Faunal and algal crusts on exposed to moderately wave-exposed circalittoral rock

English name: Faunal and algal crusts on exposed to moderately wave-exposed circalittoral rock

Quick facts

EUNIS habitat type code A4.214
Bern Convention Included in a Resolution 4 habitat type at a higher level (A4)

Description (English)

This biotope typically occurs on the vertical and upper faces of wave-exposed and moderately wave-exposed circalittoral bedrock or boulders subject to mostly moderate to weak tidal streams (a variant of this biotope containing brittlestar is found on bedrock, boulders and cobbles). The biotope is dominated by faunal (e.g. Parasmittina trispinosa) and algal (Corallinaceae) crusts, and tends to have a grazed appearance; this may be partially attributable to the abundance of Echinus esculentus found in this biotope. Occasionally, the rock may appear pink from a distance, due to the expanses of encrusting red algae on the rock surface. Alcyonium digitatum is one of the few species to stand erect from the encrusted rock surface and are frequently encountered, on the tops of rocky outcrops and boulders. Hydroids do not form a prominent feature of this biotope, with only robust species such as Abietinaria abietina frequently recorded. Sponges and Caryophyllia smithii are rarely present while erect bryozoans and ascidians are scarce (although there are exceptions, see variants). The E. esculentus grazed substratum may be interspersed with other encrusting species such as the polychaete Pomatoceros triqueter and the saddle oyster Pododesmus patelliformis. Other species present include Asterias rubens, Ophiothrix fragilis, Urticina felina, Ophiocomina nigra, Pagurus bernhardus, Flustra foliacea, Gibbula cineraria, Calliostoma zizyphinum, Ophiura albida, Ciona intestinalis and Antedon bifida. Six variants of this biotope have been recorded. A4.2141 is dominated by the silt and scour tolerant bryozoan F. foliacea. A4.2142 is dominated by A. digitatum. Unit A4.2143 is dominated by Securiflustra securifrons. A4.2145 looks extremely impoverished (even for a grazed community). A4.2144 has a dense covering of brittlestars while A4.2146r is only found under weak/very weak tides and is dominated by C. smithii.

Source: EUNIS habitat classification

Vegetation types

Relation to vegetation types (syntaxa)

Not available

Species mentioned in habitat description

Invertebrates Abietinaria abietina
Invertebrates Alcyonium digitatum
Invertebrates Antedon bifida
Invertebrates Asterias rubens
Invertebrates Calliostoma zizyphinum
Invertebrates Caryophyllia smithii
Invertebrates Ciona intestinalis
Invertebrates Echinus esculentus
Invertebrates Flustra foliacea
Invertebrates Gibbula cineraria
Invertebrates Ophiocomina nigra
Invertebrates Ophiothrix fragilis
Invertebrates Ophiura albida
Invertebrates Pagurus bernhardus
Invertebrates Parasmittina trispinosa
Invertebrates Pododesmus patelliformis
Invertebrates Pomatoceros triqueter
Invertebrates Securiflustra securifrons
Invertebrates Urticina felina
Species scientific name English common name Species group
Abietinaria abietina Invertebrates
Alcyonium digitatum Invertebrates
Antedon bifida Invertebrates
Asterias rubens Invertebrates
Calliostoma zizyphinum Invertebrates
Caryophyllia smithii Invertebrates
Ciona intestinalis Invertebrates
Echinus esculentus Invertebrates
Flustra foliacea Invertebrates
Gibbula cineraria Invertebrates
Ophiocomina nigra Invertebrates
Ophiothrix fragilis Invertebrates
Ophiura albida Invertebrates
Pagurus bernhardus Invertebrates
Parasmittina trispinosa Invertebrates
Pododesmus patelliformis Invertebrates
Pomatoceros triqueter Invertebrates
Securiflustra securifrons Invertebrates
Urticina felina Invertebrates

Other classifications

Classification Code Habitat type name Relationship type
Marine Habitat Classification Britain/Ireland 0405 CR.MCR.EcCr.FaAlCr Faunal and algal crusts on exposed to moderately wave-exposed circalittoral 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 A4.214 Faunal and algal crusts on exposed to moderately wave-exposed circalittoral rock same
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