EUNIS habitat classification 2012 amended 2019 > A - Marine habitats > A3 - Infralittoral rock and other hard substrata > A3.2 - Atlantic and Mediterranean moderate energy infralittoral rock > A3.22 - Kelp and seaweed communities in tide-swept sheltered conditions > A3.222 - Mixed kelp with foliose red seaweeds, sponges and ascidians on sheltered tide-swept infralittoral rock

Mixed kelp with foliose red seaweeds, sponges and ascidians on sheltered tide-swept infralittoral rock

English name: Mixed kelp with foliose red seaweeds, sponges and ascidians on sheltered tide-swept infralittoral rock

Quick facts

EUNIS habitat type code A3.222
Bern Convention Included in a Resolution 4 habitat type at a higher level (A3)

Description (English)

Stable, tide-swept rock characterised by dense kelp Laminaria hyperborea and/or Laminaria saccharina forest on scoured, coralline-encrusted rock. This biotope occurs in the sheltered narrows and sills of Scottish sealochs, where there is an increase in tidal flow. Although L. hyperborea (typically Common) generally occurs in greater abundance than L. saccharina (Frequent), either kelp may dominate, sometimes to the exclusion of the other. (This biotope should not be confused with sheltered, but silted A3.312). Large stands of the brown seaweed Halidrys siliquosa may also occur amongst the kelp along with Dictyota dichotoma on bedrock and boulders. In contrast to the scoured rock surface the kelp stipes themselves often support prolific growths of foliose red seaweeds such as Phycodrys rubens, Membranoptera alata, Delesseria sanguinea and Plocamium cartilagineum. Other foliose seaweeds may be present among the kelp holdfasts include Chondrus crispus and Dilsea carnosa. The scoured rock surface is characterised by encrusting coralline algae, barnacles Balanus crenatus and the tube-building polychaete Pomatoceros triqueter. The sponge Halichondria panicea, anthozoans Urticina felina, Anemonia viridis and Sagartia elegans can also occur on the scoured rock. Sponges, particularly Halichondria panicea and colonial and solitary ascidians Botryllus schlosseri and Ascidiella aspersa encrust the stipes, whilst hydroid growth of Obelia geniculata and seamats Membranoptera membranacea can cover the fronds, optimising the increased tidal flow. Mobile species such as the gastropod Gibbula cineraria can often be found on and around the kelp. The echinoderms Asterias rubens, Ophiothrix fragilis and Echinus esculentus can be found underneath the kelp canopy on the rock along with the crab Carcinus maenas. Where some protection is afforded from the scour anthozoans may occur on the rock such as Alcyonium digitatum or Metridium senile.
Situation: This biotope may be fringed by tide-swept kelp Laminaria digitata in shallower water (unit A3.221). Where mixed substrata occurs adjacent to the stable bedrock and boulders the kelp will usually diminish in density (typically Frequent), but a greater diversity of species will be found compared to the scoured bedrock, in particular there is an increase in red seaweeds and a greater infaunal component (unit A3.223). Maerl rhodoliths may be present amongst the bedrock and boulders of unit A3.222 in small amounts, and at some sites may form extensive beds surrounding the bedrock outcrops (units A5.5111 and A5.512).

Source: EUNIS habitat classification

Vegetation types

Relation to vegetation types (syntaxa)

Not available

Species mentioned in habitat description

Invertebrates Alcyonium digitatum
Invertebrates Anemonia viridis
Invertebrates Ascidiella aspersa
Invertebrates Asterias rubens
Invertebrates Balanus crenatus
Invertebrates Botryllus schlosseri
Invertebrates Carcinus maenas
Algae Chondrus crispus
Algae Delesseria sanguinea
Algae Dictyota dichotoma
Algae Dilsea carnosa
Invertebrates Echinus esculentus
Invertebrates Gibbula cineraria
Invertebrates Halichondria panicea
Algae Halidrys siliquosa
Algae Laminaria digitata
Algae Laminaria hyperborea
Algae Laminaria saccharina
Algae Membranoptera alata
Invertebrates Metridium senile
Invertebrates Obelia geniculata
Invertebrates Ophiothrix fragilis
Algae Phycodrys rubens
Algae Plocamium cartilagineum
Invertebrates Pomatoceros triqueter
Invertebrates Sagartia elegans
Invertebrates Urticina felina
Species scientific name English common name Species group
Alcyonium digitatum Invertebrates
Anemonia viridis Invertebrates
Ascidiella aspersa Invertebrates
Asterias rubens Invertebrates
Balanus crenatus Invertebrates
Botryllus schlosseri Invertebrates
Carcinus maenas Invertebrates
Chondrus crispus Algae
Delesseria sanguinea Algae
Dictyota dichotoma Algae
Dilsea carnosa Algae
Echinus esculentus Invertebrates
Gibbula cineraria Invertebrates
Halichondria panicea Invertebrates
Halidrys siliquosa Algae
Laminaria digitata Algae
Laminaria hyperborea Algae
Laminaria saccharina Algae
Membranoptera alata Algae
Metridium senile Invertebrates
Obelia geniculata Invertebrates
Ophiothrix fragilis Invertebrates
Phycodrys rubens Algae
Plocamium cartilagineum Algae
Pomatoceros triqueter Invertebrates
Sagartia elegans Invertebrates
Urticina felina Invertebrates

Other classifications

Classification Code Habitat type name Relationship type
Marine Habitat Classification Britain/Ireland 0405 IR.MIR.KT.XKT Mixed kelp with foliose red seaweeds, sponges and ascidians on sheltered tide-swept infralittoral rock source
CORINE Land Cover 5.2.3. Sea and ocean n/a
For relation to plant communities (syntaxa), see Vegetation types

History

Classification Code Habitat type name Relationship type
EUNIS Habitat Classification 200410 A3.222 Mixed kelp with foliose red seaweeds, sponges and ascidians on sheltered tide-swept infralittoral rock same
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