Mixed kelp and red seaweeds on infralittoral boulders, cobbles and gravel in tidal rapids

English name: Mixed kelp and red seaweeds on infralittoral boulders, cobbles and gravel in tidal rapids

Quick facts

EUNIS habitat type code A3.223
Bern Convention Included in a Resolution 4 habitat type at a higher level (A3)

Description (English)

Mixed substrata of boulders, cobbles, pebbles and gravel, typically found in tidal rapids with kelp Laminaria saccharina and Laminaria hyperborea and red seaweeds. L. saccharina usually dominates this habitat although L. hyperborea may occur in equal abundance at some sites. The kelp in these tidal rapids does not form the same dense canopies associated with stable tide-swept bedrock, but generally occurs at lower abundance (Frequent). Other brown seaweeds occur in significant amounts in these tidal rapids including Dictyota dichotoma, Halidrys siliquosa and Chorda filum. These mixed substrata support a greater diversity of species than scoured bedrock narrows (A3.222). In particular, there is an increase in red algal species such as Corallina officinalis, Bonnemaisonia hamifera and Ceramium nodulosum, although none occur in any great abundance. Red seaweeds common to both A3.222 and this biotope include Chondrus crispus, Delesseria sanguinea, Plocamium cartilagineum and Phycodrys rubens. Good examples of this biotope often have maerl gravel (Lithothamnion sp.) or rhodoliths between cobbles and boulders. Where maerl dominates, the biotope should be recorded as a maerl bed (unit A5.51). The sponges associated with more stable, tide-swept conditions are generally absent, but the anthozoan Anemonia viridis might be present. Cobbles and pebbles are encrusted by the ubiquitous polychaete Pomatoceros triqueter and provide shelter for scavenging crabs such as Carcinus maenas and the hermit crab Pagurus bernhardus, gastropods such as Gibbula cineraria and echinoderms such as Echinus esculentus, Asterias rubens, Ophiocomina nigra and Ophiothrix fragilis which favour these sites of increased water movement. Additional infaunal species, inhabiting the sediment pockets, include Lanice conchilega and Sabella pavonina, which can be locally abundant.
Situation: Where stable rock fringes the shallows the tide-swept Laminaria digitata biotope often occurs (A3.221). Adjacent areas of stable bedrock or boulders in these sheltered, tide-swept narrows can support a similar kelp community, often with a greater percentage of L. hyperborea (A3.222). Maerl fragments are often found amongst the mixed substrata of A3.223 and this biotope may abut more extensive areas of maerl bed (A5.512).

Source: EUNIS habitat classification

Vegetation types

Relation to vegetation types (syntaxa)

Not available

Species mentioned in habitat description

Invertebrates Anemonia viridis
Invertebrates Asterias rubens
Algae Bonnemaisonia hamifera
Invertebrates Carcinus maenas
Algae Chondrus crispus
Algae Chorda filum
Algae Corallina officinalis
Algae Delesseria sanguinea
Algae Dictyota dichotoma
Invertebrates Echinus esculentus
Invertebrates Gibbula cineraria
Algae Halidrys siliquosa
Algae Laminaria digitata
Algae Laminaria hyperborea
Algae Laminaria saccharina
Invertebrates Lanice conchilega
Invertebrates Ophiocomina nigra
Invertebrates Ophiothrix fragilis
Invertebrates Pagurus bernhardus
Algae Phycodrys rubens
Algae Plocamium cartilagineum
Invertebrates Pomatoceros triqueter
Invertebrates Sabella pavonina
Species scientific name English common name Species group
Anemonia viridis Invertebrates
Asterias rubens Invertebrates
Bonnemaisonia hamifera Algae
Carcinus maenas Invertebrates
Chondrus crispus Algae
Chorda filum Algae
Corallina officinalis Algae
Delesseria sanguinea Algae
Dictyota dichotoma Algae
Echinus esculentus Invertebrates
Gibbula cineraria Invertebrates
Halidrys siliquosa Algae
Laminaria digitata Algae
Laminaria hyperborea Algae
Laminaria saccharina Algae
Lanice conchilega Invertebrates
Ophiocomina nigra Invertebrates
Ophiothrix fragilis Invertebrates
Pagurus bernhardus Invertebrates
Phycodrys rubens Algae
Plocamium cartilagineum Algae
Pomatoceros triqueter Invertebrates
Sabella pavonina Invertebrates

Other classifications

Classification Code Habitat type name Relationship type
Marine Habitat Classification Britain/Ireland 0405 IR.MIR.KT.XKTX Mixed kelp and red seaweeds on infralittoral boulders, cobbles and gravel in tidal rapids 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 A3.223 Mixed kelp and red seaweeds on infralittoral boulders, cobbles and gravel in tidal rapids same
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