Macaronesian seaweed communities on moderate energy infralittoral rock

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.

Synthesis of Red List assessment

Confidence in the assessment

Pressures and threats