Red List habitat classification > RL - Marine habitats > RLNEA - Atlantic > NEAA3.2x Macaronesian seaweed communities on moderate energy infralittoral rock

Macaronesian seaweed communities on moderate energy infralittoral rock

Quick facts

Red List habitat type code NEAA3.2x
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)


This habitat occurs predominantly on moderately wave-exposed bedrock and boulders, that are subject to moderately strong to weak tidal streams. Two associated biotopes have been described in the Azores archipelago. The first is dominated by Codium elisabethae, Halopteris filicina and coralline crusts on moderate to sheltered bedrock. The second is characterised by dense patches of the green alga Caulerpa webbiana. This species was first reported in the Azores in 2002 and although not considered an invasive species in other parts of Macaronesia or the world it has many characteristics of such a species in the Azores.

 In the southern Macaronesian archipelagos, a more diverse sub-set of habitats are recognised, such as that defined by Stypocaulon scoparium / Halopteris filicina (A3.2X3), more frequent in Azores and Madeira archipelagos and with fewer locations in Selvagem and the Canary Islands.

Other representative biotopes in the Canarian archipelago are barren grounds of the long spined sea urchin Diadema africanum (A3.2X4) or those constructed by other sea urchin species Arbacia lixula  or Paracentrotus lividus on shallower infralittoral volcanic rocks (A3.2X5). Corynactis viridis defines another interesting biotope (A.3.2X6) mainly associated with sea urchins whereas different zooantids, such as Isaurus tuberculatus, Zoanthus spp. and Palythoa  spp  are characteristic elements of another biotope (A3.2X7) in hard bottoms.

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.

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

Threat status

Synthesis of Red List assessment

There is insufficient information to determine historical, current or future trends in quantity or quality of this habitat although it is considered likely to decline in the future if conservation measures are not introduced.
This habitat has a large EOO and AOO, and therefore qualifies as Least Concern under criterion B. However the habitat is assessed as Data Deficient both at the EU 28 and EU 28+ levels because of the lack of information on its area and any trends in quantity and quality.
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

  • Urbanisation, residential and commercial development
    • Urbanised areas, human habitation
    • Discharges
  • Biological resource use other than agriculture & forestry
    • Fishing and harvesting aquatic resources
  • Pollution
    • Pollution to surface waters (limnic, terrestrial, marine & brackish)
    • Nutrient enrichment (N, P, organic matter)
    • Marine water pollution
  • Invasive, other problematic species and genes
    • Invasive non-native species

Habitat restoration potential

There is insufficeint information to determine whether this habitat retains the capacity to recover when severely damaged.

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

This habitat is included within some Marine Protected Areas where there are associated management measures, regulations and codes of conduct but not necessarily targeting this specific habitat. Regulation of coastal development, discharges to the marine environment and control on activities that may potentially lead to the introduction of invasive species are other measures that could benefit this habitat.

List of conservation and management needs

  • Measures related to wetland, freshwater and coastal habitats
    • Restoring/Improving water quality
  • Measures related to spatial planning
    • Other marine-related measures
    • Establish protected areas/sites
  • Measures related to urban areas, industry, energy and transport
    • Managing marine traffic


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)
Macaronesia 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 725,661 178 Unknown EOO and AOO have been calculated on the available data. Although this data set is known to be incomplete the figures exceed the thresholds for threatened status.
EU28+ 178 Unknown This habitat does not occur outside the EU28
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