# Habitat

HabitatName:
[Ruppia maritima] on lower shore sediment


HabitatDescription:
Dominants are [Eleocharis acicularis], [Eleocharis parvula].


HabitatDescription:
Emergent [Eleocharis parvula] or [Eleocharis acicularis] formations of brackish seas, sea inlets, estuaries, permanent pools of mud or sand flats, and coastal lagoons, occurring in the open sea only in the Baltic, limited to coastal waterbodies elsewhere, and very rare.


HabitatDescription:
Emergent [Eleocharis parvula]-dominated formations of brackish seas, sea inlets, estuaries, permanent pools of mud or sand flats, and coastal lagoons. They occur in the open sea only in the inner Baltic, in particular in middle Sweden, southern Finland and Estonia; they are very rare elsewhere, noted in particular on a few points of the coasts of Norway and in closed limans of the northern Black Sea and Azov Sea coasts, probably extinct in France and Germany.


HabitatDescription:
Emergent [Eleocharis acicularis]-dominated formations of the open Baltic in the Gulf of Bothnia (Bothnia Sea, Bothnia Bay) and the Gulf of Finland.


HabitatDescription:
The Littoral Biogenic Reefs habitat contains two biological subtypes, littoral [Sabellaria] reefs (A2.71) and mixed sediment shores with mussels (A2.72), encompassing the littoral biotope dominated by the honeycomb worm [Sabellaria alveolata], and littoral [Mytilus edulis]- dominated communities. [S. alveolata] can form honeycomb reefs on mid to lower shore on exposed coasts, where there is a plentiful supply of sediment. The underlying substratum may consist primarily of rock or stable cobbles and boulders, or of cobbles and boulders on sand. Mixed sediment shores characterised by beds of adult mussels [Mytilus edulis] occur principally on mid and lower eulittoral mixed substrata (mainly cobbles and pebbles on muddy sediments) in a wide range of exposure conditions. In high densities the mussels bind the substratum and provide a habitat for many infaunal and epifaunal species.

Temporal variation: [S. alveolata] reefs may be susceptible to storm damage in the winter, although they can regenerate remarkably quickly in a season as long as some adults are left as they facilitate the larval settlement. [S. alveolata] is tolerant to burial under sand for several weeks. Changes in desiccation over a period of time can cause part of the population to die. One of the mussel-dominated subtypes, A2.7212, could change to A2.7213 over time as pseudofaeces build up forming a layer of mud. This cannot happen where wave action or tidal streams wash away pseudofaeces and prevent a build up. In areas where mussel spat ("mussel crumble") settles on the surface shell layer of cockle beds, the mussel cover may be ephemeral.


HabitatDescription:
The sedentary polychaete [Sabellaria alveolata] (honeycomb worm) builds tubes from sand and shell. On exposed shores, where there is a plentiful supply of sediment, [S. alveolata] can form honeycomb reefs on boulders and low-lying bedrock on the mid to lower shore. These [S. alveolata] reefs are quite distinct from the mosaic of seaweeds and barnacles or red seaweeds (A1.2) generally associated with moderately exposed rocky shores though many of the same species are present. These include the anemone [Actinia equina], the barnacles [Semibalanus balanoides] and [Elminius modestus], the limpet [Patella vulgata], the top shell [Gibbula cineraria] and the winkle [Littorina littorea]. The whelk [Nucella lappilus] and the mussel [Mytilus edulis] is also present on the boulders whereas the polychaete [Lanice conchilega] is restricted to the associated sediment areas. Scour resistent red seaweeds including [Palmaria palmata, Corallina ifficinalis, Mastocarpus stellatus, Chondrus crispus, Ceramium nodulosum, Osmundea pinnatifida, Polysiphonia] spp. and coralline crusts can also be present where suitable substrata exsist. Brown and green seaweeds also present include [Fucus serratus, Fucus vesioculosus, Cladostephus spongiosus, Enteromorpha intestinalis] and [Ulva lactuca].
Situation: Above A2.71 are biotopes dominated either by ephemeral seaweeds, such as [Enteromorpha] spp. and [Porphyra] spp. or the perennial wrack [Fucus vesiculosus] on mixed substrata (A1.213; A1.3132; A2.821; A1.452). Rockpool biotopes dominated by the red seaweed [Corallina officinalis] (A1.411), by wracks such as [Fucus] spp. or by kelp such as [Laminaria] spp. (A1.412) can usually be found above this biotope. Beneath this biotope is a community consisting of mixed scour-tolerant like the kelp [Laminaria digitata] and opportunistic foliose red seaweeds such as [Polyides rotundus] and [Ahnfeltia plicata] (A3.2111; A3.125; A3.127).


HabitatName:
[Sabellaria alveolata] reefs on sand-abraded eulittoral rock

HabitatDescription:
Exposed to moderately exposed bedrock and boulders in the eastern basin of the Irish Sea (and as far south as Cornwall) characterised by reefs of the polychaete [Sabellaria alveolata]. The sand based tubes formed by [S. alveolata] form large reef-like hummocks, which serve to stabilise the boulders and cobbles. Other species in this biotope include the barnacles [Semibalanus balanoides] and [Elminius modestus] and the limpet [Patella vulgata], the winkle [Littorina littorea], the mussel [Mytilus edulis] and the whelk [Nucella lapillus]. The anemone [Actinia equina] and the crab [Carcinus maenas] can be present in cracks and crevices on the reef. Low abundance of seaweeds tend to occur in areas of eroded reef. The seaweed diversity can be high and may include the foliose red seaweeds [Palmaria palmata], [Mastocarpus stellatus], [Osmundea pinnatifida, Chondrus crispus] and some filamentous species e.g. [Polysiphonia] spp. and [Ceramium] spp. Coralline crusts can occur in patches. Wracks such as [Fucus vesiculosus], [Fucus serratus] and the brown seaweed [Cladostephus spongiosus] may occur along with the ephemeral green seaweeds [Enteromorpha intestinalis] and [Ulva lactuca]. On exposed surf beaches in the south-west [S. alveolata] forms a crust on the rocks, rather than the classic honeycomb reef form, and may be accompanied by the barnacle [Balanus perforatus] (typically common to abundant). On wave-exposed shores in Ireland, the wrack [Himanthalia elongata] can also occur.

Situation: Above this unit are biotopes dominated either by ephemeral seaweeds, such as [Enteromorpha] spp. and [Porphyra] spp. or the perennial wrack [Fucus vesiculosus] on mixed substrata (units A1.213; A1.3132; A2.821; A1.452). Rockpool biotopes dominated by the red seaweed [Corallina officinalis] (unit A1.411), by wracks such as [Fucus] spp. or by kelp such as [Laminaria] spp. (A1.412) can usually be found above this biotope. Beneath this biotope is a community consisting of mixed scour-tolerant like the kelp [Laminaria digitata] and opportunistic foliose red seaweeds such as [Polyides rotundus] and [Ahnfeltia plicata] (units A3.2111; A3.125; A1.45; A3.127). In adjacent sediment areas [Lanice conchilega] may dominante (A2.245).

Temporal variation: These reefs may be susceptible to storm damage in the winter, although they can regenerate remarkably quickly in a season as long as some adults are left as they facilitate the larval settlement. [S. alveolata] is tolerant to burial under sand for several weeks. Changes in desiccation over a period of time can cause part of the population to die.


HabitatDescription:
Sediment shores characterised by beds of adult mussels [Mytilus edulis] occur principally on mid and lower eulittoral mixed substrata (mainly cobbles and pebbles on muddy sediments) in a wide range of exposure conditions. In high densities the mussels bind the substratum and provide a habitat for many infaunal and epifaunal species. This biotope is also found in lower shore tide-swept areas, such as in the tidal narrows of Scottish sealochs. A fauna of dense juvenile mussels may be found in sheltered firths, attached to algae on shores of pebbles, gravel, sand, mud and shell debris with a strandline of fucoid algae.

Situation: High densities of juvenile mussels attached to seaweed have been recorded from sheltered shores of the Dornoch Firth and Moray Firth. Adult mussel beds can be found below a band of ephemeral green seaweeds (A2.821) on more exposed, predominantly rocky shores. On sheltered, predominantly rocky shores either a [Fucus vesiculosus] dominated biotope or a biotope dominated by the wrack [Ascophyllum nodosum] (A1.3132; A1.3142) can be found above, or the barnacle dominated biotope (A1.1133).

Temporal variation: The temporal stability of mussel beds can vary a lot. Some beds are permanent, maintained by recruitment of spat in amongst adults. Other beds are ephemeral, an example of which are beds ocurring at South America Skear where large amounts of spat settle intermittently on a cobble basement. The mussels rapidly build up mud, and are unable to remain attached to the stable cobbles. They are then liable to be washed away during gales. A second example of ephemeral mussel dominated biotopes occurs when mussel spat ("mussel crumble") settles on the superficial shell of cockle beds, such as is known to occur in the Burry Inlet.


HabitatName:
[Mytilus edulis] beds on littoral sediments

HabitatDescription:
Dense aggregations of [Mytilus edulis] on the mid and lower shore, on mixed substrata (mainly cobbles and pebbles on fine sediments), on sand, or on sheltered muddy shores. In high densities the mussels bind the substratum and provide a habitat for many infaunal and epifaunal species. The wrack [Fucus vesiculosus] is often found attached to either the mussels or cobbles and it can be abundant. The mussels are often encrusted with the barnacles [Semibalanus balanoides], [Elminius modestus] or [Balanus crenatus]. Where boulders are present they can support the limpet [Patella vulgata]. The winkles [Littorina littorea] and [L. saxatilis] and small individuals of the crab [Carcinus maenas] are common amongst the mussels, whilst areas of sediment may contain the lugworm [Arenicola marina], the sand mason [Lanice conchilega], the cockle [Cerastoderma edule], and other infaunal species. The characterising species list shown below is based on data from epifaunal sampling only. Three sub-biotopes are recognised for this biotope, distinguished principally on the basis of the sediment type associated with the mussel beds. The three types of intertidal mussel beds may be part of a continuum on an axis that is most strongly influenced by the amount of pseudofaeces that accumulate amongst the mussels. The differences may not always be directly connected to the underlying substratum on which the mussel bed may have started a long time ago. It should be noted that there are few data available for the muddy (A2.7213) and sandy (A2.7212) subunits, therefore there are no characterising species lists or comparative tables for these two sub-biotopes.

Situation: On more exposed, predominantly rocky shores this biotope can be found below a band of ephemeral green seaweeds (unit A2.821). On sheltered, predominantly rocky shores either a [F. vesiculosus] dominated biotope or a biotope dominated by the wrack [Ascophyllum nodosum] (A1.3132; A1.3142) can be found above or the barnacle dominated biotope (A1.1133). On mudflats and sandflats, this biotope may be found alongside [Cerastoderma edule] beds (A2.242) and other A2.2 and A2.3 biotopes. The intertidal A2.721 biotope can extend seamlessly into the subtidal.

Temporal variation: The temporal stability of mussel beds can vary a lot. Some beds are permanent, maintained by recruitment of spat in amongst adults. Other beds are ephemeral, an example of which are beds ocurring at South America Skear where large amounts of spat settle intermittently on a cobble basement. The mussels rapidly build up mud, and are unable to remain attached to the stable cobbles. They are then liable to be washed away during gales. A second example of ephemeral mussel dominated biotopes occurs when mussel spat ("mussel crumble") settles on the superficial shell of cockle beds, such as is known to occur in the Burry Inlet.


HabitatName:
[Mytilus edulis] on littoral mixed substrata

HabitatDescription:
Mid and lower shore mixed substrata (mainly cobbles and pebbles on fine sediments) in a wide range of exposure conditions and with aggregations of the mussel [Mytilus edulis] colonising mainly the sediment between cobbles, though they can extend onto the cobbles themselves. The mussel aggregations can be very dense and support various age classes. In high densities the mussels bind the substratum and provide a habitat for many infaunal and epifaunal species. The wrack [Fucus vesiculosus] is often found attached to either the mussels or the cobbles and it can occur at high abundance. The mussels are also usually encrusted with the barnacles [Semibalanus balanoides], [Elminius modestus] or [Chtamalus] spp., especially in areas of reduced salinity. The winkles [Littorina littorea] and [L. saxatilis] and small individuals of the crab [Carcinus maenas] are common amongst the mussels, whilst areas of sediment may contain the lugworm [Arenicola marina], the sand mason [Lanice conchilega] and other infaunal species. Pools are often found within the mussel beds that support algae such as [Chondrus crispus]. Where boulders are present they can support the limpet [Patella vulgata], the dogwhelk [Nucella lapillus] and the anemone [Actinia equina]. [Ostrea edulis] may occur on the lowest part of the shore. There are few infaunal samples for this biotope, hence the characterising species list below shows only epifauna. Where infaunal samples have been collected for this biotope, they contain a highly diverse range of species including nematodes, [Anaitides mucosa], [Hediste diversicolor], [Polydora] spp., [Pygospio elegans], [Eteone longa], oligochaetes such as [Tubificoides] spp., [Semibalanus balanoides], a range of gammarid amphipods, [Corophium volutator], [Jaera forsmani], [Crangon crangon], [Carcinus maenas], [Hydrobia ulvae] and [Macoma balthica].

Situation: On more exposed, predominantly rocky shores this biotope can be found below a band of ephemeral green seaweeds (unit A2.821). On sheltered, predominantly rocky shores either a [F. vesiculosus] dominated biotope or a biotope dominated by the wrack [Ascophyllum nodosum] (units A1.3132; A1.3142) can be found above or the barnacle dominated biotope (A1.1133). This biotope is also found in lower shore tide-swept areas, such as in the tidal narrows of Scottish sealochs.

Temporal variation: Under sheltered conditions, pseudofaeces may build up over time, creating a layer of mud and changing the biotope to unit A2.7213. Where the stability of the mussed bed depends on the mussels being attached to stable cobbles, a build-up of mud from pseudofaeces may prevent this attachment, making the mussel bed unstable and liable to be washed away during storms.


HabitatDescription:
This sub-biotope occurs on mid to lower shore sand and muddy sand. Mussels [Mytilus edulis] grow attached to shell debris and live cockles [Cerastoderma edule], forming patches of mussels on consolidated shell material, and often growing into extensive beds. The mussel valves are usually encrusted with barnacles such as [Elminius modestus] and [Semibalanus balanoides], and the mussel bed provides a habitat for a range of species including [Littorina littorea]. The sediment infaunal community is usually rich and very similar to that of cockle beds (A2.242), including cockles [Cerastoderma edule], the baltic tellin [Macoma balthica], and a range of burrowing crustaceans and polychaetes typical for A2.242. Further species may be present are the sand mason [Lanice conchilega], the sand gaper [Mya arenaria], the peppery furrow shell [Scrobicularia plana], [Nephtys] spp., and the ragworm [Hediste diversicolor]. Scattered fronds of eelgrass [Zostera noltii] may occur.

Situation: This biotope often occurs in large sandy estuaries, or on enclosed shores, alongside other sand and muddy sand biotopes, most notably unit A2.242. It is possible that Lanice beds (unit A2.245) occur lower down on the shore.

Temporal variation: Where this sub-biotope occurs in very sheltered conditions on muddy sand, it could change to A2.7213 over time as pseudofaeces build up forming a layer of mud. This cannot happen where wave action or tidal streams wash away pseudofaeces and prevent a build up. In areas where mussel spat ("mussel crumble") settles on the surface shell layer of cockle beds, the mussel cover may be ephemeral, as is the case in the Burry Inlet (south Wales, UK).


HabitatDescription:
Dense mussel beds found in sheltered conditions on mud. There is a build up of pseudofaeces that results in a bed that is very soft to walk on, and sediment which is anoxic to the surface. Pools are often present in the mussel bed but they tend to contain few species. The sediment infauna is very poor as a result of anoxic conditions. The mussel valves are usually clean, without epifaunal growth. Where this biotope occurs naturally, all age classes are found within the mussel bed. This biotope also includes commercially laid mussel beds on soft sediments, which tend to be of uniform age structure. The species diversity of this sub-biotope is a lot lower than that of the other A2.721 sub-units.

Situation: Occurs on sheltered mudflats, or areas that were previously rocky or cobble fields, but where pseudofaeces have accumulated, leading to the presence of a thick layer of mud.

Temporal variation: Mussels may settle on areas of cobble or mixed sediment (unit A2.7211), and lead to the build-up of a thick layer of pseudofaeces, changing the biotope to unit A2.7213 over time. The layer of mud can prevent the attachment of mussels to the underlying stable substratum, thus making the mussel bed liable to be washed away during storms. This is known to occur in areas of Morecambe Bay, northern England.


HabitatDescription:
Rocky substratum macrozoobenthic community that is present in confined waters of variable salinity (like harbours and lagoons) principally composed by the polychaete neozoon [Ficopomatus enigmaticus] Fauvel 1923 syn. [Mercierella enigmaticus]; in protected waters it may cover the entire hard substratum with a mass of erect, contiguous and intertwined calcareous tubes (up to 20 cm long). The reefs it builds constitute a highly tridimensional complex biotope (up to 50 cm thick), unique in the Black Sea and harbouring a diverse fauna from the other principal macroinvertebrate hard bottom Mytilus dominated community. Mussel juveniles sometimes attach themselves on the surface of the reef but never survive to adulthood. The dominant species of this community are [Ficopomatus] and [Balanus] while the numeric subdominance is attained by [Palaemon], [Xantho], [Orchestia] and [Spaheroma] (Micu & Micu 2004).


HabitatDescription:
Features of littoral sediment include littoral habitats characterised by the presence of gases or liquids bubbling or seeping through sediments (A2.81); areas which are characterised by pioneer or ephemeral red and green algae because of variations in salinity and/or siltation (A2.82); and sedimentary shores of non-tidal, reduced salinity waters which are below the mean water level and normally water-covered, but which are regularly or occasionally exposed by the action of wind (hydrolittoral zone in the Baltic) (A2.83-A2.87).


HabitatName:
Ephemeral green or red seaweeds (freshwater or sand-influenced) on mobile substrata

HabitatDescription:
Eulittoral mixed substrata subject to variations in salinity and/or siltation characterised by dense blankets of ephemeral green and red seaweeds (A2.821). This is a biotope with a low species diversity and the relatively high number of species in the characterising species list are due to a variation in the species composition from site to site, not to high species richness on individual sites.
Note: Connor et al (2004) classify this habitat type together with A1.45 and A2.43 as LR.ELR.Eph.


HabitatDescription:
Eulittoral mixed substrata (pebbles and cobbles overlying sand or mud) that are subject to variations in salinity and/or siltation, characterised by dense blankets of ephemeral green and red seaweeds. The main species present are [Enteromorpha intestinalis], [Ulva lactuca] and [Porphyra] spp., along with colonial diatoms covering the surface of the substratum. Small numbers of other species such as barnacles [Semibalanus balanoides] and [Elminius modestus] are confined to any larger cobbles and pebbles or on the shells of larger individuals of the mussel [Mytilus edulis]. The crab [Carcinus maenas] and the winkle [Littorina littorea] can be present among the boulders, cobbles and seaweeds, while gammarids can be found in patches underneath the cobbles. In common with the other biotopes found on mixed substrata, patches of sediment are typically characterised by infaunal species including bivalves, for example, [Cerastoderma edule] and the polychaete [Arenicola marina] and the polychaete [Lanice conchilega].

Situation: This biotope is found primarily on enclosed (estuarine) stony shores sheltered from wave action (compare with unit A1.1133), with weak to moderate tidal streams and often subject to variable levels of salinity. It is found predominately in the mid shore zone above or at the same level as the biotope dominated by the barnacles [S. balanoides] and/or [E. modestus] and [Littorina] spp. (unit A2.431). If it is found in the upper shore region it can be backed by saltmarsh species such as [Salicornia] sp. and [Spartina] sp. Below are biotopes dominated by the wracks [Fucus serratus] or [Fucus vesiculosus] (units A1.3152; A1.3132) or by [M. edulis] (A1.111) or by the polychaete [Hediste diversicolor] and the tellin [Macoma balthica] (A2.312) depending on the substratum. This is a biotope with a low species diversity and the 'high' number of species in the characterising species list is due to a variation in the species composition from site to site, not to high species richness at individual sites.

Temporal variation: This biotope may be a summer variation of A2.431, in which ephemeral algal growth has exceeded the capacity of the grazing molluscs.


HabitatName:
Hydrolittoral stony substrata: level bottoms with little or no macrophyte vegetation


HabitatName:
Hydrolittoral stony substrata: level bottoms dominated by macrophyte vegetation


HabitatName:
Hydrolittoral gravel substrata: level bottoms with little or no macrophyte vegetation


HabitatName:
Hydrolittoral gravel substrata: level bottoms dominated by macrophyte vegetation


HabitatName:
Hydrolittoral sandy substrata: level bottoms with little or no macrophyte vegetation


HabitatName:
Hydrolittoral sandy substrata: level bottoms dominated by macrophyte vegetation


HabitatName:
Hydrolittoral muddy substrata: with little or no macrophyte vegetation


HabitatName:
Hydrolittoral muddy substrata: dominated by macrophyte vegetation


HabitatName:
Hydrolittoral mixed sediment substrata: with little or no macrophyte vegetation


HabitatName:
Hydrolittoral mixed sediment substrata: dominated by macrophyte vegetation


HabitatName:
Infralittoral rock and other hard substrata

HabitatDescription:
Infralittoral rock includes habitats of bedrock, boulders and cobbles which occur in the shallow subtidal zone and typically support seaweed communities. The upper limit is marked by the top of the kelp zone whilst the lower limit is marked by the lower limit of kelp growth or the lower limit of dense seaweed growth. Infralittoral rock typically has an upper zone of dense kelp (forest) and a lower zone of sparse kelp (park), both with an understorey of erect seaweeds. In exposed conditions the kelp is [Laminaria hyperborea] whilst in more sheltered habitats it is usually [Laminaria saccharina]; other kelp species may dominate under certain conditions. On the extreme lower shore and in the very shallow subtidal (sublittoral fringe) there is usually a narrow band of dabberlocks [Alaria esculenta] (exposed coasts) or the kelps [Laminaria digitata] (moderately exposed) or [L. saccharina] (very sheltered). Areas of mixed ground, lacking stable rock, may lack kelps but support seaweed communities. In estuaries and other turbid-water areas the shallow subtidal may be dominated by animal communities, with only poorly developed seaweed communities.


HabitatName:
Atlantic and Mediterranean high energy infralittoral rock

HabitatDescription:
Rocky habitats in the infralittoral zone subject to exposed to extremely exposed wave action or strong tidal streams. Typically the rock supports a community of kelp [Laminaria hyperborea] with foliose seaweeds and animals, the latter tending to become more prominent in areas of strongest water movement. The depth to which the kelp extends varies according to water clarity, exceptionally (e.g. St Kilda) reaching 45 m. The sublittoral fringe is characterised by dabberlocks [Alaria esculenta].


HabitatDescription:
Rocky habitats in the infralittoral zone subject to exposed to extremely exposed wave action or strong tidal streams. Typically the rock supports a community of kelp [Laminaria hyperborea] with foliose seaweeds and animals, the latter tending to become more prominent in areas of strongest water movement (A3.113, A3.115 and A3.1152). The depth to which the kelp extends varies according to water clarity, exceptionally (e.g. St Kilda) reaching 45 m. In some areas, there may be a band of dense foliose seaweeds (reds or browns) below the main kelp zone (A3.116). The sublitttoral fringe is characterised by dabberlocks [Alaria esculenta] (A3.111). In very strong wave action the sublittoral fringe [A. esculenta] zone extends to 5 to 10 m depth, whilst at Rockall [A. esculenta] replaces [L. hyperborea] as the dominant kelp in the infralittoral zone (A3.112).

Situation: Very exposed rocky coasts, from low water to depths up to 45m.

Temporal variation: Winter storms may remove patches of kelp, and fast-growing annuals may form a temporary forest (A3.122).


HabitatName:
[Alaria esculenta] on exposed sublittoral fringe bedrock

HabitatDescription:
Exposed sublittoral fringe bedrock with an [Alaria esculenta] forest and an encrusting fauna of the mussel [Mytilus edulis] and barnacles such as [Semibalanus balanoides]. The kelp [Laminaria digitata] can be part of the canopy. Underneath the canopy are red seaweeds such as [Mastocarpus] stellatus and [Palmaria palmata], while encrusting coralline red algae such as [Lithothamnion graciale] covers the rock surface. The limpet [Patella vulgata] can be found grazing the rock surface, while the whelk Nucella lapillus is preying on the limpets, barnacles and mussels. Two variants of this biotope are described. In more wave exposed conditions [Laminaria digitata] is absent and the rock surface is often characterised by dense patches of mussels (unit A3.1111). In slightly less exposed sites the [A. esculenta] is mixed with [L. digitata] (unit A3.1112).
Situation: This biotope is found in the sublittoral fringe on exposed shores, typically occupying the extreme lower shore down to 1 or 2 m depth, although it can also extend down to 15 m depth on very exposed coasts. It is generally found below the mussel-barnacle zone of the lower shore (unit A1.111) or a narrow band of the seaweed-dominated biotopes featuring dense [Himanthalia elongata] or red seaweeds (units A1.123, A1.125). Below the [A. esculenta] zone, the upper infralittoral rock generally supports a [Laminaria hyperborea] kelp community (A3.113, A3.1151 or A3.2141).


HabitatName:
[Alaria esculenta], [Mytilus edulis] and coralline crusts on very exposed sublittoral fringe bedrock

HabitatDescription:
Very exposed sublittoral fringe bedrock characterised by the kelp [Alaria esculenta] and dense patches of small individuals of the mussel [Mytilus edulis], both of which grow over a dense cover of encrusting coralline algae. Foliose red seaweeds may also be present, but the species composition and their abundance vary between sites. Species such as [Corallina officinalis] occur widely. The kelp [Laminaria digitata] is usually absent, although stunted plants may be present at a few sites. The limpet [Patella vulgata] and the barnacle [Semibalanus balanoides] are often common. Patches of anthozoans and the hydroid [Tubularia] spp. occur in more wave-surged areas. In extremely exposed areas the [A. esculenta] zone can extend as deep as 15 m, where it has less [S. balanoides], [M. edulis] and greater densities of [Tubularia] spp. (e.g. Barra and shallow areas of Rockall, Scotland).

Situation: This biotope is most commonly found beneath the mussel-barnacle zone (unit A1.111) of very exposed shores and above the upper infralittoral [Laminaria hyperborea] forest (  A3.113 or A3.115). It is at the extremely wave-surged sites, such as St Kilda, that A3.113 occurs below A3.1111. Occasionally, the [A. esculenta] zone occurs below a narrow but dense band of red seaweeds: typically [Mastocarpus stellatus] and/or [Palmaria palmata] and [Corallina officinalis] (unit A1.125) or very occasionally [Himanthalia elongata] (A1.123). A dense turf of [C. officinalis] (A1 122) occurs above the [A. esculenta] zone at a few extremely exposed sites, particularly on steep or vertical rock. On less exposed shores, however, an [A. esculenta] dominated zone may lie immediately above a narrow [L. digitata] zone (A3.1112). Unit A3.1111 can also occur on less exposed steep or vertical shores, where wave-surge restricts the growth of [L. digitata] which generally dominates the sublittoral fringe rock on moderately exposed shores. On seasonally unstable boulders or sites subject to disturbance by strong wave-action, a mixed kelp canopy that characterises A3.122 may occur beneath the A3.1111 zone instead of the ubiquitous [L. hyperborea] forest; this is most common on the Shetland isles.

Temporal variation: At very exposed sites, [A. esculenta] may have been so wave-battered during the season as to be reduced to a tattered midrib with no blades, altering the general appearance of the biotope. Where A3.1111 occurs on boulders and/or sites subject to disturbance during severe weather conditions, rock that is scoured clean may then be rapidly colonised by fast-growing green algae such as [Enteromorpha] spp. An assemblage of rapidly colonising species that characterise the disturbed A3.121 biotope may also develop in the sublittoral fringe. A species that can fluctuate in huge numbers at these sites is the starfish [Asterias rubens], sometimes forming dense aggregations across the narrow [A. esculenta] band whilst feeding on the mussels.


HabitatName:
[Alaria esculenta] and [Laminaria digitata] on exposed sublittoral fringe bedrock

HabitatDescription:
Exposed sublittoral fringe bedrock characterised by a mixture of the kelps [Laminaria digitata] and [Alaria esculenta] with an understorey of red seaweeds including [Palmaria palmata] and [Corallina officinalis] with encrusting coralline algal on the rock surface. Anthozoans such as [Halichondria panicea], the mussel [Mytilus edulis] and the barnacle [Semibalanus balanoides] can be found attached in cracks and crevices. The limpets [Patella vulgata] or on southern shores [Patella ulyssiponensis] can be found in their characteristic "scars" grazing the biofilm/algal crusts on the rock surface, while the limpet [Helcion pellucidum] is restricted to grazing the kelp fronds. Colonies of the bryozoan [Electra pilosa] can cover the red seaweeds [Mastocarpus stellatus] and [Chondrus crispus] or the rock surface.

Situation: This unit represents an intermediate on the wave exposure gradient, with pure stands of [A. esculenta] (unit A3.1111) being found on more exposed shores and pure [L. digitata] (unit A3.1112) on more sheltered shores. This biotope usually occurs immediately above a sublittoral [Laminaria hyperborea] forest (units A3.115 or A3.214), although a narrow band of [L. digitata] (A3.1112) may occur between these two zones, particularly on less exposed shores. In southwest England a zone of mixed kelp forest [L. hyperborea] and [Laminaria ochroleuca] may occur below the [A. esculenta] (A3.1153). A number of different biotopes can occur above A3.1112; most commonly these are the mussel-barnacle zone (A1.111), [Himanthalia elongata] (A1.123), a red algal turf or a [Fucus serratus]-red algal mosaic (A1.2141) on the less exposed shores. This biotope also occurs on steep and vertical shores of moderately exposed coasts where a localised increase in wave action restricts the growth of [L. digitata]. As a result of this increased wave action the [L. digitata] plants are usually small and often show signs of damage.

Temporal variation: There may be seasonal changes in the amount of ephemeral seaweeds due to disturbance caused by winter storms.


HabitatName:
[Alaria esculenta] forest with dense anemones and crustose sponges on extremely exposed infralittoral bedrock

HabitatDescription:
This biotope has only been recorded from Rockall, where [Alaria esculenta] appears to replace [Laminaria hyperborea] as the dominant kelp forest species on the extremely wave-exposed steep and vertical rock, a zone that extends from 14 m down to 35 m. Beneath the [A. esculenta] canopy, the rock surface is covered by a dense turf of anthozoans such as [Sagartia elegans], [Phellia gausapata] and [Corynactis viridis], encrusting sponges and coralline algae. The gastropod [Margarites helicinus] can be found grazing on the kelp fronds, whereas the crab [Cancer pagurus] can be found among the kelp stipes. The bryozoan [Tubularia indivisa] also occur, but it does not form such a dense turf as in more shallow waters, while the ascidian [Botryllus leachi] is found encrusting the large brown seaweeds. [Cryptopleura ramosa] is the dominant red seaweed on horizontal surfaces. The kelp [Laminaria digitata] is reported to occur mixed with [A. esculenta] on the nearby Helen's reef.

Situation: Above the  zone with A3.112 (about 5 m to 13 m) [A. esculenta] still dominates, but it resembles more closely the typical sublittoral fringe [A. esculenta] biotope (unit A3.1111), though it has a very dense turf of small hydroids and few foliose algae. Towards the lower part of this [A. esculenta] forest (30 m to 35 m), the density of [A. esculenta] is reduced and the rock surface is characterised by a dense turf of red algae (unit A3.116).


HabitatName:
[Laminaria hyperborea] forest with a faunal cushion (sponges and polyclinids) and foliose red seaweeds on very exposed infralittoral rock

HabitatDescription:
Very exposed and exposed, but wave-surged, upper infralittoral bedrock and massive boulders characterised by a dense forest of the kelp [Laminaria hyperborea] with a high diversity of seaweeds and invertebrates. The shallowest kelp plants are often short or stunted, while deeper plants are taller with heavily epiphytised stipes with foliose red seaweeds such as [Delesseria sanguinea], [Cryptopleura ramosa] or [Plocamium cartilagineum] or even the brown seaweed [Dictyota dichotoma]. Also found on the stipes or on the rock below the canopy are red seaweeds including [Phycodrys rubens], [Kallymenia reniformis], [Callophyllis laciniata, Caryophyllia smithii], and [Corallina officinalis], while encrusting coralline algae can cover any bare patches of rock. At some sites the red seaweeds can be virtually mono-specific, while at other sites show considerable variation containing a dense mixed turf of a large variety of species. The red seaweed [Odonthalia dentata] can be present in the north. The faunal and floral under-storey is generally rich in species due, in part, to the relatively low urchin-grazing pressure in such shallow exposed conditions. The faunal composition of this biotope varies markedly between sites, but commonly occurring are the soft coral [Alcyonium digitatum] and the anthozoans [Sagartia elegans] and [Corynactis viridis]. Sponges form a prominent part of the community with variable amounts of the sponges [Halichondria panicea] and [Pachymatisma johnstonia] and several other species. The crab [Cancer pagurus] and the starfish [Asterias rubens] are normally present in small numbers foraging beneath the canopy, while the sea urchins [Echinus esculentus] and [Urticina felina] graze on the seaweeds. The hydroid Obelia geniculata, the ascidian Botryllus schlosseri and the bryozoan Membranipora membranacea compete for space on the kelp, whereas the bryozoan Electra pilosa also can be found on foliose red seaweeds.
Situation: This kelp forest most commonly occurs beneath a zone of [Alaria] [esculenta] and [Mytilus] [edulis] (unit A3.1111) and may contain small patches of [A. esculenta]. As the force of the wave-surge diminishes with increased depth, density of the faunal turf reduces and the kelp forest or park changes to one characterised by kelp and dense red seaweeds (units A3.1151 or A3.1152). In some areas of Shetland and St Kilda the lower infralittoral zone is characterised by a park of the kelp [Laminaria saccharina] and/or [Saccorhiza polyschides] (A3.122). Where the [L. hyperborea] forest continues to depths of 15 m or greater it may give way to a zone of dense foliose red algae (A3.116 or A3.1161).


HabitatName:
Sparse [Laminaria hyperborea] and dense [Paracentrotus lividus] on exposed infralittoral limestone

HabitatDescription:
This biotope is known from only one location, the Aran Islands, Co. Galway (Ireland). Here, a limestone platform between 3 m and 6 m of depth is dominated by a dense population of the urchin [Paracentrotus lividus], which heavily graze and burrow into the soft limestone. So intense is the grazing pressure that the rock appears completely bare, except for a coralline algal crust and occasional [Laminaria hyperborea] and [Saccorhiza polyschides]. The anthozoans [Sagartia elegans] and [Corynactis viridis] are also present, though at low abundance. The grazed kelp also extends deeper to 20 to 25 m further offshore. (Only one CB record within this biotope).
Situation: This rare biotope has only been recorded from one location and the neighbouring biotopes were not fully surveyed. In deeper water (30-40m) there is unit A4.121.


HabitatName:
[Laminaria hyperborea] with dense foliose red seaweeds on exposed infralittoral rock

HabitatDescription:
Very exposed to exposed infralittoral bedrock or large boulders characterised by the kelp [Laminaria hyperborea], beneath which is a dense turf of foliose red seaweeds. Three variations of this biotope are described: the upper infralittoral kelp forest (unit A3.1151), the kelp park below (unit A3.1152) and a third type of kelp forest, confined to southern England, that is characterised by a mixture of [L. hyperborea] and [Laminaria ochroleuca] (unit A3.1153). The fauna of these biotopes is markedly less abundant than kelp forests in areas of greater wave surge (unit A3.113); sponges, anthozoans and polyclinid ascidians may be present, though never at high abundance. Beneath the under-storey of red seaweeds, the rock surface is generally covered with encrusting coralline algae.


HabitatName:
[Laminaria hyperborea] forest with dense foliose red seaweeds on exposed upper infralittoral rock

HabitatDescription:
Very exposed to exposed upper infralittoral bedrock or large boulders characterised by a dense forest of the kelp [Laminaria hyperborea]. On the rock surface beneath the kelp canopy is a dense turf of red foliose seaweeds including [Cryptopleura ramosa], [Plocamium cartilagineum], [Phycodrys rubens] and [Callophyllis laciniata] as well as encrusting coralline algae and the foliose brown seaweed [Dictyota dichotoma]. The red algal turf can be virtually mono-specific, dominated by stands of [P. cartilagineum], [C. ramosa] or [Heterosiphonia plumosa], [Kallymenia reniformis] or in the north, [Odonthalia dentata]. Other sites may contain a dense mixed turf of these and other species. The dense turf is due, in part, to the relatively low grazing pressure from the urchin [Echinus esculentus] in such shallow exposed conditions. The shallowest kelp plants are often short or stunted, while deeper plants are taller and the stipes are heavily epiphytised by red seaweeds such as [Delesseria sanguinea] and [Membranoptera alata]. The bryozoan [Electra pilosa] can form colonies on the foliose red seaweeds, while the bryozoan [Membranipora membranacea] more often can be found on the [L. hyperborea] fronds along with the ascidian [Botryllus schlosseri] and the hydroid [Obelia geniculata]. The gastropods [Gibbula cineraria] and [Calliostoma zizyphinum] are found grazing among the kelp holdfasts, while a few individuals of the barnacle [Balanus crenatus] can present along with the white calcareous tubes of the polychaete [Pomatoceros triqueter], where substratum is available. The starfish [Asterias rubens] can be found predating on polychaetes, mussels and small crustaceans. The soft coral [Alcyonium digitatum] can be present covering the rock surface as well as the anthozoan [Urticina felina].
Situation: This kelp forest biotope most commonly occurs beneath a zone of [Alaria esculenta/Mytilus edulis] (unit A3.1111) and above a [L. hyperborea] park (unit A3.1152). At very exposed sites, such as some areas of Shetland and St Kilda, the lower infralittoral zone is often characterised by a park of [Laminaria saccharina] and/or [Saccorhiza polyschides] (A3.122). This zone presumably develops due to the mobility of nearby cobbles, boulders and sediment during winter storms, removing the slower growing [L. hyperborea]. Occasionally, a band of dense foliose seaweeds, with no kelp, occurs below the kelp forest (units A3.116 or A3.1161).


HabitatName:
[Laminaria hyperborea] park with dense foliose red seaweeds on exposed lower infralittoral rock

HabitatDescription:
Very exposed to exposed lower infralittoral bedrock or large boulders characterised by a kelp park of [Laminaria hyperborea] with a dense turf of foliose red seaweeds and encrusting coralline algae. These red seaweeds dominate kelp stipes and bedrock in a similar abundance and composition to the upper infralittoral kelp forest, the most commonly occurring species being [Callophyllis laciniata], [Cryptopleura ramosa], [Plocamium cartilagineum], [Kallymenia reniformis], [Delesseria sanguinea], [Phycodrys rubens], [Hypoglossum hypoglossoides], [Heterosiphonia plumosa] and [Bonnemaisonia asparagoides]. In addition, moderate to high abundance of foliose brown seaweeds, such as [Dictyota dichotoma] are more common than in the kelp forest above. More upper circalittoral fauna occur in the park than in the kelp forest, such as the cup-coral [Caryophyllia smithii]. Some species more often present in the kelp park than the forest include the anthozoan [Alcyonium digitatum] and the featherstar [Antedon bifida]. The urchin [Echinus esculentus], the gastropods [Gibbula cineraria] and [Calliostoma zizyphinum] and the starfish [Asterias rubens] are normally present underneath the canopy along with the anthozoans [Urticina felina] and [Corynactis viridis]. The sponge [Cliona celata] is also present often found boring into shells or soft rock where available. The bryozoan [Membranipora membranacea] can be found on the [L. hyperborea] fronds along with the hydroid [Obelia geniculata] and the ascidian [Botryllus schlosseri]. The polychaete [Pomatoceros] sp. is present on the rock surface.

Situation: This biotope usually occurs below the exposed kelp forests (units A3.113 and A3.1151). At some sites, a dense band of [D. dichotoma] may form a separate zone below (A3.116). Where seasonally unstable cobbles and/or boulders are present adjacent to and/or below the bedrock supporting the [L. hyperborea] unit A3.122 may occur.

Temporal variation: In the late summer both the kelp and the foliose seaweeds can become heavily encrusted with the bryozoan crusts [Electra pilosa] and [Membranipora membranacea]. Temporal variation within the community structure is unknown.


HabitatName:
Mixed [Laminaria hyperborea] and [Laminaria ochroleuca] forest on exposed infralittoral rock

HabitatDescription:
Mixed [Laminaria hyperborea] and [Laminaria ochroleuca] forests on upper infralittoral exposed rock with a dense community of foliose red seaweeds such as [Cryptopleura ramosa], and [Plocamium cartilagineum] as well as small filamentous red seaweeds including [Bonnemaisonia asparagoides, Heterosiphonia plumosa, Pterosiphonia parasitica] and [Brongniartella byssoides]. [L. hyperborea] has a rough stipe which allow dense assemblages of epiphytic red seaweeds to form including the foliose [Callophyllis laciniata], [Delesseria sanguinea] and [Hypoglossum hypoglossoides]. Unlike [L. hyperborea], however, [L. ochroleuca] has a smooth stipe and so it lacks dense assemblages of epiphytic seaweeds [L. ochroleuca] has a smooth stipe. Encrusting coralline algae often cover much of the rock surface along with a few brown seaweeds including [Dictyota dichotoma], [Dictyopteris polypodioides] and [Desmarestia aculeata] present as well. In mixed kelp forest [L. ochroleuca] may predominate with [L. hyperborea] more common at shallower depths. Whilst foliose red seaweeds dominate the upward-facing rock beneath the kelp canopy, much of the fauna is restricted to crevices or vertical faces, possibly due to grazing pressure. Echinoderms are often common in this biotope, in particular the sea urchin [Echinus esculentus] and the starfish [Asterias rubens] and [Marthasterias glacialis]. Verticals are colonised by anthozoans including the anthozoans [Corynactis viridis], [Caryophyllia smithii, Actinothoe sphyrodeta] and [Alcyonium digitatum], while the bryozoan [Membranipora membranacea] colonise the [Laminaria] sp. fronds. This biotope is restricted to the coast of Cornwall and the Isles of Scilly. [L. ochroleuca] occurs at low abundance in other kelp biotopes (sheltered through to exposed) from Dorset to Lundy Island. In such cases, records should be treated as regional variations of these biotopes. Records should only be assigned to this unit when the canopy is dominated by [L. ochroleuca] alone, or (more usually) by a mixture of both [L. hyperborea] and [L. ochroleuca] (at similar abundance). Both this biotope and unit A3.311 are common on the Brittany and Normandy coasts of France.
Situation: Since [L. ochroleuca] is less tolerant of wave action than [L. hyperborea] this biotope commonly occurs below exposed kelp forests (unit A3.1151). On occasion it is found below [Alaria] [esculenta] in the sublittoral fringe (units A3.1111 or A3.1112). At some sites a band of dense foliose seaweeds, with no kelp, occurs below the kelp forest (A3.116 or A3.1161) whilst at other sites [L. hyperborea] kelp park occurs below (A3.1152).


HabitatDescription:
A dense turf of foliose red seaweeds on exposed or moderately exposed lower infralittoral rock, generally, at or below the lower limit of the kelp. Most of the red seaweeds are common to the kelp zone above, while the faunal component of the biotope is made up of species that are found either in the kelp zone or the animal-dominated upper circalittoral below. Foliose species commonly present include [Dilsea carnosa], [Hypoglossum hypoglossoides, Schottera nicaeensis], [Cryptopleura ramosa] and [Delesseria sanguinea]. The red seaweed species composition varies considerably; at some sites a single species may dominate (particularly [Plocamium cartilagineum]). Small filamentous red seaweeds can be found here as well. These include species such as [Heterosiphonia plumosa, Brongniartella byssoides]. As well as a varied red seaweed component, this biotope may also contain occasional kelp plants and patches of the brown foliose seaweed [Dictyota dichotoma]. Coralline crusts covers the bedrock beneath the seaweeds. The fauna generally comprises low-encrusting forms such as the tubeworms [Pomatoceros] spp., anthozoans including [Alcyonium digitatum], [Urticina felina] and [Caryophyllia smithii]) and occasional sponge crusts such as [Cliona celata, Esperiopsis fucorum], [Scypha ciliata] and [Dysidea fragilis]. More mobile fauna include the gastropod [Calliostoma zizyphinum], the echinoderms [Echinus esculentus] as well as the starfish [Asterias rubens] and [Marthasterias glacialis] and lastly, the crab [Cancer pagurus]. Bryozoan crusts such as [Electra pilosa] can be found fronds on the foliose red seaweeds while scattered hydroids such as [Nemertesia antennina] form colonies on shells, cobbles and available rock. At some sites erect bryozoans [Crisia] spp. and [Bugula] spp. are present. Ascidians such as [Clavelina lepadiformis] and [Clavelina lepadiformis] may also be common. In the north the foliose red seaweed [Callophyllis laciniata] may occur.

Situation: This biotope is generally found at or below the lower limit of the kelp, below either kelp forest or park (units A3.1151 and A3.1152).

Temporal variation: Many of the red seaweeds, which occur in this biotope, have annual fronds, which tend to die back in the autumn and regenerate again in the spring. This produces a seasonal change in the density of the seaweed cover, which is substantially reduced over winter months and reaches its most dense between April to September.


HabitatName:
Foliose red seaweeds with dense [Dictyota dichotoma] and/or [Dictyopteris membranacea] on exposed lower infralittoral rock

HabitatDescription:
A dense turf of foliose red seaweeds mixed with a dense turf of the foliose brown seaweeds [Dictyota dichotoma] and/or [Dictyopteris membranacea] on exposed and moderately exposed lower infralittoral rock, generally at or below the lower limit of the kelp zone. In some areas the lower infralittoral is subject to a moderate amount of scour from nearby sand. [D. dichotoma] is relatively tolerant of such scour and in such areas a zone forms with other sand-tolerant seaweeds. [D. membranacea] is confined to south-western coasts. Typically brown seaweeds dominate the seabed or are at least in equal abundance to the red seaweeds, some of which may also form dense stands such as [Plocamium cartilagineum], [Calliblepharis ciliata, Cryptopleura ramosa, Bonnemaisonia asparagoides], [Heterosiphonia plumosa, Delesseria sanguinea] and [Brongniartella byssoides]. The urchin [Echinus esculentus] can be found grazing the rock surface which can be covered in coralline algae. The anthozoans [Caryophyllia smithii] and [Alcyonium digitatum] are usually present in this biotope along with the tube-building worm [Pomatoceros] sp. which is more common in sand-scoured areas. The starfish [Asterias rubens] and [Henricia] sp. and sponge crusts including [Cliona celata] can also be found here. [D. dichotoma] also occurs in the kelp park, and records should only be assigned to this biotope where kelp such as [Laminaria hyperborea] is sparse or absent and a relatively high density of [D. dichotoma] and/or [D. membranacea] is present.

Situation: This biotope usually occurs at or below the lower limit of kelp [L. hyperborea] (units A3.1152 or A3.214). In south-west England a zone of mixed kelp forest [L. hyperborea] and [Laminaria ochroleuca] may occur above the dense foliose algae (unit A3.1153). Unit A3.1161 marks the lower limit of the lower infralittoral zone.

Temporal variation: Like many of the red seaweeds found in this biotope the dominant brown seaweeds [D. membranacea] and [D. dichotoma] have annual fronds which tend to die back in the autumn and regenerate again in the spring. This produces a seasonal change in the density of the seaweed cover, which is substantially reduced over winter months and reaches its most dense between April and September.


HabitatName:
[Laminaria hyperborea] and red seaweeds on exposed vertical rock

HabitatDescription:
On exposed coasts with moderately strong to weak tidal currents generally at depths of 0-10m, vertical rock communities dominated by frequent [Laminaria hyperborea] and its commonly associated red seaweeds [Delesseria sanguinea], [Cryptopleura ramosa] and [Plocamium cartilagineum] can be found. Within this biotope the jewel anemone [Corynactis viridis] is frequently found in dense aggregations attached to the vertical rock surface. This biotope contains 5 sub-biotopes, distinguished by their biogeography. On the west coast of Scotland, the Northern Isles and the Isle of Man on extremely exposed coasts a variant of this biotope characterised by frequent [Metridium senile] and occasional [Sagartia elegans] can be found. Further south on the west coast of Ireland, southern Scotland, Wales, and south west England a second variant characterised by frequent [Alcyonium digitatum] and occasional [Cliona celata] can be distinguished. A third variant has been recorded from Northern Ireland characterised by the red seaweeds [Lithophyllum] and [Ptilota gunneri], the sea squirt [Dendrodoa grossularia] and the bryozoan [Membranipora membranacea]. South from the Isle of Man, on the Welsh Coast, and on the south west and southern English coasts a fourth variant of this biotope is found, which is characterised by the barnacle [Balanus crenatus], which may be more frequent in this sub-biotope, and the rarity of [Alcyonium digitatum], a species which is more frequent in other variants. This variant has mainly been recorded in shallow water (0-5m). The final biogeographic variant of this biotope is, as with the previous variant, found on the coasts of Wales and south west England. It can be distinguished from the previous variant by the frequent [Diplosoma listerianum] and occasional [Lissoclinum perforatum], although these species are not always present.
Situation: Open rocky coasts of the south-west, west and north-west.


HabitatName:
Turf of articulated [Corallinaceae] on exposed to sheltered infralittoral bedrock and boulders


HabitatDescription:
Infralittoral rock habitats, subject to disturbance through mobility of the substratum (boulders or cobbles) or abrasion/covering by nearby coarse sediments or suspended particulate matter (sand). The associated communities can be quite variable in character, depending on the particular conditions, which prevail. The typical [Laminaria hyperborea] and red seaweed communities of stable open coast rocky habitats (A3.21) are replaced by those, which include more ephemeral species or those tolerant of sand and gravel abrasion. As such [Laminaria saccharina], [Saccorhiza polyschides] or [Halidrys siliquosa] may be prominant components of the community.


HabitatName:
[Saccorhiza polyschides] and other opportunistic kelps on disturbed upper infralittoral rock

HabitatDescription:
Exposed low-lying reefs in the sublittoral fringe or upper infralittoral (generally above 5m depth), mainly in the southwest and west, dominated by the kelp [Saccorhiza polyschides]. This opportunistic coloniser replaces [Laminaria digitata] or [Laminaria hyperborea] as the dominant kelp, following 'disturbance' of the canopy. This may be the result of storms, when loose sediment and even cobbles or boulders are mobilised, scouring most seaweeds and animals from the surrounding rock. As [S. polyschides] is essentially a summer annual (occasionally it lasts into a second year), it is also particularly common close to rock/sand interfaces which become too scoured during winter months to prevent the longer-living kelps from surviving. As a result of the transient nature of this biotope, its composition is varied; it may contain several other kelp species, including [L. digitata], [Laminaria saccharina] and [Alaria esculenta], at varying abundances. [Laminaria] spp. sporelings can also be a prominent feature of the site. Beneath the kelp, (scour-tolerant) red seaweeds including [Corallina officinalis], [Kallymenia reniformis], [Plocamium cartilagineum], [Chondrus crispus], [Dilsea carnosa] and encrusting coralline algae are often present. Foliose red seaweeds such as [Callophyllis laciniata], [Cryptopleura ramosa] and [Palmaria palmata] also occur in this biotope. [P. palmata] and [Delesseria sanguinea] often occur as epiphytes on the stipes of [L. hyperborea], when it is present. The foliose green seaweed [Ulva] spp. is fast to colonise newly cleared areas of rock and is often present along with the foliose brown seaweed [Dictyota dichotoma]. Due to the disturbed nature of this biotope, fauna are generally sparse, being confined to encrusting bryozoans and/or sponges, such as [Halichondria panicea] and the gastropod [Gibbula cineraria].

Situation: On some shores (for example in Cornwall and south-west Ireland), [S. polyschides] competes so effectively with the other laminarians that it forms a well-defined zone in shallow water, between the [L. digitata] (unit A3.3131) and [L. hyperborea] zones (units A3.115 and A3.214). Elsewhere, it is found at sites that have been physically disturbed, removing areas of established kelp ([L. hyperborea]) thus allowing this opportunistic biotope to develop over a short space of time.

Temporal variation: There may be significant variations in this biotope over time, as by its very nature, it is dominated by many fast-growing annual seaweeds. The foliose green seaweed [Ulva] sp. is fast to colonise newly cleared areas of rock and can be present as a dense growth on the rock around the [Saccorhiza polyschides]. Similarly, large patches of [Laminaria] spp. sporelings may be present at times.


HabitatName:
[Laminaria saccharina] and/or [Saccorhiza polyschides] on exposed infralittoral rock

HabitatDescription:
A forest or park of the fast-growing, opportunistic kelps [Laminaria saccharina] and/or [Saccorhiza polyschides] often occurs on seasonally unstable boulders or sand/pebble scoured infralittoral rock. The substratum varies from large boulders in exposed areas to smaller boulders and cobbles in areas of moderate wave exposure or nearby bedrock. In these cases, movement of the substratum during winter storms prevents a longer-lived forest of [Laminaria hyperborea] from becoming established. This biotope also develops on bedrock where it is affected by its close proximity to unstable substrata. Other fast-growing brown seaweeds such as [Desmarestia viridis], [Desmarestia aculeata, Cutleria multifida] and [Dictyota dichotoma] are often present. Some [L. hyperborea] plants may occur in this biotope, but they are typically small since the plants do not survive many years. The kelp stipes are usually epiphytised by red seaweeds such as [Delesseria sanguinea] and [Phycodrys rubens]. Other red seaweeds present beneath the kelp canopy include [Plocamium cartilagineum, Nitophyllum punctatum], [Callophyllis laciniata] and [Cryptopleura ramosa]. Encrusting algae often form a prominent cover on the rock surfaces, including red, brown and coralline crusts. Faunal richness and diversity is generally low compared to the more stable [L. hyperborea] kelp forest and park communities (A3.115). Where some protection is afforded the anthozoan [Alcyonium digitata] can occur in addition to the more robust species such as the tube-building worm [Pomatoceros triqueter]. Mobile species include the to shell [Gibbula cineraria] and [Calliostoma zizyphinum] and the sea urchin [Echinus esculentus]. The hydroid [Obelia geniculata] and the bryozoan [Membranipora membranacea] can often be found colonising the kelp fronds.

Situation: This biotope can be found below the [L. hyperborea] zone (units A3.113 or A3.115), especially where close to a rock/ sand interface (where it is subject to sand/pebble scour in winter). Where this biotope occurs on bedrock, not scoured by mobile sediment, it is thought to occur as a result of intense wave action in winter storms which is too severe to allow [L. hyperborea] to develop and remain in shallow water.

Temporal variation: Due to the disturbed nature of this biotope there can be significant changes in the structure of the community. Coralline and brown algal crusts with sparse kelp plants generally dominate areas that have been recently disturbed. Diversity is low and a few species of fast-growing seaweeds can dominate the seabed. A longer established community will have larger, mixed kelp plants and a greater diversity of red seaweeds.


HabitatName:
[Laminaria saccharina], [Chorda filum] and dense red seaweeds on shallow unstable infralittoral boulders and cobbles

HabitatDescription:
Seasonally disturbed unstable boulders and cobbles in very shallow water dominated by the fast-growing brown seaweed [Chorda filum] together with the kelp [Laminaria saccharina]. The brown seaweed [Desmarestia aculeata] is also typical of this disturbed environment as well encrusting coralline algae and brown crusts. Beneath the prolific growth of [C. filum], red and brown seaweeds densely cover many of the boulders, cobbles and pebbles. Other sediment-tolerant seaweeds such as species from the Ectocarpales (brown filamentous seaweeds) and the red seaweeds [Chondrus crispus], [Phyllophora pseudoceranoides], [Dilsea carnosa] and [Corallina officinalis] is normally present. Other red seaweeds which can be found here include [Chondria dasyphylla], [Brongniartella byssoides], [Polysiphonia elongata], [Ceramium nodolosum], [Cystoclonium purpureum, Heterosiphonia plumosa], [Rhodomela confervoides] and [Plocamium cartilagineum]. The brown seaweeds [Punctaria] sp. and [Cladostephus spongiosus] are generally present. The faunal component of this biotope is typically sparse - the starfish [Asterias rubens] and the crabs [Pagurus] [bernhardus] and [Necora puber] are amongst the most conspicuous animals. The bryozoan crust [Electra pilosa] colonise many of the algae along with the ascidian [Botryllus schlosseri]. Occasional the polychaete [Lanice conchilega] may occur in the sand between pebbles, and the anthozoan [Urticina felina] may be found amongst pockets of gravel along with the gastropod [Gibbula cineraria]. At some sites the rock beneath the algae can be occupied by the tube-building polychaete [Pomatoceros triqueter]. This biotope is also present at other open coast sites around the UK where suitable shallow, seasonally stable boulders, cobbles and pebbles occur. Typical examples of this biotope occur on the shallowest areas of the Sarns in Cardigan Bay, Wales, where reef crests are formed by embedded and mobile boulders, together with cobbles and pebbles in between (typically at 2-3m depth).

Situation: This biotope occurs in shallow water, often on the crest of an infralittoral boulder/cobble bank and as such will not have any biotope 'above' it. More mobile areas of smaller boulders, cobbles and pebbles nearby may support dense ephemeral red seaweeds (unit A2.82) or robust scour-tolerant red seaweeds on sand-covered rock (unit A3.127). The [Halidrys siliquosa] biotope (unit A3.126) also thrives under similar conditions, extending deeper than the shallow A3.123 biotope. Deeper still in the circalittoral zone encrusting fauna is found on highly mobile mixed substrata (A5.141). At a few sites, this biotope can occur within more extensive maerl beds (A5.51) but more commonly is surrounded by sandy sediments (A5.2).

Temporal variation: This biotope will change markedly with the seasons. During the winter months boulders and cobbles will be storm battered and overturned and much of the biota dislodged from the rocks. During more stable conditions in the late spring and summer months the fast-growing seaweeds that characterise this biotope ([C. filum] and [L. saccharina] in particular) will be quick to re-establish, growing at a phenomenal rate. The seasonal disturbance of the substratum prevents a stable [Laminaria hyperborea] forest from developing.


HabitatName:
Dense [Desmarestia] spp. with filamentous red seaweeds on exposed infralittoral cobbles, pebbles and bedrock

HabitatDescription:
Wave-exposed seasonally mobile substrata (pebbles, cobbles) dominated by dense stands of the brown seaweed [Desmarestia aculeata] and/or [Desmarestia ligulata]. Infralittoral pebbles and cobbles that are scoured through mobility during storms, but become stable in the summer allowing the growth of such algae as [Desmarestia] spp. Filamentous red seaweeds such [as Bonnemaisonia asparagoides] and [Brongniartella byssoides] are usually present. Stunted individuals of the kelp such as [Laminaria hyperborea] and [Laminaria saccharina] may be present where bedrock is available. A variety of foliose red seaweeds such as [Cryptopleura ramosa, Chondrus crispus], [Plocamium cartilagineum, Hypoglossum hypoglossoides] and [Nitophyllum punctatum] may on occasion be present underneath the kelp canopy. Other red algae including [Corallina officinalis], [Rhodomela confervoides] and coralline crusts including [Lithothamnion] spp. may be present as well as well as the foliose brown seaweed [Dictyota dichotoma] and the green [Enteromorpha intestinalis]. Due to the nature of this biotope the faunal component is very impoverished though the gastropod [Gibbula cineraria] can be found among the cobbles.
Situation: Often a narrow zone on mixed substrata below a stable zone of kelp on bedrock. Where seasonally mobile substrata affect nearby bedrock this biotope may occur in place of kelp forest.


HabitatDescription:
Bedrock and boulders, often in tide-swept areas, that are subject to scouring or periodic burial by sand, characterised by a canopy of mixed kelps such as [Laminaria saccharina], [Laminaria hyperborea] and [Saccorhiza polyschides] and the brown seaweed [Desmarestia aculeata]; there may also be an understorey of foliose seaweeds that can withstand scour such as [Plocamium cartilagineum, Chondrus crispus, Dilsea carnosa], [Callophyllis laciniata] as well as the filamentous [Heterosiphonia plumosa] and the foliose brown seaweed [Dictyota dichotoma]. The perennial red seaweed [Brongniartella byssoides] re-grows in the summer months. The [L. hyperborea] stipes often support a growth of epiphytes, such as [Delesseria sanguinea], [Phycodrys rubens] and [Cryptopleura ramosa]. The scour can reduce the rock surface to bare coralline crusts at times; sponge crusts and the colonial ascidian [Botryllus schlosseri] can also grow on the stipes and holdfasts. The faunal diversity on the rock is usually low and restricted to robust, low-profile animals such as the tube-building polychaete [Pomatoceros triqueter], the barnacle [Balanus crenatus], encrusting bryozoans such as [Membranipora membranacea], the anthozoan [Urticina felina], the starfish [Asterias rubens] and the urchin [Echinus esculentus]. Deeper sites support more hydroids and bryozoans, particularly [Bugula] spp. Where this biotope occurs in very shallow water [Laminaria digitata] may be found in combination with the other kelp species. Other species present only in shallow water include the red algae [Corallina officinalis] and the sand-binding alga [Rhodothamniella floridula].

Situation: This biotope often occurs below a [L. hyperborea] forest (unit A3.1151, A3.2141 or A3.2121), close to a rock-sediment boundary. It is also found on low-lying rock outcrops surrounded by sand or mixed sediment and nearby biotopes on mixed substrata may include units A1.45, A3.127 or in very shallow water A3.123. A [Flustra foliacea] community (A4.134) often dominates deeper sand-scoured circalittoral rock.

Temporal variation: During late autumn and winter seaweeds are sparse, leaving predominantly kelp and encrusting coralline algae. This is due in part to periods of intense scouring during stormy months, which may strip off all but the most tenacious seaweeds. In addition there will be the natural die back of many of the seaweeds such as [B. byssoides] and [C. ciliata] during the winter months which become conspicuous again during the summer months.


HabitatName:
[Halidrys siliquosa] and mixed kelps on tide-swept infralittoral rock with coarse sediment

HabitatDescription:
Tide-swept boulders and cobbles, often with a mobile component to the substrata (pebbles, gravel and sand), characterised by dense stands of the brown seaweed [Halidrys siliquosa]. It is can be mixed with the foliose brown seaweed [Dictyota dichotoma] and kelp such as [Laminaria saccharina] and [Laminaria hyperborea]. Below the canopy is an undergrowth of red seaweeds that are tolerant of sand-scour such as [Phyllophora crispa, Phyllophora pseudoceranoides, Rhodomela confervoides, Corallina officinalis] and [Chondrus crispus]. Other red seaweeds such as [Plocamium cartilagineum], [Calliblepharis ciliata], [Cryptopleura ramosa], [Delesseria sanguinea], [Heterosiphonia plumosa, Dilsea carnosa, Hypoglossum hypoglossoides] and [Brongniartella byssoides] may be locally abundant, particularly in the summer months. There may be a rich epibiota on [H. siliquosa], including the hydroid [Aglaophenia pluma], ascidians such as [Botryllus schlosseri]. There is generally a sparse faunal component colonising the boulders and cobbles, comprising the tube-building polychaete [Pomatoceros triqueter], the crab [Cancer pagurus], the starfish [Asterias rubens], the gastropod [Gibbula cineraria] and the sea anthozoan [Urticina felina]. The bryozoan [Electra pilosa] can form colonies on the kelp.

Situation: This unit can occur below the tide-swept [Laminaria digitata] zone of the sublittoral fringe bedrock or boulders (unit A3.221). Less stable substrata of boulders, cobbles or pebbles may support kelp and [Chorda filum] in the shallows (A3.123) or dense ephemeral seaweeds (unit A1.45). Sand-influenced rocky outcrops in deeper water may support a [Flustra foliacea] community (A4.134). This biotope is widespread and is found on the open coast in Wales, the south-west and the English Channel as well as more sheltered tidal rapids in the Scottish sealochs. It can form extensive forests or parks in certain areas (Dorset, Sarns). In Wales, the south-west and west of England the red seaweeds [Spyridia filamentosa] and [Halarachnion ligulatum] and brown seaweeds [Dictyopteris membranacea] and [Taonia atomaria] are frequent. In Scotland, kelp occur at a greater proportion of sites, solitary ascidians such as [Ascidiella] spp. are more common and the featherstar [Antedon bifida] and brittlestars [Ophiothrix fragilis] are found.

Temporal variation: Higher diversity of red seaweeds during the summer.


HabitatName:
[Polyides rotundus], [Ahnfeltia plicata] and [Chondrus crispus] on sand-covered infralittoral rock

HabitatDescription:
Low-lying rock surrounded by mobile sand and often subject to burying by the sand, with a turf of resilient red seaweeds [Chondrus crispus, Polyides rotundus] and [Ahnfeltia plicata] typically protruding through the sand on the upper surfaces of the rock. Other scour-tolerant seaweeds include [Rhodomela confervoides], [Phyllophora pseudoceranoides], [Phyllophora crispa, Furcellaria lumbricalis], [Gracilaria gracilis], [Ceramium rubrum, Plocamium cartilagineum, Heterosiphonia plumosa, Cryptopleura ramosa] and [Dilsea carnosa]. Coralline crusts typically cover the rock, while scattered individuals of the brown seaweeds [Halidrys siliquosa, Cladostephus spongiosus], [Dictyota dichotoma] and [Laminaria saccharina] can be present. The large anthozoan [Urticina felina] can occur in this biotope but there are few other conspicuous animals.
Situation: This biotope occurs on shallow sand-covered rock, often below bedrock and boulders supporting kelp forest, which is above the effect of, sand scour (unit A3.214) or abutting sand-scoured kelp on bedrock (unit A3.125). It may also be found adjacent to the shallow kelp and [Chorda filum] biotope (unit A3.123) and similarly can be surrounded by a variety of sediment biotopes.


HabitatName:
Pontic [Cystoseira barbata] on exposed cobbles, boulders and bedrock mixed with and scoured by sand

HabitatDescription:
The dominant species in the [Cystoseira] biocenosis is the brown alga [Cystoseira barbata], which develops on rocky substrates from the spray zone to a depth of 15 m. The mass species are: the molluscs [Mytilaster lineatus] and [Rissoa splendida]; the amphipods [Amphythoe vaillanti] and [Caprella acantifera]; and the polychaetes [Grubea clavata]. Other common species include: the polychaetes [Nereis succinea], [Nephthys hombergii] and [Terebellides stroemi]; the molluscs [Cerastoderma glaucum], [Irus irus], [Polititapes aurea], [Donacilla cornea] and [Pitar rudis] (Zaitsev and Alexandrov, 1998). Along the Romanian shores [Mytilaster lineatus], [Mytilus galloprovincialis] and [Balanus improvisus] are the species occurring with highest frequency within this habitat (which extends until 6 meters depth). Of these species [Mytilaster] is the most important species in terms of density and biomass amounting to almost 80% of the sessile fauna observed. The most important macrobenthic taxa amount to 40 species of which 77% amphipods, 9% polichaetes and 8% isopods. Most frequent amphipods, occurring annually, are [Erichtonius difformis], [Amphitoe vaillanti], [Corophium acherusicum], [Stenothoe monoculoides], [Jassa ocia], [Hyale pontica]. The most frequently occurring isopods are: [Idothea baltica], [Nassa (Dynamena) bidentata], [Synisoma capito]. The most frequently observed polychaetes are [Fabricia clavella] and [Brania clavata] (Tiganus, 1991-1992).


HabitatName:
Mediterranean and Pontic communities of infralittoral algae very exposed to wave action

HabitatDescription:
This community is characterised by the presence of many photophilic algae covering hard bottoms in wave exposed areas.


HabitatName:
Overgrazing facies with incrustant algaes and sea urchins

HabitatDescription:
This facies is characterised by a low coverage of algae due to grazing by sea urchins.


HabitatName:
Association with [Cystoseira amentacea] (var. [amentacea], var. [stricta], var. [spicata])

HabitatDescription:
This association is characterised by the brown alga [Cystoseira amentacea], [Cystoseira amentacea var. stricta] and [Cystoseira amentacea var. spicata], living in pure, rough waters with strong luminosity.


HabitatDescription:
This facies is characterised by an high presence of vermetids building a continous belt called a "trottoir".


HabitatName:
Mediterranean and Pontic facies with [Mytilus galloprovincialis]

HabitatDescription:
This facies characterised by the dominance of the mollusc bivalve [Mytilus galloprovincialis] is typical of areas with high levels of organic input. In the Black Sea this habitat is distributed across wide areas, in the mediolittoral as well as into the infralittoral, from the spray zone to 55 m, where the dominant species is the bivalve mollusc [Mytilus galloprovincialis], the most widespread mussel in the Black Sea (Zaitsev and Aleksandrov, 1998). The biocenosis consists of 105 animal species (Zaitsev and Alexandrov 1998) of which the most characteristic are: Polychaeta - [Nereis (Neanthes) succinea], [Nereis diversicolor], [Polydora ciliata limicola]; Mollusca - [Mytilus galloprovincialis], [Mytilaster lineatus]; Crustacea - [Balanus improvisus], [Jaera sarsi], [Stenothoe monoculoides], [Marinogammarus olivii], [Melita palmate], [Microdeutopus gryllotalpa], [Amphitoe viallanti], [Jassia ocia], [Erichthonius difformis] (Alexandrov, 2006). On the NW shelf the mass species are: [Mya arenaria], [Balanus improvisus], [Nereis succinea], [Prionopsio cirrifera]. On the Crimean shelf the mass species are:the mollusc, [Modiolus adriaticus], and the polychaete [Terebellides stroemi]. Along the Turkish coasts, the most encountered amphipod species are: [Jassa marmorata], [Hylae crassipes], [Ampithoe ramondi], [Corophium acherisicum], [Corophium acutum] (Sezgin et al., 2001). Ephemeral algae may cover Mytilus.


HabitatName:
Association with [Corallina elongata] and [Herposiphonia secunda]

HabitatDescription:
This association with the red algae [Corallina elongata] and [Herposiphonia secunda] is typical of the upper infralittoral with strong wave action and strong luminosity.


HabitatName:
Mediterranean and Pontic association with [Corallina officinalis]

HabitatDescription:
This association with the red alga [Corallina officinalis] is typical in the upper horizon of the infralittoral in areas with strong luminosity and sheltered waters.


HabitatDescription:
This association is characterised by the red alga [Schottera nicaeensis] living in pure, rough waters with strong luminosity.


HabitatName:
Pontic facies with [Petricola lithophaga] in very exposed vertical rock


HabitatName:
Pontic [Vermiliopsis infundibulum] bioegnic rocks


HabitatName:
Frondose algal communities (other than kelp)


HabitatName:
[Cystoseira] spp. on exposed infralittoral bedrock and boulders


HabitatName:
Pontic [Ulva rigida] communities on exposed infralittoral bedrock and boulders


HabitatName:
Pontic [Gelidium latifolium] communities on exposed infralittoral bedrock and boulders


HabitatName:
Atlantic and Mediterranean moderate energy infralittoral rock

HabitatDescription:
Predominantly moderately wave-exposed bedrock and boulders, subject to moderately strong to weak tidal streams. On the 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. Associated with the kelp are communities of seaweeds, predominantly reds and including a greater variety of more delicate filamentous types than found on more exposed coasts (cf. A3.11).


HabitatDescription:
Infralittoral rock subject to moderate wave exposure, or moderately strong tidal streams on more sheltered coasts. 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. Associated with the kelp are communities of seaweeds, predominantly reds and including a greater variety of more delicate filamentous types than found on more exposed coasts (A3.11). The faunal component of the understorey is also less prominant than in A3.11.


HabitatName:
[Laminaria digitata] on moderately exposed sublittoral fringe rock

HabitatDescription:
Exposed to moderately exposed sublittoral fringe rock characterised by the kelp [Laminaria digitata] with coralline crusts covering the rock beneath the kelp canopy. Foliose red seaweeds such as [Palmaria palmata, Membranoptera alata, Chondrus crispus] and [Mastocarpus stellatus] are often present along with the calcareous [Corallina officinalis]. The brown seaweed [Fucus serratus] and the green seaweeds [Cladophora rupestris] and [Ulva lactuca] can be present as well. The sponge [Halichondria panicea] can be found among the kelp holdfasts or underneath overhangs. Also present on the rock are the tube-building polychaete [Pomatoceros triqueter], the gastropods [Patella vulgata] and [Gibbula cineraria]. The bryozoan [Electra pilosa] can form colonies on especially [C. crispus, M. stellatus] and [F. serratus] while the hydroid [Dynanema pumila] are more common on the kelp. Three variants of this biotope are described: [L. digitata] forest on rocky shores (unit A3.2111). [L. digitata] on boulder shores (unit A3.2112) and soft rock supporting [L. digitata], such as the chalk found in south-east England (unit A3.2113). For [L. digitata] in sheltered, tide-swept conditions see unit A3.221.


HabitatName:
[Laminaria digitata] on moderately exposed sublittoral fringe bedrock

HabitatDescription:
Exposed to sheltered sublittoral fringe bedrock dominated by a dense canopy of [Laminaria digitata], often with a wide range of filamentous and foliose red seaweeds beneath. The most frequently occurring red seaweeds are [Palmaria palmata], [Corallina officinalis], [Mastocarpus stellatus], [Chondrus crispus, Lomentaria articulata] and [Membranoptera alata]. Generally the rocky substratum is covered by encrusting coralline algae, on which occasional limpets [Patella vulgata] and topshells [Gibbula cineraria] graze. A wide variety of fauna occurs, some of the most commonly occurring species being the sponge [Halichondria panicea] and the tube-building polychaete [Pomatoceros triqueter]. Kelp holdfasts provide a refuge for a varied assemblage of species such as sponges and the limpet [Helcion pellucidum], while encrusting bryozoans such as [Electra pilosa] more often are found on the fronds of foliose red seaweeds. Solitary ascidians may be locally abundant where overhanging or vertical rock occurs, while the hydroid [Dynamena pumila] can be abundant on [Fucus serratus] and [Laminaria] sp. fronds. On exposed, wave-surged shores, the robust red seaweeds [M. stellatus], [C. crispus] and [C. officinalis] can form a dense turf beneath the kelp along with the occasional green seaweed [Ulva lactuca]. Similarly on such shores the mussel [Mytilus edulis] can occur in extremely dense aggregations on the rock, beneath the kelp canopy.
Situation: This biotope is usually found on the extreme low shore below the [Fucus serratus] zone (unit A1.214) and above the truly sublittoral [Laminaria hyperborea] zone (unit A3.214).


HabitatName:
[Laminaria digitata] and under-boulder fauna on sublittoral fringe boulders

HabitatDescription:
This [Laminaria digitata] biotope is found predominantly on moderately exposed boulder shores and occasionally also on exposed or sheltered shores. Upper surfaces of the boulders are colonised by dense [L. digitata] though other kelp such as [Laminaria hyperborea] and [Laminaria saccharina] or the wrack [Fucus serratus] can be present at lower abundance. The kelp fronds can be colonised by the bryozoan [Membranipora membranacea]. Beneath the kelp canopy are a variety of red seaweeds such as [Mastocarpus stellatus], [Chondrus crispus], [Palmaria palmata], [Membranoptera alata], [Corallina officinalis] and coralline crusts. Green seaweeds include [Cladophora rupestris] and [Ulva lactuca]. Where space is available beneath the boulders (i.e. they are not buried in sediment) there may be a rich assemblage of animals. Characteristic species include the crabs [Porcellana platycheles], [Pisidia longicornis] and juvenile [Cancer pagurus]. Also present beneath the boulders are often high densities of the barnacle [Balanus crenatus], the tube-building polychaete [Pomatoceros triqueter], spirorbid worms, the polychaete [Harmotho‰] sp., gammarid amphipods and a few gastropods such as [Gibbula cineraria]. The encrusting bryozoans [Electra pilosa] and [Umbonula littoralis] and encrusting colonies of the sponges [Halichondria panicea] and [Halisarca dujardini] are also typical of this habitat. The richest examples also contain a variety of echinoderms such as [Asterias rubens], colonial ascidians such as [Botryllus schlosseri] and small hydroids.
Situation: This biotope is found in a similar situation to unit A3.2111, usually beneath the [Fucus serratus] zone (units A1.2141 or A1.2142) and above the [Laminaria hyperborea] zone (unit A3.214). Many of the animals found under boulders in the lower shore in A1.2142 are also found under boulders in the sublittoral fringe (A3.2112), particularly the sponges and crabs. Similarly, many of the seaweeds present on the lower shore are also present in the shallow sublittoral fringe.


HabitatName:
[Laminaria digitata] and piddocks on sublittoral fringe soft rock

HabitatDescription:
Soft rock, such as chalk, in the sublittoral fringe characterised by [Laminaria digitata] and rock-boring animals such as piddocks [Barnea candida] and [Pholas dactylus], the bivalve [Hiatella arctica] and worms [Polydora] spp. Beneath the kelp forest, a wide variety of foliose red seaweeds occur such as [Palmaria palmata], [Chondrus crispus], [Membranoptera alata] and [Halurus flosculosus]. Filamentous red seaweeds often present are [Polysiphonia fucoides] and [Ceramium nodulosum], while coralline crusts cover available rock surface. The bryozoan [Membranipora membranacea] and the hydroid [Dynanema pumila] can form colonies on the kelp fronds, while the bryozoan [Electra pilosa] more often occur on the foliose red seaweeds. Empty piddock burrows are often colonised by the polychaete [Sabellaria spinulosa] or in more shaded areas the sponges [Halichondria panicea] and [Hymeniacidon perleve]. The undersides of small chalk boulders are colonised by encrusting bryozoans, colonial ascidians and the tube-building polychaete [Pomatoceros lamarcki]. The boulders and any crevices within the chalk provide a refuge for small crustaceans such as [Carcinus maenas], the mussel [Mytilus edulis] or the barnacle [Semibalanus balanoides]. The echinoderm [Asterias rubens] is present as well.

Situation: This biotope occurs on moderately exposed soft rock where unit A3.2111 would normally occur. Above it may lie a zone of [Fucus serratus] on similarly bored soft rock (unit A1.2143) or a variant of one of the [F. serratus] biotopes (e.g. A1.2141). Lower shore sites influenced by sand may have more [Mytilus edulis] beneath the seaweed canopy (A1.222) or the sand-binding red seaweed [Rhodothamniella floridula] (A1.215). Below this biotope a variety of biotopes can occur such as A3.123 on unstable infralittoral cobbles and boulders or even A4.231 in the turbid waters of south-east England where the kelp generally extends to less than 4m BCD.

Temporal variation: The under-storey of foliose and filamentous seaweeds will diminish towards the autumn and regrow in the spring. Since the soft rock does not provide a strong hold for the seaweeds they are easily dislodged during storm periods. After such an event the green seaweeds [Enteromorpha] spp. and [Ulva] spp. and/or the red seaweed [P. palmata] may temporarily cover much of the rock. Eventually a more diverse range of seaweeds and associated animals will re-establish on the rock.


HabitatName:
[Laminaria hyperborea] on tide-swept, infralittoral rock

HabitatDescription:
Wave exposed to moderately wave exposed, tide-swept bedrock and boulders with [Laminaria hyperborea], characterised by a rich under-storey and stipe flora of foliose seaweeds including the brown seaweed [Dictyota dichotoma]. The kelp stipes support epiphytes such as [Cryptopleura ramosa] and [Phycodrys rubens]. At some sites, instead of being covered by red seaweeds, the kelp stipes are heavily encrusted by the ascidian [Botryllus schlosseri]. Epilithic seaweeds [Delesseria sanguinea], [Plocamium cartilagineum] [Heterosiphonia plumosa, Hypoglossum hypoglossoides], [Callophyllis laciniata], [Kallymenia reniformis], [Brongniartella byssoides] and crustose seaweeds commonly occur beneath the kelp. The kelp fronds are often covered with growth of the hydroid [Obelia geniculata] or the bryozoan [Membranipora membranacea]. On the rock surface, a rich fauna comprising the bryozoan [Electra pilosa], the sponge [Pachymatisma johnstonia], anthozoans such as [Alcyonium digitatum], [Sagartia elegans] and [Urticina felina], colonial ascidians such as [Clavelina lepadiformis], the calcareous tubeworm [Pomatoceros triqueter] and the barnacle [Balanus crenatus] occur. More mobile species include the gastropod [Calliostoma zizyphinum], the crab [Cancer pagurus] and the echinoderms [Asterias rubens] and [Echinus esculentus]. Two variants have been described: Tide-swept kelp forest (unit A3.2121) and tide-swept kelp park (unit A3.2122).
Situation: This biotope occurs below [Alaria esculenta] (Ala) at exposed sites or [L. digitata] (Ldig.Ldig) at moderately exposed locations. With increasing depth the kelp density diminishes to become tide-swept kelp park (A3.2122).


HabitatName:
[Laminaria hyperborea] forest, foliose red seaweeds and a diverse fauna on tide-swept upper infralittoral rock

HabitatDescription:
Exposed to moderately exposed, tide-swept bedrock and boulders, with dense [Laminaria hyperborea] forest, characterised by a rich under-storey and stipe flora of foliose seaweeds. The kelp stipes support epiphytes such as [Callophyllis laciniata, Corallina officinalis, Cryptopleura ramosa, Membranoptera alata], and [Phycodrys rubens]. At some sites, instead of being covered by red seaweeds, the kelp stipes are heavily encrusted by the ascidians [Botryllus schlosseri] and in the south-west [Distomus variolosus]. Epilithic seaweeds ([Dilsea carnosa], [Hypoglossum hypoglossoides], [Delesseria sanguinea, Plocamium cartilagineum], [Brongniartella byssoides], and [Dictyota dichotoma] ) and crustose seaweeds commonly occur beneath the kelp. The kelp fronds are often covered with growth of the hydroid [Obelia geniculata] or the bryozoan [Membranipora membranacea]. Although these species are also found in most kelp forests, in this biotope they are particularly dense. On the rock surface, a rich fauna comprising of the sponges [Pachymatisma johnstonia], [Halichondria panicea], [Esperiopsis fucorum] and [Dysidea fragilis], anthozoans such as [Urticina felina], [Alcyonium digitatum] and [Caryophilia smithii], the barnacle [Balanus crenatus], colonial ascidians such as [Clavelina lepadiformis], and the gastropods [Calliostoma zizyphinum] and [Gibbula cineraria], occur. Also found on the rock is the echinoderm [Asterias rubens] and the crab [Cancer pagurus].
Situation: This biotope occurs below [Alaria esculenta] (unit A3.111) at exposed sites or [L. digitata] (unit A3.2111) at moderately exposed locations. With increasing depth the kelp density diminishes to become tide-swept kelp park (unit A3.2122).


HabitatName:
[Laminaria hyperborea] park with hydroids, bryozoans and sponges on tide-swept lower infralittoral rock

HabitatDescription:
Exposed to moderately wave-exposed, strongly tide-swept, rock with [Laminaria hyperborea] park characterised by a rich under-storey and stipe flora of foliose seaweeds such as [Phycodrys rubens], [Plocamium cartilagineum], [Hypoglossum hypoglossoides, Kallymenia reniformis], [Cryptopleura ramosa] and [Delesseria sanguinea]. The red seaweed [Heterosiphonia plumosa] can be present. The foliose brown seaweed [Dictyota dichotoma] and coralline crust are often present as well. Amongst the red seaweeds is a rich fauna comprising sponges ([Pachymatisma johnstonia], [Stelligera rigida], [Esperiopsis fucorum] and [Dysidea fragilis]), anthozoans ([Alcyonium digitatum] and [Caryophyllia smithii]), hydroids ([Aglaophenia pluma] and [Nemertesia antennina]), colonial ascidians ([Clavelina lepadiformis] and [Morchellium argus]) and bryozoans such as [Electra pilosa]. Both the flora and fauna of this biotope are similar to the wave exposed kelp park (unit A3.1152), but A3.1152 has a greater faunal component including the barnacle [Balanus crenatus], the echinoderm [Asterias rubens] and the crab [Necora puber].
Situation: This biotope generally occurs below a tide-swept [L. hyperborea] kelp forest (unit A3.2121). As this biotope occurs over such a range of wave exposures a variety of circalittoral biotopes can occur beneath it: for example, Exposed, tide-swept rock (unit A4.11) or moderately exposed tide-swept rock (unit A4.21).


HabitatName:
[Laminaria hyperborea] on tide-swept infralittoral mixed substrata

HabitatDescription:
Wave-exposed through to wave-sheltered, tide-swept infralittoral mixed substrata with [Laminaria hyperborea] forest/park and other kelp species such as [Laminaria saccharina]. The rich under-storey and stipe flora is characterised by foliose seaweeds including the brown algae [Dictyota dichotoma]. The kelp stipes support epiphytes such as [Cryptopleura ramosa], [Callophyllis laciniata] and [Phycodrys rubens]. At some sites, instead of being covered by red seaweeds, the kelp stipes are heavily encrusted by the ascidians [Botryllus schlosseri] and the bryozoan [Alcyonidium diaphanum]. Epilithic seaweeds such as [Desmerestia aculeata], [Odonthalia dentate], [Delesseria sanguinea], [Plocamium cartilagineum], [Callophyllis laciniata], and crustose seaweeds commonly occur beneath the kelp. The kelp fronds are often covered with growths of the hydroid [Obelia geniculata] or the bryozoan [Membranipora membranacea]. On the rock surface, a rich fauna comprising anthozoans such as [Alcyonium digitatum] and [Urticina felina], colonial ascidians such as [Clavelina lepadiformis] and the calcareous tubeworm [Pomatoceros triqueter] occurs. More mobile species include the gastropods [Gibulla cineria] and [Calliostoma zizyphinum], the crab [Cancer pagurus] and the echinoderms [Crossaster papposus], [Henricia oculata], [Asterias rubens] and [Echinus esculentus]. Two variants are described; tide-swept kelp forest on upper infralittoral mixed substrata (unit A3.2131) and tide-swept kelp park on lower infralittoral mixed substrata (unit A3.2132).


HabitatName:
[Laminaria hyperborea] forest and foliose red seaweeds on tide-swept upper infralittoral mixed substrata

HabitatDescription:
Moderately wave-exposed to wave sheltered, tide-swept mixed substrata, with dense [Laminaria hyperborea] forest and sparser [Laminaria saccharina], characterised by an under-storey and stipe flora of foliose seaweeds. The kelp stipes support epiphytes such as [Palmaria palmata] [Callophyllis laciniata], [Cryptopleura ramosa], [Membranoptera alata], and [Phycodrys rubens]. At some sites, instead of being covered by red seaweeds, the kelp stipes are heavily encrusted by the ascidians [Botryllus schlosseri] and in the south-west [Distomus variolosus]. Epilithic seaweeds ([Delesseria sanguinea, Plocamium cartilagineum, Odonthalia dentata, Dictyota dichotoma] and [Desmarestia aculeata]) and crustose seaweeds commonly occur beneath the kelp. The kelp fronds are often covered with growth of the hydroid [Obelia geniculata] or the bryozoan [Membranipora membranacea]. Although these species are also found in most kelp forests, in this biotope they are particularly dense. On the rock surface, a rich fauna comprising anthozoans such as [Urticina felina], the barnacle [Balanus crenatus], the calcareous tubeworm [Pomatoceros triqueter], colonial ascidians such as [Clavelina lepadiformis], the gastropods [Calliostoma zizyphinum] and [Gibbula cineraria], and the bryozoans [Electra pilosa] and [Alcyonidium diaphanum] occur. Also found on the rock are the echinoderms [Echinus esculentus, Asterias rubens and Ophiothrix fragilis], and the crabs [Cancer pagurus, Pagurus bernhardus] and [Necora puber].


HabitatName:
[Laminaria hyperborea] park and foliose red seaweeds on tide-swept lower infralittoral mixed substrata

HabitatDescription:
Exposed to moderately wave-exposed, tide-swept, Infralittoral mixed substrata with [Laminaria hyperborea] park characterised by an under-storey and stipe flora of foliose seaweeds such as [Phycodrys rubens], [Plocamium cartilagineum], [Hypoglossum hypoglossoides, Kallymenia reniformis], [Cryptopleura ramosa] and [Delesseria sanguinea]. Epilithic seaweeds ([Bonnemaisonia asparagoides], [Callophyllis laciniata], [Lomentaria orcadensis] and [Brongniartella byssoides]) and crustose seaweeds commonly occur beneath the kelp. The foliose brown seaweed [Dictyota dichotoma] is often present as well. Amongst the red seaweeds is a fairly diverse fauna comprising sponges ([Scypha ciliate]), anthozoans ([Alcyonium digitatum], [Urticina felina] and [Caryophyllia smithii]), hydroids ([Tubularia indivisa], [Halecium halecinum], [Sertularia argentea] and [Nemertesia antennina]), colonial ascidians ([Botryllus schlosseri]) and bryozoans such as [Alcyonium diaphanum]. On the rock surface, the calcareous tubeworm [Pomatoceros triqueter], the crab [Cancer pagurus] and the gastropods [Gibbula cineraria] and [Calliostoma zizyphinum] may be found. A diverse range of echinoderms are also found in this biotope: [Crossaster papposus], [Henricia oculata], [Asterias rubens], [Echinus esculentus] and [Ophiothrix fragilis].


HabitatName:
[Laminaria hyperborea] and foliose red seaweeds on moderately exposed infralittoral rock

HabitatDescription:
Moderately exposed infralittoral bedrock and boulders characterised by a canopy of the kelp [Laminaria hyperborea] beneath which is an under-storey of foliose red seaweeds and coralline crusts. Some red seaweeds can be found as epiphytes on the kelp stipes and include [Delesseria sanguinea] and [Phycodrys rubens]. Other red seaweeds present include the [Plocamium cartilagineum, Callophyllis laciniata, Cryptopleura ramosa] and the brown seaweeds [Dictyota dichotoma] and [Cutleria multifida]. The kelp fronds can be colonised by the hydroid [Obelia geniculata] or the bryozoans [Membranipora membranacea]. The echinoderm [Antedon bifida], the ascidian [Clavelina lepadiformis], the tube-building polychaete [Pomatoceros triqueter], the anthozoans [Alcyonium digitatum] and [Urticina felina] can be found on the rock beneath the canopy. Mobile species often present include the gastropods [Gibbula cineraria] and [Calliostoma zizyphinum] and the echinoderms [Echinus esculentus] and [Asterias rubens]. Five variants has been described: Kelp forest (unit A3.2141), kelp park (unit A3.2142), grazed kelp forest (unit A3.2143), grazed kelp park (unit A3.2144) and kelp with [Sabellaria spinulosa] reefs (unit A3.2145). This suite of biotopes differs from the wave exposed [L. hyperborea] biotopes (KFaR) by having a lower diversity of cushion-forming faunal species. The foliose red seaweed component of the two suites of biotopes may also differ in composition with a tendency for A3.214 to include some more delicate filamentous species.


HabitatName:
[Laminaria hyperborea] forest and foliose red seaweeds on moderately exposed upper infralittoral rock

HabitatDescription:
Moderately exposed upper infralittoral bedrock and boulders characterised by a dense forest of [Laminaria hyperborea] with dense foliose red seaweeds beneath the canopy. These include [Callophyllis laciniata], [Plocamium cartilagineum], [Cryptopleura ramosa] and [Delesseria sanguinea]. Kelp stipes are usually covered in a rich mixture of red seaweeds of which [Palmaria palmata], [Phycodrys rubens] and [Membranoptera alata] are often present. Small kelp plants can also be found on the larger kelp stipes. Kelp fronds may be covered with a hydroid growth of [Obelia geniculata] or the bryozoans [Membranipora membranacea] and [Electra pilosa]. The kelp holdfasts can be colonised by bryozoans [Scrupocellaria] spp. and/or crisiids and colonial ascidians such as [Botryllus schlosseri]. The rock surface between the kelp plants is generally covered by encrusting coralline algae, often with sponge crusts [Halichondria panicea]. Small vertical surfaces within the kelp forest generally lack kelp plants, instead being characterised by foliose red seaweeds such as [Dictyota dichotoma], the anthozoans [Alcyonium digitatum, Urticina felina] and [Caryophyllia smithii], the tube-building polychaete [Pomatoceros triqueter] and gastropods including [Calliostoma zizyphinum] and [Gibbula cineraria]. Many grazers are found in the kelp forest, the most commonly occurring being the gastropods [Gibbula cineraria] and [Calliostoma zizyphinum] and the echinoderm [Echinus esculentus]. Other echinoderms present include [Asterias rubens] and [Antedon bifida] which can be locally abundant, particularly in the north-west.

Situation: This biotope occurs over a wide geographic area and is generally found below the sublittoral fringe [Laminaria digitata] zone (unit A3.3131) and above the [L. hyperborea] park (unit A3.2142). In the north, Shetland in particular, unit A3.122 can occur in the lower infralittoral; where grazing influence is present the abundance of red seaweeds may be much reduced (unit A3.2144). In turbid water kelp park is often absent and dense foliose seaweed cover may occur instead (unit A3.215). In areas affected by scour, such as the rock-sediment interface at the base of bedrock slopes, a mixed kelp canopy can develop below the kelp forest (unit A3.125).

Temporal variation: The under-storey of foliose and filamentous seaweeds will diminish towards the autumn and regrow in the spring. Otherwise this biotope is not known to vary markedly over time. Certain areas are prone to urchin grazing and this can substantially alter the community structure of the biotope, such that any site subject to intensive urchin grazing should be recorded as unit A3.2143.


HabitatName:
[Laminaria hyperborea] park and foliose red seaweeds on moderately exposed lower infralittoral rock

HabitatDescription:
Below the dense kelp forest (unit A3.2141) on moderately exposed lower infralittoral bedrock and boulders, the kelp thins out to form a park. Beneath the kelp, the rock and kelp stipes are covered by an often dense turf of foliose red seaweeds such as [Callophyllis laciniata], [Plocamium cartilagineum], [Delesseria sanguinea, Hypoglossum hypoglossoides, Cryptopleura ramosa, Callophyllis laciniata] and [Phycodrys rubens]. Coralline crusts are often present on the rock surface. Many species of red seaweed found in this biotope occur at greater abundance in the shallower kelp forest. Other seaweeds, such as the red seaweeds [Bonnemaisonia asparagoides] and [Hypoglossum hypoglossoides] as well as the brown seaweed [Dictyota dichotoma] are more abundant in this zone than the upper infralittoral. The faunal component of this biotope is similar to that found below the kelp in the upper infralittoral zone and include the hydroid [Obelia geniculata], the ascidian [Clavelina lepadiformis], the anthozoans [Urticina felina, Alcyonium digitatum] and [Caryophyllia smithii], the tube-building polychaete [Pomatoceros triqueter] and the gastropods [Calliostoma zizyphinum] and [Gibbula cineraria]. The gastropods [Gibbula cineraria] and [Calliostoma zizyphinum] and the echinoderm [Echinus esculentus] can be found grazing on the rock. Other echinoderms present include [Asterias rubens] and [Antedon bifida] which can be locally abundant, particularly in the north-west.

Situation: This biotope generally occurs below [L. hyperborea] forest (unit A3.2141) and marks the lower limit of the infralittoral rock. Occasionally a narrow band of foliose seaweeds (unit A3.116) may occur below the kelp park but generally circalittoral biotopes are found.

Temporal variation: The under-storey of foliose and filamentous seaweeds will diminish towards the autumn and regrow in the spring. When grazing urchins (predominantly [E. esculentus]) reach a large number in the kelp park their voracious grazing can substantially alter the community structure of the biotope, removing most of the seaweeds and leaving only coralline crusts on the rock. This is common around the coast of Scotland, particularly in Shetland and such sites should be recorded as unit A3.2143.


HabitatName:
Grazed [Laminaria hyperborea] forest with coralline crusts on upper infralittoral rock

HabitatDescription:
Exposed to moderately exposed [Laminaria hyperborea] forest is in some areas intensely grazed by the urchin [Echinus esculentus]. The rock surface lacks a significant turf of foliose seaweeds and generally looks bare, though encrusting algae cover the rock. In addition to these encrusting coralline algae, non-calcareous crusts such as [Cruoria pellita] and brown algal crusts also occur. The kelp stipes may or may not be grazed; in the most extremely grazed areas, the stipes are also devoid of seaweeds. More usually, however, the stipes offers a refuge from grazing, and are characterised by dense turfs of red seaweeds, especially [Phycodrys rubens, Callophyllis laciniata, Plocamium cartilagineum] and [Delesseria sanguinea]. The hydroid [Obelia geniculata] and the bryozoan [Membranipora membranacea] colonise the kelp fronds. On the rock itself certain brown seaweeds such as [Cutleria multifida] may persist in this grazed environment. Fast-growing species such as the kelp [Laminaria saccharina] may be present at sites recovering from grazing, opportunistically colonising the rock surfaces that have been cleared by grazing. The fauna within a grazed kelp forest is also relatively sparse and is mostly confined to cracks, crevices and under-boulders. Species such as the ascidian [Clavelina lepadiformis] can often be found on vertical rock. Also found on the rock surface are the anthozoans [Urticina felina] and [Alcyonium digitatum]. Encrusting species such as the tube-building polychaete [Pomatoceros triqueter] are resistant to grazing and may occur in abundance. The grazers present include the echinoderm [Echinus esculentus] and the gastropods [Calliostoma zizyphinum] and [Gibbula cineraria]. Other echinoderms present include [Asterias rubens] and [Antedon bifida] which can be abundant in the north-west. Moderate grazing occurs within many kelp forests; records should only be assigned to this biotope where the community has been intensively grazed leaving algal-encrusted rock with very few epilithic algae.

Situation: With increasing depth, the kelp forest grades into a grazed kelp park (unit A3.2144), the lower limit of which is often abrupt, representing the balance point between urchin-grazing pressure and kelp growth capabilities. In wave-exposed steep rocky areas, the shallowest water may be characterised by a forest of kelp with red seaweeds (unit A3.1151), with a grazed kelp forest beneath. This effect may be a result of the increased wave action in shallower water, which regularly dislodges the urchins thereby reducing their grazing impact. This unit is prevalent in the north of the UK where [E. esculentus] populations reach high densities. Although [E. esculentus] is widely distributed around the UK it occurs in greatest abundance in Scotland and north-east England where urchin grazing can substantially affect infralittoral communities.

Temporal variation: Fluctuations in [E. esculentus] numbers may give foliose seaweeds a chance to re-grow periodically. Further information is required on the temporal variation within these grazed forests and the changes in community structure when grazing pressure decreases.


HabitatName:
Grazed [Laminaria hyperborea] park with coralline crusts on lower infralittoral rock

HabitatDescription:
Exposed to moderately exposed [Laminaria hyperborea] kelp park in some areas is intensively grazed by the urchin [Echinus esculentus]. The rock surface lacks a significant turf of foliose seaweeds and generally looks bare, though coralline algal crusts and some grazing-resistant animals such as the tube-building polychaete [Pomatoceros triqueter] cover it. The kelp stipes may or may not be grazed; in the most extremely grazed areas, the stipes are also devoid of seaweeds. More usually, however, the stipes offers a refuge from grazing, and are characterised by dense turfs of red seaweeds, especially [Phycodrys rubens] and [Delesseria sanguinea]. Brown seaweeds present include [Cutleria multifida, Laminaria saccharina] and [Dictyota dichotoma]. The fauna within a grazed kelp park is also relatively sparse, though some species will survive in cracks and crevices or under boulders including the ascidian [Clavelina lepadiformis]. The encrusting bryozoan [Parasmittina trispinosa] and the anthozoans [Alcyonium digitatum], [Urticina felina] and [Caryophyllia smithii] often characterise vertical or overhanging rock. Mobile species include the gastropods [Gibbula cineraria] and [Calliostoma zizyphinum] and the hermit crab [Pagurus bernhardus] The echinoderms [Ophiocomina nigra], [Ophiothrix fragilis] and [Crossaster papposus], generally absent from the kelp forest, can be found in these kelp parks along with [Asterias rubens] and [Antedon bifida].

Situation: This biotope generally occurs below a grazed kelp forest (unit A3.2143) but can also occur below ungrazed kelp forests on exposed sites where wave action can dislodge urchins from shallow rock. The grazed circalittoral  unit A4.214 often occurs on the bedrock or boulders below.

Temporal variation: Fluctuations in the numbers of [E. esculentus] may give foliose seaweeds a chance to re-grow periodically. Further information is required on the temporal variation within these grazed kelp parks and the changes in community structure when grazing pressure decreases.


HabitatName:
[Sabellaria spinulosa] with kelp and red seaweeds on sand-influenced infralittoral rock

HabitatDescription:
[Laminaria hyperborea] kelp forest on shallow infralittoral bedrock and boulders characterised by encrustations of [Sabellaria spinulosa] tubes which cover much of the rock, together with sand-tolerant red seaweeds such as [Phyllophora pseudoceranoides, Dilsea carnosa] and [Polysiphonia elongata] and [Polysiphonia fucoides]. Red seaweeds such as [Plocamium cartilagineum] and [Delesseria sanguinea] may also be found beneath the kelp canopy, although typically low in abundance. They can be colonised by the ascidian [Botryllus schlosseri]. The cowrie [Trivia arctica] can also be found here. Much of the available rock is covered with encrusting coralline algae together with patches of the encrusting sponge [Halichondria panicea] and the anthozoan [Urticina felina]. More mobile fauna include the echinoderms [Asterias rubens, Henricia sanguinolenta, Echinus esculentus], and [Ophiothrix fragilis], the gastropod [Gibbula cineraria] and the hermit crab [Pagurus bernhardus]. The scouring effect of mobile sand adjacent to the rock maintains a reduced underflora and fauna compared to the association of species found in non-scoured kelp forests (unit A3.2141). Scour-resistant fauna such as the barnacle [Balanus crenatus] can be locally abundant on the rock, while the bivalve [Pododesmus patelliformis] can be found seeking shelter underneath the cobbles. Above the effect of scour, kelp stipes may be densely colonised by red seaweeds such as [Phycodrys rubens], [Palmaria palmata] and [Membranoptera alata], together with some sponges and ascidians.
Situation: This biotope is found in the sand-laden waters of north-east England in conditions in which [S. spinulosa] is able to thrive. Nearby circalittoral rock is often also dominated by [S. spinulosa] (unit A4.221) but lacks the kelp and red seaweeds. As this biotope is not commonly recorded in the UK there is a scarcity of information relating to the surrounding biotopes.


HabitatDescription:
Upward-facing surfaces of shallow, infralittoral bedrock and boulders in areas of turbid water dominated by dense red seaweeds, with the notable absence of kelp. The stable rock, which can be cobbles or boulders but is more typically bedrock, is usually silted. Individual species of foliose red seaweeds such as [Plocamium cartilagineum] or [Calliblepharis ciliata] often dominate. Other red seaweeds likely to be present include [Phyllophora crispa], [Rhodymenia holmesii], [Halurus flosculosus], [Cryptopleura ramosa], [Hypoglossum hypoglossoides], [Heterosiphonia plumosa] and coralline crusts. The brown seaweed [Dictyota dichotoma] is sometimes present, although never abundant. This biotope does not generally occur below kelp park but rather occurs on shallow, silted rock on which kelp would normally grow in less turbid conditions. The fauna can be variable but is generally typified by the presence of silt-tolerant animals such as encrusting sponges, particularly [Dysidea fragilis] and [Halichondria panicea], the hydroid [Tubularia indivisa], bryozoan crusts and scattered [Sabellaria spinulosa] and [Balanus crenatus]. In the summer months the seaweeds can become heavily encrusted with the bryozoan [Electra pilosa] and the ascidian [Molgula manhattensis] which can also form dense mats on the rock. The polychaete [Lanice conchilega] can be present, where sandy and muddy patches occur. Where this biotope occurs on chalk bedrock, such as off the Sussex coast, the piddock [Pholas dactylus] is often found bored into the rock. This biotope is recorded from the English Channel, off Kent, Sussex and the Isle of Wight. Please notice that individual sites of this biotope can vary significantly in the species composition.

Situation: This biotope generally occurs on discrete bedrock outcrops surrounded by areas of mixed sediment or mobile sand. Off Sussex, it occurs on the horizontal chalk bedrock forming the tops of cliffs (2-3m in height).

Temporal variation: The seaweeds die back in late autumn and summer leaving, silted, coralline-encrusted rock with a sparse fauna of sponges, [S. spinulosa] and occasional hydroids and bryozoans. The bryozoan [Amathia lendigera] can also become abundant amongst the seaweeds during the summer months.


HabitatName:
[Laminaria hyperborea] on moderately exposed vertical rock

HabitatDescription:
This unit is found on moderately exposed coasts in moderately strong to weak tidal streams generally in 0-20m water depth. It is characterised by the kelp [Laminaria hyperborea], the soft coral [Alcyonium digitatum] and crinoid [Antedon bifida]. This biotope is relatively species poor when compared to similar biotopes in more exposed environments e.g. unit A3.117. The urchin [Echinus esculentus] may be frequently observed grazing the vertical rock face. This biotope may have 2 sub-biotopes. One is characterised by the frequent occurrence of the sea squirt [Clavelina lepadiformis] and the red seaweeds [Phycodrys rubens] and [Cryptopleura ramosa]. The brown seaweed [Dictyota dichotoma] may also be frequent in this sub-biotope. The second sub-biotope is more species poor than the previous one and is characterised by the common occurrence of [Alcyonium digitatum], which is only occasional in the other variant.
Situation: Open rocky coasts in northern Britain, particularly North Sea coasts.


HabitatName:
[Hiatella arctica] and seaweeds on vertical limestone / chalk

HabitatDescription:
This biotope is found in the infralittoral zone on moderately exposed vertical limestone/chalk surfaces in weak tidal streams, and has been recorded most frequently between 0-10m. This biotope is characterised by abundant [Hiatella arctica] and a rich sponge community including [Cliona celata], [Dysidea fragilis] and [Pachymatisma johnstonia]. Other species that may be frequent in this biotope are the crab [Necora puber], the sea squirt [Clavelina lepadiformis], and the top shell [Calliostoma zizyphinum], although these species are found in other vertical rock biotopes, however in lesser abundance.
Situation: Shallow rocky coasts with vertical limestone faces.


HabitatDescription:
Sheltered infralittoral rock exposed to strong tidal streams. In the sublittoral fringe dense [Laminaria digitata] is found together with erect seaweeds, sponges, ascidians and bryozoans (A3.221). Below this, on bedrock and stable boulders a canopy of mixed kelp (primarily [Laminaria hyperborea] and [Laminaria saccharina]) occurs with foliose red seaweeds, sponges and ascidians (A3.222). This biotope is typically found in the sheltered narrows and sills of Scottish sealochs. Mixed substrata of boulders, cobbles, pebbles and gravel, that also occurs in the tidal rapids of Scottish sealochs, supports a reduced kelp canopy ([L. hyperborea] and [L. saccharina]; typically Frequent), with a rich red seaweed component and maerl at some sites (A3.223). In south-west Britain, sheltered, tide-swept rock is restricted to estuarine conditions where variable salinity and increased turbidity of the water have a significant effect on the biota, limiting the infralittoral zone to very shallow depths. Unlike the tide-swept channels in sealochs, the rock in these estuaries is characterised by a relatively low abundance of [L. saccharina] (&lt; Common) with foliose red seaweeds, sponges and ascidians (A3.224). [L. hyperborea] is rarely present.


HabitatName:
[Laminaria digitata], ascidians and bryozoans on tide-swept sublittoral fringe rock

HabitatDescription:
Sheltered bedrock, boulders and cobbles that are subject to moderate to strong tidal water movement characterised by dense [Laminaria digitata], coralline crusts and sponges such as [Halichondria panicea]. Other seaweeds present include the foliose red [seaweeds Chondrus crispus, Palmaria palmata, Cryptopleura ramosa] and [Mastocarpus stellatus] as well as the calcareous [Corallina officinalis]. Green seaweeds present include [Ulva lactuca, Enteromorpha intestinalis] and [Cladophora rupestris]. The increased water movement encourages several filter-feeding faunal groups to occur. The sponges [Leucosolenia] spp., [Scypha ciliata] and [Hymeniacidon perleve] frequently occur on steep and overhanging rock faces. The bryozoans [Electra pilosa], [Membranoptera membranipora] and [Alcyonidium hirsutum] encrust the kelp and other foliose seaweeds. In addition, ascidians such as [Ascidiella scabra], [Dendrodoa grossularia] and colonial ascidians [Botryllus byssoides] and [Botryllus leachi] often thrive in this environment encrusting both the rock and the seaweeds. The tube-building polychaete [Pomatoceros triqueter] can be found on the rock and on the kelp holdfasts along with the barnacle [Balanus crenatus]. More mobile species such as the gastropods [Gibbula cineraria] and [Calliostoma zizyphinum], the crab [Carcinus maenas] and the starfish [Asterias rubens] are also common. Areas where increased tidal movement influences this community can be found in the narrows and/or intertidal sills of sealochs.
Situation: This biotope often occurs immediately below the tide-swept [Fucus serratus] biotope (unit A1.152) consequently, some [F. serratus] may occur in this biotope (typically only Occasional). The sublittoral fringe of similarly sheltered shores that are not tide-swept are generally characterised by mixed [Laminaria saccharina] and [L. digitata] (unit A3.3131) or [L. saccharina] (A3.313). Below A3.221, at these sheltered, tide-swept sites, a canopy of mixed kelp species often occurs (see units A3.222 and XKTX).


HabitatDescription:
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).


HabitatDescription:
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).


HabitatName:
[Laminaria saccharina] with foliose red seaweeds and ascidians on sheltered tide-swept infralittoral rock

HabitatDescription:
Sheltered, tide-swept rock in south-western Britain tends to be restricted to estuarine conditions, where variable salinity and increased turbidity have a significant effect on the biota. Due to the turbidity of the water, the infralittoral zone is restricted to very shallow depths. Unlike the tide-swept channels in sealochs, which support a mixed kelp canopy, the rock in these estuaries is characterised by [Laminaria saccharina] alone, occurring in relatively low abundance (Frequent). The brown alga [Desmarestia ligulata] can occur in this biotope, though never dense, along with the non-native brown seaweed [Sargassum muticum]. Beneath the sparse kelp, cobbles and boulders, often surrounded by sediment, are encrusted by fauna and often a dense turf of red seaweed. The foliose red seaweeds associated with this biotope include [Callophyllis laciniata], [Nitophyllum punctatum], [Kallymenia reniformis], [Gracilaria gracilis], [Gymnogongrus crenulatus], [Hypoglossum hypoglossoides], [Rhodophyllis divaricata], [Chylocladia verticillata], [Cryptopleura ramosa] and [Erythroglossum laciniatum] as well as the filamentous [Ceramium nodulosum] and [Pterothamnion plumula]. Green seaweeds [Ulva lactuca], [Bryopsis plumosa] and [Cladophora] spp. may be locally abundant. The dominating faunal species vary from site to site but include sponges such as [Halichondria panicea], [Esperiopsis fucorum], [Dysidea fragilis] and [Hymeniacidon perleve] as well as ascidians, particularly [Dendrodoa grossularia] and [Morchellium argus], which can cover the rocks. Also present is the anthozoan [Anemonia viridis], the barnacle [Balanus crenatus] and the tube-building polychaete [Pomatoceros triqueter]. The hydroid [Plumularia setacea] can cover rocks and seaweed fronds Of the range of solitary ascidians found in the north-west, only [Ascidiella aspersa] tends also to be present in these south-western inlets. There is also a general absence of echinoderms. Where there is vertical rock present, it tends to support more fauna, including barnacles [Balanus crenatus], the ascidians [Clavelina lepadiformis] and [Botryllus schlosseri] and sometines the featherstar [Antedon bifida]. Where soft rock allows, such as the limestone in Plymouth Sound, rock-boring organisms such as [Polydora] sp. may be locally abundant. Sheltered, tide-swept rock is generally restricted to the narrows or tidal rapids of marine inlets. The clear tide-swept waters of Scottish sealochs are significantly different to the marine inlets of south-west Britain. This biotope deals with the latter.
Situation: This biotope generally occurs on rocky outcrops interspersed by sediment areas. Where the rock extends into deeper water, beyond the limit of kelp, sponges and ascidians tend to dominate these sheltered, tide-swept circalittoral sites (A4.251); also [Alcyonium digitatum] with sponges and [Nemertesia antennina] (A4.131).


HabitatName:
Filamentous red seaweeds, sponges and [Balanus crenatus] on tide-swept variable-salinity infralittoral rock

HabitatDescription:
Tide-swept infralittoral rock subject to variable salinity and turbid waters occurs in the mid to upper reaches of the rias of south-west Britain, where riverine freshwater input reduces the salinity. Very shallow rock under these conditions is characterised by a covering of filamentous red seaweed such as [Callithamnion] spp., [Antithamnion] spp., [Ceramium] spp., [Griffithsia devoniensis], [Pterothamnion plumula] and [Polysiphonia fucoides], as well as the filamentous green seaweed [Cladophora] spp. Foliose red seaweeds such as [Hypoglossum hypoglossoides], [Cryptopleura ramosa] and [Erythroglossum laciniatum] commonly occur, as does the foliose green seaweed [Ulva lactuca]. Although [Laminaria saccharina] is often present it is usually in very low abundance (Occasional). The fluctuating salinity limits the number of species able to exist in this habitat. The animal community is dominated by the sponges [Halichondria panicea] and [Hymeniacidon perleve] and the barnacle [Balanus crenatus]. The ascidians [Clavelina lepadiformis] and [Dendrodoa grossularia] can be locally abundant at some sites. The crab [Carcinus maenas] is usually present, as is the mussel [Mytilus edulis]. The bryozoan [Bugula plumosa] is sometimes present. Where vertical rock is present, the seaweeds [Ceramium nodulosum], [P. plumula], [C. ramosa], [H. hypoglossoides] and [E. laciniatum] are typically found.

Situation: This biotope is usually found amidst sediment or rock and as such there is no defined zonation of the surrounding biotopes. Shallow sediments nearby may support seagrass beds ([Zostera] spp.) or infaunal-dominated sediments (unit A5.13). Nearby, deeper tide-swept rock may support circalittoral communities dominated by sponges, hydroids and ascidians on stable rock (unit A4.2511) or dense bryozoans on mixed substrata (units A4.135 & A4.137).


HabitatName:
[Halopteris filicina] with coralline crusts on moderately exposed infralittoral rock


HabitatName:
Mediterranean and Pontic communities of infralittoral algae moderately exposed to wave action

HabitatDescription:
This community is characterised by the presence of many photophilic algae covering hard bottoms in moderately exposed areas.


HabitatName:
Association with [Codium vermilara] and [Rhodymenia ardissonei]

HabitatDescription:
This association of the green alga [Codium vermilara] and the red alga [Rhodymenia ardissonei] populates the middle horizon of the infralittoral zone, with low light and hydrodynamics.


HabitatDescription:
This association with the green alga [Dasycladus vermicularis] populates the middle horizon of the infralittoral zone with low light and hydrodynamics.


HabitatDescription:
This association is the red alga [Alsidium helminthochorton], which is typical of the upper horizon of the infralittoral zone with weak light and hydrodynamics.


HabitatName:
Association with [Cystoseira tamariscifolia] and [Saccorhiza polyschides]

HabitatDescription:
This facies is characterised by presence of the brown algae [Cystoseira tamariscifolia] and [Saccorhiza polyschides]. It is possible to find this association on seabottoms exposed to high currents (e.g. Strait of Messina, Strait of Alboran, etc.)


HabitatName:
Association with [Gelidium spinosum v. hystrix]

HabitatDescription:
This association is characterised by the high abundance of the red alga [Gelidium spinosum var. hystrix].


HabitatDescription:
This association is characterised by the high abundance of the brown alga [Lobophora variegata].


HabitatName:
Mediterranean and Pontic Association with [Ceramium rubrum]

HabitatDescription:
This association is characterised by the high abundance of the red alga [Ceramium virgatum] (ex [Ceramium rubrum]).


HabitatDescription:
This facies is characterised by the abundance of the Mediterranean coral [Cladocora caespitosa].


HabitatDescription:
This association is characterised by the brown alga [Cystoseira brachycarpa].


HabitatName:
Mediterranean and Pontic Association with [Cystoseira crinita]

HabitatDescription:
This association is characterised by the brown alga [Cystoseira crinita], living in pure, rough waters with strong luminosity.


HabitatDescription:
This association is characterised by the brown alga [Cystoseira crinitophylla].


HabitatDescription:
This association is characterised by the brown alga [Cystoseira sauvageauana].


HabitatDescription:
This association is characterised by the brown alga [Cystoseira spinosa].


HabitatDescription:
This association is characterised by the brown alga [Sargassum vulgare], living in pure, rough waters with strong luminosity.


HabitatDescription:
This association is characterised by the brown alga [Dictyopteris polypodioides], living in pure, rough waters with strong luminosity.


HabitatDescription:
This association is characterised by the brown alga [Colpomenia sinuosa].


HabitatName:
Association with [Rhodymenia ardissonei] and [Rhodophyllis divaricata]

HabitatDescription:
This association is characterised by a mixed cover of the two red algae [Rhodymenia ardissonei] and [Rhodophyllis divaricata].


HabitatDescription:
This facies is characterised by the madreporian [Astroides calycularis] and is typical of the western Mediterranean pre-coralligenous zone.


HabitatName:
Association with [Flabellia petiolata] and [Peyssonnelia squamaria]

HabitatDescription:
This association is characterised by a mixed cover of the green alga [Flabellia petiolata] and the red alga [Peyssonnelia squamaria] and is typical of semi-sciaphilous (shaded) hard bottoms.


HabitatName:
Association with [Halymenia floresia] and [Halarachnion ligatatum]

HabitatDescription:
This association is characterised by a mixed cover of the two red algae [Halymenia floresia] and [Halarachnion ligulatum] and is typical of semi-sciaphilous (shaded) hard bottoms.


HabitatName:
Association with [Peyssonnelia rubra] and [Peyssonnelia] spp.

HabitatDescription:
This association is characterised by a mixed cover of the red algae [Peyssonnelia rubra] and other members of the genus [Peyssonnelia] spp. and is typical of semi-sciaphilous (shaded) hard bottoms.


HabitatName:
Pontic association with [Cystoseira barbata] and [Ulva rigida]


HabitatName:
Pontic ephemeral mosaic of green and red seaweeds on moderately exposed or sheltered infralittoral rock (Enteromorpha , Ulva, Ceramium, Cladophora, Gelidium, Callithamnion, Corallina)

HabitatDescription:
The species concerned form belts of algae, the presence of which are seasonal according to species, with Corallina present during all seasons, and Ceramium and Cladophora present only during the summer and autumn.


HabitatName:
Pontic [Phyllophora nervosa] on vertical rock faces in the lower infralittoral


HabitatName:
Faunal communities on moderate energy infralittoral rock

HabitatDescription:
Added by CEH to accommodate level 5 units proposed at Southampton workshop


HabitatName:
Pontic [Mytilus galloprovincialis] beds on infralittoral rock

HabitatDescription:
In the Black Sea this habitat is distributed across wide areas, in the mediolittoral as well as into the infralittoral, from the spray zone to 55 m, where the dominant species is the bivalve mollusc [Mytilus galloprovincialis], the most widespread mussel in the Black Sea (Zaitsev and Aleksandrov, 1998). The biocenosis consists of 105 animal species (Zaitsev and Alexandrov 1998) of which the most characteristic are: Polychaeta - [Nereis (Neanthes) succinea], [Nereis diversicolor], [Polydora ciliata limicola]; Mollusca - [Mytilus galloprovincialis], [Mytilaster lineatus]; Crustacea - [Balanus improvisus], [Jaera sarsi], [Stenothoe monoculoides], [Marinogammarus olivii], [Melita palmate], [Microdeutopus gryllotalpa], [Amphitoe viallanti], [Jassia ocia], [Erichthonius difformis] (Alexandrov, 2006). On the NW shelf the mass species are: [Mya arenaria], [Balanus improvisus], [Nereis succinea], [Prionopsio cirrifera]. On the Crimean shelf the mass species are:the mollusc, [Modiolus adriaticus], and the polychaete [Terebellides stroemi]. Along the Turkish coasts, the most encountered amphipod species are: [Jassa marmorata], [Hylae crassipes], [Ampithoe ramondi], [Corophium acherisicum], [Corophium acutum] (Sezgin et al., 2001). Ephemeral algae may cover Mytilus.


HabitatName:
Pontic sponge crusts on lower infralittoral rock


HabitatName:
Pontic colonial ascidian and bryozoan crusts on bare infralittoral rock


HabitatName:
Pontic soft rock beds with [Pholas dactylus] burrows

HabitatDescription:
In Turkey the habitat is also found associated to the presence of Mytilus.


HabitatName:
Pontic [Teredo navalis] burrows in large wooden debris


HabitatName:
Pontic [Polydora] tubes on infralittoral soft rock


HabitatName:
Shallow smaller [Ostrea edulis] reefs adhering to rocky reefs and vertical drop-offs


HabitatName:
Atlantic and Mediterranean low energy infralittoral rock

HabitatDescription:
Infralittoral rock in wave and tide-sheltered conditions, supporting silty communities with [Laminaria hyperborea] and/or [Laminaria saccharina] (A3.31). Associated seaweeds are typically silt-tolerant and include a high proportion of delicate filamentous types. In turbid-water estuarine areas, the kelp and seaweeds (A3.32) may be replaced by animal-dominated communities (A3.36) whilst stable hard substrata in lagoons support distinctive communities (A3.34).


HabitatName:
Silted kelp on low energy infralittoral rock with full salinity

HabitatDescription:
Infralittoral rock in wave and tide-sheltered conditions, supporting silty communities with [Laminaria hyperborea] and/or [Laminaria saccharina]. Associated seaweeds are typically silt-tolerant and include a high proportion of delicate filamentous types. Some areas, particularly in the lower infralittoral zone, are subject to intense grazing by urchins and chitons and may have poorly developed seaweed communities.


HabitatName:
Mixed [Laminaria hyperborea] and [Laminaria ochroleuca] forest on moderately exposed or sheltered infralittoral rock

HabitatDescription:
Mixed [Laminaria hyperborea] and [Laminaria ochroleuca] forest on upper infralittoral moderately exposed or sheltered rock is restricted to the coast of Cornwall and the Isles of Scilly. Unlike [L. hyperborea], however, [L. ochroleuca] has a smooth stipe and it lacks the epiphytic growth of seaweeds. The bryozoan [Membranipora membranacea] may encrust the very lower part of the stipe but the rest of the stipe is characteristically bare. The fronds too are generally free of encrusting hydroids, bryozoans and grazing gastropods as compared to [L. hyperborea]. [L. ochroleuca] holdfasts, however, are often encrusted with sponges and colonial ascidians. A large variety of foliose and filamentous red seaweeds are often present underneath the canopy. These include [Callophyllis laciniata], [Plocamium cartilagineum], [Cryptopleura ramosa], [Delesseria sanguinea], [Dilsea carnosa Bonnemaisonia asparagoides, Erythroglossum laciniatum, Sphaerococcus coronopifolius, Polyneura bonnemaisonii] and [Corallina officinalis]. The foliose brown seaweed [Dictyota dichotoma] is frequently found in this biotope along with the occasional kelp such as [Saccorhiza polyschides] and [Laminaria saccharina]. The faunal composition of the biotope as a whole is often sparse. The anthozoans [Corynactis viridis] and [Caryophyllia smithii] are common on vertical surfaces with scattered bryozoan turf species such as Crisiidae. Grazers such as the gastropod [Gibbula cineraria] and the urchin [Echinus esculentus] are often present. [L. ochroleuca] occurs across a wide range of wave exposures (in common with [L. hyperborea]) and consequently it occurs at low abundance in other kelp biotopes (sheltered through to exposed) that occur in the South-West between Dorset to Lundy. In such cases, records should be considered as regional variations of the usual kelp biotopes. Records should only be assigned to this biotope when the canopy is dominated by [L. ochroleuca] alone, or by a mixture of both [L. hyperborea] and [L. ochroleuca] (though the latter is usually at greater abundance). [L. ochroleuca] commonly occurs on the Brittany and Normandy coasts.

Situation: On moderately exposed to sheltered rock [Laminaria ochroleuca] can form a dense forest below the [L. hyperborea] forest (unit A3.2141). At other sites [L. hyperborea] park (unit A3.2142) occurs below A3.311. A band of dense foliose seaweeds can also dominate the lower infralittoral zone below the kelp zone (A3.116 or A3.1161). More data is required to establish further trends in neighbouring biotopes.

Temporal variation: The under-storey of foliose and filamentous seaweeds will diminish towards the autumn and regrow in the spring. Otherwise, this biotope is not known to change significantly over time.


HabitatName:
Mixed [Laminaria hyperborea] and [Laminaria saccharina] on sheltered infralittoral rock

HabitatDescription:
Mixed [Laminaria hyperborea] and [Laminaria saccharina] on bedrock and boulders in sheltered infralittoral habitats. Typically subject to weak tidal streams and rather silty conditions. Beneath the kelp is an associated under-storey flora of foliose red seaweeds including [Plocamium cartilagineum, Cryptopleura ramosa] and [Callophyllis laciniata] as well as the brown seaweeds [Dictyota dichotoma], [Cutleria multifida] and [Desmarestia aculeata]. The stipes of [L. hyperborea] may be densely covered with red seaweeds such as [Phycodrys rubens] and [Delesseria sanguinea] as well as the solitary ascidian [Clavelina lepadiformis] and the featherstar [Antedon bifida]. The fronds are often epiphytised by the hydroid [Obelia geniculata] and the bryozoan [Membranipora membranacea]. Beneath the kelp canopy, the faunal component is generally less diverse than the more exposed kelp forests, dominated by the echinoderms [Echinus esculentus] and [Asterias rubens], but the tops shells [Gibbula cineraria] and [Calliostoma zizyphinum] can be common as well. The crab [Necora puber] and the brittlestar [Ophiothrix fragilis] can be found in cracks and crevices, while the tube-building polychaete [Pomatoceros triqueter] and coralline crusts are present on the rock surface. Although there is a reduced number of species by comparison to the more exposed [L. hyperborea] forests (A3.2141), there are considerably more algae species than occur in the more sheltered [L. saccharina] forests (A3.3132). This biotope is predominately found in the shelter of fjordic sealochs in Scotland. Where it does occur in south-west Britain the mixed kelp forest may also include the southern kelp [Laminaria ochroleuca]. Three variants has been described: The kelp forest in the upper infralittoral (A3.3121), grading to a kelp park with increasing depth (A3.3122) as well as a grazed variant (A3.3123).


HabitatName:
Mixed [Laminaria hyperborea] and [Laminaria saccharina] forest on sheltered upper infralittoral rock

HabitatDescription:
Sheltered, often silted, upper infralittoral bedrock and boulder slopes with mixed kelps [Laminaria hyperborea] and [Laminaria saccharina] and red seaweeds beneath. The kelp at these sheltered sites often has large `cape-form' fronds, which form a dense canopy over the seabed and are often epiphytised by the hydroid [Obelia geniculata] and the bryozoan [Membranipora membranacea]. Beneath the kelp, red seaweeds such as [Delesseria sanguinea] and [Cryptopleura ramosa] occur on top of encrusting coralline algae. Often, a dense algal turf of [Bonnemaisonia hamifera] (tetrasporophyte) carpets the rock. The stipes of [L. hyperborea] may be densely covered with seaweeds such as [Phycodrys rubens], [Plocamium cartilagineum] and [Porphyropsis coccinea]. There can also be a prominent faunal component on the stipes including the solitary ascidian [Clavelina lepadiformis] and the colonial ascidian [Botryllus schlosseri]. Brown seaweeds, occurring here in low abundance, include [Dictyota dichotoma]. The kelp [Saccorhiza polyschides] may also occur but rarely in equal abundance to [L. hyperborea] or [L. saccharina]. Beneath the kelp canopy, the faunal component is generally less diverse than the more exposed kelp forests (unit A3.214). The silted rock supports a sparse fauna of gastropods [Gibbula cineraria] and [Calliostoma zizyphinum], the tube-building polychaete [Pomatoceros triqueter] and occasional starfish [Asterias rubens] and the urchin [Echinus esculentus]. Steeper, less silted rock, may have the anthozoans [Caryophyllia smithii] and [Alcyonium digitatum].Sheltered, often silted, upper infralittoral bedrock and boulder slopes with mixed kelps [Laminaria hyperborea] and [Laminaria saccharina] and red seaweeds beneath. The kelp at these sheltered sites often has large `cape-form' fronds, which form a dense canopy over the seabed and are often epiphytised by the hydroid [Obelia geniculata] and the bryozoan [Membranipora membranacea]. Beneath the kelp, red seaweeds such as [Delesseria sanguinea] and [Cryptopleura ramosa] occur on top of encrusting coralline algae. Often, a dense algal turf of [Bonnemaisonia hamifera] (tetrasporophyte) carpets the rock. The stipes of [L. hyperborea] may be densely covered with seaweeds such as [Phycodrys rubens], [Plocamium cartilagineum] and [Porphyropsis coccinea]. There can also be a prominent faunal component on the stipes including the solitary ascidian [Clavelina lepadiformis] and the colonial ascidian [Botryllus schlosseri]. Brown seaweeds, occurring here in low abundance, include [Dictyota dichotoma]. The kelp [Saccorhiza polyschides] may also occur but rarely in equal abundance to [L. hyperborea] or [L. saccharina]. Beneath the kelp canopy, the faunal component is generally less diverse than the more exposed kelp forests (A3.214). The silted rock supports a sparse fauna of gastropods [Gibbula cineraria] and [Calliostoma zizyphinum], the tube-building polychaete [Pomatoceros triqueter] and occasional starfish [Asterias rubens] and the urchin [Echinus esculentus]. Steeper, less silted rock, may have the anthozoans [Caryophyllia smithii] and [Alcyonium digitatum].
Situation: This biotope occurs below [Laminaria digitata] on the sheltered sublittoral fringe (A3.2111) or a mix of [L. saccharina] and [L. digitata] in very sheltered conditions (A3.3131). It can also be found on isolated rock exposures amid a sediment seabed (A5.3541 or A5.343). Where suitable substrata allow, the kelp thins out with increased depth to form a park below the forest (A3.3122).


HabitatName:
Mixed [Laminaria hyperborea] and [Laminaria saccharina] park on sheltered lower infralittoral rock

HabitatDescription:
Sheltered silted, bedrock and boulders with a park of mixed [Laminaria hyperborea] and [Laminaria saccharina]. Both kelp species are sparse in the park (Frequent). Beneath the often 'cape-form' kelp canopy, foliose red seaweeds such as [Delesseria sanguinea, Cryptopleura ramosa], [Heterosiphonia plumosa] and [Brongniartella byssoides] are often present at high densities on the silted rock. Other red seaweeds such as encrusting coralline algae, [Phycodrys rubens, Callophyllis laciniata, Bonnemaisonia asparagoides] and [Plocamium cartilagineum] can be present. Other brown seaweeds include [Dictyota dichotoma] and [Desmarestia aculeata]. The animal component of this biotope is generally richer than the upper infralittoral mixed kelp forest (A3.3121). A variety of hydroids such as [Obelia geniculata] grow epiphytically on the kelp fronds along with the bryozoan [Membranipora membranacea]. The echinoderm [Antedon bifida] and ascidians such as [Clavelina lepadiformis] attach to the kelp stipes, above the silted rock. The rock itself supports anthozoans such as [Caryophyllia smithii] and [Urticina felina] as well as the tube-building polychaete [Pomatoceros triqueter] and the crap [Necora puber]. Grazers include the prominent echinoderm [Echinus esculentus] and the gastropods [Gibbula cineraria] and [Calliostoma zizyphinum]. Where pockets of sediment occur, there may be an increase in infaunal species such as the burrowing anthozoan [Cerianthus lloydii], the brittlestar [Ophiura albida], and starfish [Asterias rubens]. Although there is a decrease in the number of algal species in the kelp park, the abundance remains relatively high.
Situation: These mixed kelp parks are generally found below the mixed kelp forest (unit A3.3121) where there is a continuation of suitable hard substrata present. These sheltered kelps are also frequently found on bedrock or boulder exposures (XFa) adjacent to sediment seabed characterised by infaunal species. Where silted, circalittoral rock occurs below the kelp park a variety of biotopes may be found characterised by varying amounts of featherstars, anthozoans, solitary ascidians and sponge communities (e.g. units A4.313, A4.312, A4 311, A4.314 and A5.623).


HabitatName:
Grazed, mixed [Laminaria hyperborea] and [Laminaria saccharina] on sheltered infralittoral rock

HabitatDescription:
Silted infralittoral rock with mixed [Laminaria hyperborea] and [Laminaria saccharina] kelp forest, intensively grazed by the echinoderm [Echinus esculentus] and the gastropods [Gibbula cineraria] and [Calliostoma zizyphinum]. Although both kelp species can occur in equal abundance (Common), [L. hyperborea] usually dominates. The grazing-resistant brown seaweed [Desmarestia aculeata] and [Cutleria multifida] may be present. A similar variety of red seaweeds to those found in the ungrazed kelp forest (A3.3121) may occur beneath the kelp canopy, but in much lower abundance. As grazing intensity increases the seaweed cover decreases - and some sites are reduced to the bare appearance of encrusting brown and coralline algae beneath the kelp canopy. The [L. hyperborea] stipes generally support more seaweeds than the rock beneath, including [Cryptopleura ramosa], [Delesseria sanguinea], [Phycodrys rubens] and [Bonnemaisonia hamifera]. The stipes may also support sometimes dense ascidians [Clavelina lepadiformis] and [Ciona intestinalis] and the echinoderm [Antedon bifida]. The kelp fronds are often densely covered by the hydroid [Obelia geniculata]. At the most intensively grazed sites even the kelp stipes are bare. Although the rock appears bare, between boulders and in crevices there are often the brittlestar [Ophiothrix fragilis] and the crabs [Necora puber] and [Pagurus bernhardus]. The tube-building [Pomatoceros triqueter] and bryozoan crusts are commonly found on any vertical surfaces.

Situation: This biotope can be found in similar conditions as units A3.3121 and A3.3122 but where the numbers of grazers present are in high enough numbers to cause substantially community impoverishment through grazing. Generally occurs on isolated rock, surrounded by sediment biotopes. Although it has been recorded from sites astride the ungrazed kelp biotopes (A3.3121 and A3.3122) it is more usually found on bedrock or boulder exposures (A4.13) adjacent to sediment seabed characterised by infaunal species.

Temporal variation: If the grazing pressure is reduced (i.e. a decrease in the number of grazing echinoderms present) the community will eventually re-establish itself as a mixed kelp forest or park (unit A3.312).


HabitatName:
[Laminaria saccharina] on very sheltered infralittoral rock

HabitatDescription:
Very sheltered infralittoral rock dominated by the kelp [Laminaria saccharina]. Typically very silty and often with few associated seaweeds due to siltation, grazing or shading from the dense kelp canopy. The most commonly occurring red seaweeds are [Delesseria sanguinea], [Phycodrys rubens, Bonnemaisonia hamifera] and coralline crusts. In addition to the kelp the brown seaweed [Chorda filum] and Ectocarpaceae are often present. As well as lacking [Laminaria hyperborea], the A3.313 biotopes have fewer foliose and filamentous red seaweed species by comparison to A3.312 biotopes. A depauperate assemblage of animals is present (by comparison to A3.2141 and A3.2142) predominantly consisting of the encrusting polychaetes [Pomatoceros triqueter], the crabs [Carcinus maenas] and [Pagurus bernhardus] and the ubiquitous gastropod [Gibbula cineraria]. The echinoderms [Antedon bifida], starfish [Asterias rubens], brittlestar [Ophiothrix fragilis] and urchin [Echinus esculentus] occur in low abundance. Ascidians are commonly found in all the A3.313 biotopes, but the large solitary ascidian [Ascidia mentula] are most prolific in very sheltered conditions of [L. saccharina] forests (A3.3132). This biotope is most commonly associated with the sheltered fjordic sealochs of Scotland where sublittoral hard substrata can be found at the sheltered head of the lochs. Similarly the sheltered loughs of Ireland (Lough Hyne, Strangford Lough and Carlingford Lough). It is also found where suitable hard substrata exist in the sheltered inlets of south-west Britain, such as Milford Haven or Plymouth Sound. 4 variants has been described: A mixture of [L. saccharina] and [Laminaria digitata] (A3.3131), dense [L. saccharina] forest in the upper infralittoral (A3.3132), sparse [L. saccharina] in the lower infralittoral (A3.3133) and urchin-grazed (A3.3134).


HabitatName:
[Laminaria saccharina] and [Laminaria digitata] on sheltered sublittoral fringe rock

HabitatDescription:
Sheltered bedrock and boulders in the sublittoral fringe characterised by a mixed canopy of the kelp [Laminaria digitata] (usually in its broad-fronded cape-form) and [Laminaria saccharina] - both species are generally Frequent or greater. Beneath the kelp canopy, the understorey of red seaweeds often includes [Chondrus crispus, Dumontia contorta, Bonnemaisonia hamifera] and [Plocamium cartilagineum]. The surface of the rock is usually covered with encrusting coralline algae as well as non-calcified red crusts and the tube-building polychaete [Pomatoceros triqueter]. The brown seaweeds [Chorda filum], Ectocarpaceae and [Fucus serratus] can be present along with the green seaweeds [Ulva lactuca] and [Enteromorpha intestinalis]. Patches of the sponge [Halichondria panicea] can frequently be found in cracks and crevices. Beneath and between boulders a variety of mobile crustaceans such as [Carcinus maenas], the gastropod [Gibbula cineraria] and the starfish [Asterias rubens] are common.
Situation: Where hard substrata occur on the shore, this biotope will be found below the [F. serratus] zone (units A1.3151, A1.214 or A1.3152 on mixed substrata). With such sheltered shores, the transition between sublittoral fringe and the true sublittoral zone may not be distinct; this biotope therefore extends into the shallow sublittoral kelp forest below (A3.3121, A3.3121 or A3.314).


HabitatName:
[Laminaria saccharina] forest on very sheltered upper infralittoral rock

HabitatDescription:
Sheltered to extremely sheltered sublittoral fringe and infralittoral bedrock, boulders and cobbles characterised by a dense canopy of the kelp [Laminaria saccharina]. In such sheltered conditions, a distinct sublittoral fringe is not always apparent and this biotope can therefore extend from below the [Fucus serratus] zone (A1 315) into the upper infralittoral zone, though there may be a mixed [L. saccharina] and [Laminaria digitata] zone (A3.3131) in between. There is a relatively low species diversity and species density due to a combination of heavy siltation of the habitat and the lack of light penetrating through the dense kelp canopy. Only a few species of red seaweeds are present compared with A3.3131 or A3.312. The most commonly occurring red seaweeds are [Delesseria sanguinea], [Phycodrys rubens], [Bonnemaisonia hamifera] and coralline crusts. Brown seaweeds are also sparse and generally comprise [Chorda filum] and ectocarpoids. At extremely sheltered sites, where there is a heavy silt cover on the rock and the kelp fronds, the sub-flora is reduced to a few specialised species able to tolerate these conditions, such as the cartilaginous seaweeds [Polyides rotundus] and [Chondrus crispus]. Ascidians such as [Clavelina lepadiformis], [Ascidiella aspersa] and [Ascidia mentula] can remain prominent in such conditions, often occurring on steep or vertical rock which is subject to less siltation. The variety of red seaweeds is further reduced where grazers such as the urchin [Echinus esculentus] and the top shell [Gibbula cineraria] are present. The keelworm [Pomatoceros triqueter], the crab [Carcinus maenas] and the hermit crab [Pagurus bernhardus] can be present. Geographical variations: Northern sites: in sheltered sealochs the most conspicuous fauna in these forests are the large solitary ascidians [Ciona intestinalis], [Ascidiella] spp. and [A. mentula] which tend to occur in greater abundance than in the mixed kelp forests (A3.312). In common with mixed forests, echinoderms are consistently present in low abundance: the featherstar [Antedon bifida], common starfish [Asterias rubens], the brittlestar [Ophiothrix fragilis] and the urchin [Echinus esculentus] are typically present. Saddle oysters [Pododesmus patelliformis] and chitons [Tonicella marmorea] can occur in high abundance at some sites. The anthozoan [Anemonia viridis] is often more prevalent at the extremely sheltered sites. The communities of the sheltered voes and sounds of Shetland and Orkney are similar to those present in the mainland sealochs. Southern sites: Sheltered infralittoral rock is not commonly found outside of the fjordic sealochs. In south-west Britain, where sublittoral rock does occur in shallow marine inlets, the waters are more turbid than in the sealochs, generally limiting kelp to the sublittoral fringe zone. Echinoderms are rare or absent from the south-western [L. saccharina] forests. A far greater diversity of red seaweeds is associated with the south-western sites: [Palmaria palmata], [Gracilaria gracilis], [Phyllophora pseudoceranoides], [Cystoclonium purpureum], [Rhodophyllis divaricata], [Ceramium nodulosum] and [Polyneura bonnemaisonii] typically occur.
Situation: Although this biotope may occur below a mixed kelp canopy that occupies the sublittoral fringe (units A3.3131 or A3.2111) at some sites it extends directly into the sublittoral fringe and abuts the [F. serratus] zone (A1 315 or A1.3152 on mixed substrata). Where suitable hard substrata are available, the [L. saccharina] diminishes in abundance (typically Frequent) with increasing depth to form kelp park (A3.3122).


HabitatName:
[Laminaria saccharina] park on very sheltered lower infralittoral rock

HabitatDescription:
Silty bedrock or boulders with a [Laminaria saccharina] park (often the cape-form). Beneath the canopy, the rock is covered by encrusting coralline algae, and the urchin [Echinus esculentus] is often present. Due to the amount of silt cover on the rock and the reduced light intensity beneath the broad-fronded kelp, only a few red seaweeds typically survive, the most common species being [Phycodrys rubens], [Delesseria sanguinea], [Bonnemaisonia] spp. and [Brongniartella byssoides]. The brown seaweeds [Dictyota dichotoma] and [Cutleria multifida] may be present in low abundance. Compared to the kelp forest zone above (A3.3121) both the kelp and other seaweeds are sparse (Occasional). The most conspicuous animals are large solitary ascidians, particularly [Ascidia mentula] and [Ciona intestinalis], together with the smaller [Clavelina lepadiformis]. In general, the faunal component of this biotope is similar to other sheltered kelp biotopes and includes a variety of mobile crustaceans such [Carcinus maenas] and [Pagurus bernhardus], the keelworm [Pomatoceros] spp., terebellid worms, echinoderms [Asterias rubens], [Ophiothrix fragilis] and the featherstar [Antedon bifida]. The hydroid [Kirchenpauria pinnata], although only rare is often found in the kelp park along with the top shell [Gibbula cineraria] and the barnacle [Balanus crenatus].
Situation: [L. saccharina] park can be found below a similar forest (unit A3.3121) where suitable hard substrata exist or on isolated rock exposures surrounded by sediment communities. It may also occur below a zone of mixed [Laminaria hyperborea] and [L. saccharina] forest (A3.312). [L. saccharina] can also form a band below [L. hyperborea] forest (A3.2141) where some shelter from wave-action is afforded with depth ([L. saccharina] is not tolerant of surge), or more likely where [L. hyperborea] has been grazed out (below A3.2143) since [L. saccharina] grows far quicker than [L. hyperborea]. Where such a narrow band occurs it is generally less silted than that found below A3.3121 in much more sheltered conditions. A range of sheltered circalittoral biotopes may occur on any deeper rock below (e.g. units A4.313, A4 311 and A5.623).


HabitatName:
Grazed [Laminaria saccharina] with [Echinus], brittlestars and coralline crusts on sheltered infralittoral rock

HabitatDescription:
Coralline encrusted rock with scattered tufts of red seaweed and a relatively high abundance of grazing echinoderms which typically include the urchin [Echinus esculentus] and/or the brittlestars [Ophiothrix fragilis] or [Ophiocomina nigra]. The rock often looks bare, with few conspicuous species present although [Laminaria saccharina] may occur it is generally in low abundance (Rare or Occasional). The red seaweeds, reduced to small tufts through grazing, include [Phycodrys rubens], [Delesseria sanguinea] and [Brongniartella byssoides] and although these seaweeds also occur in unit A3.3122 they are far less frequent in this biotope. Brown seaweeds, such as [Desmarestia viridis], [Chorda filum] and [Cutleria multifida], may be present. Grazing molluscs, such as [Gibbula cineraria] and can be common. Under-boulder habitats can harbour the crabs Necora puber and [Pagurus bernhardus], terebellid polychaetes and the polychaete [Pomatoceros] spp. with ascidians [Ascidia mentula]. and [Clavelina lepadiformis] on the open rock along with the echinoderm [Asterias rubens] and the hydroids [Kirchenpauria pinnata] and [Obelia dichotoma].

Situation: This biotope generally occurs on rock below a dense kelp forest of [L. saccharina] (unit A3.3121) or mixed kelp (unit A3.3121).

Temporal variation: If the grazing pressure is reduced (i.e. a decrease in the number of grazing echinoderms present) a richer kelp community may develop (units A3.3122 or A3.3122).


HabitatDescription:
Cape-form of the kelp [Laminaria hyperborea] on very silted rock, particularly in extremely sheltered sealochs of western Scotland. Below the huge kelp fronds (which often trail onto the seabed) foliose seaweeds form a silted understorey on the rock including [Phycodrys rubens, Delesseria sanguinea, Cryptopleura ramosa] and [Plocamium cartilagineum] as well as coralline crusts. At some sites the filamentous red seaweed [Bonnemaisonia hamifera, Heterosiphonia plumosa] and [Brongniartella byssoides] may carpet the seabed. Ascidians, particularly [Ascidiella aspersa], [Ascidia mentula, Ciona intestinalis] and [Clavelina lepadiformis] thrive well in these conditions. The echinoderms [Antedon bifida, Echinus esculentus] and [Asterias rubens] are often present along with the gastropod [Gibbula cineraria]. An abundant growth of the hydroid [Obelia geniculata] can cover the silted kelp fronds along with the bryozoan [Membranipora membranacea]. The anthozoan [Caryophyllia smithii] can be present among the kelp holdfasts. The tube-building polychaete [Pomatoceros triqueter] can be present on the rock surface along with the crab [Necora puber]. This biotope generally occurs on shallow bedrock or boulder slopes or isolated rocks protruding through muddy sediment.
Situation: This biotope is often present on rocky outcrops surrounded by muddy sediments (such as unit A5.3541). Deeper, nearby rock, beyond the limit of foliose seaweeds, is often dominated by solitary ascidians (unit A4 311).


HabitatName:
[Sargassum muticum] on shallow slightly tide-swept infralittoral mixed substrata

HabitatDescription:
Mixed substrata from the sublittoral fringe to 5m below chart datum dominated by the brown seaweed [Sargassum muticum]. This invasive non-native brown seaweed can form a dense canopy on areas of mixed substrata (typically 0-10% bedrock on 90-100% sandy sediment). The substrate on which this [S. muticum]-dominated community is able to develop is highly variable, but particularly prevalent on broken rock and pebbles anchored in sandy sediment. The pebbles, cobbles and broken bedrock provide a substrate for alga such as the kelp [Laminaria saccharina]. During the spring, [S. muticum] has large quantities of epiphytic ectocarpales and may also support some epifauna e.g. the hydroid [Obelia geniculata] commonly found on kelp. The brown seaweed [Chorda filum], which thrives well on these mixed substrata, is also commonly found with [S. muticum] during the summer months. In Strangford Lough, where this biotope occurs, the amphipod [Dexamine spinosa] has been recorded to dominate the epiphytic fauna (this is known to be commonly found in [Zostera] spp. beds). [S. muticum] is also found on hard, bedrock substrates within [L. saccharina] canopies. [S. muticum] plants on hard substrate area, under a dense [L. saccharina] canopy, are typically smaller and at a much lower density, especially where a lush, under-storey exists with red seaweeds such as [Ceramium nodolosum, Gracilaria gracilis, Chylocladia verticillata, Pterosiphonia plumula] and [Polysiphonia elongata] and the green seaweeds [Cladophora sp., Ulva lactuca] and [Bryopsis plumosa]. The anthozoan [Anemonia viridis] and the crab [Necora puber] can be present. More information is necessary to validate this description.
Situation: Where there is a greater proportion of bedrock or boulders (15-100%) [L. saccharina] will typically dominate the canopy. Areas with pebble cover on a hard substrate are colonised by [S. muticum], but individuals quickly become peripatetic and are lost.


HabitatName:
Kelp in variable salinity on low energy infralittoral rock

HabitatDescription:
Very wave-sheltered bedrock, boulders and cobbles subject to only weak tidal streams in the sublittoral fringe and infralittoral zone, in areas of variable/reduced salinity. This habitat type is characterised by the kelp [Laminaria saccharina] and coralline crusts such as [Lithothamnion glaciale]. Grazers such as the urchins [Psammechinus miliaris] and [Echinus esculentus], and the gastropods [Gibbula cineraria] and [Buccinum undatum] may be present. The tube-dwelling polychaete [Pomatoceros triqueter], the ascidians [Ciona intestinalis], [Corella parallelogramma] and [Ascidiella scabra], the barnacle [Balanus crenatus], the starfish [Asterias rubens] and the brittlestar [Ophiothrix fragilis] may also be present. Red algal communities are composed primarily of [Phycodrys rubens]. The crabs [Carcinus maenas] and [Pagurus bernhardus], and the bivalve [Modiolus modiolus] may also be observed.


HabitatName:
[Codium] spp. with red seaweeds and sparse [Laminaria saccharina] on shallow, heavily-silted, very sheltered infralittoral rock

HabitatDescription:
Very shallow, heavily-silted infralittoral rock characterised by dense stands of [Codium] spp., together with silt-tolerant red seaweeds, the green seaweed [Ulva] spp. and often only a sparse covering of the kelp [Laminaria saccharina]. This biotope appears to have a restricted distribution, being known at present only from the sheltered voes of Shetland, some Scottish lagoons and from the harbours of south-west England. These locations suggest the habitat is likely to be subject to reduced salinity conditions (although the habitat data indicate mostly fully marine records). Dense [Codium] spp. can occur at very sheltered sites, on cobbles or boulders, often in dense patches interspersed with filamentous red seaweeds [Bonnemaisonia hamifera], [Antithamnionella spirographidis] and [Ceramium] spp. Where sediment is present the red seaweed [Polyides rotundus] is commonly found along the rock-sediment interface, and the sponge [Dysidea fragilis] often occurs on the rock. Other red seaweeds that may be present include [Chondrus crispus], [Callophyllis laciniata], [Gelidium latifolium], [Corallina officinalis] and coralline crusts. The brown seaweeds [Halidrys siliquosa], [Desmarestia viridis] or [Chorda filum] may be present in high abundance and although kelp [L. saccharina] may occur, it is usually sparse. There are no conspicuous fauna that typify this biotope, though polychaetes such as terebellids and spirorbids may occur. The opisthobranch [Elysia viridis] may be locally abundant on the seaweeds and is known to favour [Codium fragilis] in particular. Large stands of [Codium] sp. (generally Common abundance) are accompanied by red seaweeds such as [G. latifolium], [C. laciniata] and [A. spirographidis] on the rock beneath. Cod has been reported to occur in the shallows of The Fleet, Bembridge Ledges, Pagham Harbour and Jersey (Tittley et al. 1985). In Ireland, species-poor shallow, silted bedrock in the North Water of Mulroy Bay, Co. Donegal, is characterised by [Griffithsia corallinoides] (Common) and [Codium tomentosum] (Frequent) forming a narrow band below the kelp zone (unit A3.3132). Cod has not been described from any other sites in Ireland. If [Codium] spp. is less than Common amongst dense [L. saccharina] and [Chorda filum], it should not be recorded as Cod.
Situation: This biotope occurs on bedrock below a sublittoral fringe of mixed kelp [L. saccharina] and [Laminaria digitata] (unit A3.3131) or below a [L. saccharina] forest (A3.3132) or else on isolated boulders on sediment. It appears to be most frequently found in lagoons. Further information on which species of [Codium] is present and on the associated fauna is required.


HabitatName:
[Laminaria saccharina] and [Psammechinus miliaris] on variable salinity grazed infralittoral rock

HabitatDescription:
Sheltered bedrock, boulders and cobbles, in areas of reduced salinity, with kelp [Laminaria saccharina], and depauperate coralline-encrusted rock supporting few foliose seaweeds but many grazing urchins [Psammechinus miliaris] and [Echinus esculentus]. The coralline crusts are typically [Lithothamnion glaciale], while the brown crusts can be [Pseudolithoderma extensum]. Encrusting polychaetes [Pomatoceros triqueter], resistant to the grazing, are also present on most of the rock. The grazing fauna are a significant component of this biotope; large numbers of [P. miliaris] are typically present, although where absent the brittlestar [Ophiothrix fragilis] may occur. Other grazers prevalent on the rock include the chiton [Tonicella marmorea], the limpet [Tectura testudinalis] and the gastropod [Gibbula cineraria]. A combination of grazing pressure and lowered salinity maintains a low diversity of species in this biotope, with foliose and filamentous seaweeds generally absent or reduced to small tufts by grazing. In stark contrast to the range of seaweeds present in the [L. saccharina] forests (A3.3132) the only red seaweed consistently found in this biotope is [Phycodrys rubens]. The range of fauna is similarly low, with a conspicuous absence of hydroids and bryozoans. Bedrock and boulders provide a firm substrate on which ascidians [Ciona intestinalis] and [Ascidia mentula] and the bivalve [Modiolus modiolus] can attach. The crabs [Pagurus bernhardus] and [Carcinus maenas] can usually be found here, though [Necora puber] typically is absent due to the brackish conditions. The starfish [Asterias rubens] along with the whelk [Buccinum undatum] can be present. The substratum on which this biotope occurs varies from bedrock to boulders or cobbles on sediment. The kelp band is relatively narrow and shallow (upper 5 m) compared to unit A3.3121, although the grazed coralline encrusted rock extends deeper. This depth limit becomes shallower towards the heads of the sealochs. Geographical distribution This biotope is restricted to the west coast of Scotland, usually near the head of fjordic sealochs, which are influenced by freshwater run-off.

Situation: Where circalittoral rock occurs below this biotope, it often supports a brachiopod/anthozoan community (unit A4.314); where mixed substrata occurs below or adjacent, beds of [Modiolus modiolus] are common (units A5.623 or A5.442).

Temporal variation: If the grazing pressure is reduced (i.e. a decrease in the number of grazing echinoderms present) there may be an increase in filamentous and foliose seaweeds although the diversity will remain low compared to full saline sites.


HabitatName:
[Laminaria saccharina] with [Phyllophora] spp. and filamentous green seaweeds on variable or reduced salinity infralittoral rock

HabitatDescription:
Shallow infralittoral bedrock or boulder slopes, in reduced or low salinity conditions, characterised by the kelp [Laminaria saccharina] with dense stands of silted filamentous green seaweeds and red seaweeds [Phyllophora crispa], [Phyllophora pseudoceranoides] and [Phycodrys rubens]. The filamentous green seaweeds e.g. [Chaetomorpha melagonium] and [Cladophora] spp. can form a blanket cover amongst the [L. saccharina] in the upper zone, which is under greater influence of freshwater input. In deeper water the green seaweeds are replaced by red seaweed [Phyllophora] spp. or [Polysiphonia fucoides] which may form a distinct sub-zone in the biotope. Coralline crust can be present. The solitary ascidians [Corella parallelogramma] and [Ascidiella scabra] are often epiphytic on the seaweed (particularly [Phyllophora] spp.) and dominate the animal community along with the starfish [Asterias rubens]. The small ascidian [Dendrodoa grossularia], the barnacle [Balanus crenatus] and the tube-building polychaete [Pomatoceros triqueter] occur on the rock surface. More mobile species include the crab [Carcinus maenas], the hermit crab [Pagurus bernhardus] and the whelk [Buccinum undatum]. Bryozoans [Electra pilosa] and [Spirorbis] sp. may cover kelp fronds. The red seaweed [Odonthalia dentata] may be present in the north.
Situation: The ascidians found in this unit may continue onto the circalittoral rock below where dense colonies of anthozoans and brachiopods can also be found (A4.3142). Where tidal streams are increased, sponge and hydroid communities may occur below (A4.252).


HabitatName:
Mediterranean submerged fucoids, green or red seaweeds on full salinity infralittoral rock

HabitatDescription:
This community is characterised by the presence of many photophilic algae covering hard bottoms in exposed areas with normal or high salinity.


HabitatName:
Association with [Stypocaulon scoparium] (=[Halopteris scoparia])

HabitatDescription:
This association is characterised by the brown alga [Stypocaulon scoparium], living in pure, sheltered waters with strong luminosity.


HabitatName:
Association with [Trichosolen myura] and [Liagora farinosa]

HabitatDescription:
This association is characterised by the green alga [Trichosolen myura] and the red alga [Liagora farinosa], also called "soft spaghettiweed".


HabitatDescription:
This association is characterised by the brown alga [Cystoseira compressa].


HabitatName:
Association with [Pterocladiella capillacea] and [Ulva laetevirens]

HabitatDescription:
This association is characterised by a vegetation with the red alga [Pteroclediella capillacea] and the green alga [Ulva laetevirens]. It is found in areas with mixed salinity.


HabitatDescription:
This facies is characterised by the high presence of large Hydrozoa (e.g. [Aglaophenia] spp. and [Eudendrium] spp.).


HabitatName:
Pontic facies with large Hydrozoa in the infralittoral (winter aspect)


HabitatName:
Association with [Pterothamnion crispum] and [Compsothamnion thuyoides]

HabitatDescription:
This association is characterised by a mixed vegetation of the red algae [Pterothamnion crispum] and [Compsothamnion thuyoides].


HabitatName:
Mixed fucoids, [Chorda filum] and green seaweeds on reduced salinity infralittoral rock

HabitatDescription:
Permanently submerged mixed fucoids on rock in lagoons. The main species are the wracks [Fucus serratus] and [Fucus vesiculosus], but the brown seaweeds [Chorda filum], [Ascophyllum nodosum] and Ectocarpaceae can be present as well. Red seaweeds are normally present and include [Mastocarpus stellatus, Polyides rotundus, Chondrus crispus, Ceramium] spp. and coralline crusts. A variety of green seaweeds is also present and include [Enteromorpha] spp., while dense patches of [Cladophora rupestris] may occur on vertical rock faces. The faunal component is restricted to the mussel [Mytilus edulis], the polychaete [Arenicola marina] and the crab [Carcinus maenas]. Opossum shrimps Mysidae can be present as well. The kelp [Laminaria saccharina] is absent, possibly due to the low salinity conditions.
Situation: Nearby rock often supports similar biotopes of submerged fucoids (units A3.342 and A3.344) or where salinity is further reduced unit A3.343 can occur. Slightly deeper rock often supports [Laminaria saccharina] (unit A3.3132), usually surrounded by more extensive areas of sediment. Seagrass beds thrive well in the muddy sediments of the lagoons and often cover large areas. They include both [Ruppia] spp. and [Zostera marina] and some locations in the Outer Hebrides support dense beds of the nationally rare stonewort [Lamprothamnion papulosum] (units A5.5343 and A5.5331). The sublittoral mud, which abuts most of the submerged rock, can become anoxic and covered by a bacterial mat of [Beggiatoa] spp. (unit A5.7211).


HabitatName:
[Ascophyllum nodosum] and epiphytic sponges and ascidians on variable salinity infralittoral rock

HabitatDescription:
Dense subtidal stands of [Ascophyllum nodosum], heavily epiphytised by sponges and ascidians in lagoon-like habitats. The wracks [Fucus vesiculosus] and [Fucus serratus] can be present along with the brown seaweed [Chorda filum] and the red seaweed [Polyides rotundus]. The crab [Carcinus maenas] can be present between the [A. nodosum] holdfasts along with the shrimps Mysidae.
Situation: Nearby rock often supports similar biotopes of submerged fucoids and green seaweeds (unit A3.341). Slightly deeper rock often supports [Laminaria saccharina] (unit A3.3132), usually surrounded by more extensive areas of sediment. Seagrass beds thrive well in the muddy sand of these lagoons and often cover large areas. They include both [Ruppia maritima] and [Zostera marina] (units A5.5343 and A5.5331).


HabitatName:
[Polyides rotundus] and/or [Furcellaria lumbricalis] on reduced salinity infralittoral rock

HabitatDescription:
Bedrock and boulders characterised by a dense turf of the red seaweeds [Polyides rotundus] and/or [Furcellaria lumbricalis], often with a dense mat of filamentous brown and green seaweeds including Ectocarpaceae and [Cladophora] spp. Other red seaweeds presents include [Chondrus crispus, Gracilaria gracilis] and coralline crusts as well as the odd brown seaweed [Chorda filum] or [Laminaria] spp. Associated with these seaweeds are a variety of ascidians including [Clavelina lepadiformis, Ascidiella aspersa, Ascidiella scabra] and [Ciona intestinalis] as well as the anemones [Anemonia viridis] and [Actinia equina] and the sponge [Halichondria panicea]. More mobile fauna include the starfish [Asterias rubens], the crab [Carcinus maenas], the hermit crab [Pagurus bernhardus], the opossum shrimps Mysidae and the gastropod [Littorina littorea]. Attached to the rock or cobbles are spirorbid polychaetes and the mussel [Mytilus edulis]. Please notice that part of this diversity is due to large differences between sites.
Situation: Nearby rock (units A3.342 and A3.341) and seagrass [Ruppia maritima] dominating much of the surrounding muddy sediment (unit A5.5343). Mixed sediment supports filamentous green seaweeds e.g. [Cladophora] spp. and [Derbesia marina] on A5.528.


HabitatName:
[Fucus ceranoides] and [Enteromorpha] spp. on low salinity infralittoral rock

HabitatDescription:
Permanently submerged lagoon fringes with dense communities of the wrack [Fucus ceranoides] and the green seaweed [Enteromorpha] spp. There is typically a very limited associated biota due to low salinity conditions, and may include the opossum shrimps Mysidae and the freshwater/brackish gastropod [Potamopyrgus antipodarum].


HabitatName:
[Codium elisabethae], [Halopteris filicina] and coralline crusts on sheltered infralittoral bedrock


HabitatName:
Pontic association of green and red seaweeds [Enteromorpha], [Ulva] spp., [Porphyra] spp. on moderately exposed or sheltered infralittoral rock


HabitatName:
Faunal communities on low energy infralittoral rock


HabitatDescription:
Shallow subtidal rocky habitats which support faunal-dominated communities, with seaweed communities only poorly developed or absent. In some sealochs dense mussel [Mytilus edulis] beds (A3.361) develop in tide-swept channels, whilst upper estuarine rocky habitats in the south-west coast rias may support particular brackish-water tolerant faunas (A3.362; A3.363).


HabitatName:
[Mytilus edulis] on reduced salinity infralittoral rock

HabitatDescription:
This biotope occur in shallow, often tide-swept, reduced salinity conditions. Dense beds of the mussel [Mytilus edulis] with the occasional barnacle [Balanus crenatus]. A wide variety of epifaunal colonisers on the mussel valves, including seaweeds, hydroids and bryozoans can be present. Predatory starfish [Asterias rubens] can be very common in this biotope. This biotope generally appears to lack large kelp plants, although transitional examples containing mussels and kelps plants may also occur. More information needed to validate this description.
Situation: Occurs in tide-swept entrance channels in very enclosed basins of sealochs where the basins are typically of lowered salinity. Also occurs in very sheltered subtidal rock (often vertical) in lagoons.


HabitatName:
[Cordylophora caspia] and [Electra crustulenta] on reduced salinity infralittoral rock

HabitatDescription:
Shallow sublittoral rock in the upper estuary of one of the south-west inlets (Tamar) with very high turbidity and therefore no seaweeds. The brackish-water hydroid [Cordylophora caspia] and small colonies of the encrusting bryozoan [Electra crustulenta] and a few [Balanus crenatus] characterise this biotope. More information required to validate this description.


HabitatName:
[Hartlaubella gelatinosa] and [Conopeum reticulum] on low salinity infralittoral mixed substrata

HabitatDescription:
Upper estuarine mixed hard substrata colonised by very sparse communities of animals with low species richness and with a few seaweeds in very shallow water. In the Tamar estuary the hydroid [Hartlaubella gelatinosa] and bryozoan [Conopeum reticulum] are found on stones. In the River Dart the bryozoan [Bowerbankia imbricata] is most abundant. The mussel [Mytilus edulis], the crab [Carcinus maenas] and the hydroid [Obelia dichotoma] can be present. A similar brackish-water rocky biotope is recorded from the Bann Estuary, Northern Ireland. There are considerable differences in species composition between sites, but all occur in brackish turbid-water conditions. More information required to validate this description.


HabitatDescription:
Rock habitats in the Baltic infralittoral zone which are exposed to wave action, currents or ice scouring. The exposure status is that impacting on the area concerned at the relevant scale. Thus there may be enclaves of different exposure status caused by localised variation in relief (e.g. steeper rock in more moderately exposed or even sheltered areas). Note that it has been proposed that ‘exposed’ has an effective fetch of greater than 25 km: this requires verification across the Baltic.


HabitatName:
Baltic moderately exposed infralittoral rock

HabitatDescription:
Rock habitats in the Baltic infralittoral zone which are moderately exposed to wave action, currents or ice scouring. The exposure status is that impacting on the area concerned at the relevant scale. Thus there may be enclaves of different exposure status caused by localised variation in relief (e.g. steeper rock in sheltered areas). Note that it has been proposed that ‘exposed’ has an effective fetch of 5 – 25 km: this requires verification across the Baltic.


HabitatDescription:
Rock habitats in the Baltic infralittoral zone which are sheltered from wave action, currents or ice scouring. The exposure status is that impacting on the area concerned at the relevant scale. Thus there may be enclaves of different exposure status caused by localised variation in relief (e.g. sheltered areas within exposed or moderately exposed areas). Note that it has been proposed that ‘exposed’ has an effective fetch less than 5 km: this requires verification across the Baltic.


HabitatDescription:
Includes surge gulleys (A3.71), which are found throughout the infralittoral rock zone, and usually consist of vertical bedrock walls, occasionally with overhanging faces, and support communities, which reflect the degree of wave surge they are subject to and any scour from mobile substrata on the cave/gully floors. The larger cave and gully systems, such as found in Shetland, Orkney, the Western Isles and St Kilda, typically show a marked zonation from the entrance to the rear of the gully/cave as wave surge increases and light reduces. Also includes habitats in hard substrata in the infralittoral zone characterised by the presence of seeping or bubbling gases, oils or water (A3.73) and recently colonised artificial hard substrata in the infralittoral zone (A3.72).


HabitatName:
Robust faunal cushions and crusts in surge gullies and caves

HabitatDescription:
Infralittoral rocky habitats subject to strong wave surge conditions, as found in surge gullies and shallow caves, and typically colonised by faunal communities of encrusting or cushion sponges, colonial ascidians, short turf-forming bryozoans, anthozoans, barnacles and, where there is sufficient light, red seaweeds. These features usually consist of vertical bedrock walls, occasionally with overhanging faces, and support communities which reflect the degree of wave surge they are subject to, and any scour from mobile substrata on the cave/gully floors. The larger cave and gully systems, such as found in Shetland, Orkney, the Western Isles and St Kilda, typically show a marked zonation from the entrance to the rear of the gully/cave as wave surge increases and light reduces. This is reflected in communities of anthozoans, ascidians, bryozoans and red seaweeds near the entrance, leading to sponge crust-dominated communities and finally barnacle and spirorbid worm communities in the most severe surge conditions. Gully/cave floors usually have mobile boulders, cobbles, pebbles or coarse sediment. The mobile nature of the gully/cave floors leads to communities of encrusting species, tolerant of scour and abrasion or fast summer-growing ephemeral species. The lower zone of the gully side walls are also often scoured, and typically colonised by coralline crusts and barnacles.

Situation: On open rocky coasts with moderate or greater wave action.

Temporal variation: Unknown, although winter storms likly to yield scouring on gully/cave walls; some ephemeral growth likely in calmer summer months.


HabitatDescription:
This biotope is found on steep wave-surged entrances to gullies and caves and on unstable boulders in the entrance to caves and gullies. The rock may be abraded by the movement of the boulders and cobbles in heavy surge and tends to be dominated by dense foliose seaweeds that grow rapidly in the calmer summer months. Beneath the foliose seaweeds the rock surface is typically covered with coralline crusts, which are longer-lived, and tolerant of abrasion. The flora of this biotope is relatively varied, depending upon the amount of light and degree of abrasion or rock mobility with red seaweeds such as [Cryptopleura ramosa], [Plocamium cartilagineum], [Odonthalia dentata], [Callophyllis laciniata], [Phycodrys rubens], [Hypoglossum hypoglossoides], [Phyllophora crispa] and [Corallina officinalis]. The brown seaweed [Dictyota dichotoma] also occurs in these conditions, since it is tolerant of some sand scour. During the summer months small fast-growing kelp plants can arise in this biotope, although the mobility of the substratum prevents the kelp from forming a kelp forest. Dense swathes of very young kelp such as [Laminaria hyperborea] are, however, not uncommon. The faunal community consist of the anemone [Urticina felina], the sponge [Halichondria panicea] and the ascidian [Dendrodoa grossularia]. More mobile fauna include the echinoderms [Asterias rubens] and [Echinus esculentus], the top shell [Gibbula cineraria] and the crab [Cancer pagurus].
Situation: Further into the cave or gully, beyond the dense red seaweeds of A3.711, the vertical rock grades to either an ascidian and sponge dominated community or sponge crusts and anthozoans (A3.712 / A3.713). Further into the cave or gully the floor and any boulders or cobbles are generally scoured clean or may support coralline encrusting algae (unit A3.7162). Above the red seaweeds, steep rock surfaces often support a kelp community (units A3.115 or A3.214) or in shallower water [Alaria esculenta] is usually present (Ala.Myt).


HabitatName:
Anemones, including [Corynactis viridis,] crustose sponges and colonial ascidians on very exposed or wave surged vertical infralittoral rock

HabitatDescription:
Vertical very exposed and exposed bedrock gullies, tunnels and cave entrances subject to wave-surge dominated by sponge crusts such as [Clathrina coriacea, Myxilla incrustans, Pachymatisma johnstonia] and [Halichondria panicea] and anthozoans such as [Sagartia elegans, Urticina felina, Alcyonium digitatum, Corynactis viridis] and dwarf [Metridium senile] generally dominate the area; the anthozoans often appearing to protrude through the sponge layer. There may be dense aggregations of the hydroid [Tubularia] [indivisa], the cup coral [Caryophyllia smithii] and the colonial ascidians [Botrylloides leachi] and [Polyclinum aurantium]. There may be a short crisiid turf, interspersed with [Scrupocellaria reptans]. Encrusting coralline algae may occur on well-illuminated rock faces. The echinoderms [Asterias rubens], [Marthasterias glacialis], [Echinus esculentus], [Antedon bifida] and [Ophiothrix fragilis], the topshell [Calliostona zizphinum] and the calcareous tubeworm [Pomatoceros triqueter] may also be present on the rock face. The crabs [Cancer pagurus] and [Necora puber] may also be recorded. Due to the wave-surged nature and vertical orientation of these biotopes, kelps are rare and certainly never dominate.


HabitatName:
Crustose sponges and colonial ascidians with [Dendrodoa grossularia] or barnacles on wave-surged infralittoral rock

HabitatDescription:
Vertical and overhanging, exposed to moderately exposed bedrock gullies, tunnels and cave entrances subject to wave surge, and dominated by the crustose sponges [Halichondria panicea], [Myxilla incrustans], [Clathrina coriacea], [Leucosolenia botryoides], [Esperiopsis fucorum] and [Grantia compressa]. There may also be dense aggregations of the anthozoan [Sagartia elegans], dwarf [Metridium senile], [Alcyonium digitatum], and [Urticina felina], and a dense covering of the barnacle [Balanus crenatus] on the bare rock face. Dense aggregations of the robust hydroid [Tubularia indivisa] may be recorded, growing through the sponge crust. Colonial ascidians such as [Polyclinum aurantium], [Botryllus schlosseri], [Botrylloides leachi], [Aplidium nordmanni] and the solitary ascidian [Dendrodoa grossularia] may all be recorded. The echinoderms [Asterias rubens], [Echinus esculentus], [Henricia] sp., the crab [Cancer pagurus] and the calcareous tubeworm [Pomatoceros triqueter] may also be present on the rock face, along with encrusting coralline algae.


HabitatName:
[Dendrodoa grossularia] and [Clathrina coriacea] on wave-surged vertical infralittoral rock

HabitatDescription:
Vertical or overhanging infralittoral rock subject to considerable wave-surge, especially in the middle or back of caves but also in gullies and tunnels, and dominated by dense sheets of the ascidian [Dendrodoa grossularia], together with variable quantities of the sponge [Clathrina coriacea]. At some sites [D. grossularia] forms continuous sheets, with few other species present. Other sponges such as [Esperiopsis fucorum], [Pachymatisma johnstonia], [Leucosolenia botryoides], [Scypha ciliata] and [Halichondria panicea] regularly occur in this biotope, though generally at low abundance. Other ascidians, especially [Polyclinum aurantium], [Diplosoma] spp. and other didemnids may also occur, though only [P. aurantium] is ever as abundant as [D. grossularia]. Being characteristically found in the middle or towards the backs of the caves mean that there is generally insufficient light to support any foliose seaweeds, although encrusting coralline algae are not uncommon. More scoured areas may also contain the anemone [Urticina felina], whilst [Sagartia elegans] is often present in low numbers. Mobile fauna are often limited to the starfish [Asterias rubens] and [Henricia] spp., the brittlestar [Ophiopholis aculeata] and crabs [Cancer pagurus] and [Necora puber]. The barnacle [Balanus crenatus] can occur, usually in low densities.
Situation: Where this biotope develops in a cave or tunnel it can occur anywhere from the entrance to the rear of the system. Typically, it will give way to sponge crust or barnacle and encrusting tubeworm communities at the rear of the cave, where surge forces are amplified (units A3.715 or A3.7161). The vertical rock below this unit, abutting the cave/gully floor, is likely to be severely scoured, colonised by the robust A3.7161 biotope. The cave or gully floor is generally scoured clean by boulders and/or cobbles (A3.7162). The cave or gully entrance has more available light for algal growth so dense foliose seaweeds usually dominate the rock walls at the entrance, abutting the [D. grossularia] - [C. coriacea] zone further into the cave (A3.711). This dense seaweed growth may also extend to the upward-facing surfaces of boulders around the entrance. Where this unit occurs in a gully situation, the rock tends to be colonised by dense [Alaria esculenta] in the sublittoral fringe (A3.111) or by [Laminaria hyperborea] forest in the shallow infralittoral (A3.1151).


HabitatDescription:
Walls, or massive boulders, in caves or gullies that are subject to severe wave-surge and characterised by extensive thin crusts of the sponge [Halichondria panicea] with smaller patches of other sponges such as [Esperiopsis fucorum] or [Clathrina coriacea]. Small turfs of robust hydroids, such as [Diphasia rosacea] and [Ventromma halecioides], and patches of the barnacle [Balanus crenatus], coralline crusts and tube-building spirorbid polychaetes may be present. The starfish [Henricia] spp., the brittlestar [Ophiopholis aculeata] and the crabs [Cancer pagurus] and [Necora puber] can be present. The anemones [Sagartia elegans], [Urticina felina] and [Actinia equina] can be found in cracks and crevices or under boulders. The mussel [Mytilus edulis] may be present in low densities.
Situation: This surge-tolerant biotope of low-growing fauna is typically confined to the mid or rear section of caves (or the narrowest part of gullies) where the wave-surge is intensified. It generally abuts the less surged ascidian-sponge communities (units A3.712, A3.714 and A3.713). A highly scoured zone of barnacles and calcareous tubeworms often form a zone below, abutting the cave/gully floor (A3.7161).


HabitatDescription:
Scoured rock in wave-surged caves, tunnels or gullies often looks rather bare, and may be characterised by a limited scour-tolerant fauna of [Balanus crenatus] and/or [Pomatoceros triqueter] with spirorbid polychaetes. In areas where sufficient light is available and scour is severe, encrusting coralline algae and non-calcareous crusts cover the rock surface, giving a pink appearance. This biotope most commonly occurs at the bottom of walls in caves and gullies, where abrasion by cobbles and stones is severe, especially during winter. In some gullies, extreme scouring and abrasion produces a narrow band of bare coralline algal crust at the very bottom of the walls, with a band of [P. triqueter] and/or [B. crenatus] immediately above. Other scour-tolerant species, such as encrusting bryozoans may also be common. Crevices and cracks in the rock provide a refuge for sponge crusts such as [Halichondria panicea] and occasional anemones [Urticina felina] and [Sagartia elegans]. More mobile fauna is usually restricted to the echinoderms [Asterias rubens] and [Echinus esculentus] as well as the crab [Cancer pagurus]. Two variants have been identified: Wave-surged bedrock with coralline crust, [B. crenatus] and [P. triqueter] (A3.7161) and coralline crusts on mobile boulders in severely scoured caves (A3.7162).
Situation: Generally occurring at the base of walls in caves and gullies and on the floors of caves and gullies. Immediately above this zone a variety of biotopes may occur depending on the proximity to the cave/gully entrance. Typically sponge crusts and ascidians with a hydroid-bryozoan turf will occur in the outer to mid section (units A3.712, A3.713); sponge crusts and dense ascidians in the outer to rear section (A3.714); and low-growing sponge crusts at the rear of caves (A3.715). At some sites with extreme wave surge, A3.7161 can form a zone towards the rear of the cave, beyond the sponge crust zone.


HabitatName:
[Balanus crenatus] and/or [Pomatoceros triqueter] with spirorbid worms and coralline crusts on severely scoured vertical infralittoral rock

HabitatDescription:
Severely scoured bedrock in wave-surged caves, tunnels or gullies often looks rather bare, and may be characterised by a limited scour-tolerant fauna of [Balanus crenatus] and/or [Pomatoceros triqueter] with spirorbid polychaetes. In areas where sufficient light is available, encrusting coralline algae and non-calcareous crusts cover the rock surface, giving a pink appearance. This biotope most commonly occurs at the bottom of walls in caves and gullies, where abrasion by cobbles and stones is severe, especially during winter. In some gullies, extreme scouring and abrasion produces a narrow band of bare coralline algal crust at the very bottom of the walls, with a band of [P. triqueter] and or [B. crenatus] immediately above. In some caves extreme wave surge at the back of the cave leads to a zone of this biotope which may also be dominated solely by sprorbids or by the barnacle [Verruca stroemia]. Other scour-tolerant species, such as encrusting bryozoans may also be common. Crevices and cracks in the rock provide a refuge for sponge crusts, small [Mytilus edulis] and occasional [Actinia equina], [Urticina felina] and [Sagartia elegans]. More mobile fauna is usually restricted to the echinoderm [Asterias rubens] and the crab [Cancer pagurus]. During periods of relative stability in the summer, small quantities of foliose red seaweeds and opportunistic kelps may occur where sufficient light is available; the seaweeds however do not dominate (compare with A3.711).
Situation: Generally occurs at the base of walls in caves and gullies, but in extreme surge may occur as a zone at the back of caves. Immediately above this zone a variety of biotopes may occur depending on the proximity to the cave/gully entrance. Typically sponge crusts and ascidians with a hydroid-bryozoan turf will occur in the outer to mid section (units A3.712, A3.713); sponge crusts and dense ascidians in the outer to rear section (A3.714); and low-growing sponge crusts at the rear of caves (A3.715). At some sites, A3.7161 can form a zone towards the rear of the cave, beyond the sponge crust zone.


HabitatDescription:
Highly mobile and scoured boulders and cobbles found on cave and gully floors and which often appear bare. Where there is sufficient light and stability, however, the boulders are encrusted by coralline algal crusts. Barnacles [Balanus crenatus] and keelworms [Pomatoceros triqueter] may survive in areas protected from severe abrasion. Crabs such as [Cancer pagurus] and [Carcinus maenas] may occur, often beneath and between the rocks, along with the gastropod [Calliostoma zizyphinum]. The anemone [Actinia equina] may be present in low numbers.

Situation: The slightly less-scoured walls often found above this biotope in caves and gullies are generally characterised by a similar, but richer community of scour-tolerant [Balanus crenatus], [Pomatoceros triqueter], coralline crusts and spirorbid worms (A3.7161). This impoverished biotope may form an intermediate between barren gravel and slightly more stable larger pebbles and cobbles which are covered by algae that are often found in the mouths of caves (unit A3.711).

Temporal variation: Winter storms periodically mobilise the boulders and cobbles, causing abrasion to any seasonal biota that may have developed over the calmer summer months.


HabitatDescription:
Moderately exposed to wave-sheltered artificial substrata (such as steel wrecks/concrete pilings/cable debris etc) subject to moderately strong to weak tidal streams in the infralittoral zone. This habitat type is characterised by a dense covering of filamentous and foliose algae on vertical as well as the upper faces of the substrata. Although there are no biotopes currently defined under this biotope, due to the low number of records, it is suspected that this has been highly 'under-recorded', and that additional records will be added in the near future, leading to the definition of biotopes.


HabitatName:
Caves and overhangs in infralittoral rock


HabitatName:
Pontic [Phyllophora nervosa] under overhangs and in cave entrances


HabitatName:
Pontic caves dominated by sponges [Dysidea] sp. and [Haliclona] sp. with crustose corallines, [Actinia equina], and [Hemimysis] sp.


HabitatName:
Pontic cave entrances with [Palaemon elegans], [Actinia equina], [Pachygrapsus marmoratus] and [Eriphia verrucosa] and little sponges


HabitatName:
Circalittoral rock and other hard substrata

HabitatDescription:
Circalittoral rock is characterised by animal dominated communities (a departure from the algae dominated communities in the infralittoral zone). The circalittoral zone can itself be split into two sub-zones; upper circalittoral (foliose red algae present but not dominant) and lower circalittoral (foliose red algae absent). The depth at which the circalittoral zone begins is directly dependent on the intensity of light reaching the seabed; in highly turbid conditions, the circalittoral zone may begin just below water level at mean low water springs (MLWS). The biotopes identified in the field can be broadly assigned to one of three energy level categories: high, moderate and low energy circalittoral rock (used to define the habitat complex level). The character of the fauna varies enormously and is affected mainly by wave action, tidal stream strength, salinity, turbidity, the degree of scouring and rock topography. It is typical for the community not to be dominated by single species, as is common in shore and infralittoral habitats, but rather comprise a mosaic of species. This, coupled with the range of influencing factors, makes circalittoral rock a difficult area to satisfactorily classify; particular care should therefore be taken in matching species and habitat data to the classification.


HabitatName:
Atlantic and Mediterranean high energy circalittoral rock

HabitatDescription:
Occurs on extremely wave-exposed to exposed circalittoral bedrock and boulders subject to tidal streams ranging from strong to very strong. Typically found in tidal straits and narrows. The high energy levels found within this habitat complex are reflected in the fauna recorded. Sponges such as [Pachymatisma johnstonia], [Halichondria panicea], [Esperiopsis fucorum] and [Myxilla incrustans] may all be recorded. Characteristic of this habitat complex is the dense 'carpet' of the hydroid [Tubularia indivisa]. The barnacle [Balanus crenatus] is recorded in high abundance on the rocky substrata. On rocky outcrops, [Alcyonium digitatum] is often present.


HabitatName:
Very tide-swept faunal communities on circalittoral rock

HabitatDescription:
This habitat type occurs in wave-exposed, tide-swept narrows and straits on circalittoral bedrock and boulders. The biotopes within this complex are characterised by a high abundance of the robust hydroid [Tubularia indivisa]. The barnacle [Balanus crenatus] is characteristic of A4.111, the cushion sponges [Halichondria panicea] and [Myxilla incrustans] are characteristic of A4.1121 and [Alcyonium digitatum] is characteristic of A4.1122. The anemones [Sagartia elegans], [Actinothoe sphyrodeta], [Urticina felina], [Corynactis viridis] and [Metridium senile] are all found within this complex. Other species present in this high-energy complex are the sponges [Esperiopsis fucorum] and [Pachymatisma johnstonia], the bryozoans [Alcyonidium diaphanum] and [Flustra foliacea], [Cancer pagurus], [Sertularia argentea] and [Asterias rubens].


HabitatName:
[Balanus crenatus] and [Tubularia indivisa] on extremely tide-swept circalittoral rock

HabitatDescription:
This biotope typically occurs on upward-facing, extremely tide-swept, circalittoral bedrock, boulders and cobbles found in a broad spectrum of wave-exposures. It is characterised by a few species that are capable of maintaining a foothold in strong tides. These species either form a flat, adherent crust in the case of the barnacle [Balanus crenatus], or have strong attachment points and are flexible, bending with the tide, such as the turf of the hydroid [Tubularia indivisa]. Other species able to tolerate these very strong tides, or just situated slightly out of the main force of the current, include the sponge [Halichondria panicea], the robust hydroid [Sertularia argentea] and current-tolerant anemones such as [Sagartia elegans], [Urticina felina] and [Metridium senile]. Mobile species such as the starfish [Asterias rubens], the crab [Cancer pagurus] and the whelk [Nucella lapillus] may also be present.
Situation: This biotope is typically occurs in deep, very tide-swept straights, sounds and narrows with a bedrock/boulder/cobble slope. Kelp forest (unit A3.212) occurs in shallower water.


HabitatName:
[Tubularia indivisa] on tide-swept circalittoral rock

HabitatDescription:
This biotope is typically found on the vertical and upper faces of strongly tide-swept, wave-exposed circalittoral bedrock and boulders. It is characterised by a dense carpet of the robust hydroid [Tubularia indivisa]. The barnacle [Balanus crenatus], where present, is recorded as common. The accompanying species in the community are determined by tidal stream strength. On the more sheltered sides of headlands, where tidal streams are accelerated, sponges such as [Pachymatisma johnstonia], [Esperiopsis fucorum], [Myxilla incrustans] and [Halichondria panicea] proliferate forming the A4.1121 sub-unit. There may also be a scattered bryozoan turf, formed by criisid bryozoans. However, where tidal streams are slightly reduced, but on more wave-exposed coasts, anthozoans such as [Alcyonium digitatum] become more prominent forming the biotope A4.1122. Other species recorded in this biotope include the anemones [Sagartia elegans], [Actinothoe sphyrodeta], [Corynactis virdis] and [Urticina felina]. There may be scattered clumps of hydroids such as [Sertularia argentea] and [Nemertesia antennina]. Where `relative shelter' is afforded by the topography of the seabed, the bryozoans [Flustra foliacea], [Alcyonidium diaphanum] and the crab [Cancer pagurus] may be found. More ubiqutous species such as [Asterias rubens] and [Calliostoma zizyphinum] may also be present.


HabitatName:
[Tubularia indivisa] and cushion sponges on tide-swept turbid circalittoral bedrock

HabitatDescription:
This variant is typically found on the vertical and upper faces of strongly tide-swept, exposed circalittoral bedrock and boulders. It is commonly associated with areas where turbidity levels are high for much of the year, for example, around Anglesey and the Lleyn Penisula. From afar, this variant appears as a dense carpet of [Tubularia indivisa] covering tide-swept gully walls, floors and boulders. [T. indivisa] is frequently observed growing through sheets of sponges such as [Myxilla incrustans] and [Halichondria panicea] as well as through dense patches of the barnacle [Balanus crenatus] and tubes of the amphipod [Jassa] spp. Several other species of sponge appear to be tolerant of the high turbidity in areas where this variant occurs, many of which are common in other biotopes. These include [Esperiopsis fucorum], [Pachymatisma johnstonia], [Hemimycale columella], [Dysidea fragilis] and [Clathrina coriacea]. Robust hydroids (other than [T. indivisa]) such as [Nemertesia antennina] and [Sertularia argentea] occur in patches. The anemones [Urticina felina], [Actinothoe sphyrodeta] and [Sagartia elegans] are typically common. A short bryozoan turf consisting of crisiid bryozoans, [Alcyonidium diaphanum], [Bicellariella ciliata], [Bugula turbinata] and [Bugula flabellata] may be present. [Alcyonium digitatum] may occasionally be seen although it doesn't tend to be as dominant as in A4.1122. Individual [Corynactis viridis] may be seen scattered across the gully walls and boulders. The starfish [Henricia oculata] may be seen on boulders and gully floors whilst typical under-boulder fauna includes the crab [Cancer pagurus].
Situation: Above this biotope, [Laminaria] forest (unit A3.115) may be found.


HabitatName:
[Alcyonium digitatum] with dense [Tubularia indivisa] and anemones on strongly tide-swept circalittoral rock

HabitatDescription:
This variant is typically found on exposed circalittoral bedrock and boulders in sounds, narrows and around tide-swept promontories in accelerated tidal streams. It is dominated by aggregations of dead man's fingers [Alcyonium digitatum], and dense clumps or continuous cover of the robust hydroid [Tubularia indivisa], particularly on prominent ledges and ridges. Anemones such as [Sagartia elegans], [Urticina felina], [Metridium senile], [Actinothoe sphyrodeta] and [Corynactis virdis] form a prominent component of the community. Occasionally, massive sponges such as [Pachymatisma johnstonia] and [Esperiopsis fucorum] may be present. Encrusting species such as the polychaete [Pomatoceros triqueter] and the barnacle [Balanus crenatus] may be dotted around the rocks, and the top shell [Calliostoma zizyphinum] may also be observed. Clumps of the bryozoan [Flustra foliacea] are occasionally seen. The starfish [Asterias rubens] may be seen amongst a patchy turf of [Crisia denticulata] and the bryozoan [Alcyonidium diaphanum]. This variant may also be found on tideswept wrecks and other artificial sustratum.
Situation: Above this biotope, it is usual to find well-developed kelp forest in the upper infralittoral, dominated by [Laminaria hyperborea] (unit A3.115). In the lower infralittoral, it is usual to find a tide-swept turf of hydroids and red algae.


HabitatName:
Sponge communities on deep circalittoral rock

HabitatDescription:
This habitat type typically occurs on deep (commonly below 30m depth), wave-exposed circalittoral rock subject to negligible tidal streams. The sponge component of this biotope is the most striking feature, with similar species to the bryozoan and erect sponge habitat type (A4.131) although in this case, the sponges [Phakellia ventilabrum], [Axinella infundibuliformis], [Axinella dissimilis] and [Stelligera stuposa] dominate. Other sponge species frequently found on exposed rocky coasts are also present in low to moderate abundance. These include [Cliona celata], [Polymastia boletiformis], [Haliclona viscosa], [Pachymatisma johnstonia], [Dysidea fragilis], [Suberites carnosus], [Stelligera rigida], [Hemimycale columella] and [Tethya aurantium]. The cup coral [Caryophyllia smithii] and the anemone [Corynactis virdis] may be locally abundant in some areas, along with the holothurian [Holothuria forskali]. The soft corals [Alcyonium digitatum] and [Alcyonium glomeratum] are frequently observed. The bryozoans [Pentapora foliacea] and [Porella compressa] are also more frequently found in this deep-water habitat type. Bryozoan crusts such as [Parasmittina trispinosa] are also occasionally recorded. Isolated clumps of large hydroids such as [Nemertesia antennina], [Nemertesia ramosa] and [Sertularella gayi] may be seen on the tops of boulders and rocky outcrops. Large echinoderms such as [Echinus esculentus], [Luidia ciliaris], [Marthasterias glacialis], [Strichastrella rosea], [Henricia oculata] and [Aslia lefevrei] may also be present. The sea fan [Eunicella verucosa] may be locally common but to a lesser extent than in A4.1311. The top shell [Calliostoma zizyphinum] is often recorded as present.


HabitatName:
[Phakellia ventilabrum] and axinellid sponges on deep, wave-exposed circalittoral rock

HabitatDescription:
This biotope typically occurs on the upper faces of deep (commonly below 30m depth), wave-exposed circalittoral rock subject to negligible tidal streams. Although it occurs in exposed and very exposed conditions, at such depth, the turbulent wave action appears to have a much-attenuated effect on the fauna compared with shallower depths. As the majority of records are from depths between 30-50+ m, slightly deeper than the depths of most surveys, it is possible that this biotope is more widespread than the available dataset indicates. The sponge component of this biotope is the most striking feature, with similar species to the bryozoan and erect sponge biotope complex (unit A4.131) although in this case, the sponges [Phakellia ventilabrum], [Axinella infundibuliformis], [Axinella dissimilis] and [Stelligera stuposa] dominate. Other sponge species frequently found on exposed rocky coasts are also present in low to moderate abundance. These include [Cliona celata], [Polymastia boletiformis], [Haliclona viscosa], [Pachymatisma johnstonia], [Dysidea fragilis], [Suberites carnosus], [Stelligera rigida], [Hemimycale columella] and [Tethya aurantium]. The cup coral [Caryophyllia smithii] and the anemone [Corynactis virdis] may be locally abundant in some areas, along with the holothurian [Holothuria forskali]. The soft corals [Alcyonium digitatum] and [Alcyonium glomeratum] are frequently observed. The bryozoans [Pentapora foliacea] and [Porella compressa] are also more frequently found in this deep-water biotope. Bryozoan crusts such as [Parasmittina trispinosa] are also occasionally recorded. Isolated clumps of large hydroids such as [Nemertesia antennina], [Nemertesia ramosa] and [Sertularella gayi] may be seen on the tops of boulders and rocky outcrops. Large echinoderms such as [Echinus esculentus], [Luidia ciliaris], [Marthasterias glacialis], [Strichastrella rosea], [Henricia oculata] and [Aslia lefevrei] may also be present. The seafan [Eunicella verucosa] may be locally common but to a lesser extent than in unit A4.1311. The top shell [Calliostoma zizyphinum] is often recorded as present.

Situation: Unit A4.2122  probably occurs above unit A4.121 in shallower water where the exposure of the coast ensures that there is more water mixing due to wave action. Deeper down, this effect is attenuated, allowing A4.121 biotope to develop.

Temporal variation: [Axinella dissimilis] tends to grow extremely slowly.


HabitatName:
Mixed faunal turf communities on circalittoral rock

HabitatDescription:
This habitat type occurs on wave-exposed circalittoral bedrock and boulders, subject to tidal streams ranging from strong to moderately strong. This complex is characterised by its diverse range of hydroids ([Halecium halecinum], [Nemertesia antennina] and [Nemertesia ramosa]), bryozoans ([Alcyonidium diaphanum], [Flustra foliacea], [Bugula flabellata] and [Bugula plumosa]) and sponges ([Scypha ciliata], [Pachymatisma johnstonia], [Cliona celeta], [Raspailia ramosa], [Esperiopsis fucorum], [Hemimycale columella] and [Dysidea fragilis]) forming an often dense, mixed faunal turf. Other species found within this complex are [Alcyonium digitatum], [Urticina felina], [Sagartia elegans], [Actinothoe sphyrodeta], [Caryophyllia smithii], [Pomatoceros triqueter], [Balanus crenatus], [Cancer pagurus], [Necora puber], [Asterias rubens], [Echinus esculentus] and [Clavelina lepadiformis].


HabitatDescription:
This biotope is typically found on wave-exposed circalittoral bedrock or boulders subject to tidal streams ranging from moderately strong to strong. It often has a thin layer of silt covering the seabed, and is characterised by a bryozoan/hydroid turf with erect sponges. Typical bryozoans to be found include crisiids, [Alcyonidium diaphanum], [Flustra foliacea], [Pentapora foliacea], [Bugula plumosa] and [Bugula flabellata], while typical hydroids include [Nemertesia antennina], [Nemertesia ramosa] and [Halecium halecinum]. The soft coral [Alcyonium digitatum] is frequently recorded on the tops of boulders and rocky outcrops. Characteristic erect sponges include [Raspailia ramosa], [Stelligera stuposa] and [Stelligera rigida]; other sponges present include [Cliona celata], [Dysidea fragilis], [Pachymatisma johnstonia], [Polymastia boletiformis], [Hemimycale columella], [Esperiopsis fucorum], [Polymastia mamillaris] and [Tethya aurantium]. Other species present include [Caryophylia smithii], [Actinothoe sphyrodeta], [Corynactis viridis], [Urticina felina], [Balanus crenatus], [Asterias rubens], [Marthasterias glacialis], [Henricia oculata], [Echinus esculentus], [Clavelina lepadiformis], [Calliostoma zizyphinum] and [Necora puber]. Three variants of this biotope have been described, but all are characterised by a bryozoan turf with erect sponges. A4.1311 is found primarily on circalittoral bedrock and is dominated by the seafan [Eunicella verrucosa]. Unit A4.1312 is found under slightly stronger tide-swept conditions, and is characterised particularly by the sponge [D. fragilis] and the anemone [A. sphyrodeta]. Finally unit A4.1313 is characterised by the anemone [Sagartia elegans].


HabitatName:
[Eunicella verrucosa] and [Pentapora foliacea] on wave-exposed circalittoral rock

HabitatDescription:
This variant typically occurs on wave-exposed, steep, circalittoral bedrock, boulder slopes and outcrops, subject to varying tidal streams. This silty variant contains a diverse faunal community, dominated by the seafan [Eunicella verrucosa], the bryozoan [Pentapora foliacea] and the cup coral [Caryophyllia smithii]. There are frequently numerous [Alcyonium digitatum], and these may become locally abundant under more tide-swept conditions. [Alcyonium glomeratum] may also be present. A diverse sponge community is usually present, including numerous erect sponges; species present include [Cliona celata], [Raspailia ramosa], [Raspailia hispida], [Axinella dissimilis], [Stelligera stuposa], [Dysidea fragilis] and [Polymastia boletiformis]. [Homaxinella subdola] may be present in the south west. A hydroid/bryozoan turf may develop in the understorey of this rich sponge assemblage, with species such as [Nemertesia antennina], [Nemertesia ramosa], crisiids, [Alcyonidium diaphanum] and [Bugula plumosa]. The sea cucumber [Holothuria forskali] may be locally abundant, feeding on the silty deposits on the rock surface. Other echinoderms encountered include the starfish [Marthasterias glacialis] and the urchin [Echinus esculentus]. Other fauna includes aggregations of colonial ascidians [Clavelina lepadiformis] and [Stolonica socialis]. Anemones such as [Actinothoe sphyrodeta] and [Parazoanthus axinellae] may be seen dotted across the rock surface. This biotope is present in south west England and Wales.
Situation: This biotope is commonly found on rocky outcrops, surrounded by coarse sediment. This may be in the form of shelly gravel or muddy gravel, supporting [Urticina felina], [Cerianthus lloydi] and [Neopentadactyla mixta]. Above A4.1311, dense kelp forest containing [Saccorhiza polyschides] is usually found.


HabitatName:
Mixed turf of bryozoans and erect sponges with [Dysidia fragilis] and [Actinothoe sphyrodeta] on tide-swept wave-exposed circalittoral rock

HabitatDescription:
This variant typically occurs on exposed and moderately wave-exposed bedrock and boulders subject to a variety of tidal regimes (from strong through to weak). It is found mainly in the 10-20m depth range and does not usually occur deeper than 30 m. It therefore often straddles the upper circalittoral and lower infralittoral. It often has a light covering of silt and sand may be in the vicinity. Sponges form a dominant part of this variant, although cover usually appears patchy, with no single species dominating. Species present include [Dysidea fragilis], [Pachymatisma johnstonia], [Esperiopsis fucorum], [Hemimycale columella], [Cliona celata], [Stelligera rigida], [Polymastia boletiformis], [Stelligera stuposa], [Raspailia ramosa], [Tethya aurantium], [Polymastia mamillaris] and [Axinella dissimilis]. Tufts of large hydroids such as [Nemertesia antennina], frequently recorded on the tops of outcrops and boulders, stand out more clearly than the understorey of finer hydroid and bryozoan turf such as [Aglaophenia pluma], [Bugula flabellata], [Bugula plumosa], crisiids, [Cellaria sinuosa] and [Bugula turbinata]. Other bryozoans such as [Alcyonidium diaphanum] and [Flustra foliacea] are also frequently recorded. Other more widespread species present include [Asterias rubens], [Actinothoe sphyrodeta], [Balanus crenatus], [Caryophyllia smithii], [Corynactis viridis], [Necora puber] and [Clavelina lepadiformis]. This variant has been recorded off the south east coast of Ireland, the welsh coast and Lundy Island.
Situation: This biotope is typically found on exposed coasts, with exposed kelp forest in the infralittoral zone, characterised by species such as [Laminaria hyperborea] and [Saccorhiza polyschides]. The A4.1312 variant is usually found below A4.1311, with similar geographic range.


HabitatName:
Mixed turf of bryozoans and erect sponges with [Sagartia elegans] on tide-swept ciraclittoral rock

HabitatDescription:
This variant is typically found on wave-exposed circalittoral bedrock and boulders, on steep slopes and upper faces in moderate tidal streams. This species-rich biotope is characterised by a dense sponge, hydroid and bryozoan turf and frequent [Alcyonium digitatum]. There are frequently large growths of [Cliona celata] and [Pachymatisma johnstonia]. Other species present in this diverse sponge community include [Polymastia boletiformis], [Haliclona viscosa], [Polymastia mamilliaris], [Scypha ciliata], [Hemimycale columella] and [Dysidea fragilis]. Axinellid sponges such as [Stelligera stuposa] and [Raspailia ramosa] may be present in low abundance, and are usually more abundant in deeper water. A dense hydroid turf forms a significant part of this biotope, with tufts of large hydroids such as [Nemertesia antennina] and [Nemertesia ramosa] frequently recorded. Other hydroid turf component species include [Halecium halecinum], [Aglaophenia tubulifera] and [Abietinaria abietina]. Anemones are also well represented, with species such as [Urticina felina], [Sagartia elegans] and [Metridium senile] recorded. The cup coral [Caryophyllia smithii] and the anemone [Corynactis viridis] are also frequently seen. The bryozoan turf is composed predominantly of [Alcyonidium diaphanum] and [Flustra foliacea], whilst crustose species such as [Parasmittina trispinosa] contribute to a lesser extent. The delicate [Bugula plumosa] may also be present. There is a significant echinoderm component in this biotope. Species such as the starfish [Asterias rubens], [Henricia oculata], [Marthasterias glacialis] and [Luidia ciliaris], the sea urchin [Echinus esculentus] and the crinoid [Antedon bifida] are all regularly recorded. Other species which may be observed include the top shell [Calliostoma zizyphinium], the colonial ascidian [Clavelina lepadiformis] and the barnacle [Balanus crenatus]. The crab [Cancer pagurus] is typically found under boulders. This variant has been recorded from from various sites including Pembrokeshire, the Calf of Man and the west coast of Ireland.
Situation: Dense kelp forests containing [L. hyperborea] and [S. polyschides] are typically found above A4.1313.


HabitatName:
[Corynactis viridis] and a mixed turf of crisiids, [Bugula], [Scrupocellaria], and [Cellaria] on moderately tide-swept exposed circalittoral rock

HabitatDescription:
This biotope typically occurs on wave-exposed, vertical or steep, circalittoral bedrock or large boulders, usually subject to moderate or strong tidal streams. It is characterised by dense aggregations of the anemone [Corynactis viridis] and the cup coral [Caryophyllia smithii] intermixed with a short bryozoan turf of one or more [Crisia] spp., [Scrupocellaria] spp., [Bugula] spp. and [Cellaria] spp. Occasionally, this turf obscures the underlying [C. virdis] and [C. smithii]. Cushion and encrusting sponges, particularly [Pachymatisma johnstonia], [Cliona celata], [Esperiopsis fucorum] and [Dysidea fragilis], are present in moderate amounts at many sites. The axinellid sponges [Stelligera] spp. and [Raspailia] spp. are less frequently recorded. Clumps of large hydroids such as [Nemertesia antennina] and [Nemertesia ramosa] as well as the soft coral [Alcyonium digitatum] and the bryozoan [Alcyonidium diaphanum] may be found covering the hard substratum. The anemones [Actinothoe sphyrodeta] and [Sagartia elegans] are typically present in low numbers, while the hard `coral' [Pentapora foliacea] is also occasionally observed. The most frequently recorded echinoderms are [Marthasterias glacialis] and [Asterias rubens], although other species such as [Echinus esculentus] may also be seen. The rocky substratum may have a patchy covering of encrusting red seaweeds/algae. The crabs [Necora puber] and [Cancer pagurus] may be seen in crevices or under overhangs. This biotope is regularly recorded around south west England and Wales, often on vertical rock faces.
Situation: Due to its wave-exposed nature, kelp park and forest biotopes (units A3.115 and A3.111) are commonly found in the infralittoral zone shallower than this biotope, and feature species such as [Laminaria hyperborea], [Sacchoriza polyschides] and [Alaria esculenta].


HabitatName:
Mixed turf of hydroids and large ascidians with [Swiftia pallida] and [Caryophyllia smithii] on weakly tide-swept circalittoral rock

HabitatDescription:
This biotope typically occurs from exposed through to sheltered circalittoral bedrock or boulders subject to moderately strong to weak tidal streams. It is found in water depths ranging from 4m to 37m. This biotope is distinguished by frequently occurring [Swiftia pallida], abundant [Caryophilia smithii] and a diverse range of ascidians including [Clavelina lepadiformis], [Ascidia mentula], [Polycarpa pomaria], [Diazona violacea] and [Corella parallelogramma]. A sparse, yet diverse hydroid turf is often apparent, with species such as [Aglaophenia tubulifera], [Nemertesia antennina], [Polyplumaria frutescens], [Halecium halecinum], [Abietinaria abietina], [Nemertesia ramosa] and [Halopteris catharina] often recorded. Spaces amongst the turf are usually colonised by the polychaete [Pomatoceros triqueter] and encrusting red algae. Crinoids such as [Antedon petasus], [Antedon bifida] and [Leptometra celtica] may be seen filter feeding on the tops of outcrops and boulders, along with the soft coral [Alcyonium digitatum]. Other echinoderms such as [Echinus esculentus], [Crossaster papposus] and [Asterias rubens] may also be recorded. There may also be a bryozoan component to the sparse faunal turf. Species such as [Securiflustra securifrons] and [Eucratea loricata] as well as the crustose [Parasmittina trispinosa] are all usually present. There may be a few isolated growths of sponge, such as [Iophonopsis nigricans], [Axinella infundibuliformis] and [Haliclona urceolus]. Other species that may be present include the brachiopod [Terebratulina retusa] and the top shell [Calliostoma zizyphinum]. The crustacean [Munida rugosa] may be visible in crevices. All records are from the west coast of Scotland (east coast of Lewis /Outer Hebrides).
Situation: Above this biotope, kelp forests and parks are typically found in the infralittoral, with [Laminaria saccharina] and [Laminaria hyperborea]. This biotope is found in Scottish Sealochs and, in the most sheltered situations, may graduate into unit A4.314 at greater depths.


HabitatName:
[Flustra foliacea] and colonial ascidians on tide-swept moderately wave-exposed circalittoral rock

HabitatDescription:
This biotope typically occurs on the upper faces of moderately tide-swept, moderately wave-exposed circalittoral bedrock or boulders (although a variant is found on mixed substrata). It most frequently occurs between 10-20m water depth. The biotope is exposed to varying amounts of scour (due to nearby patches of sediment) and, as a consequence, is characteristically dominated by dense [Flustra folicaea], a range of colonial ascidians and a variety of other scour/silt-tolerant species. In addition to [F. foliacea], other bryozoans present in this biotope include [Alcyonidium diaphanum], [Bugula flabellata] and [Bugula plumosa]. Varying amounts of the soft coral [Alcyonium digitatum] may be recorded, depending on the amount of scouring which may vary locally. Where scour is a major factor, species such as the scour-tolerant [Urticina felina] are frequently observed. Hydroids present in this biotope include [Nemertesia antennina], [Halecium halecium], [Tubularia indivisa] and [Hydrallmania falcata]. Other species present include silt-tolerant sponges such as [Scypha ciliata], [Cliona celata], [Leucosolenia botryoides], and the ascidians [Clavelina lepadiformis] and [Botryllus schlosseri]. [Balanus crenatus] may be recorded occasionally on the boulder/rock surface, and the crab [Cancer pagurus] may be observed finding refuge in crevices and under boulders. More ubiquitous species present include [Asterias rubens], [Crossaster papposus], [Ophiothrix fragilis] and [Pagurus bernhardus]. Three variants of this biotope have been defined. Unit A4.1342 tends to have a high abundance of barnacles, which populate the rocky seabed. The second variant (A4.1341) is characterised by abundant [Polyclinum aurantium] in addition to [F. foliacea], which often incorporates sand grains into itself, giving the crustose appearance of sandy rock nodules. Finally, A4.1343 is found on mixed substrata and is characterised by a dense hydroid turf growing alongside [F. foliacea] and other scour-tolerant species.


HabitatName:
[Polyclinum aurantium] and [Flustra foliacea] on sand-scoured tide-swept moderately wave-exposed circalittoral rock

HabitatDescription:
This variant is typically found on the upper face of moderately exposed, moderately tide-swept, circalittoral bedrock or boulders. Sand and silt are periodically re-suspended in the water column, resulting in scour-tolerant species being characteristic of these areas. There is a dense covering of the scour-resistant bryozoan [Flustra foliacea] attached to the bedrock plains and boulders. The colonial ascidian [Polyclinum aurantium] commonly covers the rock surface at most locations within this biotope - itself incorporating sand grains into its surface to give it the appearance of sandy rock nodules. Other ascidians that may occur in this crust are the flat, encrusting colonial [Botrylloides leachi], [Botryllus schlosseri] and the colonial ascidian [Clavelina lepadiformis], although in varying quantities at each location. A short turf of other bryozoans such as [Alcyonidium diaphanum], [Bugula plumosa] and [Bugula flabellata] occur amongst the ascidians. Other species found in this biotope are the sponges [Cliona celata], [Leucosolenia botryoides] and [Scypha ciliata], the hydroids [Tubularia indivisa], [Nemertesia antennina], [Halecium halecinum] and the anthozoans [Alcyonium digitatum] and [Urticina felina]. Echinoderms which may be present include the starfish [Asterias rubens], [Crossaster papposus] and the brittlestar [Ophiothrix fragilis]. Crustaceans such as the crab [Cancer pagurus], the hermit crab [Pagurus bernhardus] and the lobster [Homarus gammarus] may be observed in crevices and under boulders. The palps of the polychaete [Polydora] spp. may be observed whilst the nudibranch [Janolus cristatus] may be seen preying on the hydroid/bryozoan turf. This variant is commonly found on the Northumberland coast, Flamborough Head and the Lleyn Peninsula.
Situation: As A4.1341 tends to occur in waters with a sediment load, the resulting light penetration is reduced, meaning that kelp forests such as unit A3.214, normally found shallower than A4.1341 in the infralittoral zone, are present over a narrower depth range.


HabitatName:
[Flustra foliacea], small solitary and colonial ascidians on tide-swept circalittoral bedrock or boulders

HabitatDescription:
This sub-biotope is typically found on the upper faces of exposed to moderately exposed, tide-swept, scoured, circalittoral bedrock or boulders. It most frequently occurs between 10-20m water depth. The biotope is characteristically dominated by dense [Flustra foliacea] with a variety of slightly scour/silt-tolerant species forming a dense turf. This turf is primarily composed of bryozoans ([Alcyonidium diaphanum], [Bugula flabellata], [Bugula plumosa], [Bicellariella ciliata]) and hydroids ([Tubularia indivisa], [Nemertesia antennina], [Sertularia argentea], [Hydrallmania falcata], [Abietinaria abietina]). Where space permits, barnacles such as [Balanus crenatus] may be found encrusting on the rock surface. There may also be occasional crusts formed by the polychaete [Sabellaria spinulosa], especially where the rock is most influenced by sand. Anthozoans which may be observed include [Urticina felina], [Sagartia elegans], whilst the soft coral [Alcyonium digitatum] may be recorded on the tops of boulders and bedrock ridges. A range of small solitary and colonial ascidians may be seen, including [Polycarpa scuba], [Dendrodoa grossularia], [Molgula manhattensis], [Botryllus schlosseri], [Clavelina lepadiformis] and polyclinids. Sponges found include [Scypha ciliata], [Cliona celata], [Esperiopsis fucorum] and [Dysidea fragilis]. Echinoderms such as [Asterias rubens], [Henricia oculata] and [Crossaster papposus] may be seen on the rock surface. Other species found include the top shell [Calliostoma zizyphinum], the crabs [Cancer pagurus] and [Necora puber].
Situation: Above this variant, exposed kelp forest supporting [Laminaria hyperborea] is commonly found (unit A3.115). At locations where wave-exposure and/or tidal streams are less, this biotope may be replaced by [Alcyonium digitatum] and [Securiflustra securifrons] (unit A4.2143). Where the substrata changes to a less stable mixed substrata, then this biotope will be replaced by the sub-biotope A4.1343, with more `sediment' species such as [Cerianthus lloydii] and [Chaetopterus variopedatus].


HabitatName:
[Flustra foliacea] and colonial ascidians on tide-swept exposed circalittoral mixed substrata

HabitatDescription:
This variant is typically found on very exposed to moderately exposed, circalittoral mixed substrata subject to moderately strong tidal streams. It most frequently occurs between 10m and 20m water depth. This variant is characterised by a dense hydroid and [Flustra foliacea] turf, along with other scour-tolerant species, growing on the more stable boulders and cobbles which overlie coarse muddy sand and gravel. Although [Nemertesia antennina] is the dominant species within the hydroid turf, other species such as [Halecium halecinum], [Nemertesia ramosa] and [Hydrallmania falcata] may also be present. Other bryozoans found amongst the hydroid and [Flustra] turf include [Cellepora pumicosa], [Bugula flabellata], [Bugula turbinata], and a crisiid turf. Encrusting red algae, the polychaete [Pomatoceros triqueter] and barnacles such as [Balanus crenatus] may be found on the smaller cobbles and pebbles, which may become mobile during extreme storms. Echinoderms such as [Asterias rubens] and [Ophiothrix fragilis] may be present on the boulders, or the coarse sediment in between. On the larger, more stable boulders, isolated sponge communities may develop, with species such as [Scypha ciliata], [Dysidea fragilis], [Hemimycale columella], [Esperiopsis fucorum] and [Stelligera rigida]. In addition, small [Alcyonium digitatum], various ascidians ([Clavelina lepadiformis], [Botryllus schlosseri]), [Pododesmus patelliformis] and top shells ([Calliostoma zizyphinum], [Gibbula cineraria]) may colonise the upper faces and vertical sides of larger boulders. At some shallower sites, the foliose red algae [Hypoglossum hypoglossoides] may be found on the tops of larger boulders. Within the coarse sediment underlying these boulders and cobbles, anemones such as [Cerianthus lloydii] and [Urticina felina] may be recorded. Under-boulder fauna typically consists of terebellid worms, and crabs such as [Pisidia longicornis] and [Cancer pagurus].
Situation: This variant is found in wave-exposed locations, resulting in kelp forest in the infralittoral zone being dominated by [Alaria esculentus] and [Laminaria hyperborea]. When the substratum becomes rockier, this biotope will graduate into the variant A4.1342.


HabitatName:
Sparse sponges, [Nemertesia] spp., and [Alcyonidium diaphanum] on circalittoral mixed substrata

HabitatDescription:
This biotope is found on moderately wave-exposed sand-scoured, circalittoral boulders, cobbles and pebbles that are subject to moderately strong tidal streams (referred to as lag-cobbles locally). It is characterised by sparse sponges and a diverse bryozoan and hydroid turf. The sparse sponge community is primarily composed of [Dysidea fragilis] and [Scypha ciliata]. The mixed faunal turf is composed of [Nemertesia antennina], [Nemertesia ramosa], [Halecium halecinum], [Sertularia argentea], [Alcyonium digitatum], [Bugula flabellata], [Bugula turbinata], [Bugula plumosa], [Flustra foliacea], [Cellepora pumicosa], [Alcyonidium diaphanum], [Cellaria fistulosa] and crisiid bryozoans. The anemones [Epizoanthus couchii], [Sagartia elegans] and [Cerianthus lloydii] may also be recorded. Echinoderms such as the starfish [Asterias rubens], [Crossaster papposus], [Henricia oculata] and the crinoid [Antedon bifida]. Other species present include the colonial ascidian [Clavelina lepadiformis], the barnacle [Balanus crenatus], the top shell [Gibbula cineraria], the polychaete [Pomatoceros triqueter], the ascidian [Morchellium argus], [Prosthecareus vittatus] and the crab [Cancer pagurus]. It is distributed off Pen Llyn and over considerable areas of the Irish Sea.


HabitatName:
[Suberites] spp. with a mixed turf of crisiids and [Bugula] spp. on heavily silted moderately wave-exposed shallow circalittoral rock

HabitatDescription:
This biotope is found on heavily silted, moderately wave-exposed circalittoral bedrock and boulders (often limestone) that are subject to moderately strong tidal streams. A very high silt loading in the water column means that this 'circalittoral' biotope occurs at unusually shallow depths (1 - 10 m BCD). It is characterised by a mixed faunal turf and `massive' examples of the sponges [Suberites ficus], [Suberites carnosus] and [Hymeniacidon perleve]. Other sponges recorded in this biotope are [Cliona celata], [Halichondria panicea], [Esperiopsis fucorum], [Raspailia ramosa], [Polymastia mamillaris], [Dysidea fragilis], [Scypha ciliata], [Stelligera rigida] and [Haliclona oculata]. Also characteristic of this biotope is a dense bryozoan turf with one or more crisiid species, [Flustra foliacea] and [Bugula plumosa]. The polychaete [Polydora] spp. and the rock-boring bivalve [Hiatella arctica] are able to bore into the relatively soft limestone. There is an ascidian component to the biotope, with [Morchellium argus] and [Clavelina lepadiformis] among the most abundant. There may be scattered clumps of the hydroids [Abietinaria abietina] and [Hydrallmania falcata]. Other species present include the anemones [Metridium senile], [Sagartia elegans] and [Urticina felina], the starfish [Asterias rubens], the crab [Necora puber], the nudibranch [Janolus cristatus] and the soft coral [Alcyonium digitatum]. This biotope has currently only been recorded off the east coast of Anglesey, Wales.


HabitatName:
[Flustra foliacea] and [Haliclona oculata] with a rich faunal turf on tide-swept circalittoral mixed substrata

HabitatDescription:
This biotope is typically found on exposed slopes of silty cobble and pebble subject to strong to moderate tidal streams. From afar, large 'finger' growths of the sponge [Haliclona oculata] occur amongst a rich faunal turf of hydroids and bryozoans with [Flustra foliacea] prominent. The dense faunal turf growing on the cobbles is composed of the bryozoans [F. foliacea], [Alcyonidium diaphanum] and [Crisia eburnea] and sporadic occurrences of the hydroids [Nemertesia antennina], [Hydrallmania falcata], [Tubularia larynx], [Rhizocaulus verticillatus] and [Halecium halecinum]. Caprellid shrimps may be observed within this faunal turf. The hard substratum frequently has a dense covering of the sponge [H. oculata] and occasionally [Esperiopsis fucorum], while the softer gravely/sand between the cobbles provides a habitat for anemones such as [Urticina felina] and [Cerianthus lloydii]. The nudibranch [Janolus cristatus] may be seen preying on the faunal turf and the fan worm [Sabella pavonia] is occasionally seen amongst the cobbles. The soft coral [Alcyonium digitatum] is often attached to the upper faces of more stable cobbles and rocks, while in the crevices between cobbles, the anemone [Sagartia elegans], the crab [Cancer pagurus], the prawn [Pandalus montagui] and the amphipod [Dyopedos porrectus] may be observed. Under-cobble fauna includes terebellid worms and [Harmothoe] spp. This biotope has been recorded from the Menai Strait, Milford Haven and Morecambe Bay.


HabitatName:
[Molgula manhattensis] with a hydroid and bryozoan turf on tide-swept moderately wave-exposed circalittoral rock

HabitatDescription:
This biotope is typically found on slightly sand-scoured, tide-swept, moderately exposed circalittoral bedrock and cobbles. It is commonly recorded from the shallower reaches of the circalittoral around depths from 5m to 15m BCD, as it occurs mostly in very turbid waters. From afar, the physical characteristics are usually silted bedrock reefs and cobble, interspersed with patches of clean sand, causing a scour effect on the rock. Dense aggregations of the ascidian [Molgula manhattensis] form a silty mat on the rock and there is a sparse hydroid and bryozoan turf. A hydroid turf, composed of [Nemertesia antennina], [Halecium beanii], [Hydrallmania falcata], [Sertularella gaudichaudi], [Tubularia indivisa] and [Alcyonium digitatum], in varying amounts, occurs at most sites on the tops of boulders and ridges. A bryozoan turf is also present, but not usually dense and includes [Flustra foliacea], [Alcyonidium diaphanum], [Electra pilosa] and the crust-forming bryozoan [Conopeum reticulum]. The polychaete [Lanice conchilega] thrives in the sandy patches which often occur between the rock ridges. The scour effect tends to reduce the diversity of sponges present with only [Halichondria panicea] occasionally present. Isolated clumps of the polychaete [Sabellaria spinulosa] may be present but they do not occur in dense aggregations as in the A4.2211 biotope. The anemones [Urticina felina] and [Sagartia troglodytes] may occur in cracks between cobbles or on stones buried in the sandy substratum. The anemone [Sagartia elegans] is more commonly found attached to crevices in the bedrock. Other species such as the hermit crab [Pagurus bernhardus], the barnacle [Balanus crenatus], the polychaete [Sabella pavonia] and [Pomatoceros triqueter] may all be present whilst the crab [Pisidia longicornis] may be found under cobbles and stones. Records of this biotope are distributed along the south coast of England and the north Wales coast as well as Pembrokeshire near the entrance to Milford Haven.
Situation: As this biotope is often recorded on soft rock (chalk), soft rock communities (A4.23 biotope complex) would be observed in close proximity with species of the genus [Polydora] and piddocks ([Pholas] spp. and [Barnea] spp). Moderately exposed kelp forests may be found within the shallow infralittoral zone.


HabitatDescription:
This biotope is found on exposed to moderately wave exposed , vertical and overhanging, circalittoral bedrock, subject to strong through to weak tidal streams. This biotope is characterised by a mixed faunal turf of hydroids ([Nemertesis antennina], [Tubularia indivisa] and [Halecium halecium]) and bryozoans ([Alcyonidium diaphanum] and crisiid turf). There is frequently a diverse range of sponges recorded, including [Cliona celata], [Pachymatisma johnstonia], [Dysidea fragilis] and [Hemimycale columella]. There may be dense aggregation of dead mans fingers [Alcyonium digitatum] along with clumps of the cup coral [Caryophyllia smithii], and the anthozoans [Corynactis viridis], [Actinothoe sphyrodeta], [Sagartia elegans] and [Metridium senile]. Other species present include the echinoderms [Echinus esculentus], [Asterias rubens], [Marthasterias glacialis], [Henricia oculata], [Holothuria forskali] and [Antedon bifida], clumps of the lightbulb tunicate [Clavelina lepadiformis] and the top shell [Calliostoma zizyphinum]. Three regional variations of this biotope have been recorded. The first variant is characterised by a [Bugula] turf along with the pink sea fan [Eunicella verrucosa], and has been recorded from around southwest England and Wales. The second variant, characterised by a dense 'carpet' of [Corynactis viridis] and [Metridium senile] has been recorded predominantly from the west coast of Ireland. The final variant is characterised by a very diverse, dense faunal turf of hydroids, bryozoans and ascidians and has been recorded from the coasts around Northern Ireland.


HabitatName:
Atlantic and Mediterranean moderate energy circalittoral rock

HabitatDescription:
Mainly occurs on exposed to moderately wave-exposed circalittoral bedrock and boulders, subject to moderately strong and weak tidal streams. This habitat type contains a broad range of biological subtypes, from echinoderms and crustose communties (A4.21) to Sabellaria reefs (A4.22) and circalittoral mussel beds (A4.24).


HabitatName:
Echinoderms and crustose communities on circalittoral rock

HabitatDescription:
This habitat type occurs on wave-exposed, moderately strong to weakly tide-swept, circalittoral bedrock and boulders. Echinoderms, faunal ([Parasmittina trispinosa]) and algal crusts (red encrusting algae) dominate this biotope, giving a sparse appearance. Typical echinoderms present are the starfish [Asterias rubens], the brittlestar [Ophiothrix fragilis] and the sea urchin [Echinus esculentus]. There may be isolated clumps of the hydroids [Nemertesia antennina] and [Abietinaria abietina], [Alcyonium digitatum], the anemone [Urticina felina] and the cup coral [Caryophyllia smithii]. Other species present may include the polychaete [Pomatoceros triqueter] and the top shell [Calliostoma zizphinum].


HabitatName:
[Caryophyllia smithii] and [Swiftia pallida] on circalittoral rock

HabitatDescription:
This biotope is typically found on the upper and vertical faces of very exposed through to wave-sheltered circalittoral bedrock and boulders, which are typically subject to weak tidal streams. It is characterised by dense aggregations of the cup coral [Caryophyllia smithii] and the sea fan [Swiftia pallida] on the silty substratum. Under the silt, bryozoan crusts such as [Parasmittina trispinosa] and encrusting red algae may be seen. This biotope may have a grazed appearance, perhaps attributable to the frequently occurring [Echinus esculentus]. There may be a sparse hydroid turf present, with species such as [Nemertesia antennina], [Nemertesia ramosa] and [Halecium halecinum] present. The soft corals [Alcyonium glomeratum] and [Alcyonium digitatum] may be present on the tops of boulders along with the crinoids [Antedon petasus] and [Antedon bifida]. Other echinoderms occasionally observed include the starfish [Marthasterias glacialis], [Asterias rubens] and [Luidia ciliaris]. Sponges feature only occasionally in this biotope, including species such as [Cliona celata]. The bryozoan [Porella compressa] may also be recorded. Ascidians occasionally present include [Ascidia mentula], [Clavelina lepadiformis] and [Ciona intestinalis]. Under-boulder fauna typically consists of the crustacean [Munida rugosa]. The polychaete [Pomatoceros triqueter] may be seen encrusting the rocky surface. Two variants of this biotope have been identified; Units A4.2111 and A4.2112. A4.2111 is a heavily silted biotope characterised by the sea fan [S. pallida], the cup coral [C. smithii] and the soft coral [A. glomeratum] and is only present in Irish waters. A4.2112 has been recorded off the west coast of Scotland, and is characterised by large solitary ascidians and the cup coral [C. smithii].


HabitatName:
[Caryophyllia smithii], [Swiftia pallida] and [Alcyonium glomeratum] on wave-sheltered circalittoral rock

HabitatDescription:
This variant typically occurs on sheltered, ridged, circalittoral bedrock or boulders subject to only weak tidal streams, but may be found in somewhat more exposed conditions. It is found in water depths ranging from 15m to 32m. Commonly occurring [Swiftia pallida] characterises this heavily silted biotope along with [Caryophyllia smithii] and frequent [Alcyonium glomeratum]. Under the silt, bryozoan crusts such as [Parasmittina trispinosa] may be found. There is a strong echinoderm component to the community, with the tentacles of [Aslia lefevrei] frequently seen protruding from crevices in the ridged bedrock. [Holothuria forskali] is often seen on the upper faces of boulders and bedrock. [Marthasterias glacialis], [Asterias rubens], [Echinus esculentus], [Henricia oculata] and [Luidia ciliaris] may also be present. A sparse hydroid turf may also be present, with species such as [Polyplumaria frutescens], [Halecium halecinum] and [Nemertesia antennina]. In addition, there may be anthozoans such as [Isozoanthus sulcatus] and [Corynactis viridis]. The sponge [Suberites carnosus] is typically associated with a heavily silted habitat. Other sponges present include [Cliona celata], [Stelligera stuposa] and [Polymastia boletiformis]. The only records are from the west coast of Ireland.
Situation: Usually found on bedrock ridges and outcrops surrounded by sand and muddy gravel.


HabitatName:
[Caryophyllia smithii], [Swiftia pallida] and large solitary ascidians on exposed or moderately exposed circalittoral rock

HabitatDescription:
This variant typically occurs on exposed to moderately wave-exposed, circalittoral bedrock and boulders rock subject to mainly weak tidal streams and has a thin layer of silt present. It is found predominantly from 10-30m water depth. From afar, this biotope is mostly distinguished by the frequently occurring seafan [Swiftia pallida], encrusting red algae and the abundant cup coral [Caryophyllia smithii]. This biotope has quite an impoverished appearance, compared with unit A4.133 which has a strong sponge component. Other species present are typically in low abundance. Echinoderms such as [Echinus esculentus], [Antedon bifida], [Antedon petasus], [Leptometra celtica], [Marthasterias glacialis], [Luidia ciliaris] and [Asterias rubens] may be recorded. Large hydroids such as [Nemertesia antennina] and [Nemertesia ramosa] may occasionally be seen in isolated clumps on the tops of boulders and rocky outcrops. The anthozoan [Parazoanthus anguicomus] may be recorded. Bryozoans such as [Parasmittina trispinosa] and [Porella compressa] are occasionally observed. The polychaete [Pomatoceros triqueter] may be observed encrusting the sides of rocks and boulders while occasional [Alcyonium digitatum] may also be seen. A small suite of large ascidians may be present, including [Ascidia mentula], [Clavelina lepadiformis], [Ciona intestinalis], [Diazona violacea] and [Ascidia virginea]. Sponges are typically absent from this biotope, although [Cliona celata] may be recorded occasionally. The top shell [Gibbula cineraria] is usually present. Under boulders and overhangs, the squat lobster [Munida rugosa] can usually be seen hiding. All these records are from the west coast of Scotland (East coast of Lewis /Outer Hebrides).
Situation: Above this biotope in the infralittoral zone, sheltered kelp forests are usually found, with species such as [Laminaria hyperborea], [Laminaria saccharina] and [Sacchoriza polyschides]. This biotope is found on bedrock and boulders, which may either be protruding from the surrounding sediment, or the sediment may be in a separate zone below the bedrock. These sediments may either be deep mud (with species such as [Pachycerianthus] and [Nephrops] ) on the sheltered sites or slightly coarser sediments (with [Pennatula] and [Virgularia]) on slightly more exposed sites.


HabitatName:
[Caryophyllia smithii], sponges and crustose communities on wave-exposed circalittoral rock

HabitatDescription:
This biotope typically occurs on the upper and vertical faces of wave-exposed, moderately strong to weakly tide-swept, circalittoral bedrock or boulders, with a water depth range of 20-30m. This often silty biotope has a typically sparse fauna, appearing grazed, and is characterised by common cup corals [Caryophyllia smithii], frequent [Alcyonium digitatum] and occasional urchins [Echinus esculentus]. There may be occasional large growths of the sponge [Cliona celata], [Haliclona viscosa], [Pachymatisma johnstonia] and the axinellid sponge [Stelligera stuposa]. Echinoderms form a prominent feature of the fauna within this biotope, with species such as [Marthasterias glacialis], [Asterias rubens], [Luidia ciliaris], [Henricia oculata], [Holothuria forskali], [Antedon bifida] and [Aslia lefevrei] present. Bryozoan crusts such as [Parasmittina trispinosa] and encrusting red algae cover the rock/boulder surface. The bryozoan [Porella compressa] may also be recorded occasionally. Isolated clumps of hydroids feature species such as [Nemertesia antennina], [Nemertesia ramosa], [Abietinaria abietina], [Halecium halecinum] and [Sertularella gayi]. Other species observed include the anemone [Corynactis viridis], [Urticina felina], [Sagartia elegans], [Calliostoma zizyphinum], [Balanus crenatus] and [Pomatoceros triqueter]. Two variants within this biotope have been distinguished: units A4.2122 and A4.2121. While A4.2122 tends to have the bryozoans [Pentapora foliacea] and [P. compressa], while A4.2121 features a dynamic community of brittlestars covering the seabed in a dense mat. [Ophiothrix fragilis] is usually the dominant species in shallow water but tends to be replaced by [Ophiocomina nigra] in deeper water.


HabitatName:
Brittlestars overlying coralline crusts, [Parasmittina trispinosa] and [Caryophyllia smithii] on wave-exposed circalittoral rock

HabitatDescription:
This variant is typically found on the upper faces of wave-exposed circalittoral bedrock or boulders subject to moderately strong to weak tidal streams, on open coasts. However, the depth at which the variant occurs means that wave action is not so severe on the seabed as to displace the dense mat of brittlestars that covers the seabed. [Ophiothrix fragilis] is usually the most dominant species in shallow water, with [Ophiocomina nigra] usually found amongst them, but sometimes becoming the dominant species in deeper water. Although brittlestar biotopes are typically species-poor, the underlying fauna in this variant is relatively diverse and resembles that of A4.2122. Species such as the anemone [Urticina felina], the cup coral [Caryophyllia smithii], and the anemone [Corynactis viridis] may occasionally be present. There may also be sparse clumps of various hydroids including [Halecium halecinum], [Nemertesia antennina], [Nemertesia ramosa], [Sertularella gayi] and [Abietinaria abietina]. Soft coral [Alcyonium digitatum] is occasionally present and there may be sparse specimens of the sponges [Cliona celata] and [Polymastia boletiformis]. In addition, various echinoderms such as [Asterias rubens], [Antedon bifida], [Echinus esculentus], [Henricia oculata], [Marthasterias glacialis] and [Luidia ciliaris] may be observed. The barnacle [Balanus crenatus] and the polychaete [Pomatoceros triqueter] may be seen attached to any available space on the bedrock and boulders not smothered by brittlestars. Bryozoan crusts such as [Parasmittina trispinosa] may also be present.
Situation: Wave-exposed seabed composed of bedrock ridges and/or boulder or cobble slope. Shallower than this biotope, the lower infralittoral kelp park is dominated by [Laminaria hyperborea]. A dense understorey may be present, containing [Antedon] spp., [Phycodrys rubens] and [Plocamium cartilagineum].


HabitatName:
[Caryophyllia smithii] and sponges with [Pentapora foliacea], [Porella compressa] and crustose communities on wave-exposed circalittoral rock

HabitatDescription:
This variant is typically found on the upper faces and vertical sides of wave-exposed bedrock or boulders subject to moderately strong to weak tidal streams. The fauna is often sparse with the frequently observed [Echinus esculentus] giving it a grazed appearance, but the community may also be affected by violent storm action working into deep water during winter storms. Despite this spartan appearance, the community is relatively diverse and contains a wide range of sponges, hydroids, bryozoans and echinoderms. This variant is found on open coasts or offshore, and is characterised by the cup-coral [Caryophyllia smithii], [Alcyonium digitatum], the sea urchin [Echinus esculentus], large specimens of the sponge [Cliona celata], encrusting bryozoans and encrusting red algae. Although this variant tends to occur in deep water (depth range of 20-30m), a high degree of water clarity allows some red algae to grow at these depths. Other species recorded include large specimens of [Haliclona viscosa], the bryozoans [Parasmittina trispinosa], [Porella compressa] and [Pentapora foliacea], the sea cucumbers [Holothuria forskali] and [Aslia lefevrei] and sparse hydroids such as [Abietinaria abietina], [Nemertesia antennina], [Nemertesia ramosa] and [Halecium halecinum]. Anemones such as [Corynactis viridis], [Sagartia elegans] and [Urticina felina] are also frequently seen. Various other species characteristic of wave-exposed rock include the sponges [Pachymatisma johnstonia], [Stelligera stuposa], the starfish [Luidia ciliaris], [Marthasterias glacialis], [Asterias rubens], [Henricia oculata], the crinoid [Antedon bifida], the barnacle [Balanus crenatus], the top shell [Calliostoma zizyphinum] and the polychaete [Pomatoceros triqueter]. The majority of the records within this variant originate from the west coast of Ireland.
Situation: Exposed kelp forest and park biotopes such as unit A3.115 with species such as [Laminaria hyperborea] are typically found shallower than this biotope. Deeper, this biotope is believed to graduate into A4.121 (deep erect sponges), as both these biotopes are common around the west coast of Ireland.


HabitatName:
[Urticina felina] and sand-tolerant fauna on sand-scoured or covered circalittoral rock

HabitatDescription:
This biotope typically occurs on tide-swept circalittoral bedrock, rock adjacent to mobile sand/gravel in gullies, and cobbles on gravel and sand, characterised by scour-tolerant robust species. Although many of these species are found on subtidal rock, they tend to occur in larger numbers in these highly sand-influenced conditions. The dominant species by far is the anemone [Urticina felina] which commonly occurs on rocks at the sand-rock interface, where the scour levels are at a maximum and few species can tolerate this abrasion. The sponge [Ciocalypta penicillus] is also very characteristic of shifting sand-covered rock. This biotope is only occasionally recorded as a separate entity, because its extent is typically restricted to a very narrow band of rock at the sediment interface. Only occasionally does it cover a large extent of rock (e.g. where the wave action is strong enough to cause sand abrasion well up the rock face or where the rock is low-lying). More often, this scoured zone is recorded as part of whatever biotope occurs on the nearby hard substrata. Other species (which are able to survive, and benefit from the reduced competition) include [Balanus crenatus], [Pomatoceros triqueter], [Cellepora pumicosa], [Alcyonidium diaphanum], [Cliona celata], encrusting red algae and [Asterias rubens].
Situation: This biotope tends to be found in close proximity to mobile sand or gravel, producing scour that tends to limit the number of species found.


HabitatDescription:
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].


HabitatName:
[Flustra foliacea] on slightly scoured silty circalittoral rock

HabitatDescription:
This variant is typically found on the upper faces of moderately wave-exposed circalittoral bedrock or boulders subjected to moderately strong tidal streams. These rocky patches may be interspersed with gravelly sand patches, causing a scouring effect. From afar, the variant appears dominated by the bryozoan [Flustra foliacea]. [Alcyonium digitatum] may also be seen attached to the rocky substratum. Under closer inspection, the white tubes of the polychaete [Pomatoceros triqueter] may be observed on the rock and boulders, especially on vertical faces. There may be sandy/gravelly patches in between the boulders colonised by the anemone [Urticina felina]. The regular occurrence of large numbers of the sea urchin [Echinus esculentus] in this biotope may be responsible for grazing the faunal and algal turf, thus keeping species richness relatively low. Other echinoderms that may be seen include the ubiquitous starfish [Asterias rubens] and the common brittlestar [Ophiothrix fragilis]. Sparse clumps of the hydroids [Thuiaria thuja], [Abietinaria abietina], [Nemertesia antennina] and [Tubularia indivisa] are occasionally seen attached to the rocky substratum. The hermit crab [Pagurus bernhardus], the polychaete [Sabella pavonina] and sparse bryozoan crusts may also be present. This biotope is characteristic of the bedrock terraces along the Northumberland coast that are generally species impoverished compared to similar [F. foliacea] biotopes on the west coasts of the UK, which have a more diverse range of sponges, hydroids and bryozoans. As the turbidity levels increase in this fairly silty biotope, so the species diversity is reduced.
Situation: This biotope typically occurs around coasts subject to sand scour and siltation. Associated biotopes common around the north-east coast of England include circalittoral gravel and coarse sands. Typical species present include [Echinocardium], [Lanice conchilega], [Ensis] spp., [Mya truncata] and [Myxicola]. Where suitable substratum is available, exposed kelp forests occur in the infralittoral (the latter normally occupies a narrow band due to the high silt loading in the water column). Where this biotope occurs along with chalk or limestone bedrock and boulders, piddock dominated biotopes (Pid) may also be found.


HabitatName:
[Alcyonium digitatum], [Pomatoceros triqueter], algal and bryozoan crusts on wave-exposed circalittoral rock

HabitatDescription:
This variant is typically found on the vertical, steep and upper faces of wave-exposed circalittoral bedrock or boulders subject to varying amounts of current. The variant has a very grazed, sparse appearance, dominated only by the presence of [Alcyonium digitatum] and large expanses of encrusting red alage and bryozoan crusts particularly ([Parasmittina trispinosa]). The sparse appearance can be attributed to the frequently observed sea urchin [Echinus esculentus]. The polychaete [Pomatoceros triqueter] can be locally abundant, and may in some cases cover far more rock surface than [A. digitatum], especially on vertical faces. Clumps of robust hydroids such as [Abietinaria abietina] occur occasionally. Other species present include the echinoderms [Asterias rubens], [Henricia sanguinolenta], [Ophiothrix fragilis], the anemone [Urticina felina], [Calliostoma zizyphinum] and [Cancer pagurus].
Situation: Shallower than this biotope, dense kelp forest is typically found, containing species such as [Laminaria hyperborea] and [Alaria esculentus]. Occasionally, this biotope may be found on rocky outcrops surrounding by coarse sand. With this increased scour, A4.213 may develop at the rock/sand interface. Below this biotope, coarse sediments, muddy gravel and sand are typically recorded.


HabitatName:
[Alcyonium digitatum] with [Securiflustra securifrons] on tide-swept moderately wave-exposed circalittoral rock

HabitatDescription:
This variant is typically found on the upper and vertical faces of moderately wave-exposed circalittoral bedrock subject to moderately strong to weak tidal streams. The rock surface is dominated by [Alcyonium digitatum] and the bryozoan [Securiflustra securifrons]. The rock between these species appears fairly sparse and grazed, with expanses of encrusting red algae. The sea urchin [Echinus esculentus] is frequently seen, and in collaboration with the light attenuating effects of depth, is probably the principal reason for the lack of algal turf. Other species found include the hydroids [Abietinaria abietina], [Nemertesia antennina], [Thuiaria thuja], the bryozoans [Cellepora pumicosa], [Parasmittina trispinosa], [Flustra foliacea], [Alcyonidium diaphanum] and other bryozoan crusts. Encrusting species such as the polychaete [Pomatoceros triqueter] and the barnacle [Balanus balanus] are frequently observed. Other species present include [Asterias rubens], [Antedon bifida], [Ophiura albida], [Ophiothrix fragilis], [Caryophyllia smithii], [Urticina felina], [Clavelina lepadiformis], [Calliostoma zizphinium] and [Pandalus montagui].

Situation: Above this biotope, you tend to find exposed kelp forest and park (unit A3.115). There is a tendency for slight scouring to occur in this biotope. However, if this scour increases further, for example if water movement increases, mobilising more sand, this biotope may graduate into UrtScr. In more silty sites, there is a tendency for [S. securifrons] to be replaced by [F. foliacea] as the dominant bryozoan, turning the biotope into A4.2141.

Temporal variation: Whilst the great majority of species in this variant are most likely present throughout the year, [C. lepadiformis] grows in spring and may show great variation in abundance from year to year.


HabitatDescription:
This variant is typically found on the upper faces of exposed and moderately wave-exposed circalittoral bedrock, boulders and cobbles subject to moderately strong to weak tidal streams. It is characterised by high densities of brittlestars (predominantly [Ophiothrix fragilis], [Ophiocomina nigra] and [Ophiura albida]). In fact, they may form such dense beds that the seabed underneath may not be visible. The rocky substratum is usually colonised by species such as encrusting red algae and the white, calcareous tubes of the polychaete [Pomatoceros triqueter]. Only robust hydroids such as [Abietinaria abietina], [Alcyonium digitatum] and bryozoan crusts such as [Parasmittina trispinosa] are able to tolerate the significant smothering effect from the dense mat of brittlestars. Other species typically seen include [Echinus esculentus], [Asterias rubens], [Pagurus bernhardus], [Anapagurus hyndmanni], [Gibbula cineraria], [Urticina felina], [Pododesmus patelliformis] and [Ciona intestinalis].
Situation: Shallower than the A4.2144 variant, kelp park and forest may be found with species such as [Laminaria saccharina] and [Laminaria hyperborea].


HabitatName:
Faunal and algal crusts with [Pomatoceros triqueter] and sparse [Alcyonium digitatum] on exposed to moderately wave-exposed circalittoral rock

HabitatDescription:
This variant is typically found on the upper faces of exposed and moderately exposed circalittoral bedrock or boulders subjected to moderately strong to weak tidal streams. From afar, the seabed has a rather sparse, grazed appearance, reminiscent of a brittlestar bed after the brittlestars have moved elsewhere. The rocky substratum is generally covered with encrusting red algae and the white, calcareous tubes of the polychaete [Pomatoceros triqueter], dotted with the abundant urchin [Echinus esculentus]. Under closer inspection, [Alcyonium digitatum] are usually seen attached to the rocky surface underneath rock overhangs and large boulders. Although they may be recorded as abundant or common in some areas, their relatively small size means that their biomass is generally lower than in other biotopes. Sparse clumps of robust hydroids such as [Abietinaria abietina] are frequently observed, and bryozoan crusts such as [Parasmittina trispinosa] are occasionally seen. Echinoderms such as the brittlestars [Ophiothrix fragilis] and [Ophiocomina nigra], and the crab [Cancer pagurus] may be seen within crevices in the boulders/rock whilst the starfish [Asterias rubens] may be seen on the rock surface. Muddy-gravel patches between boulders (especially within Scottish sealochs) provide a suitable habitat for the anemone [Urticina felina]. The top shell [Gibbula cineraria] is occasionally seen grazing on the rock surface. Within this biotope, there is some regional variation. The robust hydroid [A. abietina] is typically found in higher abundances in northern (Scottish) regions, especially around the Isle of May.
Situation: Above the A4.2145 variant in the infralittoral zone, species such as [Alaria esculenta] and [Laminaria hyperborea] are found in more wave exposed sites (A3.111 / A3.113) while species such as [Laminaria saccharina] may be found above A4.2145 in the more sheltered examples. Due to moderately tide-swept conditions this variant is found in, clean, coarse sediment biotopes are generally found below A4.2145. Typical species found in these coarse sand/gravelly biotopes include [Neopentadactyla mixta] and [Lanice conchilega] (A5.44). Where wave exposure increases, this variant tends to change to A4.2122,, dominated by [Caryophyllia smithii], [Corynactis viridis], encrusting red algae and bryozoan crusts. Where tidal stream and wave-exposure decreases, this variant develops into a similar biotope dominated by encrusting red algae, [Echinus esculentus] and [C.smithii] (A4.2146).


HabitatName:
[Caryophyllia smithii] with faunal and algal crusts on moderately wave-exposed circalittoral rock

HabitatDescription:
This variant is typically found on the upper and vertical faces of exposed and moderately wave-exposed circalittoral rock, subject to very little water movement. Where this variant is found on slightly more wave-exposed sites, it tends to be found towards the bottom of its depth range. The rocky substratum has a grazed appearance, with encrusting red algae. Diversity of species is very low, possibly due to grazing pressure from the sea urchin [Echinus esculentus]. From afar, there is little evident epifauna attached to the rocks apart from the white, calcareous tubes of the polychaete [Pomatoceros triqueter] and the cup-coral [Caryophyllia smithii]. In addition, bryozoan crusts such as [Parasmittina trispinosa] are frequently seen. Under closer inspection, a few more species become apparent but few are typically characterising of this particular variant. The echinoderms [Antedon bifida], [Asterias rubens], [Ophiothrix fragilis], [Marthasterias glacialis], [Ophiocomina nigra] and [Crossaster papposus] are occasionally present. Sparse clumps of hydroids such as [Halecium halecinum], [Kirchenpaueria pinnata] and [Nemertesia antennina] may be found attached to rocky outcrops or boulders. Small specimens of [Alcyonium digitatum] may be present. The ascidians [Ciona intestinalis], [Clavelina lepadiformis] and [Ascidia mentula] also occur in this variant but are found in greater numbers in other biotopes. The top shells [Calliostoma zizyphinum], [Gibbula cineraria], and the saddle oyster [Pododesmus patelliformis] may be seen on the rock surface whilst the crab [Cancer pagurus] may be seen under boulders and in crevices. The anemone [Metridium senile] may be found under rocky overhangs and on the sides of boulders.
Situation: As A4.2146 occurs on moderately wave-exposed coasts, kelp forests in the infralittoral zone shallower than this variant tend to be dominated by robust kelp species such as [Laminaria hyperborea] (unit A3.214) and [Saccorhiza polyschides]. Immediately below A4.2146 (typically bedrock/boulder substratum), sublittoral sediment biotopes such as muddy sands, containing [Nephrops norvegicus], [Virgularia mirabilis] and [Funiculina quadrangularis] are found. Occasionally, biotopes composed of coarser sand/gravelly material may be present, with species such as [Peachea cylindrica] and [Neopentadactyla mixta]. When wave exposure and tidal stream increase, A4.2146 tends to grade into A4.2145.


HabitatName:
[Alcyonium digitatum] and faunal crust communities on vertical circalittoral bedrock

HabitatDescription:
This biotope typically occurs on the vertical faces and overhangs of exposed to moderately exposed lower infralittoral and upper circalittoral bedrock subject to moderately strong to weak tidal streams. Due to the large numbers of the urchin [Echinus esculentus] often recorded, this biotope tends to have a grazed appearance, and the bedrock is often encrusted with pink coralline algae, encrusting bryozoans such as [Parasmittina trispinosa] and the calcareous tubeworm [Pomatoceros triqueter]. Dense aggregations of dead mans fingers [Alcyonium digitatum] may be present along with the cup coral [Caryophyllia smithii]. Other species present include the echinoderms [Asterias rubens], [Ophiothrix fragilis] and [Antedon bifida], the ascidians [Clavelina lepadiformis], [Ciona intestinalis] and [Ascidia mentula], the anthozoans [Urticina feline], [Cortynactis viridis], [Metridium senile] and [Sagartia elegans], the gastropod [Calliostoma zizyphinum] and the crustacean [Cancer pagurus]. Three regional variations of this biotope have been recorded. One variant found typically off the north-east coast of Scotland and around the Northern Isles, has a very impoverished appearance dominated by anthozoans. A second variant occurs along the west coast of Scotland, extending to Rockall in the west, and the Northern Isles in the north-east, and has a more fauna, characterised by hydroids, sponges, anthozoans and echinoderms. A third variant occurs along the north-east coast of England (Northumberland) up to the Northern Isles and is dominated by [Alcyonium digitatum], brittlestars and [Echinus esculentus].


HabitatName:
[Sabellaria] reefs on circalittoral rock

HabitatDescription:
This habitat type occurs on moderately wave-exposed, circalittoral bedrock, boulders and cobbles subject to moderately strong tidal streams. It is characterised by dense crusts of the polychaete [Sabellaria spinulosa] covering the substratum. Other fauna present in many cases reflects the biotopes found on nearby rock, so to a certain extent, is quite variable. Species typically present include the bryozoans [Flustra foliacea], [Alcyonidium diaphanum] and [Pentapora foliacea], the hydroid [Nemertesia antennina], the sponges [Tethya aurantium] and [Phorbas fictitius], the anemones [Urticina felina] and [Sagartia elegans], and the ascidians [Distomus variolosus], [Polycarpa pomaria] and [Polycarpa scuba]. The barnacle [Balanus crenatus], the polychetes [Pomatoceros triqueter] and [Salmacina dysteri], the starfish [Crossaster papposus], and [Alcyonium digitatum] may also be recorded.


HabitatName:
[Sabellaria spinulosa] encrusted circalittoral rock

HabitatDescription:
This biotope is typically found encrusting the upper faces of wave-exposed and moderately wave-exposed circalittoral bedrock, boulders and cobbles subject to strong/moderately strong tidal streams in areas with high turbidity. The crusts formed by the sandy tubes of the polychaete worm [Sabellaria spinulosa] may even completely cover the rock, binding the substratum together to form a crust. A diverse fauna may be found attached to, and sometimes obscuring the crust, often reflecting the character of surrounding biotopes. Bryozoans such as [Flustra foliacea], [Pentapora foliacea] and [Alcyonidium diaphanum], anemones such as [Urticina felina] and [Sagartia elegans], the polychaete [Pomatoceros triqueter], [Alcyonium digitatum], the hydroid [Nemertesia antennina] and echinoderms such as [Asterias rubens] and [Crossaster papposus] may all be recorded within this biotope. There are two variants. The first (unit A4.2211) contains significant cover of barnacles ([Balanus crenatus]) and bryozoans. The second (unit A4.2212) has a dense turf of didemnid ascidians as well as scour-tolerant bryozoans such as [F. foliacea], sponges such as [Tethya aurantium] and [Phorbas fictitius], colonies of the serpulid worm [Salmacina dysteri] and patchy occurrences of the ascidians [Distomus variolosus], [Polycarpa pomaria] and [Polycarpa scuba]. This biotope has been recorded from the Lleyn Peninsula, Lundy Island (including the wreck of the MV Robert) and the north-east and south coast of England.


HabitatName:
[Sabellaria spinulosa] with a bryozoan turf and barnacles on silty turbid circalittoral rock

HabitatDescription:
This variant is typically found encrusting the upper faces of exposed and moderately exposed circalittoral rock and mixed substrata, subject to strong and moderately strong currents and high turbidity levels. The crusts formed by the sandy tubes of the polychaete worm [Sabellaria spinulosa] may completely cover the rock, binding gravel and pebbles together. A diverse fauna may be found attached to this crust, and in many cases reflects the character of nearby biotopes. There is normally considerable variation in the associated fauna encountered. There may be a sparse bryozoan turf ([Flustra foliacea], [Alcyonidium diaphanum], [Bicellariella ciliata], [Bugula plumosa] and [Vesicularia spinosa]) attached to the [Sabellaria] crust and available rocky substrata. Other scour-tolerant species such as [Urticina felina] are occasionally observed. Clumps of robust hydroids such as [Tubularia indivisa], [Nemertesia antennina], [Hydrallmania falcata] and [Halecium halecinum] may also be observed. Other species which may be present include the polychaete [Pomatoceros triqueter], [Balanus crenatus], [Asterias rubens], [Pagurus bernhardus] and [Gibbula cineraria]. Occasionally, sponges such as [Haliclona oculata] and [Halichondria panicea], and ascidians such as [Dendrodoa grossularia] may also be observed.


HabitatName:
[Sabellaria spinulosa], didemnid and small ascidians on tide-swept moderately wave-exposed circalittoral rock

HabitatDescription:
This variant is typically found on tide-swept, moderately wave-exposed circalittoral bedrock, boulders and cobbles subject to slight sand-scour. It occurs predominantly in the lower circalittoral. This variant normally appears as a bedrock/boulder outcrop or reef with a dense crust of the polychaete [Sabellaria spinulosa] and a dense turf of didemnid ascidians and scour-tolerant bryozoans such as [Flustra foliacea], [Pentapora foliacea] and [Cellaria] species. There may be discreet clumps of [Alcyonium digitatum] and sparse sponges such as [Tethya aurantium] and [Phorbas fictitius]. Patchy occurrences of the small ascidians [Polycarpa scuba], [Polycarpa pomaria] and [Distomus variolosus] may be present on the tops of rocks and boulders whilst in crevices between, the anemone [Urticina felina] may be found. Species such as [Asterias rubens], [Crossaster papposus], the serpulid worm [Salmacina dysteri] and the anemone [Sagartia elegans] are occasionally seen on the rock surface. This variant has been recorded from the Lleyn Peninsula, the Skerries and around Pembrokeshire in Wales.


HabitatDescription:
This habitat type occurs on moderately wave-exposed, circalittoral soft bedrock subject to moderately strong tidal streams. As this complex is found in highly turbid water conditions, the circalittoral zone may begin at the low water mark, due to poor light penetration. This complex is dominated by the piddock [Pholas dactylus]. Other species typical of this complex include the polychaete [Polydora] and [Bispira volutacornis], the sponges [Cliona celata] and [Suberites ficus], the bryozoan [Flustra foliacea], [Alcyonium digitatum], the starfish [Asterias rubens], the mussel [Mytilus edulis] and the crab [Necora puber] and [Cancer pagurus]. Foliose red algae may also be present. Please note: in areas subject to very high turbidity, biotopes within this habitat type may occur in the infralittoral and even the littoral zone.


HabitatDescription:
This biotope occurs on circalittoral soft rock, such as soft chalk or clay, most often in moderately exposed tide-swept conditions. As soft chalk and firm clay are often too soft for sessile filter-feeding animals to attach and thrive in large numbers, an extremely impoverished epifauna results on upward-facing surfaces, although vertical faces may be somewhat richer. The rock is sufficiently soft to be bored by bivalves. Species vary with location, but [Pholas dactylus] is the most widespread borer and may be abundant. Other species present may include the sponges [Dysidea fragilis] and [Suberites carnosus] and the polychaete [Bispira volutacornis]. Foliose red algae may be present on the harder, more stable areas of rock. Mobile fauna often include the crabs [Necora puber] and [Cancer pagurus].
Situation: Subtidal chalk reefs or clay outcrops, mostly known from south-east England.


HabitatName:
[Polydora] sp. tubes on moderately exposed sublittoral soft rock

HabitatDescription:
Large patches of chalk and soft limestone are occasionally covered entirely by [Polydora] sp. tubes to the exclusion of almost all other species. This tends to occur in highly turbid conditions and spans the infralittoral and circalittoral in limestone areas such as the Great and Little Ormes (North Wales) and Gower (South Wales). It is even present on the lower shore in the Severn estuary. The boring form of the sponge [Cliona celata] often riddles the surface layer of the stone. Other sponges present include [Halichondria panicea], [Haliclona oculata] and [Hymeniacidon perleve]. [Polydora] sp. also frequently occurs in small patches as part of other biotopes (e.g. unit A4.134). Other species present include [Alcyonium digitatum], [Sarcodictyon roseum], the hydroids [Halecium halecinum], [Abietinaria abietina] and [Tubularia indivisa], the ascidians [Clavelina lepadiformis], [Botryllus schlosseri] and [Morchellium argus], the anemones [Urticina felina], [Metridium senile] and [Sagartia elegans] and the bryozoans [Flustra foliacea] and a crisiid turf. The starfish [Asterias rubens], the crabs [Inachus phalangium] and [Carcinus maenas], the polychaete [Pomatoceros triqueter], the barnacle [Balanus crenatus] and the brittlestar [Ophiothrix fragilis] may also be seen. Please note: this biotope may extend into the infralittoral and littoral zone in areas where water turbidity is sufficiently high.


HabitatName:
[Hiatella]-bored vertical sublittoral limestone rock

HabitatDescription:
Moderately exposed vertical and overhanging soft rock (typically chalk), subject to moderately strong to weak tidal streams, bored by the rock-boring mollusc [Hiatella arctica]. As with other biotopes in the soft rock complex, it is found in areas of high turbidity, where there is poor light penetration. There may be isolated clumps of the hydroid [Nemertesia antennina] and a sparse bryozoan turf formed by various crisiids, [Bugula plumosa] and [Bugula flabellate] (often being grazed on by the nudibranch [Janolus cristatus]), [Alcyonidium diaphanum], [Flustra foliacea] and [Cellapora pumicosa]. A patchy 'carpet' of the brittlestar [Ophiothrix fragilis] is often recorded along with other echinoderms such as [Asterias rubens] and [Henricia sanguinolenta]. Other species present include the colonial ascidians [Polyclinum aurantium], [Botrylloides leachi], [Clavelina lepadiformis], [Aplidium punctatum] and [Botryllus schlosseri], dead mans fingers [Alcyonium digitatum] and the crab [Cancer pagurus]. Sponges present include the boring sponge [Cliona celata], [Halichondria panicea], [Myxilla incrustans], [Leucosolenia botryoides]and [Dysidea fragilis]. Occasionally, the foliose red seaweed [Delessaria sanguinea] may be recorded.


HabitatDescription:
This habitat type occurs on moderately wave-exposed upper circalittoral bedrock subject to strong or moderately strong tidal streams. This complex is characterised by dense aggregations of the mussels [Mytilus edulis] or [Musculus discors] carpeting the underlying substrata. Sponges that may be recorded in this complex are [Scypha ciliata], [Tethya aurantium], [Pachymatisma johnstonia], [Dysidea fragilis] and [Cliona celata]. A sparse hydroid/bryozoan turf composed primarily of [Nemertesia antennina], [Alcyonidium diaphanum] and [Flustra foliacea] is often recorded. Anemones present are [Urticina felina] and [Sagartia elegans]. Other species recorded are the crabs [Cancer pagurus], [Carcinus maenas] and [Necora puber], the starfish [Crossaster papposus] and [Asterias rubens], and [Alcyonium digitatum] and in this upper circalittoral complex, algae species such as [Dictyota dichotoma], [Cryptopleura ramosa] and [Plocamium cartilagineum].


HabitatName:
[Mytilus edulis] beds with hydroids and ascidians on tide-swept exposed to moderately wave-exposed circalittoral rock

HabitatDescription:
This biotope typically occurs on the upper faces of tide-swept circalittoral bedrock, boulders and mixed substrata exposed to varying amounts of wave action. The mussel [Mytilus edulis] forms dense beds, to the exclusion of other species. The starfish [Asterias rubens] is frequently recorded, and it predates heavily on the mussels. Occasionally, the anemone [Urticina felina] may be seen within crevices in the rock or on gravel patches. Crabs such as [Necora puber] and [Carcinus maenas] may be seen on the rock or mussels whilst fauna observed in crevices typically consists of the lobster [Homarus gammarus] and the crab [Cancer pagurus]. The anemone [Sargatia elegans] can be seen attached to bedrock and cobbles, whereas the barnacle [Balanus crenatus] may be seen attached to the mussels themselves.


HabitatName:
[Musculus discors] beds on moderately exposed circalittoral rock

HabitatDescription:
This biotope typically occurs on the upper faces of moderately exposed, moderately tide-swept bedrock, boulders and cobbles in slightly silty conditions. The mussel [Musculus discors] occurs in dense mats and occasionally completely coats all available surfaces. There is also often a layer of pseudofaeces, forming a thick, silty matrix. A relatively diverse fauna of cushion and branching sponges is often present on rocky outcrops and other hard substratum that is free of mussels. These include [Tethya aurantium], [Scypha ciliata], [Pachymatisma johnstonia], [Dysidea fragilis], [Cliona celata] and [Stelligera stuposa]. There may be isolated clumps of silt-tolerant bryozoans such as [Flustra foliacea] and [Bugula plumosa]. Various species may be observed on top of the mussels, including [Asterias rubens], [Crossaster papposus] and the brittlestar [Ophiura albida]. Occasional [Alcyonium digitatum] and clumps of the hydroid [Nemertesia antennina] are found attached to rocky outcrops and boulders whilst the anemone [Urticina felina] may be seen in crevices in the rock or on gravely patches between boulders. Colonial ascidians such as [Clavelina lepadiformis] and didemnids may occasionally be present. A wide range of seaweeds may be present, including [Dictyota dichotoma], [Plocamium cartliagineum], [Dictyopteris membranacea], [Cryptopleura ramosa] and [Heterosiphonia plumosa]. The crab [Cancer pagurus] may be observed in crevices. The majority of the records for this biotope are from the Lleyn Peninsula.


HabitatName:
Pontic [Mytilus galloprovincialis] beds on circalittoral rock


HabitatDescription:
This habitat type occurs on wave-sheltered, variable salinity bedrock and cobbles, subject to moderately strong to weak tidal streams. This complex contains a suite of sponges able to tolerate the variable salinity conditions like [Hymeniacidon perleve], [Suberites ficus], [Halichondria panicea], [Halichondria bowerbanki], [Cliona celata] and [Leucosolenia botryoides]. The barnacle [Balanus crenatus] is frequently recorded in this complex. A sparse hydroid/bryozoan turf composed primarily of [Nemertesia antennina], [Nemerteis ramosa], [Plumularia setacea], [Alcyonidium diaphanum] and [Bugula plumosa] is often recorded. Other species recorded are the ascidians [Clavelina lepadiformis], [Morchellium argus] and [Dendrodoa grossularia], the anemones [Metridium senile] and [Sagartia troglodytes], the starfish [Asterias rubens] and the crab [Carcinus maenas].


HabitatDescription:
This biotope is found in variable salinity environments and tends to occur on the upper faces of circalittoral bedrock and boulders, in sheltered sites subject to moderately strong tidal streams. This biotope is characterised by aggregations of cushion sponges such as [Hymeniacidon perleve], [Halichondria panicea], [Halichondria bowerbanki] and [Cliona celata], other sponges ([Leucosolenia botryoides] and [Suberites ficus]) along with occasional hydroid tufts of [Nemertesia antennina], [Nemertesia ramosa] and [Plumularia setacea]. Other species that may be present include the colonial ascidians [Clavelina lepadiformis] and [Morchellium argus], [Dendrodoa grossularia], the anemones [Metridium senile] and [Sagartia troglodytes], the barnacle [Balanus crenatus], [Asterias rubens], [Carcinus maenas] and [Bugula plumosa]. Two variants of this biotope have been recorded: units A4.2511 and A4.2512.


HabitatDescription:
This sub-biotope typically occurs in a mixture of turbid, full and variable salinity water, on wave-sheltered and moderately exposed bedrock or boulders. Tidal streams are typically moderately strong but may vary considerably. This sub-biotope occurs in relatively shallow water (typically 5m to 11m water depth) and is dominated by cushion sponges, hydroids and ascidians. On the silty, rocky substrata, large growths of sponge are usually associated with this biotope ([Suberites ficus], [Hymeniacidon perleve], [Cliona celata], [Halichondria panicea], [Raspailia ramosa]). The tasselled form of [Esperiopsis fucorum] is also notably present. Other epifauna present includes silty hydroids such as [Nemertesia antennina], [Nemertesia ramosa], [Plumularia setacea], [Hydrallmania falcata] and [Halecium halecinum]. Individual colonies of dead mans fingers [Alcyonium digitatum] and plumose anemones [Metridium senile] may be seen attached to the tops of boulders and ridges. At some sites, whole sides of rocks may be colonised by the anemones [Sagartia elegans], [Sagartia troglodytes] and [Actinothoe sphyrodeta]. Within crevices in the rocky substratum and at the base of boulders [Urticina felina] and [Cereus pedunculatus] may be found. Ascidians such as [Clavelina lepadiformis], [Morchellium argus], [Dendrodoa grossularia], [Diplosoma listerianum] and [Distomus variolosus] may all be observed. Other ubiquitous species which may be recorded include [Polydora], terebellid worms, [Balanus crenatus], [Alcyonidium diaphanum] and [Asterias rubens].


HabitatDescription:
This sub-biotope typically occurs in turbid, variable salinity water, on wave-sheltered bedrock in estuaries subject to strong tidal regimes where circalittoral communities occur in relatively shallow water (typically 5m to 8m water depth). Cushion sponges, hydroids and ascidians dominate the biotope. Large growths (often up to 50cm across) of the sponges [Halichondria panicea] mixed with [Halichondria bowerbanki] almost entirely cover the bedrock, appearing in places like a continuous cushion. [Haliclona oculata], [Suberites ficus], [Leucosolenia botryoides], various hydroids such as [Plumularia setacea], [Nemertesia antennina], [Nemertesia ramosa] and various bryozoans such as [Bugula plumosa], [Bugula turbinata] and [Bowerbankia pustulosa] protude through the [Halichondria] spp. sponge growth. Colonial ascidians such as the lightbulb ascidian [Clavelina lepadiformis] and [Morchellium argus] may also be observed. Other more ubiquitous species include [Balanus crenatus], [Carcinus maenas], [Asterias rubens], [Metridium senile], [Sagartia elegans] and [Ophiothrix fragilis].


HabitatName:
[Halichondria bowerbanki], [Eudendrium arbusculum] and [Eucratea loricata] on reduced salinity tide-swept circalittoral mixed substrata

HabitatDescription:
This biotope typically occurs on circalittoral mixed substrata (bedrock, boulders, cobbles, pebbles and gravel) in the moderately strong, tide-swept narrows near the entrance of Loch Etive, although not in the extremely tide-swept Falls of Lora. This sea loch is unique in having a substantial freshwater input from the surrounding moorland, yielding the most brackish, large sea loch in Scotland. Large growths of the brackish-tolerant sponge [Halichondria bowerbanki] cover the cobble and boulder seabed, interspersed with [Mycale lobata], the hydroid [Eudendrium arbusculum] and the bryozoan [Alcyonidium diaphanum] which are particularly characteristic of these conditions. Tufts of the bryozoan [Eucratea loricata] are occasional in most areas. Other species recorded include [Carcinus maenas], [Asterias rubens], [Crossaster papposus], [Buccinum undatum], [Pagurus berhardus], [Henricia] spp., [Onchidoris bilamellata] and [Palio dubia], tolerant of the low salinity, are found in the circalittoral throughout this area. Ascidians such as [Ascidiella scabra] and [Corella parallelogramma] may also be present. A very impoverished low salinity version is present in the upper basin of Loch Etive. Unit A4.251 is similar in several respects to this biotope and will develop in less brackish situations where species-richness is generally greater.


HabitatName:
Mediterranean coralligenous communities moderately exposed to hydrodynamic action

HabitatDescription:
This habitat is present in the Mediterranean on hard rocky and/or biogenic horizontal substrata formed by coralligenous formations developed within sedimentary beds that are well supplied by currents, up to 100 metres in depth, in clear waters with moderate hydrodynamic action. Coralligenous concretions are found on rock faces or on rocks where calcareous algae can build biogenic constructions.


HabitatDescription:
This association is characterised by the high abundance of the brown alga [Cystoseira zosteroides]. The association can include in its higher levels both sciaphilous and photophilous species such as the brown algae [Phyllariopsis brevipes], [Arthrocladia villosa], and others.


HabitatDescription:
This association characterised by the brown alga [Cystoseira usneoides] is present in relatively deep rocky areas crossed by currents.


HabitatDescription:
This association characterised by the brown alga [Cystoseira dubia] occurs on hard substrata subject to weak hydrodynamics and relatively strong sedimentation.


HabitatDescription:
This association characterised by the brown alga [Cystoseira corniculata] occurs on hard substrata in the circalittoral zone.


HabitatDescription:
This association characterised by the abundance of the brown algae [Sargassum] spp. occurs on hard substrata, simultaneously relatively deep and well-lit, in oligotrophic conditions.


HabitatDescription:
This association characterised by the red alga [Mesophyllum lichenoides] occurs on hard substrata with strong deep currents.


HabitatName:
Algal bioconcretion with [Lithophyllum frondosum] and [Halimeda tuna]

HabitatDescription:
This association characterised by the red encrusting alga [Lithophyllum strictaeforme] ([Lithophyllum frondosum]) and the green alga [Halimeda tuna] is present on coralligenous horizontal formations developing within sedimentary beds affected by sea bottom currents.


HabitatDescription:
This association characterised by the brown alga [Laminaria ochroleuca] occurs on hard or detritic substrata composed by sparse rocks located at 30 - 100 metres depth in areas affected by strong currents and the Atlantic influx (e.g. Strait of Messina, Sea of Alboran, Algerian coasts).


HabitatDescription:
This facies is characterised by the high density of colonies of the gorgonian (sea-fan) [Eunicella cavolinii].


HabitatDescription:
This facies is characterised by the high density of colonies of the gorgonian (sea-fan) [Eunicella singularis].


HabitatDescription:
This facies is characterised by the high density of colonies of the gorgonian (red sea-fan) [Paramuricea clavata].


HabitatDescription:
This facies is characterised by the high density of the cnidarian (sea anemone) [Parazoanthus axinellae].


HabitatDescription:
These are coralligenous horizontal formations developing within sedimentary beds subject to currents, at up to at least 100 metres depth in clear waters.These formations are not usually built on rock substrata but result from the active development of constructor organisms (e.g. calcified algae, hard-skeleton invertebrates) from scattered elements on loose beds, shells, stones, and graves.


HabitatName:
Faunal communities on deep moderate energy circalittoral rock

HabitatDescription:
These communities populate hard substrata with low hydrodynamics and strong sedimentation.


HabitatName:
Pontic faunal communities on deep moderate energy circalittoral rock


HabitatName:
Atlantic and Mediterranean low energy circalittoral rock

HabitatDescription:
Occurs on wave-sheltered circalittoral bedrock and boulders subject to mainly weak/very weak tidal streams. The biotopes identified within this habitat type are often dominated by encrusting red algae, brachiopods ([Neocrania anomala]) and ascidians ([Ciona intestinalis] and [Ascidia mentula]).


HabitatName:
Brachiopod and ascidian communities on circalittoral rock

HabitatDescription:
This habitat type occurs on the wave-sheltered, circalittoral bedrock and boulders subject to weak tidal streams. The biotopes within this complex are typically found in the Scottish sealochs (with the exception of A4.312, recorded off Ireland) and are characterised by brachipod and ascidian communities. Ascidians often recorded in this complex are [Ciona intestinalis], [Ascidia mentula], [Ascidia virginea] and [Clavelina lepadiformis]. The brachiopod [Neocrania anomala] is also characteristic of the biotopes within this complex recorded in Scottish sealochs. The polychaete [Pomatoceros triqueter], the saddle oyster [Pododesmus patelliformis], the cup coral [Caryophyllia smithii] and encrusting red algae are frequently recorded on the rocky substrata. Echinoderms such as the brittlestars [Ophiothrix fraglis], [Ophiocomina nigra] and [Ophiura albida], the starfish [Asterias rubens], [Crossaster papposus] and [Henricia oculata], the crinoid [Antedon bifida] and the urchin [Echinus esculentus] are all found in this complex. Other species present include the squat lobster [Munida rugosa], the hermit crab [Pagurus bernhardus], [Alcyonium digitatum], the anemone [Protanthea simplex] and the hydroid [Kirchenpaueria pinnata].


HabitatName:
Solitary ascidians, including [Ascidia mentula] and [Ciona intestinalis], on wave-sheltered circalittoral rock

HabitatDescription:
This biotope predominantly occurs on the upper faces of wave-sheltered (often sealochs) circalittoral bedrock, boulder and cobble slopes with little tidal flow. Apart from the solitary ascidians [Ciona intestinalis] and [Ascidia mentula], this biotope has a rather barren, pink appearance (due to the encrusting red algae), possibly due to grazing pressure from the sea urchin [Echinus esculentus]. Other organisms found encrusting the rocky surface include the polychaete [Pomatoceros triqueter] and the cup coral [Caryophyllia smithii]. Other species occasionally encountered include [Alcyonium digitatum], [Asterias rubens], [Pagurus berhardus], [Crossaster papposus], [Antedon bifida] and [Metridium senile]. Crustaceans such as [Munida rugosa] and [Cancer pagurus] may be recorded in crevices. Two variants of this biotope exist: Units A4.3111 and A4.3112. A4.3112 occurs where is a dense carpet of brittlestars which sometimes completely cover the rocky substratum. Species present include [Ophiothrix fragilis], [Ophiocomina nigra] and [Ophiura albida].
Temporal variation: The abundance of [C. intestinalis] tends to fluctuate seasonally, so it may appear absent at a site at one time of year and then be present at other times, altering the visual appearance of the biotope. Other solitary ascidian species such as [A. mentula] and [Ascidiella aspersa] tend to be longer-lived (approximately 7 years and 3 years, respectively).


HabitatName:
Solitary ascidians, including [Ascidia mentula] and [Ciona intestinalis], with [Antedon] spp. on wave-sheltered circalittoral rock

HabitatDescription:
This variant occurs on circalittoral bedrock or boulder slopes in generally wave-sheltered conditions (often in sea lochs) with little tidal flow. It is frequently found on vertical or steeply-sloping rock. Apart from the large ascidians, [Ascidia mentula] and [Ciona intestinalis], the rock surface usually has a rather sparse appearance. Scyphistomae larvae are often present on any vertical surfaces. Grazing by the sea urchin [Echinus esculentus] leaves only encrusting red algae (giving the bedrock/boulder substratum a pink appearance), cup corals [Caryophyllia smithii] and the keelworm [Pomatoceros triqueter]. There may be a few hydroid species present, such as [Nemertesia] spp. and [Kirchenpaueria pinnata], occasional [Alcyonium digitatum] and occasional [Metridium senile]. Barnacles [Balanus] spp. and the colonial ascidian [Clavelina lepadiformis] also occasionally occur. At some sites, echinoderms such as the crinoid [Antedon] spp., the starfish [Crossaster papposus] and [Asterias rubens] and the brittlestar [Ophiothrix fragilis] (in low densities) may be found. The squat lobster [Munida rugosa] is likely to be found in crevices, under boulders, and the hermit crab [Pagurus bernhardus] may be observed moving around the rock surface. The brachiopod [Neocrania anomala] is frequently observed (especially where this biotope occurs shallower than unit A4.314 for example). The saddle oyster [Pododesmus patelliformis] may occasionally be seen attached to the rock/boulder face.

Situation: This biotope is typical of one found in sheltered sealochs. On slightly more wave and tide exposed sites, a transition to the more diverse A4.313 biotope will occur. Below A4.3111, you may find the A4.314 biotope (especially situated on the sills of sealochs).

Temporal variation: The abundance of [C. intestinalis] tends to fluctuate seasonally, so it may appear absent at a site at one time of year and then be present at other times, altering the visual appearance of the biotope. Other solitary ascidian species such as [A. mentula] and [Ascidiella aspersa] tend to be longer-lived (approximately 7 years and 3 years respectively).


HabitatName:
Dense brittlestars with sparse [Ascidia mentula] and [Ciona intestinali]s on sheltered circalittoral mixed substrata

HabitatDescription:
This biotope is typically found on wave-sheltered sites (although it may be found in wave-exposed through to extremely wave-sheltered conditions), on circalittoral mixed substrata (Bedrock, boulders, cobbles, pebbles and gravel), subject to moderately strong to weak tidal streams. This biotope often has a silty appearance in parallel with A4.3111 but is characterised by a dense carpet of brittlestars ([Ophiothrix fragilis], [Ophiocomina nigra] and to a lesser extent [Ophiura albida]) which virtually cover the seabed. Where the underlying substratum is visible, pink coralline crusts and the white calcareous tubes of the keelworm [Pomatoceros triqueter] are often observed. Hydroids and bryozoans are scarce, perhaps partly due to the smothering effect of the brittlestars and possibly due to the grazing pressure of the sea urchin [Echinus esculentus] which is occasionally recorded. Other echinoderms present include [Asterias rubens] and [Crossaster papposus]. The solitary ascidian [Ciona intestinalis] may be seen attached to isolated rocks and boulders, whilst on the tops and sides of larger boulders, dead man's fingers [Alcyonium digitatum] may be recorded. The hermit crab [Pagurus bernhardus] is often recorded, whilst under boulders and in crevices the claws belonging to the long-clawed squat lobster [Munida rugosa] may be seen.
Situation: A4.3112 is found in predominantly sheltered areas, so in the infralittoral zone above, kelp forest formed by dense [Laminaria saccharina] and cape-form [Laminaria hyperborea] are frequently recorded. A dense understorey of red algae is also present.


HabitatDescription:
A4.312 is characteristic of the wave-sheltered conditions found in the Kenmare River on the west coast of Ireland. This biotope is typically found on silty circalittoral bedrock and boulders in wave-sheltered channels subject to varying amounts of tidal flow. These fully marine inlets and channels have steep, often vertical sides with small terraces or ledges. This biotope, characterised by erect sponges and large solitary ascidians, appears to be biologically diverse. A diverse ascidian fauna is generally present, including [Ascidia mentula], [Aplidium punctum], [Corella parallelogramma], [Ascidia virginea], [Botryllus schlosseri], [Clavelina lepadiformis] and [Ciona intestinalis]. An equally diverse sponge fauna, with massive erect sponges particularly noticeable, compliments these species. Dominant species include [Esperiopsis fucorum], [Dysidea fragilis], [Tethya aurantium], [Polymastia boletiformis], [Raspailia ramosa], [Stelligera stuposa], [Polymastia mamilliaris] and [Pachymatisma johnstonia]. Other sponges present are [Suberites carnosus], [Haliclona fistulosa], [Stelligera rigida], [Mycale rotalis], [Haliclona simulans], [Iophon hyndmani] and [Hemimycale columella]. Various sponge crusts may also be present but in most cases in lower abundances. Other significant components of the community include the cup coral [Caryophyllia smithii] and various echinoderms, including the sea urchin [Echinus esculentus] and the starfish [Henricia oculata] and [Marthasterias glacialis]. Small isolated clumps of [Nemertesia antennina] and individual [Alcyonium digitatum] may be seen, whilst the top shell [Calliostoma zizyphinum] may also be present. At present, there are relatively few records in this biotope, as it is only reported from around the south-western coast of Ireland, where sponge diversity is very high.

Situation: Due to the sheltered nature of the biotope, this unit  is usually situated on bedrock/boulder outcrops associated with mud slopes and plains. Typical species found within these circalittoral muds include the seapen [Virgularia mirablis] and the anemone [Pachycerianthus multiplicatus]. In the infralittoral zone, sheltered kelp biotopes such as A5.521 with [Laminaria saccharina] occur frequently. In areas where there is a slightly stronger tidal-stream, the circalittoral muddy plains become more muddy gravel plains and slopes. Typical species found within these habitats include the anemones [Mesacmaea mitchellii] and [Aureliana heterocera]. When tidal-streams becomes negligible, but with similar wave-sheltered conditions, you tend to find A4.2111 biotopes occurring, especially in the same geographical location (around south-west/west Ireland) as A4.312.


HabitatName:
[Antedon] spp., solitary ascidians and fine hydroids on sheltered circalittoral rock

HabitatDescription:
This biotope is typically found on silty boulder or rock slopes, in the sheltered parts of sealochs, subject to weak or very weak tidal currents. The seabed consists of smooth, silty bedrock or boulders, often as outcrops on mixed muddy sediment. There are often small vertical faces on the sides of rock ridges, and at few sites, there may be more extensive steep or vertical bedrock. In sharp contrast to the barren, grazed appearance of A4.3111, the species composition of unit A4.313 is quite diverse, although no one phyla dominates. A wide range of encrusting species may be found, including the brachiopod [Neocrania anomala], the saddle oyster [Pododesmus patelliformis], encrusting red algae and polychaetes ([Pomatoceros triqueter] and [Protula tubularia]). Other conspicuous species include crinoids on the tops of boulders ([Antedon bifida], commoner in shallower water and [Antedon petasus], commoner in deeper water), scattered solitary and colonial ascidians ([Ascidia mentula], [Ascidia virginea], [Corella parallelogramma], [Clavelina lepadiformis] and [Ciona intestinalis]) and tufts of fine hydroids ([Kirchenpaueria pinnata], [Nemertesia antennina], [Obelia dichotoma] and [Halceum halecinum]). The cup coral [Caryophyllia smithii] and the crustose bryozoan [Parasmittina trispinosa] are all typically present, as are a wide range of echinoderms, including the sea urchin [Echinus esculentus], the starfish [Asterias rubens] and [Crossaster papposus], and the brittlestars [Ophiothrix fragilis] and [Ophiura albida]. Other species recorded are the squat lobster [Munida rugosa], the hermit crab [Pagurus bernhardus] and the chiton [Tonicella marmorea].
Situation: The range of biotopes shallower and deeper than A4.313 is typical of a sheltered sealoch. Silted kelp biotopes (e.g. units A3.312, A3.313) are typically found shallower than A4.313 in the infralittoral zone. Deeper than A4.313, the boulder slope typically grades into a muddy slope or plain (units A5.3 or A5.4), along with fauna commonly associated with soft-sediments (e.g. seapens and the mud snail [Turritella]).


HabitatName:
[Neocrania anomala] and [Protanthea simplex] on sheltered circalittoral rock

HabitatDescription:
This biotope typically occurs in full to variable salinity conditions on very wave-sheltered circalittoral bedrock and boulder slopes subject to negligible tidal streams (this tends to be in the landward, very sheltered basins of fjordic sealochs). This biotope is characterised by often dense populations of the anemone [Protanthea simplex], growing on the silty bedrock. The underlying rock surfaces are usually covered by encrusting red algae, the polychaete [Pomatoceros triqueter], the brachiopods [Neocrania anomala] and [Terebratulina retusa], the saddle oyster [Pododesmus patelliformis] and the polychaete [Sabella pavonina]. Scattered colonies of [Alcyonium digitatum] and the hydroid [Bougainvillia ramosa] may occasionally be recorded. A diverse range of ascidians including [Ciona intestinalis], [Ascidia mentula], [Corella parallelogramma], [Ascidia virginea], [Polycarpa pomaria] and [Dendrodoa grossularia] are also occasionally recorded. Echinoderms such as the common brittlestar [Ophiothrix fragilis] are frequently reported with their arms protruding from crevices in the rock, whilst the starfish [Asterias rubens], [Henricia oculata], and the sea urchin [Echinus esculentus] and [Psammechinus miliaris] are occasionally found on the boulder/rock surface. The whelk [Buccinum undatum] is often present but in very low numbers. The squat lobster [Munida rugosa] may be seen hiding in crevices. The hermit crab [Pagurus bernhardus] may also be recorded.


HabitatName:
[Neocrania anomala] and [Protanthea simplex] on very wave-sheltered circalittoral rock

HabitatDescription:
This variant typically occurs on deep, lower circalittoral bedrock or boulder slopes (often-vertical walls) in the landward, very sheltered basins of fjordic sealochs. In these very sheltered conditions, there are frequently dense populations of the anemone [Protanthea simplex] growing on the silty boulder or rock slope, and on the tubes of the parchment worm [Chaetopterus variopedatus]. The underlying rock surfaces are usually covered with encrusting red algae, the polychaete [Pomatoceros triqueter], the brachiopod [Neocrania anomala], the saddle oyster [Pododesmus patelliformis] and the conspicuous fan worm [Sabella pavonina]. Scattered colonies of [Alcyonium digitatum] are occasionally present along with the hydroid [Bougainvillia ramosa]. The barnacle [Balanus balanus] and the hermit crab [Pagurus bernhardus] is occasionally seen on boulder or rock surface, whilst underneath in crevices, the squat lobster [Munida rugosa] may be present. A diverse range of solitary ascidians, typically found in sheltered conditions, are often present including [Ciona intestinalis], [Corella parallelogramma], [Polycarpa pomaria], [Ascidia mentula] and [Ascidia virginea]. Echinoderms such as brittlestars [Ophiothrix fragilis] are frequently seen with their arms protruding from crevices in the rock, whilst the starfish [Asterias rubens], the sea urchin [Echinus esculentus] and [Psammechinus miliaris] are occasionally found on the boulder or rock surface. The whelk [Buccinum undatum] is often present but in very low numbers.
Situation: Where this biotope occurs on vertical rock cliffs, you tend to find silted sugar kelp [Laminaria saccharina] communities above A4.314, in the infralittoral zone (A3.313). Where A4.314 occurs on a rock or boulder slope and due to the very sheltered nature of the habitat, it is common to find a mud plain community where slope ends (A5.3). Species such as the seapen [Funiculina quadrangularis], the anemone [Cerianthus lloydii] and the Norway lobster [Nephrops norvegicus] are typically abundant.


HabitatName:
[Neocrania anomala], [Dendrodoa grossularia] and [Sarcodictyon roseum] on variable salinity circalittoral rock

HabitatDescription:
This variant typically occurs on lower circalittoral silty, bedrock or boulder cliffs and ridges in very wave-sheltered fjordic sealochs subjected to variable salinity regimes (such as Loch Etive, Scotland). In these sheltered conditions, there are frequently dense populations of the ascidian [Dendrodoa grossularia], the brachiopod [Neocrania anomala] and to a lesser extent, the brachiopod [Terebratulina retusa], which are able to tolerate the variable salinity. Other solitary ascidians that may be present include [Ciona intestinalis], [Corella parallelogramma], [Ascidiella scabra], [Ascidia mentula], [Ascidia virginea] and [Polycarpa pomaria]. The anemone [Protanthea simplex] is occasionally seen, although to a lesser extent than in unit A4.314, possibly due to the variable salinity. The hydroids [Bougainvillia ramosa] and [Lafoea dumosa], the cup-coral [Caryophilia smithii] and [Sarcodictyon roseum] are occasionally present. The tubes formed by the polychaete [Sabella pavonina] may be observed standing erect from the rock surface. The rest of the rock surface is usually covered by encrusting red algae and the polychaete [Pomatoceros triqueter] and [Protula tubularia]. The sea cucumber [Psolus phantapus] may be found on the underside of boulders. Other species such as the hermit crab [Pagurus bernhardus] and the spider crab [Hyas araneus] may be found amongst the rock/boulders. The starfish [Asterias rubens], [Crossaster papposus], and [Henricia] spp. and the sea urchin [Psammechinus miliaris] are also recorded within this variant. The relatively bare, silty rock supports low numbers of a relatively few species. Although barren rock grazed by the sea urchin [Echinus esculentus] is found in other sea loch biotopes (see units A4.2145 and A4.2146), [E.esculentus] is virtually absent within A4.3142.
Situation: Due to the variable or reduced salinity conditions present where this biotope is found, you tend to find reduced salinity kelp biotopes above A4.3142, such as A3.322 and A3.323. The very sheltered conditions give rise to muddy sediment slopes or plains beneath A4.314 (A5.3) where species such as the seapen [Funiculina quadrangularis], the anemone [Cerianthus lloydii] and the Norway lobster [Nephrops norvegicus] are typically abundant.


HabitatName:
Mediterranean coralligenous communities sheltered from hydrodynamic action

HabitatDescription:
Coralligenous concretions are found on rock faces or on rocks where calcareous algae can build biogenic constructions. These communities are present in the Mediterranean on hard rocky and/or biogenic substrata at 10 - 100 metres depth with low hydrodynamic action.


HabitatDescription:
This association populates hard poorly-lit substrata, in a sheltered environment, at about 25-45 metres depth.


HabitatDescription:
This facies is characterised by the high density of colonies of the gorgonian (sea-fan) [Lophogorgia sarmentosa].


HabitatName:
Faunal communities on deep low energy circalittoral rock


HabitatName:
Baltic moderately exposed circalittoral rock


HabitatDescription:
Circalittoral rock features include circalittoral fouling communities (A4.72) and circalittoral caves and overhangs (A4.71). These features are present throughout the circalittoral zone in a variety of wave exposures and tidal streams. Two fouling subtypes have also been identified: A4.722 has been recorded from disused fishing nets and other artificial substrata, and is characterised by aggregations of [Ascidiella aspersa] whilst A4.721 has been recorded from steel wrecks, and is characterised by dense aggregations of [Alcyonium digitatum] and [Metridium senile]. Habitats in hard substrata in the circalittoral zone characterised by the presence of seeping or bubbling gases, oils or water are also included (A4.73).


HabitatName:
Communities of circalittoral caves and overhangs

HabitatDescription:
Caves and overhanging rock in the circalittoral zone, away from significant influence of strong wave action (compare A3.71). This habitat may be colonised by a wide variety of species, with sponges such as [Dercitus bucklandi], anemones [Parazoanthus] spp. and the cup corals [Caryophyllia inornatus], [Hoplangia durotrix] and others particularly characteristic.


HabitatDescription:
This biotope occurs on shaded and overhanging rock, such as on cave walls and ceilings although there are very few records of caves in conditions not subject to wave surge (i.e. deeper circalittoral habitats) and almost all are different in species composition. There are also a few examples of similar communities on very deep (70-100 m+) upward-facing rock (in Loch Hourn) and more may be found through the use of ROVs. These often species-rich habitats are almost invariably adjacent to well-mixed turbulent water. Characteristic species include the sponges [Stryphnus ponderosus], [Dercitus bucklandi], [Chelonaplysilla noevus], [Pseudosuberites] sp. and [Spongosorites] sp., the anemones [Parazoanthus] spp., the cup corals [Leptopsammia pruvoti], [Hoplangia durotrix], [Caryophyllia inornatus] and the soft coral [Parerythropodium coralloides]. [Thymosia guernei] is sometimes present. This biotope is likely to need further splitting with further data and analysis.
Situation: Subtidal rocky coasts.


HabitatName:
Caves and overhangs with [Parazoanthus axinellae]

HabitatDescription:
This facies, characterised by the colonial sea anemone [Parazoanthus axinellae], occurs on hard bottoms affected by very rough water and relatively dim light. Found attached to rocks and sponges in open coast rocky habitats, it is often observed on vertical faces or beneath overhangs, at 6-100m depth.


HabitatName:
Caves and overhangs with [Corallium rubrum]

HabitatDescription:
This facies, characterised by the high presence of the cnidarian (red coral) [Corallium rubrum], occurs on walls of caves and/or cavities with coralligenous concretions and semi-dark overhangs. The vertical distribution of this facies occurs from 10 to 200 metres depth.


HabitatName:
Caves and overhangs with [Leptopsammia pruvoti]

HabitatDescription:
This facies with the madreporian (yellow coral) [Leptopsammia pruvoti] occurs on hard substrata at the entrance to caves and under overhangs.


HabitatName:
Caves and ducts in total darkness (including caves without light or water movement at upper levels)

HabitatDescription:
This habitat occurs in very large submerged cavities especially present in drowned karstic networks, isolated little cavities and microcavities in heaps of stones and within certain concretions. The caves in total darkness are enclaves of the aphotic area in the littoral area. These habitats present extremely original environmental conditions, close to those found on the continental slope. The two most important ecological factors are the absence of light, which rules out photosynthetic organisms, and the confined space.


HabitatDescription:
This habitat type contains two biotopes which, although have different physical habitat characteristics, share the fact that they colonise new areas of artificial substrata relatively quickly. The [Ascidiella aspersa] fouling biotope (A4.722) is found on wave-sheltered artificial substrata such as discarded fishing nets/mooring lines. A separate fouling biotope (A4.721) is described for open coast wrecks. This biotope has a characteristic faunal community of [Alcyonium digitatum] and the anemone [Metridium senile]. Other species recorded in this complex (primarily under subunit A4.721) include the hydroid [Nemertesia antennina], the anemones [Actinothoe sphyrodeta] and [Sagartia elegans], the cup coral [Caryophyllia smithii], the bryozoans [Flustra foliacea] and [Bugula plumosa], the crabs [Necora puber], [Cancer pagurus] and [Maja squinado] and the lobster [Homarus gammarus].


HabitatName:
[Alcyonium digitatum] and [Metridium senile] on moderately wave-exposed circalittoral steel wrecks

HabitatDescription:
This biotope is found on moderately wave-exposed circalittoral steel wrecks that are subject to moderately strong to weak tidal streams. The vertical and upward facing sides of the wreck stand proud of the seabed, and may be colonised by dense aggregations of [Alcyonium digitatum], [Metridium senile] and [Actinothoe sphyrodeta]. [Caryophyllia smithii] and [Corynactis viridis] are also recorded with varying abundance. A mixed faunal turf may also be present on the vertical sides, with [Nemertesia antennina], [Flustra foliacea] and [Bugula plumosa]. Where tidal stream strength is elevated, for example if the wreck is situated in a straight or sound, the hydroid [Tubularia indivisa] may prevail. Crustaceans such as the crabs [Necora puber], [Maja squinado] and [Cancer pagurus], the lobster [Homarus gammarus] and barnacles are all recorded. The top shell [Calliostoma zizyphinum] is also recorded.


HabitatName:
[Ascidiella aspersa] on circalittoral artificial substrata

HabitatDescription:
Sheltered artificial substrata (such as discarded fishing nets or scrap metal on muddy sediment plains), sometimes subject to variable salinity, with high numbers of the ascidian [Ascidiella aspersa] which is capable of rapidly colonising hard substrata. Other species that are quickly able to take advantage of such substrata include the dahlia anemone [Urticina felina] and the plumose anemone [Metridium senile]. The edible crab [Cancer pagurus], the velvet swimming crab [Necora puber] and the shore crab [Carcinus maenas] may occasionally be found hiding under the discarded nets, lobster pots or anchor chains.

Situation: As a fouling community, this biotope may be found throughout the circalittoral zone in coastal waters. It may be more prevalent around harbours, moorings, and fishing grounds where suitable substratum is available. In situations where wave exposure or tidal stream increase, biotopes dominated by bryozoans and/or robust hydroids (unit A4.21) may arise.

Temporal variation: A gradual development of more long-lived species is expected, where the artificial substrata are of a more permanent nature (e.g. wooden or concrete pier pilings).


HabitatName:
Pontic large Hydrozoa and [Molgula manhattensis] on circalittoral steel wrecks


HabitatName:
Pontic sulphide vents in infralittoral and circalittoral rock


HabitatName:
Pontic methane seeps in infralittoral and circalittoral rock


HabitatDescription:
Sediment habitats in the sublittoral near shore zone (i.e. covering the infralittoral and circalittoral zones), typically extending from the extreme lower shore down to the edge of the bathyal zone (200 m). Sediment ranges from boulders and cobbles, through pebbles and shingle, coarse sands, sands, fine sands, muds, and mixed sediments. Those communities found in or on sediment are described within this broad habitat type.


HabitatName:
Infralittoral coarse sediment in low or reduced salinity

HabitatDescription:
Includes bare Baltic gravel and shell bottoms in the infralittoral photic zone and the aphotic zone


HabitatName:
Baltic level gravel bottoms of the infralittoral photic zone with little or no macrophyte vegetation


HabitatName:
Baltic gravel banks of the infralittoral photic zone


HabitatName:
Baltic shell gravel bottoms in the infralittoral photic zone


HabitatName:
Baltic gravel bottoms of the aphotic zone


HabitatName:
Baltic shell gravel bottoms of the aphotic zone


HabitatDescription:
Moderately exposed habitats with coarse sand, gravelly sand, shingle and gravel in the infralittoral, are subject to disturbance by tidal steams and wave action. Such habitats found on the open coast or in tide-swept marine inlets are characterised by a robust fauna of infaunal polychaetes such as [Chaetozone setosa] and [Lanice conchilega], cumacean crustacea such as [Iphinoe trispinosa] and [Diastylis bradyi], and venerid bivalves. Habitats with the lancelet [Branchiostoma lanceolatum] may also occur.


HabitatDescription:
Sublittoral clean shingle and pebble habitats with a lack of conspicuous fauna. Unstable, rounded pebbles and stones (as opposed to sub-angular cobbles, which are often found lying on or embedded in other sediment) that are strongly affected by tidal steams and/or wave action can support few animals and are consequently faunally impoverished. The species composition of this biotope may be highly variable seasonally and is likely to comprise of low numbers of robust polychaetes or bivalves with occasional epibiota including echinoderms and crustacea such as [Liocarcinus] spp. and [Pagurus] spp. In more settled periods there may be colonisation by anemones such as [Urticina felina] and small populations of hydroids and Bryozoa.

Situation: This biotope is found in marine inlets with very strong tidal currents as well as in very wave exposed open coast environments.

Temporal variation: The faunal composition of this biotope is likely to be highly variable as a result of seasonal changes in wave and tidal energy.


HabitatName:
[Halcampa chrysanthellum] and [Edwardsia timida] on sublittoral clean stone gravel

HabitatDescription:
Periodically (seasonally?) disturbed sublittoral stone gravel with small pebbles characterised by the presence of the anemones [Halcampa chrysanthellum] and [Edwardsia timida]. Associated species are often typical of a hydroid/bryozoan turf with polychaetes such as [Pomatoceros] spp. encrusting larger pebbles and low numbers of syllid and phyllodocid polychaetes living interstitially. In some areas this biotope may also contain opportunistic red seaweeds and infauna such as [Sabella pavonina]. It should be noted that this habitat may show considerable variation in community composition and it is possible that it is a sub-biotope of other gravel biotopes.

Situation: This biotope tends to occur at the entrance to marine inlets where tidal currents are moderately strong.

Temporal variation: The faunal composition and species richness of this biotope may vary seasonally as a result of disturbance from increased wave or tidal action.


HabitatName:
[Moerella] spp. with venerid bivalves in infralittoral gravelly sand

HabitatDescription:
Infralittoral medium to coarse sand and gravelly sand which is subject to moderately strong water movement from tidal streams may be characterised by [Moerella] spp. with the polychaete [Glycera lapidum] (agg.) and venerid bivalves. Typical species include [Moerella pygmaea] or [M. donacina] with other robust bivalves such as [Dosinia lupinus], [Timoclea ovata], [Goodallia triangularis] and [Chamelea gallina]. Other infauna include nephtyd and spionid polychaetes and amphipod crustacea. Another important component of this biotope in some areas is the bivalve [Spisula solida] (see Khne & Rachnor 1996) which may be common or abundant. In conjunction with unit A5.242 this biotope may form part of the 'Shallow [Venus] Community', the 'Boreal Off-shore Sand Association' and the '[Goniadella-Spisula] association' of previous workers (see Petersen 1918; Jones 1951; Thorson 1957; Salzwedel, Rachor & Gerdes 1985). Epifaunal communities may be reduced in this biotope when compared to A5.242; both types may have surface sand waves which may be indicative of the presence of venerid bivalves (Warwick & Davies 1977). This hypothesis, however, requires testing. Remote grab sampling is likely to under-estimate venerid bivalves and other deep-burrowing and more dispersed species such as [Paphia], [Ensis] and [Spatangus]. In southern areas of the UK and the North Sea, in slightly siltier sand and shelly sand, A5.133 may give way to the other [Spisula] biotope A5.244.

Situation: This biotope is found on the exposed open coast and in estuaries with moderately strong tidal currents.


HabitatName:
[Hesionura elongata] and [Microphthalmus similis] with other interstitial polychaetes in infralittoral mobile coarse sand

HabitatDescription:
On infralittoral sandbanks and sandwaves and other areas of mobile medium-coarse sand, populations of interstitial polychaetes may be found. These habitats consist of loosely packed grains of sand forming waves up to several metres high often with gravel, or occasionally silt, in the troughs of the waves. This biotope is commonly found both inshore along the east coast of the UK e.g. around the Race Bank, Docking Shoal and Inner Dowsing banks (IECS, 1995; IECS, 1999), and in the Southern Bight of the North Sea and off the Belgian coast (Degraer [et al]. 1999; Vanosmael [et al]. 1982). These habitats support interstitial communities living in the spaces between the grains of sand, in particular hesionurid polychaetes such as [Hesionura elongata] and [Microphthalmus similis], along with protodrilid polychaetes such as [Protodrilus] spp. and [Protodriloides] spp. Other important species may include Turbellaria spp. and larger deposit feeding polychaetes such as [Travisia forbesii]. An important feature of this biotope which is not reflected in much of the available data is the importance of the meiofaunal population which may exceed the macrofaunal population both in terms of abundance and biomass (Willems [et al]. 1982).
Situation: This biotope is commonly found both in shore adjacent to the coast, and further away from the coast.


HabitatName:
[Glycera lapidum] in impoverished infralittoral mobile gravel and sand

HabitatDescription:
In infralittoral mixed slightly gravelly sands on exposed open coasts impoverished communities characterised by the polychaete [Glycera lapidum] (agg.) may be found. [Glycera lapidum] is a species complex and as such some variability in identification may be found in the literature. It is also quite widespread and may occur in a variety of coarser sediments and is often present in other A5.1 subunits. However, it is rarely considered a characteristic species and where this is the case it is normally due to the exclusion of other species. Consequently it is considered that habitats containing this biotope may be subject to continual or periodic sediment disturbance from wave action, which prevents the establishment of a more stable community. Other taxa include spionid polychaetes such as [Spio martinensis] and [Spiophanes bombyx, Nephtys] spp. and in some areas the bivalve [Spisula elliptica]. It is possible that A5.135 is not a true biotope, rather an impoverished, transitional community, which in more settled conditions develops into other more stable communities.

Situation: In many cases e.g. along the East Yorkshire coast this biotope is found in shallow inshore areas facing directly into the prevailing wind and subject to considerable wave action.

Temporal variation: Due to the variability in sediment regime at these habitats there may be high seasonal or spatial variability within this community.


HabitatName:
Cumaceans and [Chaetozone setosa] in infralittoral gravelly sand

HabitatDescription:
In shallow medium-fine sands with gravel, on moderately exposed open coasts, communities dominated by cumacean crustaceans such as [Iphinoe trispinosa] and [Diastylis bradyi] along with the cirratulid polychaete [Chaetozone setosa] (agg.) may occur. [Chaetozone setosa] is a species complex so it is likely that some variability in nomenclature will be found in the literature. Other important taxa may include the polychaetes [Anaitides] spp., [Lanice conchilega], [Eteone longa] and [Scoloplos armiger]. This community may be subject to periodical sedimentary disturbance, such that a sub-climactic community may develop with opportunistic taxa such as [C. setosa] and [S. armiger] often dominating the community (Allen 2000).

Situation: This biotope may be found in areas with moderate currents and wave action often facing into the prevailing wind and along the Holderness coast of the North Sea. It is possible that this biotope has developed due to chronic sedimentary disturbance in areas where the units A5.261 or A5.242 would normally develop as these biotopes are often found in more sheltered areas adjacent to A5.136.

Temporal variation: The importance of the cumacean crustaceans in this biotope is unusual, and their numbers are likely to fluctuate over time; at times of increased disturbance it is likely that C. setosa will become more dominant.


HabitatName:
Dense [Lanice conchilega] and other polychaetes in tide-swept infralittoral sand and mixed gravelly sand

HabitatDescription:
Dense beds of [Lanice conchilega] occur in coarse to medium fine gravelly sand in the shallow sublittoral, where there are strong tidal streams or wave action. Several other species of polychaete also occur as infauna e.g. [Spiophanes bombyx], [Scoloplos armiger], [Chaetozone setosa] and [Magelona mirabilis]. Lanice beds are found in a wide range of habitats including muddier mixed sediment. The dense [Lanice] biotope (A5.137) on certain lower shores may be a littoral extension of the current biotope. The presence of [L. conchilega] in high numbersmay, over time, stabilise the sediment to the extent where a more diverse community may develop (Wood, 1987). Possibly as a result of this, there is a high level of variation with regard the infauna found in A5.137. It is likely that a number of sub-biotopes may subsequently be identified for this biotope. Offshore from the Wash and the North Norfolk coast [Lanice] beds are often found intermixed with [Sabellaria spinulosa] beds in muddier mixed sediment, particularly in the channels between the shallow sandbanks, which are so prevalent in this area (IECS, 1995; NRA, 1995). It is possible that the presence of [Lanice] has stabilised the habitat sufficiently to allow the deposition of finer material, which has subsequently assisted the development of [S. spinulosa]. It may be more accurate to define A5.137 as an epibiotic biotope which overlays a variety of infaunal biotopes (e.g. A5.233 in finer sands and A5.261 or A5.242 in slightly muddier areas).


HabitatName:
Association with rhodolithes in coarse sands and fine gravels mixed by waves

HabitatDescription:
This association occurs on coarse sands and fine gravels subjected to strong hydrodynamic action. Calcareous algae are attached to a small mineral or organic surface and then grow in successive layers to form rhodolithes of more or less nodulous shape and varying size.


HabitatDescription:
This facies is characterised by the abundance of the little clingfish [Gouania willdenovii] that live in shallow waters.


HabitatName:
Greenland cockle [Serripes] in shallow coarse sand (influenced by warm low-salinity melt water) of the Arctic


HabitatName:
Pontic clean medium-coarse sands with bivalve associations


HabitatName:
Medium-coarse clean sands with [Donax trunculus] and sometimes [Donacilla cornea]

HabitatDescription:
Other species present in the biocenosis: [Ciclopa perinitea], [Nassarius nitidus], [Diogenus pugillatus].


HabitatName:
Medium-coarse clean sands with [Chamelea gallina]


HabitatName:
Medium-coarse clean sands with [Anadara inaequivalvis]


HabitatName:
Coarse sands with [Gouldia minima] and amphipods


HabitatName:
Pontic offshore infralittoral coarse sand banks


HabitatName:
Pontic [Aonides ornatus], [Modiolus adriaticus] and [Gouldia minima] in coarse sand with shell gravel


HabitatName:
Pontic [Branchiostoma lanceolatum], [Protodorvillea kefersteini] and [Ophelia limacina] in coarse sand with shell gravel


HabitatName:
Pontic infralittoral wave-lashed fine gravels and coarse sands


HabitatName:
Pontic infralittoral sheltered cobbles, pebbles and shelly gravels with encrusting spirorbid worms


HabitatName:
Pontic scoured sublittoral cobbles and pebbles with sparse crustaceans


HabitatName:
Pontic silted cobbles with [Balanus eburneus], ascidians, [Actinia aequina], [Mytilus galloprovincialis] and [Pisidia longicornis]


HabitatDescription:
Tide-swept circalittoral coarse sands, gravel and shingle generally in depths of over 15-20m. This habitat may be found in tidal channels of marine inlets, along exposed coasts and offshore. This habitat, as with shallower coarse sediments, may be characterised by robust infaunal polychaetes, mobile crustacea and bivalves. Certain species of sea cucumber (e.g. [Neopentadactyla]) may also be prevalent in these areas along with the lancelet [Branchiostoma lanceolatum].


HabitatName:
[Pomatoceros triqueter] with barnacles and bryozoan crusts on unstable circalittoral cobbles and pebbles

HabitatDescription:
This biotope is characterised by a few ubiquitous robust and/or fast growing ephemeral species which are able to colonise pebbles and unstable cobbles and slates which are regularly moved by wave and tidal action. The main cover organisms tend to be restricted to calcareous tube worms such as [Pomatoceros triqueter] (or [P. lamarcki)], small barnacles including [Balanus crenatus] and [Balanus balanus], and a few bryozoan and coralline algal crusts. Scour action from the mobile substratum prevents colonisation by more delicate species. Occasionally in tide-swept conditions tufts of hydroids such as [Sertularia argentea] and [Hydrallmania falcata] are present. This biotope often grades into A5.444 which is characterised by large amounts of the above hydroids on stones also covered in [Pomatoceros] and barnacles. The main difference here is that A5.444, seems to develop on more stable, consolidated cobbles and pebbles or larger stones set in sediment in moderate tides. These stones may be disturbed in the winter and therefore long-lived and fragile species are not found.
Situation: This biotope is found on exposed open coasts as well as at the entrance to marine inlets.


HabitatName:
[Mediomastus fragilis], [Lumbrineris] spp. and venerid bivalves in circalittoral coarse sand or gravel

HabitatDescription:
Circalittoral gravels, coarse to medium sands, and shell gravels, sometimes with a small amount of silt and generally in relatively deep water (generally over 15-20m), may be characterised by polychaetes such as [Mediomastus fragilis], [Lumbrineris] spp., [Glycera lapidum] with the pea urchin [Echinocyamus pusillus]. Other taxa may include Nemertea spp., [Protodorvillea kefersteini, Owenia fusiformis, Spiophanes bombyx] and [Amphipholis squamata] along with amphipods such as [Ampelisca spinipes]. This biotope may also be characterised by the presence of conspicuous venerid bivalves, particularly [Timoclea ovata]. Other robust bivalve species such as [Moerella] spp., [Glycymeris glycymeris] and [Astarte sulcata] may also be found in this biotope. [Spatangus purpureus] may be present especially where the interstices of the gravel are filled by finer particles, in which case, [Gari tellinella] may also be prevalent (Glemarec 1973). Venerid bivalves are often under-sampled in benthic grab surveys and as such may not be conspicuous in many infaunal datasets. Such communities in gravelly sediments may be relatively species-rich and they may also contain epifauna such as [Hydroides norvegicus] and [Pomatoceros lamarcki]. In sand wave areas this biotope may also contain elements of the A5.242 biotope, particularly [Magelona] species. This biotope has previously been described as the 'Deep [Venus] Community' and the 'Boreal Off-Shore Gravel Association' by other workers (Ford 1923; Jones 1950) and may also be part of the Venus community described by Thorson (1957) and in the infralittoral etage described by Glemarec (1973). A5.142 may be quite variable over time and in fact may be closer to a biotope complex in which a number of biotopes or sub-biotopes may yet be defined. For example, Ford (1923) describes a 'Series A' and a 'Series B' characterised by [Echinocardium cordatum-Chamelea gallina] and [Spatangus purpurea-Clausinella fasciata]. Furthermore, mosaics of cobble and lag gravel often contain ridges of coarse gravelly sand and these localised patches are also characterised by robust veneriid and similar bivalves including [Arcopagia crassa, Laevicardium crassum] and others including [Glycymeris glycymeris] (E.I.S. Rees pers. comm. 2002). This high porosity fine gravel or coarse sand may be a separate biotope.

Situation: This biotope and variants of it make up a significant proportion of the offshore Irish Sea benthos (Mackie, Oliver & Rees 1995).

Temporal variation: A5.142 may be quite variable over time.


HabitatName:
[Protodorvillea kefersteini] and other polychaetes in impoverished circalittoral mixed gravelly sand

HabitatDescription:
In coarse gravelly or shelly sand sometimes with a slight mud content, along open coasts in depths of 10 to 30m, and in shallower offshore areas, an impoverished community characterised by [Protodorvillea kefersteini] may be found. This biotope has a number of other species associated with it including Nemertea spp., [Caulleriella] [zetlandica], [Minuspio cirrifera], [Glycera lapidum], [Ampelisca spinipes] and numerous other polychaete species all occurring at low abundances. The polychaete [Sabellaria spinulosa] is also found in low numbers in this biotope

Situation: This biotope has been reported in the North Sea along the Norfolk/Lincolnshire coast located in and around marine aggregate dredging areas (IECS, 1999).

Temporal variation: This biotope may be quite variable both spatially and temporally in terms community structure and also sediment type which is often borderline between  A5.1 & subunits and A5.4 and subunits.


HabitatName:
[Neopentadactyla mixta] in circalittoral shell gravel or coarse sand

HabitatDescription:
Sublittoral plains of clean, shell, maerl and / or stone gravels or sometimes coarse sands, with frequent [Neopentadactyla mixta]. [Pecten maximus] may occur occasionally along with [Lanice conchilega]. Other epifaunal species may include [Ophiura albida, Pagurus] spp. and [Callionymus] spp. These sediments may be thrown into dunes by wave action or tidal streams. Widespread species such as [Cerianthus lloydii] and [Chaetopterus variopedatus] are present in many examples of this biotope. Scarcely recorded species such as [Molgula oculata], [Ophiopsila annulosa] and [Amphiura securigera] may also be found. [O. annulosa] only occurs in records from the south-west of the British Isles. It should be noted that [Neopentadactyla] may exhibit periodicity in its projection out of, and retraction into, the sediment (Picton 1993).This biotope may be an epibiotic overlay of  unit A5.142.

Situation: This biotope may occur adjacent to maerl beds and to some extent in the lower infralittoral where some seaweeds may occur in low abundances.


HabitatDescription:
Gravel and coarse sand with shell gravel often contains communities of robust venerid bivalves (A5.142). Shallower examples, such as the biotope presented here, may support a significant population of [Branchiostoma lanceolatum]. Other conspicuous infauna may include [Echinocyamus pusillus], [Glycera lapidum], [Polygordius, Pisione remota] and [Arcopagia crassa] (in the south of UK). Sessile epifauna are typically a minor component of this community. This biotope has been described from a limited number of records and as such may need revising when further data become available. This biotope is related to the 'Boreal Offshore Gravel Association' and 'Deep [Venus] Community' described by other workers (Ford 1923; Jones 1951), and may also be closely allied (the same?) as the '[Venus fasciata]' community of Cabioch (Glemarec 1973). This biotope may be an epibiotic overlay of the biotope A5.133 or A5.142.


HabitatName:
Scallops on shell gravel and sand with some sand scour


HabitatDescription:
Offshore (deep) circalittoral habitats with coarse sands and gravel or shell. This habitat may cover large areas of the offshore continental shelf although there is relatively little quantitative data available. Such habitats are quite diverse compared to shallower versions of this habitat and generally characterised by robust infaunal polychaete and bivalve species. Animal communities in this habitat are closely related to offshore mixed sediments and in some areas settlement of [Modiolus modiolus] larvae may occur and consequently these habitats may occasionally have large numbers of juvenile [M. modiolus]. In areas where the mussels reach maturity their byssus threads bind the sediment together, increasing stability and allowing an increased deposition of silt leading to the development of the biotope A5.622.


HabitatName:
[Glycera lapidum], [Thyasira] spp. and [Amythasides macroglossus] in offshore gravelly sand

HabitatDescription:
Offshore (deep) circalittoral habitats with coarse sands and gravel, stone or shell and occasionally a little silt (&lt;5%) may be characterised by the polychaetes [Glycera lapidum] and [Amythasides macroglossus] with the bivalve [Thyasira] spp. (particularly [Thyasira succisa]). Other taxa include polychaetes such as [Exogone verugera], [Notomastus latericeus], [Spiophanes kroyeri],[Aphelochaeta marioni] ([Tharyx marioni]) and [Lumbrineris gracilis] and occasional numbers of the bivalve [Timoclea ovata]. This biotope bears some resemblance to the shallow A5.135 and also to the circalittoral and offshore venerid biotopes (units A5.142 and A5.451) but differs by the range of polychaete and bivalve fauna present. This biotope is notable for the presence of the rarely recorded ampharetid polychaete [Amythasides macroglossus] and also for the small ear file clam [Limatula subauriculata] which is common in some examples of this biotope.


HabitatName:
[Hesionura elongata] and [Protodorvillea kefersteini] in offshore coarse sand

HabitatDescription:
Offshore (deep) circalittoral habitats with coarse sand may support populations of the interstitial polychaete [Hesionura elongata] with [Protodorvillea kefersteini]. Other notable species include the phyllodocid polychaete [Protomystides limbata] and the bivalve [Moerella pygmaea]. This biotope was reported in the offshore northern North Sea by Eleftheriou and Basford (1989). Relatively little data exists for this biotope.


HabitatName:
Pontic offshore shell gravel in strong currents


HabitatName:
Pontic offshore shell gravel with crustose corallines, sparse [Phyllophora crispa] and [Mytilus galloprovincialis]


HabitatName:
Pontic offshore barren shell gravel with [Polydora ciliata]


HabitatName:
Pontic very deep Wurmian shell gravel of the shelf margin


HabitatName:
Sublittoral sand in low or reduced salinity

HabitatDescription:
Shallow sand and muddy sand in areas of low or reduced, although relatively stable salinity (may vary annually), with largely ephemeral faunal communities. The species are often similar to that found in A5.31 and are characterised by [Arenicola marina] with other species, including mysids, tubificoid and enchytraeid oligochaetes, [Corophium volutator], [Hediste diversicolor], [Pygospio elegans], [Hydrobia ulvae] and [Cerastoderma glaucum], which commonly occur in lagoons. Filamentous green algae such as [Chaetomorpha linum] may also be present. In some examples of this biotope the polychaete [Fabricia sabella] may be super-abundant and the isopod [Sphaeroma hookeri] common.


HabitatName:
Baltic level sandy bottoms of the infralittoral photic zone with little or no macrophyte vegetation


HabitatName:
Baltic sand bars of the infralittoral photic zone


HabitatName:
Baltic sand banks of the infralittoral photic zone


HabitatName:
[Macoma balthica] in brackish environment (seasonally ice-covered)


HabitatDescription:
Very mobile sand in areas of strong tidal currents and variable salinity. No stable community is able to develop within this extremely mobile and abrasive habitat. The fauna encountered in this habitat consists of epifaunal crustaceans or relatively low numbers of robust species, such as the isopod [Eurydice pulchra] or [Mesopodopsis slabberi]. The polychaete [Capitella capitata] may occur frequently in some areas. Other taxa such as the polychaetes [Eteone] spp. and [Arenicola marina], the mysid [Neomysis integer] and the amphipods [Bathyporeia] spp. and [Haustorius arenarius] may also be washed in from adjacent communities. This biotope is found in tidal channels of estuaries and areas where water movement keeps silt and mud in suspension, and excludes even the more robust infauna. If oligochaetes, polychaetes and bivalves are present in any numbers within this habitat type then care must be taken to avoid the inclusion of juvenile or spat recruitment counts which may mask the presence of this biotope. This is particularly relevant as sampling usually occurs at slack water periods when settlement takes place


HabitatName:
[Nephtys cirrosa] and [Macoma balthica] in variable salinity infralittoral mobile sand

HabitatDescription:
Mobile sand in variable salinity conditions where tidal currents create an unstable shifting habitat. Characteristic species include the polychaetes [Nephtys cirrosa] and [Scoloplos armiger] along with amphipods of the genus [Bathyporeia] and [Haustorius arenarius]. The bivalve [Macoma balthica] may occur in more stable examples of this biotope, although not in the abundances found in unit A5.331. The biotope contains relatively few species, each typically in low to moderate abundance. It is found in tidal channels with moderate tidal streams. Care should be taken in identification of this biotope due to the presence juveniles and species washed in during slack water.


HabitatName:
[Neomysis integer] and [Gammarus] spp. in fluctuating low salinity infralittoral mobile sand

HabitatDescription:
Upper estuary mobile fine muddy sands with very low fluctuating salinity characterised by the mysid shrimp [Neomysis integer] (see Arndt 1991) and amphipods of the genus [Gammarus] spp. This habitat has a rather sparse infauna and species such as [N. integer] will most likely be found on the sediment surface or just above it whilst [Gammarus] may be under loose weed, stones or other detritus on the sediment surface. The harsh physicochemical regime imposed by such environmental conditions in the upper estuary leads to a relatively impoverished community but high densities of the mobile, salinity-tolerant, crustaceans can occur. The biotope is found in the transitional zone between freshwater and brackish environments, relying on the decreased freshwater input during the summer for penetration of the brackish species up-stream. As such this biotope may also contain elements of freshwater communities.

Situation: It may be found in conjunction with A5.327, although it lacks appreciable numbers of oligochaetes.

Temporal variation: Numbers of [Neomysis] may to fluctuate on a seasonal basis due high over wintering mortality (Gameson 1982) and the location of this biotope within the estuary may also shift upstream or downstream on a seasonal or yearly basis related in part to the freshwater flow into the estuary as has been noted in the Humber (Allen [et al]. 2003).


HabitatName:
Pontic mobile sands of the Danube mouths


HabitatDescription:
Clean sands which occur in shallow water, either on the open coast or in tide-swept channels of marine inlets. The habitat typically lacks a significant seaweed component and is characterised by robust fauna, particularly amphipods ([Bathyporeia]) and robust polychaetes including [Nephtys cirrosa] and [Lanice conchilega].


HabitatDescription:
Medium to fine sandy sediment in shallow water, often formed into dunes, on exposed or tide-swept coasts often contains very little infauna due to the mobility of the substratum. Some opportunistic populations of infaunal amphipods may occur, particularly in less mobile examples in conjunction with low numbers of mysids such as [Gastrosaccus spinifer], the polychaete [Nephtys cirrosa] and the isopod [Eurydice pulchra]. Sand eels [Ammodytes] sp. may occasionally be observed in association with this biotope (and others). This biotope is more mobile than A5.233 and may be closely related to A2.221 on the shore. Common epifaunal species such as [Pagurus bernhardus], [Liocarcinus depurator], [Carcinus maenas] and [Asterias rubens] may be encountered and are the most conspicuous species present.


HabitatName:
[Sertularia cupressina] and [Hydrallmania falcata] on tide-swept sublittoral sand with cobbles or pebbles

HabitatDescription:
Shallow sands with cobbles and pebbles, exposed to strong tidal streams, with conspicuous colonies of hydroids, particularly [Hydrallmania falcata] and to a lesser extent [Sertularia cupressina] and [S. argentea]. These hydroids are tolerant to periodic submergence and scour by sand. Both diving and dredge surveys will easily record this biotope. [Flustra foliacea, Balanus crenatus] and [Alcyonidium diaphanum] may also occur on the more stable cobbles and pebbles, with [Urticina felina] and occasional [Lanice conchilega] present in the sand. Infaunal components of the other biotopes in the A5.1 or A5.2 complex may occur in this biotope as may elements of the 'Venus' associations; indeed, this biotope may be at one extreme of the spectrum of such associations (E.I.S. Rees pers. comm. 1997) and this biotope may be best considered an epibiotic overlay.


HabitatName:
[Nephtys cirrosa] and [Bathyporeia] spp. in infralittoral sand

HabitatDescription:
Well-sorted medium and fine sands characterised by [Nephtys cirrosa] and [Bathyporeia] spp. (and sometimes [Pontocrates] spp.) which occur in the shallow sublittoral to at least 30 m depth. This biotope occurs in sediments subject to physical disturbance, as a result of wave action (and occasionally strong tidal streams). The magelonid polychaete [Magelona mirabilis] may be frequent in this biotope in more sheltered, less tideswept areas whilst in coarser sediments the opportunistic polychaete [Chaetozone setosa] may be commonly found. The faunal diversity of this biotope is considerably reduced compared to less disturbed biotopes (such as unit A5.242) and for the most part consists of the more actively-swimming amphipods. Sand eels [Ammodytes] sp. may occasionally be observed in association with this biotope (and others) and spionid polychaetes such as [Spio filicornis] and [S. martinensis] may also be present. Occasional [Lanice conchilega] may be visible at the sediment surface.
Temporal variation: Stochastic recruitment events in the [Nephtys cirrosa] populations may be very important to the population size of other polychaetes present and may therefore create a degree of variation in community composition (Bamber 1994).


HabitatDescription:
Sublittoral marine sand in moderately exposed or sheltered inlets and voes in shallow water may support large populations of semi-permanent tube-building amphipods and polychaetes. Typically dominated by [Corophium crassicorne] with other tube building amphipods such as [Ampelisca] spp. also common. Other taxa include typical shallow sand fauna such as [Spiophanes bombyx], [Urothoe elegans], [Bathyporeia] spp. along with various polychaetes including [Exogone hebes] and [Lanice conchilega]. [Polydora ciliata] may also be abundant in some areas. At the sediment surface, Arenicola marina worm casts may be visible and occasional seaweeds such as [Laminaria saccharina] may be present. As many of the sites featuring this biotope are situated near to fish farms it is possible that it may have developed as the result of moderate nutrient enrichment. The distribution of this biotope is poorly known and like the muddier A5.335, to which it is related, appears to have a patchy distribution.
Temporal variation: It is possible that this biotope is a temporal or spatial variant of other more stable biotopes resulting from localised changes to sediment stability and organic status.


HabitatName:
Mediterranean communities of fine sands in very shallow waters

HabitatDescription:
These assemblages occur in very shallow water with seabottoms characterised by fine sands, usually with homogenous granulometry and of terrigenous origin.


HabitatDescription:
This facies is present in shallow water and is characterised by the mollusc bivalve [Lentidium mediterraneum].


HabitatName:
Mediterranean communities of well sorted fine sands

HabitatDescription:
This biocenosis often occupies vast areas along low coasts and in the bottoms of wide bays at depths 2 - 25 metres.The characteristic species are pelecypod molluscs (e.g. [Donax venustus], [Tellina pulchella], [Tellina planata], [Cardium tuberculatum]), gastropods (e.g. [Nassa mutabilis] and [Neverita josephina]), crustaceans (e.g. [Crangon crangon] and [Iphinoe josephina]) and small fish (e.g. [Gobius microps], [Callionymus belenus], [Solea solea] and [Trachinus draco]).


HabitatName:
Pontic communities of well sorted fine sands


HabitatName:
Pontic shallow fine sands with [Lentidium mediterraneum], [Cerastoderma glaucum], [Cyclope neritea] and amphipod tubes


HabitatName:
Pontic well sorted fine sands with [Lentidium mediterraneum], [Mya arenaria], [Anadara inaequivalvis] and [Crangon crangon]


HabitatName:
Pontic fine sands with [Donax venustus], [Lentidium mediterraneum] and [Lucinella divaricata]


HabitatName:
Pontic shallow clean fine sands with [Chamelea gallina], [Lentidium mediterraneum] and [Divaricella divaricata]

HabitatDescription:
This is a facies of the Pontic well sorted infralittoral fine sands. The [Chamelea gallina] community characterised by the dominant species - [Neanthes succinea], [Spio filicornis], [Mohrensternia lineolata], occurred in Karkinitska Bay (Sinegub 2006). Since 2005 this mollusc (with [Neanthes succinea], [Polydora ciliata], [Heteromastus filiformis], [Melinna palmata], [Balanus improvisus]) has formed a community in the Odessa region (Sinegub unpubl). This habitat has been commercially exploited in Turkey between 1985-2000.


HabitatName:
Pontic fine sands with [Loripes lacteus], [Pestarella candida] and [Tellina tenuis ]


HabitatName:
Pontic fine sands with [Lucinella divaricata], [Abra alba] and [Upogebia pusilla]


HabitatName:
Pontic fine sands with [Arenicola marina]


HabitatName:
Pontic fine sands with [Chamelea gallina], [Cyclope neritea] and [Nassarius nitidus]


HabitatName:
Pontic fine sands with [Solen marginatus]

HabitatDescription:
This habitat is found in or around [Zostera] meadows when the latter is sparse.


HabitatName:
Pontic fine sand with [Anadara inequivalvis]

HabitatDescription:
This facies was found out in Zhebriyanska Bay (1992-2002) and is considered a habitat that is vulnerable to pollution.


HabitatName:
Pontic fine and muddy sands with [Mya arenaria]

HabitatDescription:
The [Mya arenaria] biocoenosis can be found on sandy and silty-sandy sediments, in habitats which mainly disperse into fresh waters (Gomoiou 1981, Petran and Gomoiou 1972, Zaitsev and Alexandrov 1998). This allochtonous species, recorded for the first time in the Black Sea in 1966, is tolerant to pollution and as such has substituted [Lentidium mediterraneum], where this biocenosis has disappeared as a result of habitat degradation. This biocenosis is now present in the estuarine regions of the northwestern Black Sea. The dominant species (Mya) accounts for an average of 80% of the total density and biomass of the biocenosis itself. In areas with conspicuous river run-off such as the Danube-Dnester this value can rise to as much as 96%. The accompanying species are the polichaetes [Nereis succinea] and [Polydora ciliata limicola]. (Zaitsev and Alexandrov 1998).


HabitatDescription:
Non-cohesive muddy sand (with 5% to 20% silt/clay) in the infralittoral zone, extending from the extreme lower shore down to more stable circalittoral zone at about 15-20 m. The habitat supports a variety of animal-dominated communities, particularly polychaetes ([Magelona mirabilis], [Spiophanes bombyx] and [Chaetozone setosa]), bivalves ([Fabulina fibula] and [Chamelea gallina]) and the urchin [Echinocardium cordatum].


HabitatName:
[Echinocardium cordatum] and [Ensis] spp. in lower shore and shallow sublittoral slightly muddy fine sand

HabitatDescription:
Sheltered lower shore and shallow sublittoral sediments of sand or muddy fine sand in fully marine conditions, support populations of the urchin [Echinocardium cordatum] and the razor shell [Ensis siliqua] or [Ensis ensis]. Other notable taxa within this biotope include occasional [Lanice conchilega], [Pagurus] and [Liocarcinus] spp. and [Asterias rubens]. This biotope has primarily been recorded by epifaunal dive, video or trawl surveys where the presence of relatively conspicuous taxa such as E. cordatum and Ensis spp. have been recorded as characteristic of the community. However, these species, particularly [E. cordatum] have a wide distribution and are not necessarily the best choice for a characteristic taxa (Thorson, 1957). Furthermore, detailed quantitative infaunal data for this biotope is often rather scarce, possibly as a result of survey method as remote grab sampling is likely to under-estimate deep-burrowing species such as [Ensis] sp. (Warwick & Davis 1977). Consequently, it may be better to treat this biotope as an epibiotic overlay which is likely to overlap a number of other biotopes such as units A5.242, A5.233 and A5.261 with infaunal components of these biotopes occurring within A5.241. The precise nature of this infaunal community will be related to the nature of the substratum, in particular the quantity of silt/clay present. Infaunal species may include the polychaetes [Spiophanes bombyx], [Magelona mirabilis], [Nephtys cirrosa] and [Chaetozone setosa] and the amphipod [Bathyporeia] spp. This biotope is currently broadly defined and needs further consideration as to whether it should be placed at biotope or biotope complex level. A5.243 is another biotope based primarily on epibiotic data. It is likely that this biotope and A5.241 form a wider epibiotic sand /muddy sand community with A5.241 biased towards sandier areas and A5.243 towards slightly muddier areas.


HabitatName:
[Fabulina fabula] and [Magelona mirabilis] with venerid bivalves and amphipods in infralittoral compacted fine muddy sand

HabitatDescription:
In stable, fine, compacted sands and slightly muddy sands in the infralittoral and littoral fringe, communities occur that are dominated by venerid bivalves such as [Chamelea gallina]. This biotope may be characterised by a prevalence of [Fabulina fabula] and [Magelona mirabilis] or other species of [Magelona (e.g. [M. filiformis)]. Other taxa, including the amphipod [Bathyporeia] spp. and polychaetes such as [Chaetozone setosa], [Spiophanes bombyx] and [Nephtys] spp. are also commonly recorded. In some areas the bivalve [Spisula elliptica] may also occur in this biotope in low numbers. The community is relatively stable in its species composition, however, numbers of [Magelona] and [F. Fabulina] tend to fluctuate. Around the Scilly Isles numbers of [F. fabulina] in this biotope are uncommonly low whilst these taxa are often found in higher abundances in muddier communities (presumably due to the higher organic content). Consequently it may be better to revise this biotope on the basis of less ubiquitous taxa such as key amphipod species (E.I.S. Rees pers. comm. 2002) although more data is required to test this. A5.242 and A5.133 are collectively considered to be the 'shallow [Venus] community' or 'boreal off-shore sand association' of previous workers (see Petersen 1918; Jones 1950; Thorson 1957). These communities have been shown to correlate well with particular levels of current induced 'bed-stress' (Warwick & Uncles 1980). The 'Arctic [Venus] Community' and 'Mediterranean [Venus] Community' described to the north and south of the UK (Thorson 1957) probably occur in the same habitat and appears to be the same biotope described as the [Ophelia borealis] community in northern France and the central North Sea (Künitzer [et al]. 1992). Sites with this biotope may undergo transitions in community composition. The epibiotic biotopes A5.241 and A5.243 may also overlay this biotope in some areas.


HabitatName:
[Arenicola marina] in infralittoral fine sand or muddy sand

HabitatDescription:
In shallow fine sand or non-cohesive muddy sand in fully marine conditions (or occasionally in variable salinity) a community characterised by the polychaete [Arenicola marina] may occur. This biotope appears quite faunally sparse. Those other taxa present however, include scavenging crustacea such as [Pagurus bernhardus] and [Liocarcinus depurator], terebellid polychaetes such as [Lanice conchilega] and the burrowing anemone [Cerianthus lloydii]. Occasional [Sabella pavonina] and frequent [Ensis] spp. may also be observed in some areas. The majority of records for this biotope are derived from epifaunal surveys and consequently there is little information available for the associated infaunal species. It is possible that this biotope, like unit A5.241 (to which it is broadly similar) is an epibiotic overlay on other biotopes from the A5.2 complex.
Temporal variation: At certain times of the year a diatom film may be present on the sediment surface.


HabitatName:
[Spisula subtruncata] and [Nephtys hombergii] in shallow muddy sand

HabitatDescription:
In shallow non-cohesive muddy sands, in fully marine conditions, a community characterised by the bivalve [Spisula subtruncata] and the polychaete [Nephtys hombergii] may occur. The sediments in which this community is found may vary with regard silt content but they generally have less than 20% silt/clay and in some areas may contain a degree of shell debris. This biotope falls somewhere between A5.242 and A5.261 with regard sediment type (i.e. somewhat muddier than A5.242 and less muddy than A5.261) and may have species in common with both. As a result, other important species in this community include [Abra alba], [Fabulina fabula] spp. and [Mysella bidentata] spp. In addition, [Diastylis rathkei/typical], [Philine aperta] (in muddier sediments), [Ampelisca] spp., [Ophiura albida], [Phaxas pellucidus] and occasionally [Bathyporeia] spp, may also be important, although this is not clear from the data available. In areas of slightly coarser, less muddy sediment [S. solida] or [S. elliptica] may appear occasionally in this biotope. Abundances of [Spisula subtruncata] in this biotope are often very high and distinguish it from other closely related biotopes. Extensive areas of this community to the north east of the Dogger Bank were recorded in the 1950s, but these seem to have declined since then (Kroncke 1990). More information is required with regard the status of this biotope.
Temporal variation: In some areas this biotope may be a temporal variant or sub-biotope of A5.242 and A5.261 rather than an established biotope in itself. For example A5.244 has been recorded in Red Wharf Bay and Conwy Bay where it appears to be short term variant of other more established biotopes (e.g. A5.261) and appears to have only intermittent occurrence in single age cohort patches possibly due to predation in some areas (e.g. Red Wharf Bay) by the common Scoter [Melanitta nigra] (E.I.S. Rees pers. comm. 2002).


HabitatName:
[Ervillia castanea] beds in infralittoral sand


HabitatName:
Pontic thalassinid-dominated muddy sands with [Upogebia pusilla]


HabitatName:
Pontic muddy sands with [Mya arenaria] and [Anadara inaequivalvis]


HabitatDescription:
Clean fine sands with less than 5% silt/clay in deeper water, either on the open coast or in tide-swept channels of marine inlets in depths of over 15-20 m. The habitat may also extend offshore and is characterised by a wide range of echinoderms (in some areas including the pea urchin [Echinocyamus pusillus]), polychaetes and bivalves. This habitat is generally more stable than shallower, infralittoral sands and consequently supports a more diverse community.


HabitatName:
[Echinocyamus pusillus], [Ophelia borealis] and [Abra prismatica] in circalittoral fine sand

HabitatDescription:
Circalittoral and offshore medium to fine sand (from 40m to 140m) characterised by the pea urchin [Echinocyamus pusillus], the polychaete [Ophelia borealis] and the bivalve [Abra prismatica]. Other species may include the polychaetes [Spiophanes bombyx], [Pholoe] sp., [Exogone] spp., [Sphaerosyllis bulbosa], [Goniada maculata], [Chaetozone setosa], [Owenia fusiformis], [Glycera lapidum], [Lumbrineris latreilli] and [Aricidea cerrutii] and the bivalves [Thracia phaseolina] and [Moerella pygmaea] and to a lesser extent [Spisula elliptica] and [Timoclea ovata]. This biotope has been found in the central and northern North Sea.


HabitatName:
[Abra prismatica], [Bathyporeia elegans] and polychaetes in circalittoral fine sand

HabitatDescription:
In circalittoral and offshore medium to fine sands between 25m and 100m a community characterised by the bivalve [Abra prismatica], the amphipod [Bathyporeia elegans] and polychaetes such as [Scoloplos armiger], [Spiophanes bombyx], [Aonides paucibranchiata], [Chaetozone setosa], [Ophelia borealis] and [Nephtys longosetosa] may be found. Crustacea such as the cumacean [Eudorellopsis deformis] and the opheliid polychaetes such as [Ophelia borealis], [Travisia forbesii] or [Ophelina neglecta] are often present in this biotope and the brittlestar [Amphiura filiformis] may also be common at some sites. This biotope has been reported in the central and northern North Sea ( Basford and Eleftheriou, 1989; Künitzer et al., 1992).


HabitatName:
Medium to very fine sand, 100-120 m, with polychaetes [Spiophanes kroyeri], [Amphipectene auricoma], [Myriochele] sp., [Aricidea wassi] and amphipods [Harpinia antennaria]


HabitatDescription:
Circalittoral non-cohesive muddy sands with the silt content of the substratum typically ranging from 5% to 20%. This habitat is generally found in water depths of over 15-20 m and supports animal-dominated communities characterised by a wide variety of polychaetes, bivalves such as [Abra alba] and [Nucula nitidosa], and echinoderms such as [Amphiura] spp and [Ophiura] spp., and [Astropecten irregularis]. These circalittoral habitats tend to be more stable than their infralittoral counterparts and as such support a richer infaunal community.


HabitatName:
[Abra alba] and [Nucula nitidosa] in circalittoral muddy sand or slightly mixed sediment

HabitatDescription:
Non-cohesive muddy sands or slightly shelly/gravelly muddy sand characterised by the bivalves [Abra alba] and [Nucula nitidosa]. Other important taxa include [Nephtys] spp., [Chaetozone setosa] and [Spiophanes bombyx] with [Fabulina fabula] also common in many areas. The echinoderms [Ophiura albida] and [Asterias rubens] may also be present. The epibiotic biotope A5.241 may overlap this biotope. This biotope is part of the [Abra] community defined by Thorson (1957) and the infralittoral etage described by Glemarec (1973).


HabitatName:
[Amphiura brachiata] with [Astropecten irregularis] and other echinoderms in circalittoral muddy sand

HabitatDescription:
In shallow, circalittoral non-cohesive muddy sand (typically less than 20% silt/clay) abundant populations of the brittlestar [Amphiura brachiata] may occur with other echinoderms such as [Astropecten irregularis], [Asterias rubens], [Ophiura ophiura] and [Echinocardium cordatum]. Other infaunal species typically include [Mysella bidentata, Lanice conchilega] and [Magelona filiformis]. This biotope is likely to form part of the non-cohesive/cohesive muddy sand communities, which make up the 'off-shore muddy sand association' described by other workers (Jones 1951; Mackie 1990). It is possible that in some areas this biotope forms an epifaunal overlay which may cover a range of biotopes in years of good recruitment but does not develop into a settled or established community.


HabitatName:
Pontic muddy sands with [Spisula subtruncata], [Abra alba], [Parvicardium exiguum] and [Cerastoderma glaucum]


HabitatName:
Pontic muddy sands with [Paphia aurea] and [Spisula subtruncata]


HabitatName:
Pontic upper circalittoral mud with [Spisula subtruncata] and [Aricidea claudiae]

HabitatDescription:
This type of habitat occurs in the Black Sea around mussel bed patches. The distinguishing species are [Aricidea claudiae] and [Spisula subtruncata]. In general the community is characterised by the extremely high abundance of polychaetes such as [Aricidea claudiae], [Melinna palmata] and [Heteromastus filiformis]. Todorova & Konsulova (2003) state that this community has equivalents to Marinov's (1990) traditional classification of the [Melinna palmata] coastal mud community.


HabitatName:
Maldanid polychaetes and [Eudorellopsis deformis] in deep circalittoral sand or muddy sand

HabitatDescription:
In deep offshore sand or non-cohesive muddy sand dense populations of maldanid polychaetes such as [Maldane sarsi] and the cumacean [Eudorellopsis deformis] may be found. Accompanying these species are abundant ophiuroids including [Amphiura filiformis], polychaetes such as Terebellidae sp., [Chaetozone setosa], [Levinsenia gracilis], [Scoloplos armiger], the amphipod [Harpinia antennaria] and the bivalves [Nuculoma tenuis] and [Parvicardium minimum]. This biotope is similar to the [Maldane sarsi]-[Ophiura sarsi] community defined by Glemarec (1973).


HabitatName:
[Owenia fusiformis] and [Amphiura filiformis] in deep circalittoral sand or muddy sand

HabitatDescription:
Areas of slightly muddy sand (generally &lt;20% mud) in offshore waters may be characterised by high numbers of the tube building polychaete [Owenia fusiformis] often with the brittlestar [Amphiura filiformis]. Whilst [O. fusiformis] is also found in other circalittoral or offshore biotopes it usually occurs in lower abundances than in A5.272. Other species found in this community are the polychaetes [Goniada maculata], [Pholoe inornata], [Diplocirrus glaucus], [Chaetozone setosa] and [Spiophanes kroyeri] with occasional bivalves such as [Timoclea ovata] and [Thyasira equalis]. The sea cucumber [Labidoplax buski] and the cumacean [Eudorella truncatula] are also commonly often found in this biotope.


HabitatName:
Baltic sandy bottoms of the aphotic zone


HabitatName:
Mediterranean communities of superficial muddy sands in sheltered waters

HabitatDescription:
These habitats are located in protected coves, in sheltered environments, where a substrate consisting of a muddy-sandy sediment, sometimes mixed with a small amount of gravel, occurs. Depth is mostly around 1 metre, rarely more than 3 metres. These shallow areas are characterised by very variable environmental conditions and may present facies with epiflora or major developments of filtering or burrowing species.


HabitatName:
Facies with [Callianassa tyrrhena] and [Kellia corbuloides]

HabitatDescription:
This facies of superficial muddy sands in sheltered waters is characterised by the dominance of the ghost shrimp [Callianassa tyrrhena] and the bivalve mollusc [Kellia corbuloides].


HabitatName:
Facies with fresh water resurgences with [Cerastoderma glaucum] and [Cyathura carinata]

HabitatDescription:
This facies, typical of fresh water springs, is characterised by the bivalve mulluscs [Cerastoderma glaucum] and [Cyathura carinata].


HabitatName:
Facies with [Loripes lacteus], [Tapes] spp.

HabitatDescription:
This facies is characterised by the bivalve molluscs [Loripes lacteus] and [Tapes] spp.


HabitatName:
Association with [Caulerpa prolifera] on superficial muddy sands in sheltered waters

HabitatDescription:
This facies is characterised by the green alga [Caulerpa prolifera] and is present in the warmest areas.


HabitatName:
Facies of hydrothermal oozes with [Cyclope neritea] and nematodes

HabitatDescription:
These facies are characterised by the gastropod [Cyclope neritea] and some species of nematodes. The facies are present between 3 - 15 metres depth with high hydrothermal activity.


HabitatDescription:
Sublittoral mud and cohesive sandy mud extending from the extreme lower shore to offshore, circalittoral habitats. This biotope is predominantly found in sheltered harbours, sealochs, bays, marine inlets and estuaries and stable deeper/offshore areas where the reduced influence of wave action and/or tidal streams allow fine sediments to settle. Such habitats are often by dominated by polychaetes and echinoderms, in particular brittlestars such as [Amphiura] spp. Seapens such as [Virgularia mirabilis] and burrowing megafauna including [Nephrops norvegicus] are common in deeper muds. Estuarine muds tend to be characterised by infaunal polychaetes and oligochaetes.


HabitatName:
Sublittoral mud in low or reduced salinity

HabitatDescription:
Shallow, typically anoxic, muddy and sandy mud sediments in areas of low or reduced, although stable, salinity (may vary annually) with largely ephemeral faunal communities. Characterised by [Arenicola marina] and blue-green algae with other species, including mysids, [Carcinus maenas] and [Corophium volutator] which commonly occur in lagoons. Important infaunal species may include [Hediste diversicolor], [Heterochaeta costata] and chironomids; however infaunal records for this biotope are limited.


HabitatName:
Baltic brackish water sublittoral muddy biocenoses influenced by varying salinity


HabitatName:
Baltic muds of the infralittoral photic zone with little or no macrophyte vegetation


HabitatName:
Boreal Baltic narrow inlets with soft mud substrate


HabitatDescription:
Shallow sublittoral muds, extending from the extreme lower shore into the subtidal in variable salinity (estuarine) conditions. Such habitats typically support communities characterised by oligochaetes, and polychaetes such as [Aphelochaeta marioni]. In lowered salinity conditions the sediments may include a proportion of coarser material, where the silt content is sufficient to yield a similar community to that found in purer muds.


HabitatName:
[Polydora ciliata] and [Corophium volutator] in variable salinity infralittoral firm mud or clay

HabitatDescription:
Variable salinity clay and firm mud characterised by a turf of the polychaete [Polydora ciliata] along with the amphipod [Corophium volutator]. Other important taxa include the polychaetes [Pygospio elegans], [Hediste diversicolor, Streblospio shrubsolii] and the oligochaete [Tubificoides benedii]. [P. ciliata] also occurs in high densities elsewhere (see unit A4.232) and may be a specific feature of the Humber Estuary in these conditions. This biotope occurs only in very firm mud and clay and possibly submerged relict saltmarsh with a high detrital content. It is characterised, and can be separated from other biotopes, by a combination of the sediment characteristics and the very high density of [Polydora ciliata]. In some areas, such as the Humber estuary, cyclical behaviour with regard its characteristic taxa has been reported with either [P. ciliata] or [C. volutator] increasing in dominance at the expense of the other (Gameson 1982). It is possible that changes in water quality or the sediment regime may be responsible for this.


HabitatName:
[Aphelochaeta marioni] and [Tubificoides] spp. in variable salinity infralittoral mud

HabitatDescription:
Variable salinity cohesive muddy sediment (sometimes with some coarser material) dominated by the polychaete [Aphelochaeta marioni] (or other [Aphelochaeta] species e.g. [A. amplivasatus]) and the oligochaete [Tubificoides] spp. These taxa are generally accompanied by [Nephtys hombergii] whilst the polychaetes [Capitella capitata] and [Melinna palmata] may also occur in high numbers in some areas. Other members of the cirratulid polychaete group e.g. [Caulleriella zetlandica]. and [Tharyx] spp[]. may also occur in high numbers, sometimes replacing [A. marioni] as the dominant polychaete. However, there is still inconsistency in the identification of the cirratulid group which is further compounded by fragmentation during sample processing. This biotope is very common in stable muddy environments and may extend from reduced salinity to fully marine conditions.
Situation: This biotope may also be found in conjunction with A5.331.


HabitatName:
[Nephtys hombergii] and [Tubificoides] spp. in variable salinity infralittoral soft mud

HabitatDescription:
Variable salinity soft infralittoral mud and sandy mud characterised by the polychaete [Nephtys hombergii] and oligochaetes of the genus [Tubificoides]. Other characterising species that may be present are the polychaetes [Streblospio shrubsolii] and [Aphelochaeta marioni], and the cumacean [Diastylis rathkei typica].
Situation: The biotope is found in areas of silt deposition in soft and sandy muds but may not form a stable habitat. It may be found adjacent to A5.322, separated by the abundance of [Aphelochaeta marioni] and its more cohesive sediments


HabitatDescription:
Fluid mobile mud suspended and deposited on each tide. In areas with very high quantities of suspended particulate material in the water column it may become deposited around slack water when tidal currents fall. This can form fluid mud layers up to several metres thick (Warwick & Uncles 1980) becoming a transient habitat in its own right. Species present within this biotope will be those washed in from other communities such as [Nephtys hombergii] or [Capitella capitata]. This biotope may be under-recorded due to sampling problems, and also where sediment descriptions are absent from field data.

Situation: It may be found adjacent to; A5.326, A5.323 and to some extent A5.322.


HabitatName:
[Capitella capitata] and [Tubificoides] spp. in reduced salinity infralittoral muddy sediment

HabitatDescription:
Reduced or variable salinity muddy sediment characterised by the [Capitella capitata] species complex with a relatively low species richness. Large numbers of the oligochaetes [Tubificoides] spp. may be found in conjunction with [C. capitata], along with other species such as [Marenzellaria] sp, [Macoma balthica], [Arenicola marina] and [Eteone longa]. In some estuaries this biotope may also include high numbers of the polychaete [Ophryotrocha]. This biotope usually has a moderate organic content, and is found away from tidal channels in estuaries. The presence of dense [Capitella] has classically been associated with organically enriched and physically disturbed habitats in the marine environment (Warren 1977; Pearson & Rosenberg 1978) and areas of higher organic loads in estuaries will typically fall into unit A5.336. Where Capitella is less abundant and accompanied by other typical estuarine species the dominance of Capitella may be associated with other natural factors including the occurrence of a competitive refuge for [C. capitata] in the reduced-salinity environment (Wolff 1973).


HabitatDescription:
Reduced or variable salinity muddy and sandy mud sediments characterised by oligochaetes, particularly of the genus [Tubificoides] or from the group Enchytraeidae. The abundance of the oligochaetes may vary by several orders of magnitude but very few other species will be present. Organic loading and poor water-exchange within the sediment lead to anoxic conditions which may explain the low species richness within this biotope.
Situation: This biotope is found towards the edges of tidal channels in estuaries where current velocities allow deposition of silt and the establishment of an infaunal community. The biotope may occur downstream of A5.327, differentiated by the absence of the freshwater species, and adjacent to more mobile and sandier biotopes in the tidal channels.


HabitatName:
[Limnodrilus hoffmeisteri], [Tubifex tubifex] and [Gammarus] spp. in low salinity infralittoral muddy sediment

HabitatDescription:
Upper estuary muddy sediments with very low fluctuating salinity, characterised by the oligochaetes [Limnodrilus hoffmeisteri] and [Tubifex tubifex]. Other taxa may include [Marenzelleria wireni], [Gammarus zaddachi], [Paranais litoralis] and [Heterochaeta costata]. The biotope contains elements of both freshwater and brackish communities.

Situation: This biotope is found in the transitional zone between the freshwater and brackish environments where tidal currents are sufficiently reduced to allow the deposition of fine silt and the establishment of an infaunal community. It may be found adjacent to A5.223 away from the stronger tidal streams.

Temporal variation: The position of this biotope in the estuary may vary seasonally depending on freshwater input (Gameson, 1982).


HabitatName:
Pontic mud with [Spisula subtruncata], [Syndesmia fragilis], and [Cardium paucicostatum] in low and variable salinity

HabitatDescription:
The biocenosis has been observed in areas of low salinity in proximity of estuaries (Tiganus, 1976 describes an area in proximity of the Danube estuary). The dominant species is [Syndesmia fragilis] in terms of numerical presence. The biocenosis is characterised by a lower quantitative presence of [Spisula subtruncata] and [Cardium paucicostatum], a high presence of the polychaete [Melinna palmata] and a rich meiobenthic fauna characterised by Kinorhyncha, Nematoda, Oligochaeta and Copepods (Tiganus 1976). The biocenosis is recently characterised by the dominant presence of the allochtonous mollusc, [Mya arenaria], which has caused a variation in the composition of this biocenosis (Gomoiu 1976).


HabitatDescription:
Infralittoral, cohesive sandy mud, typically with over 20% silt/clay, in depths of less than 15-20 m. This habitat is generally found in sheltered bays or marine inlets and along sheltered areas of open coast. Typical species include a rich variety of polychaetes including [Melinna palmate], tube building amphipods ([Ampelisca] spp.) and deposit feeding bivalves such as [Macoma balthica] and [Mysella bidentata]. Sea pens such as [Virgularia mirabilis] and brittlestars such as [Amphiura] spp. may be present but not in the same abundances as found in deeper circalittoral waters.


HabitatName:
[Nephtys hombergii] and [Macoma balthica] in infralittoral sandy mud

HabitatDescription:
Near-shore shallow sandy muds and muds, and sometimes mixed sediments, may be characterised by the presence of the polychaete [Nephtys hombergii] and the bivalve [Macoma balthica]. [Abra alba], and [Nucula nitidosa] may also be important although they may not necessarily occur simultaneously or in high numbers. Other taxa include [Spiophanes bombyx], Lagis koreni], and [Echinocardium cordatum]. In some areas [Scoloplos armiger] and [Crangon crangon] may also be present. The community appears to be quite stable (Dewarumez [et al]. 1992) and the substratum is typically rich in organic content. This community has been included in the 'Boreal Offshore Muddy Sand Association' of Jones (1950) and is also described by several other authors (Petersen 1918; Cabioch & Gla‡on 1975). A similar community may occur in deep water in the Baltic (Thorson 1957). This biotope may occur in slightly reduced salinity estuarine conditions where [Mya] sp. may become a significant member of the community (Thorson 1957).

Situation: The community may occur in small patches or swathes in shallow waters parallel to the shore (Jones 1950; Cabioch & Gla‡on 1975) or in shallow nearshore depressions or trenches where finer material collects e.g. off the Suffolk coast (IECS 1991). This biotope is known to occur in patches between Denmark and the western English Channel.

Temporal variation: Sites with A5.331 may develop into [Amphiura] biotopes with time (E.I.S. Rees pers. comm. 1996)


HabitatName:
[Sagartiogeton undatus] and [Ascidiella aspersa] on infralittoral sandy mud

HabitatDescription:
Sheltered sublittoral mud or sandy mud in shallow water with relatively few conspicuous species may be characterised by the anemone [Sagartiogeton undatus] in low numbers and the tunicate [Ascidiella] [aspersa]. Other taxa may include [Carcinus maenas], [Pagurus bernhardus] and terebellid polychaetes. The burrowing anemones [Cerianthus lloydii] may also be found occasionally. The status of this biotope is uncertain at present as it is not known whether it is an impoverished, disturbed or epifaunal variant of other sheltered, shallow mud biotopes such as A5.343 or if the areas in which it has been recorded have been incompletely surveyed.


HabitatName:
[Mysella bidentata] and [Abra] spp. in infralittoral sandy mud

HabitatDescription:
Cohesive sandy mud, sometimes with a small quantity of shell in shallow water may contain the bivalves [Mysella bidentata] and [Abra] spp. (typically [A. alba] and [A. nitida]). Other characteristic taxa may include [Scoloplos armiger], [Mya] sp., and [Thyasira flexuosa]. Tube building amphipods are also characteristic of this biotope in particular [Ampelisca] spp. and Aoridae such as [Microprotopus maculatus].
Situation: This biotope is generally found in sheltered marine inlets or sealochs such as Strangford Lough.


HabitatName:
[Melinna palmata] with [Magelona] spp. and [Thyasira] spp. in infralittoral sandy mud

HabitatDescription:
In infralittoral cohesive sandy mud, in sheltered marine inlets, and occasionally variable salinity environments, dense populations of the polychaete [Melinna palmata] may occur, often with high numbers of [Magelona] spp. and the bivalve [Thyasira flexuosa]. Other important taxa may include [Chaetozone gibber, Nephtys hombergii, Galathowenia oculata], [Euclymene oerstedii], [Ampelisca tenuicornis], [Ampharete lindstroemi], [Abra alba], and [Phoronis] sp. In addition the polychaete [Aphelochaeta] spp. and the gastropod [Turritella communis] may be common or abundant in some areas. At the sediment surface visible taxa may include occasional [Virgularia mirabilis], and mobile epifauna such as [Pagurus bernhardus]. This biotope is characteristic in many southern UK marine inlets and in some areas e.g. Plymouth Sound during high levels of recruitment when [M. palmata] often occurs in abundances between 500 to 1000 per m2 moderate numbers of the species often 'overspill' into adjacent biotopes (Allen [et al]. 2001).

Situation: In many areas this biotope is found on or near the boundary between euryhaline and polyhaline waters and in such areas moderately high numbers of [Aphelochaeta] spp. are often recorded.

Temporal variation: Numbers of [M. palmata] tend to vary considerably from year to year presumably due to recruitment and/or adult mortality.


HabitatName:
[Ampelisca] spp., [Photis longicaudata] and other tube-building amphipods and polychaetes in infralittoral sandy mud

HabitatDescription:
Sublittoral stable cohesive sandy muds occurring over a wide depth range may support large populations of semi-permanent tube-building amphipods and polychaetes. In particular large numbers of the amphipods [Ampelisca] spp. and [Photis longicaudata] may be present along with polychaetes such as [Lagis koreni]. Other important taxa may include bivalves such as [Nucula nitidosa], [Chamelea gallina], [Abra alba] and [Mysella bidentata] and the echinoderms [Echinocardium cordatum] and [Amphiura brachiata]. In some areas polychaetes such as [Spiophanes bombyx] and [Polydora ciliata] may also be conspicuously numerous. This community is poorly known, appearing to occur in restricted patches. In some areas it is possible that A5.335 may develop as a result of moderate organic enrichment. A similar community in mud has also been reported in the Baltic which is characterised by large populations of amphipods such as [Ampelisca] spp., [Corophium] spp. and [Haploops tubicola] (see Petersen 1918; Thorson 1957) and it is not known if A5.335 is a UK variant of this biotope.
Temporal variation: In some areas of the Irish Sea this biotope is reported to be a temporal variant of units A5.244, A5.261 and A5.355. Some researchers consider these biotopes to be part of a wider muddy sand community which varies temporally depending on changes in sediment deposition and recruitment as was reported in areas of Red Wharf Bay off the Welsh coast (E.I.S. Rees pers. comm. 2002)


HabitatName:
[Capitella capitata] in enriched sublittoral muddy sediments

HabitatDescription:
The polychaete [Capitella capitata] (agg.) a widely-occurring, opportunist species complex that is particularly associated with organically enriched and polluted sediments (Warren 1977; Pearson & Rosenberg 1978) where it may be superabundant. In very polluted/disturbed areas only [Capitella], Nematodes and occasional [Malacoceros fuliginosus] may be found whilst in slightly less enriched areas and estuaries species such as [Tubificoides], [Cirriformia tentaculata], [Pygospio elegans] and [Polydora ciliata] may also be found. In some areas e.g. the Tees estuary, high numbers of the polychaete [Ophryotrocha] may also be present. A5.336 may become established as a result of anthropogenic activities such as fish farming and sewerage effluent but may also occur with natural enrichment as a result of, for example, coastal bird roosts. This biotope may also occur to some extent in the intertidal and in estuaries.

Situation: This biotope typically occurs in marine inlets, embayments or estuaries where organic enrichment allows [C. capitata] to out compete other taxa, although the species may also occur in enriched muddy coastal sediments and also offshore where there is a high organic input from adjacent oil drilling platforms (units A5.374 & A5.3741).


HabitatDescription:
The most abundant species is [Aricidea claudiae], considered as a species sensitive to disturbance. However the habitat is named after the terebellid worm ([Melinna palmata]) which ranks second in the abundance but has highest contribution to within-group similarity and is a key structural species. Its dense vertical tubes consolidate the sediment and determine the specific character of the habitat. The [Melinna palmata] biocenosis is considered a new biocenosis recorded in the mid 1970s along the Rumenian coasts (Gomoiu 1976) but was already known in 1971 in Bulgaria for quite some time (Kalugina-Gitneck, 1975). Bacescu had described this community in 1971 but had included it as a subtype of Mytilus beds.


HabitatName:
Pontic sandy mud with [Abra alba], Cardiidae and [Mytilus]


HabitatDescription:
Shallow sublittoral muds, extending from the extreme lower shore to about 15-20 m depth in fully marine or near marine conditions, predominantly in extremely sheltered areas with very weak tidal currents. Such habitats are found in sealochs and some rias and harbours. Populations of the lugworm [Arenicola marina] may be dense, with anemones, the opisthobranch [Philine aperta] and synaptid holothurians also characteristic in some areas. The extent of the oxidised layer may be shallow with some areas being periodically or permanently anoxic. In these areas bacterial mats may develop on the sediment surface. Infaunal records for this habitat type are limited encompassing only one biotope. They are therefore not representative of the full suite of infaunal species found in this biotope.


HabitatName:
[Cerastoderma edule] with [Abra nitida] in infralittoral mud

HabitatDescription:
Sheltered shallow sublittoral muds and gravelly muds in marine embayments, inlets or harbours may contain populations of the edible cockle [Cerastoderma edule] with [Abra nitida]. Other taxa may include the gastropod [Hydrobia ulvae], cirraltulid polychaetes such as [Caulleriella] spp. and other polychaetes including [Hediste diversicolor] and [Aphelochaeta marioni]. Available data for this biotope are limited to parts of Southampton Water, Chichester Harbour and also in the Wash. The species list given here may therefore be far from complete. It is not known at this stage whether this biotope is a sublittoral extension of intertidal cockle beds (e.g. A2.242) or whether it exists independently of intertidal populations of [C. edule].


HabitatDescription:
In very shallow, extremely sheltered, very soft muds [Arenicola marina] may form very conspicuous mounds and casts. This biotope may also contain synaptid holothurians such as [Labidoplax media] and [Leptosynapta bergensis] or [L. inhaerens]. However these species may be under recorded (possibly due to periodicity in feeding) and are not considered characteristic of this biotope. Other conspicuous fauna may include [Carcinus maenas], [Asterias rubens] and [Pagurus bernhardus] whilst the scallop [Pecten maximus] and the turret shell [Turritella] [communis] may also be present in some areas.

Situation: This biotope typically occurs in waters shallower than about 5 m in sheltered basins of sealochs and lagoons that may be partially separated from the open sea by tidal narrows or rapids.

Temporal variation: Sediment surfaces may become covered by a diatom film at certain times of the year


