Marine macro-pollution (i.e. plastic bags, styrofoam)
  • Natural System modifications
    • Siltation rate changes, dumping, depositing of dredged deposits

Habitat restoration potential

There is insufficient data and knowledge of this habitat to assess its capacity to recover.

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

Conservation and management measures which would benefit this habitat include measures to maintain physical and biological integrity, including pollution control and regulation, improvement of water quality management outside EU member states, contingency plans to be followed in the event of a major pollution incident, survey and monitoring programs, raised public awareness of ecological value and vulnerability, enhanced legal protection for occurrences of the habitat and key species (e.g. establish a unified list of Black Sea species and habitats requiring conservation measures, etc.), and the designation of MPAs with actual measures that will protect this habitat

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 urban areas, industry, energy and transport
    • Other 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)
Black Sea Present Unknown Unknown Unknown
Sea of Marmara

Extent of Occurrence, Area of Occupancy and habitat area

Extent of Occurrence (EOO) (Km2) Area of Occupancy (AOO) Current estimated Total Area Comment
EU28 Unknown Unknown Unknown The habitat is known to occur in the Black Sea but there is insufficient data to accurately calculate EOO and AOO.
EU28+ Unknown Unknown The habitat is known to occur in the Black Sea but there is insufficient data to accurately calculate 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