Kelp and red seaweeds on moderate energy Atlantic infralittoral rock

This habitat is found on infralittoral rock in areas subject to moderate wave exposure, or on more sheltered coasts in areas subject to moderately strong tidal streams. Kelp forests develop in these situations and both the rock surfaces and kelp holdfasts and stipes are typically colonised by other algae. These are predominantly red algae with  good variety of delicate filamentous types. The most conspicuous sessile fauna include ascidians, bryozoans, echinoderms, crustaceans, and bryozoans.

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. The depth limit of kelp and/or red seaweeds is used in some countries as a Water Framework Directive parameter for assessing ecological status.

Characteristic species:

On bedrock and stable boulders there is typically a narrow band of kelp Laminaria digitata in the sublittoral fringe which lies above a Laminaria hyperborea forest and park. Other seaweeds typically present include Saccharina latissima, Delesseria sanguinea, Plocamium cartilagineum, Phycodrys rubens, Corallinaceae and Dictyota dichotoma. Characteristic fauna include Halichondria panacea, Urticina felina, Pomatoceros triqueter, Gibbula cineraria, Asterias rubens, and, Echinus esculentus as well as bryozoans Membranipora membranacea and Electra pilosa.

Synthesis of Red List assessment

Confidence in the assessment

Pressures and threats