Red List habitat classification > RL - Marine habitats > RLBLS - Black Sea > BLSA4.2A Marmara circalittoral biogenic habitats- worm reefs

Marmara circalittoral biogenic habitats- worm reefs

Quick facts

Red List habitat type code BLSA4.2A
Threat status
Europe Data Deficient
EU n/a
Relation to
Source European Red List habitat factsheet
European Red List of habitats reports
European Red List of habitats (Excel table)


Worm reefs (formations) in the circalittoral zone in the Sea of Marmara are formed by several species, depending on the bottom composition. The most common are the Hydroides spp. and to a lesser extent Salmacina incrustans and Salmacina dysteri . Worms grow on hard substrates and also build carbonate tubes.

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 a particular factor, as well as more integrated indices which describe habitat function and structure such as trophic index, or successful stages of development in habitats that have a natural cycle of change over time. There are no known commonly agreed indicators of quality for this habitat, although particular parameters may be set in certain situations, e.g. protected features within Natura 2000 sites, where reference values may 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 therefore considered to be Data Deficient.
Red List Category Red List Criteria
n/a -
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 passive fishing
    • Professional active fishing
    • Benthic or demersal trawling
  • Pollution
    • Marine water pollution
  • Invasive, other problematic species and genes
    • Invasive non-native species
  • Climate change
    • Changes in abiotic conditions
    • Temperature changes (e.g. rise of temperature & extremes)
    • Sea-level changes
    • Decline or extinction of species

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

No occurrence Unknown
EU28 EU28+

Trends in quality

Average current trend in quality

No occurrence Unknown
EU28 EU28+

Conservation and management needs

Conservation and management measures which would benefit this habitat include implementing measures to maintain physical and biological integrity, including pollution control and regulation; improvement of water quality management outside EU member states; coastal development controls; contingency plans to be followed in the event of a major pollution incident; survey and monitoring programmes; raised public awareness of ecological value and vulnerability; and implementing measures to reduce global warming and sea level rise.

List of conservation and management needs

  • Measures related to marine habitats
    • Other marine-related measures
  • Measures related to spatial planning
    • Establish protected areas/sites
  • 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)
Sea of Marmara Present Unknown Unknown Unknown

Extent of Occurrence, Area of Occupancy and habitat area

Extent of Occurrence (EOO) (Km2) Area of Occupancy (AOO) Current estimated Total Area Comment
EU28 This habitat is only present in the Sea of Marmara therefore it does not occur in the EU28
EU28+ 19 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)
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