# Habitat

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.


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 (200m). 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:
Sublittoral coarse sediment (unstable cobbles and pebbles, gravels and coarse sands)

HabitatDescription:
Coarse sediments including coarse sand, gravel, pebbles, shingle and cobbles which are often unstable due to tidal currents and/or wave action. These habitats are generally found on the open coast or in tide-swept channels of marine inlets. They typically have a low silt content and a lack of a significant seaweed component. They are characterised by a robust fauna including venerid bivalves.


HabitatName:
Sublittoral coarse sediment in variable salinity (estuaries)

HabitatDescription:
Clean gravels that occur in the upper reaches of marine inlets, especially estuaries, where water movement is sufficiently strong to remove the silt content of the sediment. The habitat typically lacks a significant seaweed component and is characterised by a sparse but very robust brackish-water tolerant fauna.


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.


HabitatName:
Sparse fauna on highly mobile sublittoral shingle (cobbles and pebbles)

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.


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.


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 FfabMag 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 FfabMag; 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, SCS.MoeVen may give way to the other Spisula biotope SSA.SsubNhom. Together these two biotopes replace the old biotope IGS.Sell.


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).


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 SCS biotopes. 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 SCS.Glap it is not a true biotope, rather an impoverished, transitional community, which in more settled conditions develops into other more stable communities.


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).


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 (LGS.Lan) 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 SCS.SLan. 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 SLan as an epibiotic biotope which overlays a variety of infaunal biotopes (e.g. NcirBat in finer sands and AalbNuc or FfabMag in slightly muddier areas).


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 SMX.FluHyd which is characterised by large amounts of the above hydroids on stones also covered in Pomatoceros and barnacles. The main difference here is that SMX.FluHyd, 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.


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 FfabMag 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). SCS.MedLumVen 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.


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


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 the biotope MedLumVen.


HabitatName:
Branchiostoma lanceolatum in circalittoral coarse sand with shell gravel

HabitatDescription:
Gravel and coarse sand with shell gravel often contains communities of robust venerid bivalves (SCS.MedLumVen). 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 SCS.MoeVen or SCS.MedLumVen.


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 SBR.ModMx.


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 (<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 SCS.Glap and also to the circalittoral and offshore venerid biotopes (SCS.MedLumVen and SMX.PoVen) 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.


HabitatDescription:
Clean medium to fine sands or non-cohesive slightly muddy sands on open coasts, offshore or in estuaries and marine inlets. Such habitats are often subject to a degree of wave action or tidal currents which restrict the silt and clay content to less than 15%. This habitat is characterised by a range of taxa including polychaetes, bivalve molluscs and amphipod crustacea.


HabitatName:
Sublittoral sand in low or reduced salinity (lagoons)

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 SMuLS 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:
Sublittoral sand in variable salinity (estuaries)

HabitatDescription:
Clean sands that occur in the upper reaches of marine inlets, especially estuaries, where water movement is moderately strong, allowing the sedimentation of sand but not the finer silt fraction. The habitat typically lacks a significant seaweed component and is characterised by brackish-water tolerant fauna, particularly amphipods, polychaetes and mysid shrimps.


HabitatName:
Infralittoral mobile sand in variable salinity (estuaries)

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 the NhomMac. 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 variable 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.


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.


HabitatName:
Infralittoral mobile clean sand with sparse fauna

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 SSA.NcirBat and may be closely related to LSa.BarSa 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 SSA or SCS 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 FfabMag) 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.


HabitatName:
Semi-permanent tube-building amphipods and polychaetes in sublittoral sand

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 SMU.AmpPlon, to which it is related, appears to have a patchy distribution.


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 FfabMag, NcirBat and AalbNuc with infaunal components of these biotopes occurring within EcorEns. 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. AreISa is another biotope based primarily on epibiotic data. It is likely that this biotope and EcorEns form a wider epibiotic sand /muddy sand community with EcorEns biased towards sandier areas and SSA.AreISa 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. FfabMag and MoeVen 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 (Knitzer et al. 1992). Sites with this biotope may undergo transitions in community composition. The epibiotic biotopes EcorEns and AreISa may also overlay this biotope in some areas.


HabitatName:
Arenicola marina in infralittoral fine sand or 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 SSA.FfabMag and SSA.AalbNuc with regard sediment type (i.e. somewhat muddier than SSA.FfabMag and less muddy than SSA.AalbNuc) 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.


HabitatName:
Spisula subtruncata and Nephtys hombergii in shallow 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 EcorEns (to which it is broadly similar) is an epibiotic overlay on other biotopes from the SSA complex.


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 15-20m. 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; Knitzer et al., 1992).


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 15-20m 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 EcorEns 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.


HabitatDescription:
Offshore (deep) circalittoral habitats with fine sands or non-cohesive muddy sands. Very little data is available on these habitats however they are likely to be more stable than their shallower counterparts and characterised by a diverse range of polychaetes, amphipods, bivalves and echinoderms.


HabitatName:
Maldanid polychaetes and Eudorellopsis deformis in offshore 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 offshore circalittoral sand or muddy sand

HabitatDescription:
Areas of slightly muddy sand (generally <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 SSA.OfusAfil. 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:
Sublittoral cohesive mud and sandy mud communities

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 (lagoons)

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:
Sublittoral mud in variable salinity (estuaries)

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 MCR.Pol) 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.


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.


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.


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 the biotope Cap. 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).


HabitatName:
Oligochaetes in variable or reduced salinity infralittoral muddy sediment

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.


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.


HabitatDescription:
Infralittoral, cohesive sandy mud, typically with over 20% silt/clay, in depths of less than 15-20m. 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).


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 PhiVir 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.


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).


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 AmpPlon 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 SMU.AmpPlon is a UK variant of this biotope.


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. Cap 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.


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 biotope complex are limited encompassing only one biotope. They are therefore not representative of the full suit 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. LSA.CerPo) 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.


HabitatName:
Philine aperta and Virgularia mirabilis in soft stable infralittoral mud

HabitatDescription:
Physically very stable muds, occasionally with small stones, with a high proportion of fine material (typically greater than 80 %) may contain the opisthobranch Philine aperta and the seapen Virgularia mirabilis. These muds typically occur in shallow water down to about 12-15 m where significant seasonal variation in temperature is presumed to occur. This habitat is restricted to the most sheltered basins in, for example, sealochs. Although most records suggest full salinity conditions are prevalent, some sites may be subject to variable salinity. Philine aperta is the most characteristic species of this habitat, occurring in high densities at many sites, whilst Virgularia mirabilis, a species found more widely in muddy sediments, appears to reach its highest densities in this shallow mud but may not be present in all examples of this biotope. Other conspicuous species found in this shallow muddy habitat include Cerianthus lloydii, Pagurus bernhardus, Sagartiogeton spp. and Hydractinia echinata. Burrowing crustacean megafauna, characteristic of deeper mud, are rare or absent from this shallow sediment although Nephrops norvegicus may sometimes be recorded. This biotope has been primarily recorded on the basis of its epifauna and a few conspicuous infauna. Little data exists on the infaunal component of this biotope but it may include Nephtys spp., spionid polychaetes, Ampelisca spp. and the bivalves Nucula spp., Thyasira flexuosa, Mysella bidentata and Abra spp. In the south of Great Britain, the polychaete Sternaspis scutata is also characteristic of this biotope. This polychaete is rare in Great Britain (Sanderson 1996). Indeed, this southern variant of the biotope is very restricted in the UK to Portland Harbour but is known to occur further south in the Gulf of Gascony and the Mediterranean (Glemarec 1973; Dauvin et al. 1994).


HabitatName:
Ocnus planci aggregations on sheltered sublittoral muddy sediment

HabitatDescription:
Dense aggregations of Ocnus planci [?brunneus] on various substrata, typically muddy but occasionally with stones or shells, in sheltered conditions such as sealochs. Philine aperta also characterises this biotope but is present in lower abundances than in PhiVir. Other associated species vary but are typical of very sheltered muddy habitats and include the ophiuroids Ophiura spp. and Ophiothrix fragilis. Melanella alba, which parasitises holothurians, has been found in large numbers at one site.


HabitatName:
Beggiatoa spp. on anoxic sublittoral mud

HabitatDescription:
Sublittoral soft anoxic mud, often in areas with poor water exchange with the open sea, can have a conspicuous bacterial mat covering of Beggiatoa spp. The anoxia may be a result of natural conditions of poor water exchange in some sealochs (and many Scandinavian fjords) or artificially under fish farm cages from nutrient enrichment. The fauna is normally impoverished at such sites, with few elements of the infaunal communities present in other muddy biotopes. Scavenging species such as Asterias rubens and Carcinus maenas are typically present where the habitat is not too anoxic along with occasional Arenicola marina but in extreme conditions of anoxia little survives other than the Beggiatoa. The polychaete Ophiodromus flexuosus occurs in high densities at the interface between oxygenated and deoxygenated sediments (in Norwegian fjords).


HabitatDescription:
Circalittoral, cohesive sandy mud, typically with over 20% silt/clay, generally in water depths of over 10m, with weak or very weak tidal streams. This habitat is generally found in deeper areas of bays and marine inlets or offshore from less wave exposed coasts. Sea pens such as Virgularia mirabilis and brittlestars such as Amphiura spp. are particularly characteristic of this habitat whilst infaunal species include the tube building polychaetes Lagis koreni and Owenia fusiformis, and deposit feeding bivalves such as Mysella bidentata and  Abra spp.


HabitatName:
Amphiura filiformis, Mysella bidentata and Abra nitida in circalittoral sandy mud

HabitatDescription:
Cohesive sandy mud off wave exposed coasts with weak tidal streams can be characterised by super-abundant Amphiura filiformis with Mysella bidentata and Abra nitida. This community occurs in muddy sands in moderately deep water (Hiscock 1984; Picton et al. 1994) and may be related to the 'off-shore muddy sand association' described by other workers (Jones 1951; Thorson 1957; Mackie 1990) and is part of the infralittoral etage described by Glemarec. This community is also characterised by the sipunculid Thysanocardia procera and the polychaetes Nephtys incisa, Phoronis sp. and Pholoe sp., with cirratulids also common in some areas. Other taxa such as Nephtys hombergii, Echinocardium cordatum, Nucula nitidosa, Callianassa subterranea and Eudorella truncatula may also occur in offshore examples of this biotope (e.g. Knitzer et al. 1992).


HabitatName:
Thyasira spp. and Nuculoma tenuis in circalittoral sandy mud

HabitatDescription:
Circalittoral cohesive sandy muds with small quantities of gravel, off sheltered or moderately exposed coasts may support populations characterised by Thyasira spp. and in particular Thyasira flexuosa. Other characteristic taxa may include Nuculoma tenuis, Goniada maculate and in some areas Rhodine gracilior. Mysella bidentata, Abra alba, Harpinia antennaria and Amphiura filiformis may be abundant in some examples of this biotope. Whilst moderately diverse, animal abundances are often low and it is possible that the biotope is the result of sedimentary disturbance e.g. from trawling and is possibly an impoverished version of AfilNten. Collectively the biotopes ThyNten, AfilMysAnit, AfilNten and OfusAfil, may form the Amphiura dominated components of the 'off-shore muddy sand association' described by other workers (Jones 1951; Thorson 1957; Mackie 1990) and the infralittoral etage described by Glemarec (1973).


HabitatName:
Amphiura filiformis and Nuculoma tenuis in circalittoral and offshore sandy mud

HabitatDescription:
In cohesive and non-cohesive sandy mud, off moderately exposed coasts in deep water dense populations of Amphiura filiformis with the bivalve Nuculoma tenuis may occur. This biotope together with AfilMysAnit, ThyNten and OfusAfil may be part of the Amphiura filiformis dominated infralittoral etage described by Glemarec (1973) and part of the 'off-shore muddy sand association' described by other workers (Jones 1951; Mackie 1990). Other species characteristic of this biotope may include the echinoderms Ophiura albida and Echinocardium flavescens and the bivalve Mysella bidentata. Phaxas pellucidus, Owenia fusiformis and Virgularia mirabilis may also be present. At the sediment surface the hydroid Sertularia argentea may be present although only at very low abundances. Variations of this biotope exist in the northern North Sea (see below) and it is possible that more than one entity exists for this biotope.


HabitatName:
Virgularia mirabilis and Ophiura spp. with Pecten maximus on circalittoral sandy or shelly mud

HabitatDescription:
Circalittoral fine sandy mud may contain Virgularia mirabilis and Ophiura spp. A variety of species may occur, and species composition at a particular site may relate, to some extent, to the proportions of the major sediment size fractions. Several species are common to most sites including Virgularia mirabilis which is present in moderate numbers, Ophiura albida and Ophiura ophiura which are often quite common, and Pecten maximus which is usually only present in low numbers. Virgularia mirabilis is usually accompanied by occasional Cerianthus lloydii, Liocarcinus depurator and Pagurus bernhardus. Amphiura chiajei and Amphiura filiformis may occur in some examples of this biotope. Polychaetes and bivalves are generally the main components of the infauna, although the nemerteans, Edwardsia claparedii, Phoronis muelleri and Labidoplax buski may also be widespread. Of the polychaetes Goniada maculata, Nephtys incisa, Minuspio cirrifera, Chaetozone setosa, Notomastus latericeus and Owenia fusiformis are often the most widespread species whilst Myrtea spinifera, Lucinoma borealis, Mysella bidentata, Abra alba and Corbula gibba are typical bivalves in this biotope. This biotope is primarily identified on the basis of its epifauna and may be an epibiotic overlay over other closely related biotopes such as SpnMeg, AfilMysAnit and AfilNten.


HabitatName:
Virgularia mirabilis and Ophiura spp. with Pecten maximus, hydroids and ascidians on circalittoral sandy or shelly mud with stones

HabitatDescription:
Circalittoral fine sandy mud with shell gravel and notable quantities of shells or small stones scattered over the sediment surface. These sediments, like SMU.VirOphPmax, may contain Virgularia mirabilis, Pecten maximus and Ophiura spp. but shells and small stones scattered over the sediment surface provided sufficient stable substrata for a variety of sessile epifaunal species to occur. Of these the hydroids Kirchenpaueria pinnata, Nemertesia antennina and Nemertesia ramosa are most common with solitary ascidians such as Corella parallelogramma and Ascidia mentula also present. The anemone Cerianthus lloydii is often found in the sediment together with occasional Lanice conchilega. The serpulids Protula tubularia, Serpula vermicularis and Pomatoceros triqueter and the barnacles Balanus balanus and Balanus crenatus are also often present on pebbles and shells. Munida rugosa are occasionally found under larger stones. All these species are typical of more rocky habitats in such sheltered conditions. As with SMU.VirOphPmax this biotope is primarily identified on the basis of its epifauna and may be an epibiotic overlay over other closely related biotopes such as AfilMysAnit and AfilNten.


HabitatName:
Lagis koreni and Phaxas pellucidus in circalittoral sandy mud

HabitatDescription:
In stable circalittoral sandy mud dense populations of the tube building polychaete Lagis koreni may occur. Other species found in this habitat typically include bivalves such as Phaxas pellucidus, Mysella bidentata and Abra alba and polychaetes such as Mediomastus fragilis, Spiophanes bombyx, Owenia fusiformis and Scalibregma inflatum. At the sediment surface easily visible fauna include Lagis koreni and Ophiura ophiura. Lagis koreni is an important source of food for commercially important demersal fish, especially dab and plaice (Macer, 1967; Lockwood, 1980 and Basimi & Grove, 1985).


HabitatDescription:
Sublittoral muds, occurring below moderate depths of 15-20 m, either on the open coast or in marine inlets such as sealochs. The seapens Virgularia mirabilis and Pennatula phosphorea are characteristic of this biotope complex together with the burrowing anemone Cerianthus lloydii and the ophiuroid Amphiura spp. The relatively stable conditions often lead to the establishment of communities of burrowing megafaunal species, such as Nephrops norvegicus.


HabitatName:
Seapens and burrowing megafauna in circalittoral fine mud

HabitatDescription:
Plains of fine mud at depths greater than about 15 m may be heavily bioturbated by burrowing megafauna; burrows and mounds may form a prominent feature of the sediment surface with conspicuous populations of seapens, typically Virgularia mirabilis and Pennatula phosphorea. The burrowing crustacea present typically include Nephrops norvegicus, which is frequently recorded from surface observations although grab sampling may fail to sample this species. Indeed, some forms of sampling may also fail to indicate seapens as characterising species. This biotope also seems to occur in deep offshore waters in the North Sea, where densities of Nephrops norvegicus may reach 68 per 10 m-2 (see Dyer et al. 1982, 1983), and the Irish Sea. The burrowing anemone Cerianthus lloydii and the ubiquitous epibenthic scavengers Asterias rubens, Pagurus bernhardus and Liocarcinus depurator are present in low numbers in this biotope whilst the brittlestars Ophiura albida and Ophiura ophiura are sometimes present, but are much more common in slightly coarser sediments. Low numbers of the anemone Pachycerianthus multiplicatus may also be found, and this species, which is scarce in the UK, appears to be restricted to this habitat (Plaza & Sanderson 1997). The infauna may contain significant populations of the polychaetes Pholoe spp., Glycera spp., Nephtys spp., spionids, Pectinaria belgica and Terebellides stroemi, the bivalves Nucula sulcata, Corbula gibba and Thyasira flexuosa, and the echinoderm Brissopsis lyrifera.


HabitatName:
Seapens, including Funiculina quadrangularis, and burrowing megafauna in undisturbed circalittoral fine mud

HabitatDescription:
Deep muds, especially in sealochs, support forests of the nationally scarce Funiculina quadrangularis, in addition to populations of the seapens Virgularia mirabilis and Pennatula phosphorea. The sediment is usually extensively burrowed by crustaceans, the most common of which is Nephrops norvegicus, but Calocaris macandreae and Callianassa subterranea may also be present (the latter is likely to be under-recorded by grab sampling because it is deep burrowing). The burrowing anemone Cerianthus lloydii is present in low numbers in this biotope and the rare anemone Pachycerianthus multiplicatus may also be found occasionally. Amphiura spp. are also often present in high densities.


HabitatName:
Burrowing megafauna and Maxmuelleria lankesteri in circalittoral mud

HabitatDescription:
In circalittoral stable mud distinctive populations of megafauna may be found. These typically include Nephrops norvegicus, Calocaris macandreae and Callianassa subterranea. Large mounds formed by the echiuran Maxmuelleria lankesteri are also frequent in this biotope. The seapen Virgularia mirabilis may occur occasionally in this biotope but not in the same abundance as SpnMeg to which MegMax is closely allied. Infaunal species may include Nephtys hystricis, Chaetozone setosa, Amphiura chiajei and Abra alba.


HabitatName:
Brissopsis lyrifera and Amphiura chiajei in circalittoral mud

HabitatDescription:
Mud in deep offshore, or shallower stable nearshore, waters can be characterised by the urchin Brissopsis lyrifera and the brittle star Amphiura chiajei. Where intense benthic dredge fishing activity occurs, populations of the indicator species, Brissopsis lyrifera may be depressed, although broken tests may still remain (E.I.S. Rees pers. comm. 1997; M. Costello pers. comm. 1997). Low numbers of the seapen Virgularia mirabilis may be found in many examples of this biotope. In addition, in certain areas of the UK such as the northern Irish Sea, this community may also contain Nephrops norvegicus and can consequently be the focus for fishing activity (Mackie, Oliver & Rees 1995). Infaunal species in this community are similar to those found in SpnMeg and include the polychaetes Nephtys hystricis, Pectinaria belgica, Glycera spp. and Lagis koreni and the bivalves Myrtea spinifera and Nucula sulcata. This community is the 'Boreal Offshore Mud Association' and 'Brissopsis - Chiajei' communities described by other workers (Petersen 1918; Jones 1950).


HabitatDescription:
In mud and cohesive sandy mud in the offshore circalittoral zone, typically below 50-70 m, a variety of faunal communities may develop, depending upon the level of silt/clay and organic matter in the sediment. Communities are typically dominated by polychaetes but often with high numbers of bivalves such as Thyasira spp., echinoderms and foraminifera.


HabitatName:
Ampharete falcata turf with Parvicardium ovale on cohesive muddy sediment near margins of deep stratified seas

HabitatDescription:
Dense stands of Ampharete falcata tubes which protrude from muddy sediments, appearing as a turf or meadow in localised areas. These areas seem to occur on a crucial point on a depositional gradient between areas of tide-swept mobile sands and quiescent stratifying muds. Dense populations of the small bivalve Parvicardium ovale occur in the superficial sediment. Other infauna in this diverse biotope includes Lumbrineris scopa, Levinsenia sp., Prionospio steenstrupi, Diplocirrus glaucus and Praxillella affinis although a wide variety of other infaunal species may also be found. Both the brittlestars Amphiura filiformis and Amphiura chiajei may be present together with Nephrops norvegicus in higher abundance than the BlyrAchi or AfilEcor biotopes. Substantial populations of mobile epifauna such as Pandalus montagui and smaller fish also occur, together with those that can cling to the tubes, such as Macropodia spp. A similar turf of worm tubes formed by the maldanid polychaete Melinna cristata has been recorded from Northumberland (Buchanan 1963). Nephrops trawling may severely damage this biotope and it is possible that such activity has destroyed examples of this biotope in the Irish Sea (E.I.S. Rees pers. comm. 2002).


HabitatName:
Foraminiferans and Thyasira sp. in deep circalittoral fine mud

HabitatDescription:
In deep water and soft muds of Boreal and Arctic areas, a community dominated by foraminiferans and the bivalve Thyasira sp. (e.g. T. croulinensis and T. pygmaea) may occur (Thorson 1957; Knitzer et al. 1992). Foraminiferans such as Saccammina, Psammosphaera, Haplophragmoides, Crithionina and Astorhiza are important components of this community with dead tests numbering thousands per m2 (see Stephen 1923; McIntyre 1961) and sometimes visible from benthic photography (Mackie, Oliver & Rees 1995). It is likely that a community dominated by Astorhiza in fine sands in the Irish Sea may be another distinct biotope (E.I.S. Rees pers. comm. 2002). Polychaetes, e.g. Paraonis gracilis, Myriochele heeri, Spiophanes kroyeri, Tharyx sp., Lumbrineris tetraura, are also important components of this biotope. These communities appear to have no equivalent on the continental plateau further south (Glemarec 1973) but are known from the edge of the Celtic Deep in the Irish Sea (Mackie, Oliver & Rees 1995). The benthos in these offshore areas has been shown to be principally Foraminifera and similar, rich communities may exist in Scottish sealochs (McIntyre 1961). Communities from yet deeper (northern) waters at the extremes of the North Sea may be reminiscent, although dissimilar to ForThy (see Pearson et al. 1996) reflecting a higher proportion of silt/clay. A fully Arctic version of this biotope has also been described (Thorson 1934, 1957) although it should be noted that Jones (1950) considered this Boreal foraminiferan community to be part of a 'Boreal Deep Mud Association'.


HabitatName:
Styela gelatinosa, Pseudamussium septemradiatum and solitary ascidians on sheltered deep circalittoral muddy sediment

HabitatDescription:
This biotope is known only from deep water in Loch Goil (Clyde sealochs) in fine mud at 65 m with terrigenous debris. Large numbers of solitary ascidians, including Styela gelatinosa, Ascidia conchilega, Corella parallelogramma and Ascidiella spp., are characteristic of this biotope together with the bivalve Pseudamussium septemradiatum. Terebellid worms, the bivalve Abra alba and the polychaete Glycera tridactyla may also occur. It is possibly an ice age relict biotope.


HabitatName:
Capitella capitata and Thyasira spp. in organically-enriched offshore circalittoral mud and sandy mud

HabitatDescription:
In circalittoral and deep offshore mud and sandy mud adjacent to oil or gas platforms, organic enrichment from drill cuttings leads to the development of communities dominated by the Capitella capitata, an opportunist especially associated with organically enriched and polluted sediments as described for Cap (Warren 1977; Pearson & Rosenberg 1978). The bivalves Thyasira flexuosa or T. sarsi may also be found in moderate numbers at some sites. Other taxa may be present in low numbers in areas of less severe enrichment including Pholoe inornata, Lagis koreni, Philine scabra, Anaitides groenlandica, Mediomastus fragilis and Paramphinome jeffreysii.


HabitatName:
Capitella capitata, Thyasira spp. and Ophryotrocha dubia in organically-enriched offshore circalittoral sandy mud

HabitatDescription:
In deep offshore sandy mud adjacent to oil or gas platforms, organic enrichment from drill cuttings leads to the development of communities dominated by the pollution tolerant opportunist Capitella capitata and the polychaete Ophryotrocha dubia (or other species of Ophryotrocha). These species are generally found in extremely high abundances and accompanied by Thyasira spp., Raricirrus beryli, Paramphinome jeffreysii and Chaetozone setosa. Other taxa including Exogone verugera, Pholoe inornata and Idasola simpsoni may also be present.


HabitatName:
Levinsenia gracilis and Heteromastus filifirmis in offshore circalittoral mud and sandy mud

HabitatDescription:
In deep offshore mud and sandy mud a community characterised by the polychaetes Levinsenia gracilis and Heteromastus filiformis may occur. Other important taxa may include Paramphinome jeffreysii, Nephtys hystricis and N. incisa, Spiophanes kroyeri, Orbinia norvegica, Terebellides stroemi, Thyasira gouldi and T. equalis. Burrowing megafauna such as Calocaris macandreae may also be found in this biotope. This biotope has been found in the central and northern North Sea. A similar community, dominated by L. gracilis but accompanied by Glycera spp. (particularly Glycera rouxii) and Monticellina dorsobranchialis, has also been reported from the Irish Sea. This Irish community also contains Calocaris macandreae, Mediomastus fragilis, Tubificoides amplivasatus, Nephtys incisa, Ancistrosyllis groenlandica, Nucula sulcata, Litocorsa stremma and Minuspio sp. and it is not known at present whether this represents a separate biotope or whether it is a geographic variant of a wider Levinsenia biotope.


HabitatName:
Paramphinome jeffreysii, Thyasira spp. and Amphiura filiformis in offshore circalittoral sandy mud

HabitatDescription:
Deep, offshore cohesive sandy mud communities characterised by the polychaete Paramphinome jeffreysii, bivalves such as Thyasira equalis and T. gouldi and the brittlestar Amphiura filiformis. Other taxa may include Laonice cirrata, the sea cucumber Labidoplax buski and the polychaetes Goniada maculata, Spiophanes kroyeri and Aricidea catherinae. Amphiura chiajei may be occasional in this biotope as may Philine scabra, Levinsenia gracilis and Pholoe inornata. This biotope along with SMU.ThyNten, SMU.AfilMysAnit, SMU.AfilNten and SSA.OfusAfil, may comprise the Amphiura dominated components of the 'off-shore muddy sand association' (Jones 1951; Mackie 1990) and the infralittoral etage described by Glemarec (1973).


HabitatName:
Myrtea spinifera and polychaetes in offshore circalittoral sandy mud

HabitatDescription:
Deep, offshore habitats with cohesive sandy mud (>20% mud) may support communities characterised by infaunal polychaetes and the bivalve Myrtea spinifera. Polychaetes typically include Chaetozone setosa, Paramphinome jeffreysii, Levinsenia gracilis, Aricidea catherinae and Prionospio malmgreni. The bivalves Thyasira spp. and Abra nitida may also be found as may seapens, such as Pennatula phosphorea. Some examples of the biotope AfilNten contain Myrtea spinifera (Mackie 1990) in lower numbers but these habitats are generally sandier than those in MyrPo.


HabitatDescription:
Sublittoral mixed (heterogeneous) sediments found from the extreme low water mark to deep offshore circalittoral habitats. These habitats incorporate a range of sediments including heterogeneous muddy gravelly sands and also mosaics of cobbles and pebbles embedded in or lying upon sand, gravel or mud. There is a degree of confusion with regard nomenclature within this complex as many habitats could be defined as containing mixed sediments, in part depending on the scale of the survey and the sampling method employed. The BGS trigon can be used to define truly mixed or heterogeneous sites with surficial sediments which are a mixture of mud, gravel and sand. However, another 'form' of mixed sediment includes mosaic habitats such as superficial waves or ribbons of sand on a gravel bed or areas of lag deposits with cobbles/pebbles embedded in sand or mud and these are less well defined and may overlap into other habitat or biotope complexes. These habitats may support a wide range of infauna and epibiota including polychaetes, bivalves, echinoderms, anemones, hydroids and Bryozoa. Mixed sediments with biogenic reefs or macrophyte dominated communities are classified separately in the SBR and SMP habitat complexes respectively.


HabitatName:
Sublittoral mixed sediment in low or reduced salinity (lagoons)

HabitatDescription:
Shallow, muddy mixed sediments in areas of low or reduced, although stable, salinity (may vary annually) with largely ephemeral faunal communities. Characterised infaunally by oligochaetes, including Heterochaeta costata and members of the Enchytraeidae, polychaetes such as Hediste diversicolor, Polydora ciliata and Pygospio elegans,and bivalves such as Mya arenaria and the lagoon cockle Cerastoderma glaucum. These bivalve species may also form conspicuious members of the epifauna together with more ubiquitous species like the common goby Pomatoschistus microps.


HabitatName:
Sublittoral mixed sediment in variable salinity (estuaries)

HabitatDescription:
Shallow sublittoral mixed sediments in estuarine conditions, often with surface shells or stones, enabling the development of diverse epifaunal communities, e.g. Crepidula fornicata (IMX.CreAph), as well as infaunal communities. This biotope complex is therefore often quite species rich, compared with purer sediments.


HabitatName:
Aphelochaeta spp. and Polydora spp. in variable salinity infralittoral mixed sediment

HabitatDescription:
In sheltered muddy mixed sediments in estuaries or marine inlets with variable or reduced/low salinity communities characterised by Aphelochaeta marioni and Polydora ciliata may be present. Other important taxa may include the polychaetes Nephtys hombergii, Caulleriella zetlandica and Melinna palmata, tubificid oligochaetes and bivalves such as Abra nitida. Conspicuous epifauna may include members of the bivalve family Cardiidae (cockles) and the slipper limpet Crepidula fornicata. This biotope is often found in polyhaline waters.


HabitatName:
Crepidula fornicata and Mediomastus fragilis in variable salinity infralittoral mixed sediment

HabitatDescription:
Variable salinity mixed sediment characterised by the slipper limpet Crepidula fornicata and the polychaetes Mediomastus fragilis and Aphelochaeta marioni. Other numerically important taxa include the oligochaetes Tubificoides benedii, syllids such as Exogone naidina and Sphaerosyllis, and Nephtys hombergii. Lepidonotus squamatus and Scoloplos armiger may also be common. Shell debris and cobbles are colonised by the ascidians Ascidiella aspersa, Ascidiella scabra, Molgula sp. and Dendrodoa grossularia (the ascidians may not be recorded adequately by remote infaunal survey techniques).


HabitatDescription:
Shallow mixed (heterogeneous) sediments in fully marine or near fully marine conditions, supporting various animal-dominated communities, with relatively low proportions of seaweeds. This habitat may include well mixed muddy gravelly sands or very poorly sorted mosaics of shell, cobbles and pebbles embedded in mud, sand or gravel. Due to the quite variable nature of the sediment type, a widely variable array of communities may be found, including those characterised by bivalves (SMX.VsenAsquAps, SMX.CreAsAn, and SMX.Ost), polychaetes (SMX.SpavSpAn) and file shells (SMX.Lim). This has resulted in many species being described as characteristic of this biotope complex all contributing only a small percentage to the overall similarity (see below). This biotope complex may also include a newly proposed Chaetopterus biotope (Rees pers com.) recently found in the eastern English Channel. This biotope is characterised by an undescribed Chaetopterus sp. and small Lanice conchilega. Further sampling is need in order to assess and fully characterise this potential biotope. As a result, the Chaetopterus biotope has not been included in this revision. Infaunal data for this biotope complex are limited to that described in the biotope SMX.VsenAsquAps and so are not representative of the infaunal component of the whole biotope complex.


HabitatName:
Crepidula fornicata with ascidians and anenomes on infralittoral coarse mixed sediment

HabitatDescription:
Medium-coarse sands with gravel, shells, pebbles and cobbles on moderately exposed coasts may support populations of the slipper limpet Crepidula fornicata with ascidians and anemones. C. fornicata is common in this biotope though not as abundant as in the muddier estuarine biotope CreMed to which this is related. Anemones such as Urticina felina and Alcyonium digitatum and ascidians such as Styela clava are typically found in this biotope. Bryozoans such as Flustra foliacea are also found along with polychaetes such as Lanice conchilega. Little information is available with regard the infauna of this biotope but given the nature of the sediment the infaunal communities are liable to resemble those in biotopes from the SCS habitat complex. As with FluHyd this biotope could be considered a superficial or epibiotic overlay but more data is required to support this.


HabitatName:
Sabella pavonina with sponges and anemones on infralittoral mixed sediment

HabitatDescription:
Muddy gravelly sand with pebbles off shallow, sheltered or moderately exposed coasts or embayments may support dense populations of the peacock worm Sabella pavonina. This community may also support populations of sponges such as Esperiopsis fucorum, Haliclona oculata and Halichondria panicea and anemones such as Sagartia elegans, Cerianthus lloydii and Urticina felina. Hydroids such as Hydrallmania falcata and the encrusting polychaete Pomatoceros triqueter are also important. This biotope may have an extremely diverse epifaunal community. Less is known about its infaunal component, although it is likely to include polychaetes such as Nephtys spp., Harmothoe spp., Glycera spp., syllid and cirratulid polychaetes, bivalves such as Abra spp., Aoridae amphipods and brittlestars such as Amphipholis squamata.


HabitatName:
Venerupis senegalensis, Amphipholis squamata and Apseudes latreilli in infralittoral mixed sediment

HabitatDescription:
Sheltered muddy sandy gravel and pebbles in marine inlets, estuaries or embayments with variable salinity or fully marine conditions, support large populations of the pullet carpet shell Venerupis senegalensis with the brittlestar Amphipholis squamata and the tanaid Apseudes latreilli. This biotope may be found at a range of depths from 5m to 30m although populations of V. senegalensis may also be found on the low shore. Other common species within this biotope include the gastropod Calyptraea chinensis, a range of amphipod crustacea such as Corophium sextonae and Maera grossimana and polychaetes such as Mediomastus fragilis, Melinna palmata, Aphelochaeta marioni, Syllids and tubificid oligochaetes. Many of the available records for this biotope are from southern inlets and estuaries such as Plymouth Sound and Milford Haven but V. senegalensis has a much wider distribution and it should be noted that northern versions of this biotope may a have a much lower species diversity than reported here.


HabitatName:
Limaria hians beds in tide-swept sublittoral muddy mixed sediment

HabitatDescription:
Mixed muddy gravel and sand often in tide-swept narrows in the entrances or sills of sealochs with beds or 'nests' of Limaria hians. The Limaria form woven 'nests' or galleries from byssus and fragments of seaweeds so that the animals themselves cannot be seen from above the seabed. Modiolus modiolus sometimes occur at the same sites lying over the top of the Limaria bed. Other fauna associated with this biotope include echinoderms (Ophiothrix fragilis, Ophiocomina nigra and Asterias rubens), Buccinum undatum, mobile crustaceans (e.g. Pagurus bernhardus), Alcyonium digitatum and hydroids such as Plumularia setacea, Kirchenpaueria pinnata and Nemertesia spp. Sometimes red seaweeds such as Phycodrys rubens occur if the beds are in shallow enough water.


HabitatName:
Ostrea edulis beds on shallow sublittoral muddy mixed sediment

HabitatDescription:
Dense beds of the oyster Ostrea edulis can occur on muddy fine sand or sandy mud mixed sediments. There may be considerable quantities of dead oyster shell making up a substantial portion of the substratum. The clumps of dead shells and oysters can support large numbers of Ascidiella aspersa and Ascidiella scabra. Sponges such as Halichondria bowerbanki may also be present. Several conspicuously large polychaetes, such as Chaetopterus variopedatus and terebellids, as well as additional suspension-feeding polychaetes such as Myxicola infundibulum and Sabella pavonina may be important in distinguishing this biotope, whilst the Opisthobranch Philine aperta may also be frequent in some areas. A turf of seaweeds such as Plocamium cartilagineum, Nitophyllum punctatum and Spyridia filamentosa may also be present. This biotope description may need expansion to account for oyster beds in England.


HabitatDescription:
Mixed (heterogeneous) sediment habitats in the circalittoral zone (generally below 15-20m) including well mixed muddy gravelly sands or very poorly sorted mosaics of shell, cobbles and pebbles embedded in or lying upon mud, sand or gravel. Due to the variable nature of the seabed a variety of communities can develop which are often very diverse. A wide range of infaunal polychaetes, bivalves, echinoderms and burrowing anemones such as Cerianthus lloydii are often present in such habitat and the presence of hard substrata (shells and stones) on the surface enables epifaunal species to become established, particularly hydroids such as Nemertesia spp and Hydrallmania falcata. The combination of epifauna and infauna can lead to species rich communities. Coarser mixed sediment communities may show a strong resemblance, in terms of infauna, to biotopes within the SCS complex. However, infaunal data for this biotope complex is limited to that described under the biotope MysThyMx, and so are not representative of the infaunal component of this biotope complex.


HabitatName:
Cerianthus lloydii and other burrowing anemones in circalittoral muddy mixed sediment

HabitatDescription:
Circalittoral plains of sandy muddy gravel may be characterised by burrowing anemones such as Cerianthus lloydii. Other burrowing anemones such as Cereus pedunculatus, Mesacmaea mitchellii and Aureliania heterocera may be locally abundant. Relatively few conspicuous species are found in any great number in this biotope but typically they include ubiquitous epifauna such as Asterias rubens, Pagurus bernhardus and Liocarcinus depurator with occasional terebellid polychaetes such as Lanice conchilega and also the clam Pecten maximus. Ophiura albida may be frequent in some areas, and where surface shell or stones are present ascidians such as Ascidiella aspersa may occur in low numbers.


HabitatName:
Cerianthus lloydii with Nemertesia spp. and other hydroids in circalittoral muddy mixed sediment

HabitatDescription:
In sheltered muddy sandy gravel with appreciable quantities of surficial cobbles, pebbles and shells a community similar to ClloMx may develop with frequent Cerianthus lloydii and other burrowing anemones. However, the pebbles and cobbles embedded in the sediment are colonised by hydroids and in particular Nemertesia antennina and N. ramosa. Other hydroids may include Kirchenpaueria pinnata and Halecium halecinum whilst ascidians such as Ascidiella aspersa or Corella parallelogramma may also be present locally. Pecten maximus and Pomatoceros triqueter may also be frequent in certain areas.


HabitatName:
Sparse Modiolus modiolus, dense Cerianthus lloydii and burrowing holothurians on sheltered circalittoral stones and mixed sediment

HabitatDescription:
Pebbles and cobbles on mud or muddy gravel in sealochs with frequent Cerianthus lloydii and occasional Modiolus modiolus. Large burrowing holothurians may include Psolus phantapus, Paracucumaria hyndmani, Thyonidium commune, Thyone fusus and Leptopentacta elongate. Many of these species only extend their tentacles above the sediment surface seasonally and are likely to be under recorded by epifaunal surveys. Other more conspicuous characterising taxa include Pagurus bernhardus, Asterias rubens, and Buccinum undatum. This biotope is well developed in the Clyde sealochs, although many examples are rather species-poor. Some examples in south-west Scottish sealochs have greater quantities of boulders and cobbles and therefore have a richer associated biota (compared with other sheltered Modiolus bed biotopes such as ModHAs). Examples in Shetland are somewhat different in having the cucumber Cucumaria frondosa amongst sparse Modiolus beds and a slightly different balance in abundance of other species; for example the brittlestar Ophiopholis aculeata is more abundant in these far northern examples in the voes and narrows


HabitatName:
Mysella bidentata and Thyasira spp. in circalittoral muddy mixed sediment

HabitatDescription:
In moderately exposed or sheltered, circalittoral muddy sands and gravels a community characterised by the bivalves Thyasira spp. (often Thyasira flexuosa), Mysella bidentata and Prionospio fallax may develop. Infaunal polychaetes such as Lumbrineris gracilis, Chaetozone setosa and Scoloplos armiger are also common in this community whilst amphipods such as Ampelisca spp. and the cumacean Eudorella truncatula may also be found in some areas. The brittlestar Amphiura filiformis may also be abundant at some sites. Conspicuous epifauna may include encrusting bryozoans Escharella spp. particularly Escharella immersa and, in shallower waters, maerl (Phymatolithon calcareum), although at very low abundances and not forming maerl beds.


HabitatName:
Flustra foliacea and Hydrallmania falcata on tide-swept circalittoral mixed sediment

HabitatDescription:
This biotope represents part of a transition between sand-scoured circalittoral rock where the epifauna is conspicuous enough to be considered as a biotope and a sediment biotope where an infaunal sample is required to characterise it and is possibly best considered an epibiotic overlay. Flustra foliacea and the hydroid Hydrallmania falcata characterise this biotope; lesser amounts of other hydroids such as Sertularia argentea, Nemertesia antennina and occasionally Nemertesia ramose, occur where suitably stable hard substrata is found. The anemone Urticina feline and the soft coral Alcyonium digitatum may also characterise this biotope. Barnacles Balanus crenatus and tube worms Pomatoceros triqueter may be present and the robust bryozoans Alcyonidium diaphanum and Vesicularia spinosa appear amongst the hydroids at a few sites. Sabella pavonina and Lanice conchilega may be occasionally found in the coarse sediment around the stones. In shallower (i.e. upper circalittoral) examples of this biotope scour-tolerant robust red algae such as Polysiphonia nigrescens, Calliblepharis spp. and Gracilaria gracilis are found.


HabitatName:
Ophiothrix fragilis and/or Ophiocomina nigra brittlestar beds on sublittoral mixed sediment

HabitatDescription:
Circalittoral sediment dominated by brittlestars (hundreds or thousands m-2) forming dense beds, living epifaunally on boulder, gravel or sedimentary substrata. Ophiothrix fragilis and Ophiocomina nigra are the main bed-forming species, with rare examples formed by Ophiopholis aculeate. Brittlestar beds vary in size, with the largest extending over hundreds of square metres of sea floor and containing millions of individuals. They usually have a patchy internal structure, with localized concentrations of higher animal density. Ophiothrix fragilis or Ophiocomina nigra may dominate separately or there may be mixed populations of the two species. Ophiothrix beds may consist of large adults and tiny, newly-settled juveniles, with animals of intermediate size living in nearby rock habitats or among sessile epifauna. Unlike brittlestar beds on rock, the sediment based beds may contain a rich associated epifauna (Warner, 1971; Allain, 1974; Davoult & Gounin, 1995). Large suspension feeders such as the octocoral Alcyonium digitatum, the anemone Metridium senile and the hydroid Nemertesia antennina are present mainly on rock outcrops or boulders protruding above the brittlestar-covered substratum. The large anemone Urticina feline may be quite common. This species lives half-buried in the substratum but is not smothered by the brittlestars, usually being surrounded by a 'halo' of clear space (Brun, 1969; Warner, 1971). Large mobile animals commonly found on Ophiothrix beds include the starfish Asterias rubens, Crossaster papposus and Luidia ciliaris, the urchins Echinus esculentus and Psammechinus miliaris, edible crabs Cancer pagurus, swimming crabs Necora puber, Liocarcinus spp., and hermit crabs Pagurus bernhardus. The underlying sediments also contain a diverse infauna including the bivalve Abra alba. Warner (1971) found that numbers and biomass of sediment dwelling animals were not significantly reduced under dense brittlestar patches.


HabitatDescription:
Offshore (deep) circalittoral habitats with slightly muddy mixed gravelly sand and stones or shell. This habitat may cover large areas of the offshore continental shelf although there is relatively little data available. Such habitats are often highly diverse with a high number of infaunal polychaete and bivalve species. Animal communities in this habitat are closely related to offshore gravels and coarse sands and in some areas populations of the horse mussel Modiolus modiolus may develop in these habitats (see SBR.ModMx). Only one biotope is currently described under this biotope complex.


HabitatName:
Polychaete-rich deep Venus community in offshore gravelly muddy sand

HabitatDescription:
In offshore circalittoral slightly muddy mixed sediments, a diverse community particularly rich in polychaetes with a significant venerid bivalve component may be found. Typical species include the polychaetes Glycera lapidum, Aonides paucibranchiata, Laonice bahusiensis, Mediomastus fragilis, Lumbrineris gracilis, Pseudomystides limbata, Protomystides bidentata and syllid species and bivalves such as Timoclea ovata, Glycymeris glycymeris, Spisula elliptica and Goodallia triangularis. This biotope has been recorded on surveys of the Lambay and Codling Deeps and other areas of the Irish Sea and collectively with MedLumVen comprise the 'Deep Venus Community' and the 'Boreal Off-Shore Gravel Association' as defined by other workers (Ford 1923; Jones 1950). Some examples of this biotope may have abundant juvenile Modiolus modiolus


HabitatName:
Sublittoral macrophyte-dominated communities on sediments

HabitatDescription:
This complex includes maerl beds, seaweed dominated mixed sediments (including kelps such as Laminaria saccharina and filamentous/foliose red and green algae), seagrass beds, and lagoonal angiosperm communities. These communities develop in a range of habitats from exposed open coasts to lagoons and are found in a variety of sediment types and salinity regimes.


HabitatDescription:
Beds of maerl in coarse clean sediments of gravels and clean sands, which occur either on the open coast or in tide-swept channels of marine inlets (the latter often stony). In fully marine conditions the dominant maerl is typically Phymatolithon calcareum (SMP.Pcal), whilst under variable salinity conditions in some sealochs beds of Lithothamnion glaciale (SMP.Lgla) may develop.


HabitatName:
Phymatolithon calcareum maerl beds in infralittoral clean gravel or coarse sand

HabitatDescription:
Maerl beds characterised by Phymatolithon calcareum in gravels and sands. Associated epiphytes may include red algae such as Dictyota dichotoma, Halarachnion ligulatum, Callophyllis laciniata, Cryptopleura ramosa, Brongniartella byssoides and Plocamium cartilagineum. Algal species may be anchored to the maerl or to dead bivalve shells amongst the maerl. Polychaetes, such as Chaetopterus variopedatus, Lanice conchilega, Kefersteinia cirrata,  Mediomastus fragilis, Chone duneri, Parametaphoxus fultoni and Grania may be present. Gastropods such as Gibbula cineraria, Gibbula magus, Calyptraea chinensis Dikoleps pusilla and Onoba aculeus may also be present. Liocarcinus depurator and Liocarcinus corrugatus are often present, although they may be under-recorded; it would seem likely that robust infaunal bivalves such as Circomphalus casina, Mya truncata, Dosinia exoleta and other venerid bivalves are more widespread than available data currently suggests. It seems likely that stable wave-sheltered maerl beds with low currents may be separable from SMP.Pcal; having a generally thinner layer of maerl overlying a sandy /muddy substratum with a diverse cover of epiphytes (e.g. Bosence 1976; Blunden et al. 1977; 1981; Davies & Hall-Spencer 1996) but insufficient data currently exists on a national scale. Wave and current-exposed maerl beds, where thicker depths of maerl accumulate, frequently occur as waves and ridge / furrows arrangements (see Bosence 1976; Blunden et al. 1977; 1981; Irvine & Chamberlain 1994; Hall-Spencer 1995). At some sites where Pcal occurs, there may be significant patches of maerl gravel containing the rare burrowing anemone Halcampoides elongatus; this may be a separate biotope, but insufficient data exists at present. Northern maerl beds in the UK do not appear to contain L. corallioides but in south-west England and Ireland L. corallioides may occur to some extent in Pcal as well as Lcor, where it dominates.


HabitatName:
Phymatolithon calcareum maerl beds with red seaweeds in shallow infralittoral clean gravel or coarse sand

HabitatDescription:
Upper infralittoral maerl beds characterised by Phymatolithon calcareum in gravels and sand with a wide variety of associated red seaweeds. These algae typically include Dictyota dichotoma, Plocamium cartilagineum, Phycodrys rubens, Chondrus crispus, Halarachnion ligulatum, Chylocladia verticillata, Hypoglossum hypoglossoides and Nitophyllum punctum. These species are not restricted to maerl beds but their abundance on maerl beds differentiates this biotope from Pcal.Nmix. Anthozoans and echinoderms are much less common in this biotope than in Pcal.Nmix, which typically occurs deeper than Pcal.R.


HabitatName:
Phymatolithon calcareum maerl beds with Neopentadactyla mixta and other echinoderms in deeper infralittoral clean gravel or coarse sand

HabitatDescription:
Lower infralittoral maerl beds characterised by Phymatolithon calcareum in gravels and sand with a variety of associated echinoderms. The echinoderm Neopentadactyla mixta is frequently observed in this biotope. Other echinoderms such as Echinus esculentus, Ophiura albida and rarely Luidia ciliaris may also be present. Red seaweed such as Plocamium cartilagineum may be present but at a much lower abundance than in Pcal.R and with fewer species present. Other, more ubiquitous echinoderms such as Asterias rubens may also be found in low numbers throughout Pcal biotopes.


HabitatName:
Lithothamnion corallioides maerl beds on infralittoral muddy gravel

HabitatDescription:
Live maerl beds in sheltered, silty conditions which are dominated by Lithothamnion corallioides with a variety of foliose and filamentous seaweeds. Live maerl is at least common but there may be noticeable amounts of dead maerl gravel and pebbles. Other species of maerl, such as Phymatolithon calcareum and Phymatolithon purpureum, may also occur as a less abundant component. Species of seaweed such as Dictyota dichotoma, Halarachnion ligulatum. and Ulva spp. are often present, although are not restricted to this biotope, whereas Dudresnaya verticillata tends not to occur on other types of maerl beds. The anemones Anemonia viridis and Cerianthus lloydii, the polychaetes Notomastus latericeus and Caulleriella alata, the isopod Janira maculosa and the bivalve Hiatella arctica are typically found in SMP.Lcor where as Echinus esculentus tends to occur more in other types of maerl. The seaweeds Laminaria saccharina and Chorda filum may also be present in some habitats. Lcor has a south-western distribution in Britain and Ireland. Sheltered, stable, fully saline maerl beds in the north of Great Britain (where L. corallioides has not been confirmed to occur) may need to be described as an analogous biotope to Lcor (see Pcal).


HabitatName:
Lithophyllum fasciculatum maerl beds on infralittoral mud

HabitatDescription:
Shallow, sheltered infralittoral muddy plains with Lithophyllum fasciculatum maerl. This rarely recorded maerl species forms flattened masses or balls several centimetres in diameter (Irvine & Chamberlain 1994). Lfas may be found on mud and muddy gravel mixed with shell. Species of anemone typical of sheltered conditions may be found in association, for example, Anthopleura ballii, Cereus pedunculatus and Sagartiogeton undatus. Polychaetes such as Myxicola infundibulum and terebellids, also characteristic of sheltered conditions, may be present as may hydroids such as Kirchenpaueria pinnata. Occasional Chlamys varia and Thyone fuscus are present in all records of this biotope and red seaweeds such as Plocamium cartilagineum, Calliblepharis jubata and Chylocladia verticillata are often present.


HabitatName:
Lithothamnion glaciale maerl beds in tide-swept variable salinity infralittoral gravel

HabitatDescription:
Upper infralittoral tide-swept channels of coarse sediment in full or variable salinity conditions support distinctive beds of Lithothamnion glaciale maerl 'rhodoliths'. Phymatolithon calcareum may also be present as a more minor maerl component. Associated fauna and flora may include species found in other types of maerl beds (and elsewhere), e.g. Pomatoceros triqueter, Cerianthus lloydii, Sabella pavonina, Chaetopterus variopedatus, Lanice conchilega, Mya truncata, Plocamium cartilagineum and Phycodrys rubens. Lgla, however, also has a fauna that reflects the slightly reduced salinity conditions, e.g. Psammechinus miliaris is often present in high numbers along with other grazers such as chitons and Tectura spp. Hyas araneus, Ophiothrix fragilis, Ophiocomina nigra and the brown seaweed Dictyota dichotoma are also typically present at sites. In Scottish lagoons this biotope may show considerable variation but the community falls within the broad description defined here.


HabitatName:
Kelp and seaweed communities on sublittoral sediment

HabitatDescription:
Shallow sublittoral sediments which support seaweed communities, typically including the kelp Laminaria saccharina, the bootlace weed Chorda filum and various red and brown seaweeds, particularly filamentous types. The generally sheltered nature of these habitats enables the seaweeds to grow on shells and small stones which lie on the sediment surface; some communities develop as loose-lying mats on the sediment surface.


HabitatName:
Laminaria saccharina and red seaweeds on infralittoral sediments

HabitatDescription:
On infralittoral mixed muddy substrata communities characterised by the kelp Laminaria saccharina and mixed filamentous and foliose red algae can be found. This biotope contains a number of sub-biotopes distinguished by the degree of either wave or tidal exposure. In moderately strong tidal streams in exposed areas Laminaria is sparse and dense stands of red seaweeds are found attached to the boulders and cobbles that make up a large proportion of the sediment (LsacR.CbPb). As the degree of wave and/or tidal exposure decreases there is a change in community structure, with the density of Laminaria and the diversity of red algal species increasing (LsacR.Gv). As the environment becomes more stable a number of brown algal species are able to inhabit this environment and a rich infauna develops (LsacR.Sa). In the most sheltered examples of this biotope a diverse muddy sediment infauna can be found and the 'Trailliella' phase of Bonnemaisonia hamifera may develop (LsacR.Mu).


HabitatName:
Red seaweeds and kelps on tide-swept mobile infralittoral cobbles and pebbles

HabitatDescription:
Shallow mixed substrata of cobbles and pebbles swept by moderately strong tidal streams in exposed areas, and characterised by dense stands of red seaweeds. Tide-swept infralittoral cobbles and pebbles which may be highly mobile, create an environment that is difficult for many algae to survive in. Foliose and filamentous seaweeds with an encrusting phase in their life history, or those that are able to withstand rolling of the substratum and scouring, can form dense turfs of seaweed in the more settled summer months. Characteristic red seaweeds include Halarachnion ligulatum which is able to survive attached to the pebbles and cobbles. Ephemeral algae grow rapidly in periods of relative stability. Other characteristic red seaweeds include Plocamium cartilagineum, Hypoglossum hypoglossoides, Bonnemaisonia asparagoides and Brongniartella byssoides. Coralline encrusting algae cover many of the cobbles and pebbles; some areas of cobbles may be quite barren, dominated only by encrusting coralline algae and brittlestars. Of the brown seaweeds scattered Laminaria spp. and Desmarestia spp. may be present on more stable large boulders or bedrock outcrops. Chorda filum and Halidrys siliquosa may be present in low abundance but where these seaweeds occur in greater abundance (typically >Frequent) refer to MIR.LsacChoR and MIR.HalXK respectively. Although the faunal component of this biotope is usually relatively sparse it can include a wide variety of species. Turfs of hydroids (Nemertesia spp., Aglaophenia tubulifera) and bryozoans (Crisia spp. and Bugula spp.) are the major components but sponges and anemones may also occur. Brittlestars, sea-urchins, hydroids and solitary ascidians are more prominent in the Scottish examples of this biotope, which tend to occur in deeper water, due in part to clearer waters.


HabitatName:
Laminaria saccharina and robust red algae on infralittoral gravel and pebble

HabitatDescription:
Shallow kelp community found on gravel and gravelly sand in slightly less exposed areas than SMP.LsacR.CbPb but in moderately strong tidal currents, and characterised by occasional Laminaria saccharina with an undergrowth of robust red seaweeds. Characteristic red seaweeds, as with LsacR.CbPb, include Plocamium cartilagineum, Halarachnion ligulatum and Brongniartella byssoides; however the greater stability of this biotope allows a slightly more diverse range of red seaweeds to become established including Polyides rotundus, Rhodophyllis divaricata, Delesseria sanguinea and Nitophyllum punctatum. Coralline encrusting algae may be found covering the larger pebbles. Laminaria hyperborea may also be present within this biotope, although at low densities. Other brown algal species present include Desmarestia spp., Dictyota dichotoma and Chorda filum, all at low abundance. The ubiquitous green seaweed Ulva sp. may be found attached to larger pebbles.


HabitatName:
Laminaria saccharina and filamentous red algae on infralittoral sand

HabitatDescription:
Shallow kelp community found on sand and slightly gravelly sand, in moderately exposed and sheltered conditions, with weak tidal currents. The community is characterised by occasional Laminaria saccharina with an undergrowth of red algae. Characteristic red seaweeds, as with LsacR.Gv, include Plocamium cartilagineum, Polyides rotundus, Polysiphonia elongate and Lomentaria clavellosa. Coralline encrusting algae is much less important in this biotope as a result of a lack of suitable substrate. Brown algal species present, as with other LsacR biotopes, include Desmarestia spp., Dictyota dichotoma and Chorda filum, all at low abundance. The ubiquitous green seaweed Ulva sp. may also be present. The sandy substrate is home to a variety of typical sand dwelling infauna including polychaetes (Scoloplos armiger, Exogone hebes, and Aricidea minuta), amphipods (Ampelisca brevicornis), and bivalves (Lucinoma borealis and Abra alba). Arenicola worm casts and Lanice worm tubes may be visible at the sediment surface.


HabitatName:
Laminaria saccharina with red and brown seaweeds on lower infralittoral muddy mixed sediment

HabitatDescription:
Slightly deeper kelp community in the lower infralittoral, found on sandy gravelly mud, in sheltered and very sheltered conditions, with very weak tidal currents. The community is characterised by occasional Laminaria saccharina with an undergrowth of red and brown algae. Characteristic red seaweeds, as with other LsacR biotopes include Plocamium cartilagineum and Phycodrys rubens. However, the sheltered conditions of this biotope allow the 'Trailliella' phase of Bonnemaisonia hamifera to develop (although not to the extent of forming distinct mats as in SMP.Tra), and the related species Bonnemaisonia asparagoides. Brown algal species present, as with other LsacR biotopes, include Desmarestia spp at low abundance. The ubiquitous green seaweed Ulva sp. may also be present. The muddy substrate is home to a variety of typical mud dwelling fauna including the burrowing anemone Cerianthus lloydii. The gravelly component of this biotope provides a substrate for encrusting species such as the polychaete Pomatoceros triqueter and coralline encrusting algae.


HabitatName:
Laminaria saccharina and Chorda filum on sheltered upper infralittoral muddy sediment

HabitatDescription:
Shallow kelp community found on sandy mud and gravelly sandy mud, in sheltered or extremely sheltered conditions, with very weak tidal currents. The community is characterised by a reasonable covering of Laminaria saccharina and Chorda filum. Beneath the kelp canopy, Ulva lactuca is often frequent and some filamentous and foliose red algae may be present, along with filamentous brown ectocarpoid algae although in much lower abundance than in the LsacR biotopes. At the sediment surface ubiquitous fauna such as Asterias rubens, crabs such as Pagurus bernhardus, Carcinus maenas, and the gastropod Gibbula cineraria may be visable and in some areas Sabella pavonina may be present. Given the nature of the sediment it is likely that a wide range of infaunal bivalves and polychaetes are present including Arenicola marina, Mediomastus fragilis and Anaitides mucosa. In more tideswept areas with coarser and generally less muddy sediments SMP.LsacCho may be replaced by one of the sub biotopes of SMP.LsacR.


HabitatName:
Laminaria saccharina with Psammechinus miliaris and/or Modiolus modiolus on variable salinity infralittoral sediment

HabitatDescription:
Shallow kelp community found on stoney mixed sediment, in full or variable salinity, in sheltered or moderately exposed conditions, with weak or very weak tidal currents. The community is characterised by a dense covering of Laminaria saccharina. Beneath the kelp canopy, frequent Psammechinus miliaris may be found grazing the algal turf and scattered Modiolus modiolus are characteristic of this biotope. Encrusting the suface of stones and pebbles are Pomatoceros triqueter and in the sediment between the stones, the burrowing anemone Cerianthus lloydii may also be present. Small patches of Lithothamnion glaciale may be found in this biotope, although these patches do not form distict beds as in SBR.Lgla. In addition, a more ubiquitous fauna such as Asterias rubens and Pagurus bernhardus are also present. This biotope is generally found in sealochs.


HabitatName:
Laminaria saccharina, Gracilaria gracilis and brown seaweeds on full salinity infralittoral sediment

HabitatDescription:
Shallow kelp community found on muddy sand, in moderately exposed or sheltered, fully marine conditions, with weak tidal currents. The community is characterised by a reasonable covering of Laminaria saccharina. Frequent Chorda filum may also form part of the canopy although not at the abundance in LsacCho. Beneath the canopy the community is characterised by the red algae Gracilaria gracilis, and various brown algal species particularly Dictyota dichotoma. Other members of the understory may include a variety of other filamentous and foliose red algae in particular Ceramium nodulosum and the green alga Ulva. The muddy sand substrate supports a variety of faunal species including polychaetes (Lanice conchilega) and gastropods (Hinia reticulata).


HabitatName:
Laminaria saccharina and Gracilaria gracilis with sponges and ascidians on variable salinity infralittoral sediment

HabitatDescription:
Shallow kelp community found on stony sediment, in extremely sheltered, variable salinity conditions, with moderately strong tidal currents. The community is characterised by a more sparse covering of Laminaria saccharina, particularly when compared to the fully marine version of this sub biotope (SMP.LsacGraFS). Beneath the canopy the community is characterised by the red algae Gracilaria gracilis, and a variety of faunal species in particular sponges (Suberites ficus and Halichondria panacea) and ascidians (Ascidiella aspersa and Dendrodoa grossularia). The stony substrate provides a surface for attachment for these and many other filter and suspension feeding species, particularly barnacles (Balanus crenatus), hydroids (Urticina feline and Hydractinia echinata) and anemones. Other members of the understory may include a variety of filamentous and foliose red algae in particular Pterothamnion plumula, and the green alga Ulva.


HabitatName:
Mats of Trailliella on infralittoral muddy gravel

HabitatDescription:
Dense loose-lying beds of the 'Trailliella' phase of Bonnemaisonia hamifera may occur in extremely sheltered shallow muddy environments. Beds of this alga are often 10 cm thick but may reach 100 cm at some sites. Other loose-lying algae may also occur such as Audouinella floridula, Phyllophora crispa and species of Derbesia. Often the mud is gravelly or with some cobbles and may be black and anoxic close to the sediment surface. This biotope is widely distributed in lagoons, sealochs and voes but should only be described as SMP.Tra when a continuous mat is found. It is likely that the infaunal component of this biotope may be considerably modified by the overwhelming quantity of loose-lying algae.


HabitatName:
Loose-lying mats of Phyllophora crispa on infralittoral muddy sediment

HabitatDescription:
Infralittoral muddy sand and sandy mud, sometimes with some shells or pebbles, and a dense, loose-lying cover of Phyllophora crispa. This biotope occurs in very sheltered conditions such as those found in sealochs and voes. SMP.Pcri is similar to other biotopes described with dense, loose-lying algae but has been less frequently recorded, and from the few records available, appears to occur in slightly deeper infralittoral waters primarily between 10m to 30m and typically in fully saline waters. The seaweeds in this biotope may be epiphytised by ascidians such as Ascidiella aspera. Kelp such as Laminaria saccharina and red seaweeds including Plocamium cartilagineum may be present in some areas. The scallops Pecten maximus and Aequipecten opercularis may also be found occasionally in this biotope and Trailliella/Bonnemaisonia hamifera may also be present but not at the levels found in SMP.Tra.


HabitatName:
Filamentous green seaweeds on low salinity infralittoral mixed sediment or rock

HabitatDescription:
Shallow muddy sediments, often with boulders, cobbles and pebbles around the edges of lagoons, or other areas that are exposed to wide salinity variations are unsuitable for colonisation by many species. Such areas may be colonised by a dense blanket of ephemeral green algae such as Enteromorpha spp., Chaetomorpha linum, Cladophora liniformis or Rhizoclonium riparium. This biotope may also contain some red seaweeds, such as Furcellaria lumbricalis, but always at low abundance (compare with PolFur). Amongst the filamentous green algae, grazing molluscs and solitary ascidians may be present. Infauna may typically include Corophium volutator, Heterochaeta costata, Tubificoides benedeni and other taxa suited for low/variable salinity environments.


HabitatDescription:
Beds of seagrass (Zostera marina or Ruppia spp.) in shallow sublittoral sediments. These communities are generally found in extremely sheltered embayments, marine inlets, estuaries and lagoons, with very weak tidal currents. They may inhabit low, variable and full salinity marine habitats. Whilst generally found on muds and muddy sands they may also occur in coarser sediments, particularly marine examples of Zostera communities.


HabitatName:
Zostera marina/angustifolia beds on lower shore or infralittoral clean or muddy sand

HabitatDescription:
Expanses of clean or muddy fine sand and sandy mud in shallow water and on the lower shore (typically to about 5 m depth) can have dense stands of Zostera marina/angustifolia [Note: the taxonomic status of Z. angustifolia is currently under consideration]. In Zmar the community composition may be dominated by these Zostera species and therefore characterised by the associated biota. Other biota present can be closely related to that of areas of sediment not containing Zostera marina, for example, Laminaria saccharina, Chorda filum and infaunal species such as Ensis spp. and Echinocardium cordatum (e.g. Bamber 1993). From the available data it would appear that a number of sub-biotopes may be found within this biotope dependant on the nature of the substratum and it should be noted that sparse beds of Zostera marina may be more readily characterised by their infaunal community. For example, coarse marine sands with seagrass have associated communities similar to MoeVen, SLan or Glap whilst muddy sands may have infaunal populations related to EcorEns, AreISa and FfabMag. Muddy examples of this biotope may show similarities to SundAasp, PhiVir, Are or AfilMysAnit. At present the data does not permit a detailed description of these sub-biotopes but it is likely that with further study the relationships between these assemblages will be clarified. Furthermore, whilst the Zostera biotope may be considered an epibiotic overlay of established sedimentary communities it is likely that the presence of Zostera will modify the underlying community to some extent. For example, beds of this biotope in the south-west of Britain may contain conspicuous and distinctive assemblages of Lusitanian fauna such as Laomedea angulata, Hippocampus spp. and Stauromedusae. In addition, it is known that seagrass beds play an important role in the trophic status of marine and estuarine waters, acting as an important conduit or sink for nutrients and consequently some examples of Zostera marina beds have markedly anoxic sediments associated with them.


HabitatName:
Ruppia maritima in reduced salinity infralittoral muddy sand

HabitatDescription:
In sheltered brackish muddy sand and mud, beds of Ruppia maritima and more rarely Ruppia spiralis may occur. These beds may be populated by fish such as Gasterosteus aculeatus which is less common on filamentous algal-dominated sediments. Seaweeds such as Chaetomorpha spp., Enteromorpha spp., Cladophora spp., and Chorda filum are also often present in addition to occasional fucoids. In some cases the stoneworts Lamprothamnium papulosum and Chara aspera occur. Infaunal and epifaunal species may include mysid crustacea, the polychaete Arenicola marina, the gastropod Hydrobia ulvae, the amphipod Corophium volutator and oligochaetes such as Heterochaeta costata. In some areas Zostera marina may also be interspersed with the Ruppia beds.


HabitatName:
Angiosperm communities in reduced salinity

HabitatDescription:
Lagoon communities, subject to reduced or low salinity conditions, dominated by angiosperms, including Potamogeton pectinatus beds and fringing habitats with reeds Phragmites australis.


HabitatDescription:
Low and variable salinity infralittoral mud with beds of Potamogeton pectinatus. Other associated species are broadly similar to that of Rup, with blankets of filamentous green algae such as Enteromorpha intestinalis, Cladophora liniformis and Rhizoclonium riparium. The grazing gastropod Potamopyrgus antipodarum is found in this biotope and juvenile Mytilus edulis have been observed settled on Potamogeton leaves and amongst the algae. The nationally scarce charaphyte Lamprothamnium papulosum may be found to some extent in this biotope but more often in neighbouring habitats (see Plaza & Sanderson 1997). Mysids, trout (Salmo trutta), and sticklebacks Gasterosteus aculeatus can be found swimming amongst the vegetation. Mya arenaria may be found in some examples of this biotope, but the infaunal component of this biotope requires further investigation but is likely to contain oligochaetes, Arenicola marina, Corophium volutator and Gammarus spp.


HabitatName:
Phragmites australis swamp and reed beds

HabitatDescription:
Permanently low salinity muds or peaty muddy sands with some gravel which supports Phragmites australis reed beds. These reed beds are often found in enclosed water bodies influenced by freshwater inflow and may have notable quantities of decaying reed material. The substratum may be mixtures of mud, peaty mud, sand and some gravel. Filamentous green algae and charaphytes such as Lamprothamnium papulosum and Chara aspera may also be found in association with this biotope as well as a the freshwater quillwort Myriophyllum spp. The infaunal component of this biotope is poorly known. This biotope is further described as NVC type S4 (Rodwell 1995).


HabitatDescription:
Sublittoral biogenic reef communities. This complex includes polychaete reefs, bivalve reefs (e.g. mussel beds) and cold water coral reefs. These communities develop in a range of habitats from exposed open coasts to estuaries, marine inlets and deeper offshore habitats and may be found in a variety of sediment types and salinity regimes.


HabitatName:
Polychaete worm reefs (on sublittoral sediment)

HabitatDescription:
Sublittoral reefs of polychaete worms in mixed sediments found in a variety of hydrographic conditions. Such habitats may range from extensive structures of considerable size to loose agglomerations of tubes. Such communities often play an important role in the structural composition or stability of the seabed and provide a wide range of niches for other species to inhabit. Consequently polychaete worm reefs often support a diverse flora and fauna.


HabitatName:
Sabellaria spinulosa on stable circalittoral mixed sediment

HabitatDescription:
The tube-building polychaete Sabellaria spinulosa at high abundances on mixed sediment. These species typically forms loose agglomerations of tubes forming a low lying matrix of sand, gravel, mud and tubes on the seabed. The infauna comprises typical sublittoral polychaete species such as Protodorvillea kefersteini, Pholoe synophthalmica, Harmothoe spp, Scoloplos armiger, Mediomastus fragilis, Lanice conchilega and cirratulids, together with the bivalve Abra alba, and tube building amphipods such as Ampelisca spp. The epifauna comprise a variety of bryozoans including Flustra foliacea, Alcyonidium diaphanum and Cellepora pumicosa, in addition to calcareous tubeworms, pycnogonids, hermit crabs and amphipods. The reefs formed by Sabellaria consolidate the sediment and allow the settlement of other species not found in adjacent habitats leading to a diverse community of epifaunal and infauna species. The development of such reefs is assisted by the settlement behaviour of larval Sabellaria which are known to selectively settle in areas of suitable sediment and particularly on existing Sabellaria tubes (Tait and Dipper, 1997; Wilson 1929). These reefs are particularly affected by dredging or trawling and in heavily dredged or disturbed areas an impoverished community may be left (e.g. Pkef) particularly if the activity or disturbance is prolonged. However, it is likely that reefs of S. spinulosa can recover quite quickly from short term or intermediate levels of disturbance as found by Vorberg (2000) in the case of disturbance from shrimp fisheries and recovery will be accelerated if some of the reef is left intact following disturbance as this will assist larval settlement of the species.


HabitatName:
Sabellaria alveolata on variable salinity sublittoral mixed sediment

HabitatDescription:
Tide-swept sandy mixed sediments with cobbles and pebbles, in variable salinity or fully marine conditions, may be characterised by surface accumulations of the reef building polychaete Sabellaria alveolata. The presence of Sabellaria sp. has a strong influence on the associated infauna as the tubes bind the surface sediments together and provide increased stability. Such reefs may form large structures up to a metre in height although they are considerably less extensive than the intertidal reefs formed by this species (Salv). Other associated species may include the polychaete Melinna cristata, itself often as dense aggregations, mobile surface feeding polychaetes including Typosyllis armillary and Eulalia tripunctata. Other polychaetes may include Mediomastus fragilis and Pygospio elegans whilst amphipods such as Harpinia pectinata and tubificid oligochaetes may also be found.


HabitatName:
Serpula vermicularis reefs on very sheltered circalittoral muddy sand

HabitatDescription:
Large clumps (mini 'reefs') of the calcareous tubes of Serpula vermicularis, typically attached to stones on muddy sediment in very sheltered conditions in sealochs and other marine inlets. A rich associated biota attached to the calcareous tube may include Esperiopsis fucorum, thin encrusting sponges, and the ascidians Ascidiella aspersa, Ascidia mentula, Dendrodoa grossularia and Diplosoma listerianum. The echinoderms Ophiothrix fragilis and Psammechinus miliaris and the queen scallop (Aequipecten opercularis) are also found throughout this biotope. In shallow water dense Phycodrys rubens may grow on the 'reefs'. This biotope has been recorded in the U.K. from Loch Creran, where these reefs have been well studied (Moore 1996), and Loch Sween, where they are reported to have deteriorated. The only other known sites for this biotope are Salt Lake, Cliffden and Killary Harbour, Co. Galway.


HabitatName:
Sublittoral mussel beds (on sublittoral sediment)

HabitatDescription:
Sublittoral mussel beds comprised of either the horse mussel Modiolus modiolus or the common mussel Mytilus edulis. These communities may be sublittoral extensions of littoral reefs or exist independently. Found in a variety of habitats ranging from sheltered estuaries and marine inlets to open coasts and offshore areas they may occupy a range of substrata, although due to the stabilising effect such communities have on the substratum muddy mixed sediments are typical. A diverse range of epibiota and infauna often exists in these communities.


HabitatName:
Modiolus modiolus beds with hydroids and red seaweeds on tide-swept circalittoral mixed substrata

HabitatDescription:
Modiolus beds on mixed substrata (cobbles, pebbles and coarse muddy sediments) in moderately strong currents or wave exposed areas, typically on the open coast but also in tide-swept channels of marine inlets. Ophiothrix fragilis are often common in this biotope along with the calcareous tubes of Pomatoceros triqueter, anemones such as Alcyonium digitatum and Urticina felina and hydroids such as Abietinaria abietina and Sertularia argentea. Buccinum undatum may also be important and in some areas the clam Chlamys varia may be frequent but not in the same abundances as in ModCvar. Little information on the infaunal component is given here although it is likely that it is very rich and may highlight more subtle differences in the Modiolus biotopes. This biotope is typified by examples off the north-west Lleyn Peninsula in N Wales and off Co. Down, Northern Ireland.


HabitatName:
Modiolus modiolus beds on open coast circalittoral mixed sediment

HabitatDescription:
Muddy gravels and coarse sands in deeper water of continental seas may contain venerid bivalves with beds of Modiolus modiolus. The clumping of the byssus threads of the M. modiolus creates a stable habitat that attracts a very rich infaunal community with a high density of polychaete species including  Glycera lapidum, Paradoneis lyra, Aonides paucibranchiata, Laonice bahusiensis, Protomystides bidentata, Lumbrineris spp., Mediomastus fragilis and syllids such as Exogone spp. and Sphaerosyllis spp. Bivalves such as Spisula elliptica, Timoclea ovata and other venerid species are also common. Brittlestars such as Amphipholis squamata may also occur with this community. This biotope is very similar to SMX.PoVen and the 'boreal off-shore gravel association' and the 'deep Venus community' described by previous workers (Ford 1923; Jones 1951). Similar Modiolus beds (though with a less diverse infauna) on open coast stable boulders, cobbles and sediment are described under MCR.ModT.


HabitatName:
Modiolus modiolus beds with fine hydroids and large solitary ascidians on very sheltered circalittoral mixed substrata

HabitatDescription:
Beds or scattered clumps of Modiolus modiolus in generally sheltered conditions with only slight tidal movement. Typically occurs in sealochs and the Shetland voes. Brittlestars Ophiothrix fragilis and Ophiocomina nigra, as well as Ophiopholis aculeata are often frequent, sometimes forming a dense bed as described in OphMx. The queen scallop Aequipecten opercularis is often present in moderate abundances. Large solitary ascidians (Ascidiella aspersa, Corella parallelogramma, Dendrodoa grossularia) and fine hydroids (Kirchenpaueria pinnata) are present attached to the mussel shells. Decapods such as hermit crabs (Pagurus bernhardus) and spider crabs (Hyas araneus) are typically present. Coralline algal crusts may be found on the mussel shells, with some red seaweeds in shallower water such as Phycodrys rubens. Little information on the infaunal component is given here although it is likely that it is very rich and may highlight more subtle differences in the Modiolus biotopes.


HabitatName:
Modiolus modiolus beds with Chlamys varia, sponges, hydroids and bryozoans on slightly tide-swept very sheltered circalittoral mixed substrata

HabitatDescription:
Dense Modiolus modiolus beds, covered by hydroids and bryozoans, on soft gravelly, shelly mud with pebbles in areas of slight or moderate tidal currents. The variable scallop (Chlamys varia) is frequently found in large numbers amongst the Modiolus shells. Hydroids such as Halecium spp. and Kirchenpaueria pinnata and ascidians such as Ascidiella aspersa, Corella parallelogramma and Ciona intestinalis may be found attached to pebbles or mussel shells. The echinoderms Ophiothrix fragilis and Antedon bifida are often frequent in this biotope as is the encrusting polychaete Pomatoceros triqueter. Similar communities have been found on cobble and pebble plains in stable, undisturbed conditions in some sealochs, although not all these examples have Modiolus beds.


HabitatName:
Mytilus edulis beds on sublittoral sediment

HabitatDescription:
Shallow sublittoral mixed sediment, in fully marine coastal habitats or sometimes in variable salinity conditions in the outer regions of estuaries, are characterised by beds of the common mussel Mytilus edulis. Other characterising infaunal species may include the amphipod Gammarus salinus and oligochaetes of the genus Tubificoides. The polychaetes Harmothoe spp., Kefersteinia cirrata and Heteromastus filiformis are also important. Epifaunal species in addition to the M. edulis include the whelks Nucella lapillus and Buccinum undatum, the common starfish Asterias rubens the spider crab Maja squinado and the anemone Urticina felina. Relatively few records are available for this biotope and it is possible that as more data is accumulated separate estuarine and fully marine sub-biotopes may be described. Further clarification may also be required with regard to the overlap between littoral and sublittoral mussel beds and with regard to mussel beds biotopes on hard substratum.


HabitatDescription:
The coral reef structures in UK waters are found in cold (12-4øC), largely aphotic waters, generally along the shelf edge and in offshore waters down to 2000m. In the north east Atlantic, Lophelia pertusa is the dominant colonial coral and is the characterising species of the biotope described under this biotope complex. Lophelia and its deep-water allies lack the symbiotic algae of their tropical relatives, so can live in the permanent darkness of the deep sea. These corals form colonies and can aggregate into patches and banks which may be described as reefs. These deep-sea corals can support and shelter hundreds of other species, including sponges, polychaete worms, echinoderms (starfish, sea urchins, brittle stars) and bryozoans (sea mats). Some 200-300 species can be found in one of these coral habitats, a number comparable to that found in other important deep-water habitats. Unlike tropical coral reef systems, they are dominated by only a few hard-coral species, and there are far fewer fish species.


HabitatDescription:
Reefs of the coral Lophelia pertusa, typically supporting a range of other biota. Lophelia reefs are generally found in areas of elevated current. The coral provides a 3 dimensional structure and a variety of microhabitats that provide shelter and a surface of attachment for other species. Boring sponges, anemones, bryozoans, gorgonians including Paragorgia arborea, Paramuricea placomus, Primnoa resedaeformis, polychaetes, barnacles, squat lobsters (Munida sarsi) and bivalves have all been recorded within and among the corals (Wilson, 1979; Mortensen et al., 1995) Other hard corals such as Madrepora oculata and Solenosmilia variabilis may also be present. Mobile species present include the redfish (Sebastes viviparous and Sebastes marinus), Ling (Molva molva) and tusk (Brosme brosme) (Husebo et al., 2002).


HabitatDescription:
Marine habitats are directly connected to the oceans, i.e. part of the continuous body of water which covers the greater part of the earth’s surface and which surrounds its land masses. Marine waters may be fully saline, brackish or almost fresh. Marine habitats include those below spring high tide limit (or below mean water level in non-tidal waters) and enclosed coastal saline or brackish waters, without a permanent surface connection to the sea but either with intermittent surface or sub-surface connections (as in lagoons). Rockpools in the supralittoral zone are considered as enclaves of the marine zone. Includes marine littoral habitats which are subject to wet and dry periods on a tidal cycle including tidal saltmarshes; marine littoral habitats which are normally water-covered but intermittently exposed due to the action of wind or atmospheric pressure changes; freshly deposited marine strandlines characterised by marine invertebrates. Waterlogged littoral saltmarshes and associated saline or brackish pools above the mean water level in non-tidal waters or above the spring high tide limit in tidal waters are included with marine habitats. Includes constructed marine saline habitats below water level as defined above (such as in marinas, harbours, etc) which support a semi-natural community of both plants and animals. The marine water column includes bodies of ice.


HabitatDescription:
Extremely exposed to moderately exposed or tide-swept bedrock and boulder shores. Extremely exposed shores dominated by mussels and barnacles, occasionally with robust fucoids or turfs of red seaweed. Tide-swept shores support communities of fucoids, sponges and ascidians on the mid to lower shore. Three biological subtypes have been described: Communities on very exposed to moderately exposed upper and mid eulittoral bedrock and boulders dominated by the mussel [Mytilus edulis], barnacles [Chthamalus] spp. and/or [Semibalanus balanoides] and the limpets [Patella] spp. (A1.11); red and brown seaweeds able to tolerate the extreme conditions of exposed rocky shores, primarily the physical stresses caused by wave action (A1.12), and tide-swept shores in more sheltered areas (such as narrow channels in sea loch) with canopy forming fucoids and a rich filter-feeding community (A1.15).


HabitatDescription:
Communities on very exposed to moderately exposed upper and mid eulittoral bedrock and boulders dominated by the mussel [Mytilus edulis] (A1.111), barnacles [Chthamalus] spp. and/or [Semibalanus balanoides] and limpets [Patella] spp. (A1.112, A1.113). Several variants are identified. Some shores are characterised by dense bands of the barnacle [Semibalanus balanoides] and the limpet [Patella vulgata] (A1.113). The barnacles may be covered by [Porphyra umbilicalis] on the upper shore of exposed sites. Cracks and crevices in the rock provide a refuge for small individuals of the mussel [M. edulis], winkles [Littorina saxatilis] and the whelk [Nucella lapillus]. Red seaweeds also frequently occupy damp crevices, particularly [Ceramium shuttleworthianum], [Corallina officinalis], [Osmundea pinnatifida] and encrusting coralline algae, but the non-vesiculate form of the wrack [Fucus vesiculosus] might be present (A1.1132). Large numbers of the winkle [Littorina littorea] often dominate fields of large boulders or shores with a more mixed substratum (A1.1133). There is much regional variation affecting the zonation of barnacles in the British Isles. In the north-west [C. montagui] and/or [C. stellatus] can form a distinct band above [S. balanoides]. In the south-west [C. montagui] and/or [C. stellatus] can be the dominant barnacles throughout the eulittoral zone (A1.1121). On the east coasts [S. balanoides] is able to extend to the upper shore due to the absence of [Chthamalus] spp. and thereby any competition. The lichen [Lichina pygmaea] may be prominent, especially in the south, where it can form distinct patches or even a separate zone among the [Chthamalus] spp. (A1.1122). In areas of soft rock (e.g. shales), the barnacles may be scarce or absent and the rock dominated by [P. vulgata].
Situation: This habitat type is found in the mid to upper eulittoral on very to moderately exposed shores below the lichen dominated biotopes (B3.11) and is typically characterised by patches of mussels [M. edulis] interspersed with barnacles. Below A1.11 is a community dominated by the wrack [Himanthalia elongata] and red seaweeds such as [C. officinalis], [Mastocarpus stellatus] and [O. pinnatifida] (A1.12). With decreasing wave exposure [F. vesiculosus] is able to survive, gradually replacing the barnacles and [P. vulgata] biotope (A1.213). On such moderately exposed shores A1.11 may occur on steep and vertical faces, while fucoids dominate the flatter areas (A1.1132, A1.213).


HabitatName:
[Mytilus edulis] and barnacles on very exposed eulittoral rock

HabitatDescription:
On very exposed to exposed rocky shores the eulittoral zone, particularly the mid and lower shore, is typically characterised by patches of small individuals of the mussel [Mytilus edulis] interspersed with patches of the barnacle [Semibalanus balanoides] and individuls of the limpet [Patella vulgata]. Amongst the mussels small individuals of red seaweeds including [Ceramium] spp., [Corallina officinalis] and [Mastocarpus stellatus] can be found. The foliose red seaweeds [Porphyra umbilicalis] and [Palmaria palmata] are commonly found as epiphytes on [M. edulis] where they can form luxuriant growths. The abundance of the red seaweeds generally increases down the shore and in the lower eulittoral they may form a distinct zone in which mussels or barnacles are scarce (A1.12, A1.1221 or A1.123). Where [M. edulis] occurs on steep rock, red seaweeds are scarce and restricted to the lower shore. The whelk [Nucella lapillus] and a few winkles such as [Littorina] spp. can occur where cracks and crevices provide a refuge in the rock. Fucoids are generally absent, although some non-vesiculate [Fucus vesiculosus] may occur where the shore slopes more gently. This biotope also occurs on steep moderately exposed shores which experience increased wave energy.

Situation: This unit is generally found above a zone of either mixed turf-forming red seaweeds (A1.12), [Himanthalia elongata] (A1.123) or above the sublittoral fringe kelp [Alaria esculenta] (A3.111) zone. Above A1.111 there may be a [Verrucaria maura] zone (B3.1132), a [V. maura] and sparse barnacle zone (B3.1131), often with [P. umbilicalis] or a denser barnacle and limpet zone (A1.113; A1.213). In addition, patches of lichen [Lichina pygmaea] with the barnacle [Chthamalus montagui] (A1.1121) may also occur above this biotope, particularly on southern shores.

Temporal variation: Severe winter storms can cause periodic removal of this mussel and barnacle community.


HabitatName:
[Chthamalus] spp. On exposed upper eulittoral rock

HabitatDescription:
Very exposed to moderately exposed upper and mid eulittoral bedrock and boulders characterised by a dense community of barnacles, including [Chthamalus montagui], [Chthamalus stellatus] and [Semibalanus balanoides], and the limpet [Patella vulgata]. Damp cracks and crevices in the rock provide a refuge for small individuals of the mussel [Mytilus edulis] and the winkles [Melarhaphe neritoides] and [Littorina saxatilis]. These crevices can also be occupied by encrusting coralline algae and the anemone [Actinia equina]. Black patches of the lichen [Verrucaria maura] may be found in this zone. There is much regional variation in the distribution and zonation of [Chthamalus] spp. On the west coast [Chthamalus] spp. dominate the upper eulittoral, often forming a distinct white band above a darker band of [S. balanoides] in the mid eulittoral zone. [C. montagui] is better adapted to resist desiccation and, therefore, extends further up the shore. On some shores, particularly in the south-west, [Chthamalus] spp. is the dominant barnacle throughout the eulittoral zone (A1.1121). On other shores, particularly in the south, [Lichina pygmaea] can form a distinct zone (A1.1122).
Situation: This unit is found below the black lichen [Verrucaria maura] (B3.1131 or B3.1132) on very exposed shores and above the mussel [Mytilus edulis] and barnacle biotope (A1.111). On slightly less exposed shores the wrack [Fucus vesiculosus] is able to survive and a mixed barnacle and [F. vesiculosus] biotope may occur (A1.1132) beneath A1.112. On such moderately exposed shores A1.112 may still occur on steep and vertical faces, while fucoids dominate the flatter areas (A1.1132 or A1.1132), though these communities should not be confused with A1.1132. This unit can also occur above A1.113. On very sheltered sea lochs in Argyll, West Scotland [Chthamalus] spp. are unusually abundant in the upper eulittoral zone.


HabitatName:
[Chthamalus montagui] and [Chthamalus stellatus] on exposed upper eulittoral rock

HabitatDescription:
Very exposed to moderately exposed upper and mid eulittoral bedrock and boulders characterised by a dense community of barnacles, including [Chthamalus montagui], [Chthamalus stellatus] and [Semibalanus balanoides], and the limpet [Patella vulgata]. Damp cracks and crevices in the rock provide a refuge for small individuals of the mussel [Mytilus edulis], and the winkles [Melarhaphe neritoides] and [Littorina saxatilis]. These crevices can also be occupied by encrusting coralline algae and the anemone [Actinia equina]. Patches of the black lichen [Verrucaria maura] and the green seaweed [Enteromorpha intestinalis] may be present, though in low abundance (Occasional). Shaded vertical littoral fringe and upper eulittoral bedrock may be characterised by the shade-tolerant red seaweeds [Catenella caespitosa], [Bostrychia scorpioides] and/or [Lomentaria articulata]. Where the turf of [C. caespitosa] is well established, barnacles are rare. Geographical variation: There is much regional variation in the distribution and zonation of [Chthamalus] spp. On the west coast [Chthamalus] spp. dominate the upper eulittoral, often forming a distinct white band above a darker band of [S. balanoides] in the mid eulittoral zone. [C. montagui] is better adapted to resist desiccation and, therefore, extends further up the shore. In the south-west [Chthamalus] spp. can be the dominant barnacles throughout the eulittoral zone.

Situation: This unit is found below the black lichen [Verrucaria maura] (B3.1131 or B3.1132) on very exposed shores. It is found above the mussel [Mytilus edulis] and barnacles biotope (A1.111). On slightly less exposed shores the wrack [Fucus vesiculosus] is able to survive and a mixed barnacle and [F. vesiculosus] biotope may occur (A1.1132) beneath  A1.1121. On such moderately exposed shores A1.1121may still occur on steep and vertical faces, while fucoids dominate the flatter areas (A1.1132 or A1.1132), though these communities should not be confused with A1.1132.  On very sheltered sea lochs in Argyll, West Scotland [Chthamalus] spp. are unusually abundant in the upper eulittoral zone.


HabitatName:
[Chthamalus] spp. and [Lichina pygmaea] on steep exposed upper eulittoral rock

HabitatDescription:
Areas of steep and vertical rock in the upper eulittoral on very exposed to moderately exposed shores characterised by tufts of the dark brownish lichen [Lichina pygmaea] and the barnacles [Chthamalus montagui] and [Chthamalus stellatus], although long-established patches of [L. pygmaea] ultimately exclude barnacles. The rigid branching thallus of [L. pygmaea] provides an ideal habitat for the bivalve [Lasaea adasoni], the winkles [Littorina saxatilis] and [Melarhaphe neritoides]. The anemone [Actinia equina] and the mussel [Mytilus edulis] are confined to moist cracks and crevices, while the limpet [Patella vulgata] is found on the open bedrock. In the south-west the top shell [Gibbula umbilicalis] can be found on [L. pygmaea]. On the north-east coast this biotope does not have [Chthamalus] spp., [L. pygmaea] being the most important characterising species on these sites.

Situation: The band of [L. pygmaea] lies between the [Verrucaria maura] zone (B3.1131 or B3.1132) above and the barnacle-[P. vulgata] zone  below. Other upper shore biotopes (B3.1131 or B3.1132) may contain occasional patches of [L. pygmaea], particularly on steep sunny faces, though not forming a distinct zone. [L. pygmaea] also occurs on less steeply-sloping shores if they are in a sunny aspect. In some areas, a high abundance of [L. pygmaea] results in a distinct zone, particularly in the south. On [Chthamalus] spp[]. dominated shores (south and west coasts) the band of [L. pygmaea] lies within the barnacle zone, whereas on [Semibalanus balanoides] dominated shores (north and east coasts) A1.1122 lies astride the upper limit of the barnacles.


HabitatName:
[Semibalanus balanoides] on exposed to moderately exposed or vertical sheltered eulittoral rock

HabitatDescription:
Exposed to moderately exposed mid to upper eulittoral bedrock and large boulders characterised by dense barnacles [Semibalanus balanoides] and the limpet [Patella vulgata]. The community has a relatively low diversity of species though occasional cracks and crevices in the rock can provide a refuge for small individuals of the mussel [Mytilus edulis], the winkle [Littorina saxatilis] and the whelk [Nucella lapillus]. Seaweeds are usually not found in high numbers though fissures and crevices in the bedrock can hold a sparse algal community including the green seaweed [Enteromorpha intestinalis]. On some shores the olive green lichen [Verrucaria mucosa] can be present in some abundance (Frequent). Three variants have been described: A [S. balanoides] and [P. vulgata] dominated community on bedrock (A1.1131); [S. balanoides] and sparse [Fucus vesioculosus] and red seaweeds (A1.1132); and barnacles and [L. littorea] eulittoral boulders and cobbles (A1.1133).

Situation: On very exposed to exposed shores [Chthamalus] spp. (see A1.112 and subunits for geographical variation) often forms a distinct white band above a darker band of [S. balanoides] in the mid eulittoral zone. Alternatively, the black lichen [Verrucaria maura] dominated biotopes (B3.1131 or B3.1132) may be found above A1.113. In the lower eulittoral and the sublittoral fringe a community dominated by the wrack [Himanthalia elongata] and various red seaweeds such as [Corallina officinalis], [Mastocarpus stellatus] and [Osmundea pinnatifida] (A1.123; A1 122; A1.126) often occurs. A1.113 may also occur on steep and vertical faces on more sheltered shores, while fucoids dominate the flatter areas (A1.213; A1.1132).

Temporal variation: Periods with little scour or calmer weather can allow a seaweed community to develop, creating a more diverse biotope (i.e. A1.313 or A1.213). This is a dynamic process, which will change individual sites over time. More information is required to determine the exact nature of this process.


HabitatName:
[Semibalanus balanoides], [Patella vulgata] and [Littorina] spp. on exposed to moderately exposed or vertical sheltered eulittoral rock

HabitatDescription:
Very exposed to sheltered mid to upper eulittoral bedrock and large boulders characterised by dense barnacles [Semibalanus balanoides] and the limpet [Patella vulgata]. The community has a relatively low diversity of species though occasional cracks and crevices in the rock can provide a refuge for small individuals of the mussel [Mytilus edulis], the winkle [Littorina] spp. and the whelk [Nucella lapillus]. Seaweeds are usually not found in high numbers though fissures and crevices in the bedrock can hold a sparse algae community, though patches of the red seaweed [Osmundea pinnatifida] can be present throughout the zone. On some shores the olive green lichen [Verrucaria mucosa] can be present in some abundance (Frequent). Records should not be assigned to this species impoverished biotope if there is a significant number or abundance of seaweeds.

Situation: On very exposed to exposed shores [Chthamalus] spp. (see A1.1121 for geographical variation) often forms a distinct white band above a darker band of [S. balanoides] in the mid eulittoral zone. Alternatively, found above A1.113 are the black lichen [Verrucaria maura] dominated biotopes (B3.1131 or B3.1132). In the lower eulittoral and the sublittoral fringe is a community dominated by the wrack [Himanthalia elongata] and various red seaweeds including [Corallina officinalis], [Mastocarpus stellatus] and [Osmundea pinnatifida] (A1.123; A1 122; A1.126) or the mussel and barnacle dominated biotope A1.111. This unit may occur on steep and vertical faces on more sheltered shores, while fucoids dominate the flatter areas (A1.1132; A1.213).

Temporal variation: Periods with little scour or less severe storms can allow a seaweed community to develop creating a more diverse biotope (i.e. A1.313). This is a dynamic process, which will change individual sites over time. More information is required to validate this hypothesis.


HabitatName:
[Semibalanus balanoides], [Fucus vesiculosus] and red seaweeds on exposed to moderately exposed eulittoral rock

HabitatDescription:
Exposed and moderately exposed upper and mid eulittoral bedrock characterised by the barnacle [Semibalanus balanoides], the limpet [Patella vulgata] and the whelk [Nucella lapillus] with a sparse community of seaweeds. Turfs of the wrack [Fucus vesiculosus] can be present on the more horizontal parts of the shore though usually in low abundance (Occasional). Individuals of [F. vesiculosus] can lack the characteristic twin air bladders due to environmental stress (i.e. wave exposure). A sparse seaweed community consisting of foliose red seaweeds such as [Osmundea pinnatifida] and [Mastocarpus stellatus] are usually present along with the [Corallina officinalis] and the green seaweed [Enteromorpha intestinalis]. The algal community is usually restricted to fissures and cracks in the bedrock surface. Moist cracks and crevices also provide a refuge for small individuals of the mussel [Mytilus edulis] and the winkles [Littorina saxatilis] and [Littorina littorea]. These crevices can also be occupied by encrusting coralline algae and the anemone [Actinia equina].

Situation: On exposed and moderately exposed shores. This unit is found below the black lichen [Verrucaria maura] and sparse barnacles biotope (B3.1131) and/or below the [Chthamalus] spp. and [P. vulgata] biotopes (A1.112). It is found above the biotope dominated by the wrack [Himanthalia elongata] (A1.123) or the red seaweed biotopes (A1 122).

Temporal variation: On some shores, particularly those which are moderately exposed to wave action, temporal fluctuations in the abundance of limpets, barnacles and fucoid seaweeds may occur. As a result, over a number of years, a single shore may cycle between the barnacle-[P. vulgata] dominated biotope (A1.1132) and a [F. vesiculosus]-dominated biotope (A1.313). Individuals of [F. vesiculosus] growing in stressed environmental conditions (i.e. high wave exposure) do not always develop the characteristic twin air bladders.


HabitatName:
[Semibalanus balanoides] and [Littorina] spp. on exposed to moderately exposed eulittoral boulders and cobbles

HabitatDescription:
Large patches of boulders, cobbles and pebbles in the eulittoral zone on exposed to moderately exposed shores colonised by the barnacle [Semibalanus balanoides] and, on larger rocks, the limpet [Patella vulgata]. The winkles [Littorina littorea] and [Littorina saxatilis] and the whelk [Nucella lapillus] are typically found in high numbers on and around cobbles and smaller boulders, while the anemone [Actinia equina] occurs in damp areas between and underneath larger boulders. Between the cobbles and pebbles, the mussel [Mytilus edulis] occasionally occurs, but always at low abundance, as do the crab [Carcinus maenas] and gammarid amphipods. Ephemeral green seaweeds such as [Enteromorpha intestinalis] may cover cobbles and boulders. The foliose red seaweeds [Chondrus crispus, Mastocarpus stellatus] and [Osmundea pinnatifida] as well as the wrack [Fucus vesiculosus] may also occur in low abundance on cobbles and boulders. The top shells [Gibbula cineraria] and [Gibbula umbilicalis] can, on more sheltered shores, be found among the seaweeds or underneath the boulders. The barnacle [Elminius modestus] is present on some shores.

Situation: On exposed shores with large boulders this unit is found below the black lichen [Verrucaria maura] and sparse barnacles biotope (B3.1131or B3.1132) and/or below the [Chthamalus] spp. and [P. vulgata] biotope (A1.112). Below this biotope the [Himanthalia elongata] dominated biotopes may occur (A1 122; A1.123). On less exposed shores it can be found above the [Fucus serratus] biotope on boulders (A1.2142).

Temporal variation: Seasonally mobile boulders, cobbles and pebbles are likely to have a sparser coverage of flora and fauna, because the rocks can be subject to turning. Ephemeral green seaweeds can dominate during the summer.


HabitatDescription:
This habitat type encompasses those seaweeds that are able to tolerate the extreme conditions of very exposed to moderately exposed rocky shores. The physical stresses caused by wave action often results in dwarf forms of the individual seaweeds. The strong holdfasts and short tufts structure of the wracks [Fucus distichus] and [Fucus spiralis f. nana] allow these fucoids to survive on extremely exposed shores in the north and north-west (A1.121). Another seaweed able to tolerate the wave-wash is the red seaweed [Corallina officinalis], which can form a dense turf on the mid to lower shore (A1.122). The wrack [Himanthalia elongata] occurs on the lower shore and can extend on to moderately exposed shores (A1.123). The red seaweed [Mastocarpus stellatus] is common on both exposed and moderately exposed shores, where it may form a dense turf (particularly on vertical or overhanging rock faces, A1.125). Very exposed to moderately exposed lower eulittoral rock can support a pure stand of the red seaweed [Palmaria palmata]. It is found either as a dense band or in large patches above the main sublittoral fringe (A1.124). Exposed to moderately exposed lower eulittoral rock characterised by extensive areas or a distinct band of [Osmundea] [pinnatifida] (A1.126). Outcrops of fossilised peat in the eulittoral are soft enough to allow a variety of piddocks, such as [Barnea candida] and [Petricola pholadiformis], to bore into them (A1.127). This biotope is rare. Other species such as the anemone [Halichondria panicea], the barnacle [Semibalanus balanoides], the limpet [Patella vulgata], the mussel [Mytilus edulis] and the whelk [Nucella lapillus] can be present as well, but they are never dominant as in A1.11. There is also a higher number of seaweeds present including the red [Palmaria palmata], [Lomentaria articulata], [Ceramium] spp. and the brown seaweeds [Laminaria digitata] and [Fucus serratus. The green seaweeds [Enteromorpha intestinalis], [Ulva lactuca] and [Cladophora rupestris] are occasionally present.
Situation: This habitat type is present on extremely exposed to moderately exposed upper to lower shores.


HabitatName:
[Fucus distichus] and [Fucus spiralis] f. [nana] on extremely exposed upper eulittoral rock

HabitatDescription:
Extremely exposed gently or steeply sloping upper shore bedrock which supports a mixture of the wracks [Fucus distichus] and [Fucus spiralis f. nana], the latter often at the top of the zone. On some sites [F. distichus] dominates and [F. spiralis] is not present. Other seaweeds normally found on exposed coasts are common in this biotope. These include ephemeral species such as the foliose red [Porphyra umbilicalis] and the green [Enteromorpha] spp. The winkles [Melarhaphe neritoides] and [Littorina saxatilis] can be found grazing on the bedrock or on the fucoids, while red crusts of [Hildenbrandia rubra] and the mussel [Mytilus edulis] are restricted to moist cracks and crevices. A sparse covering of the black lichens [Verrucaria maura] and [Verrucaria mucosa] can be found in the upper part of this biotope competing for space with barnacle [Semibalanus balanoides] and the limpet [Patella vulgata]. This biotope is very rare and restricted to the far north and west coasts.

Situation: This mixed band of [F. distichus] and [F. spiralis f. nana] is generally found between the [Verrucaria maura] and [Porphyra] spp. zone (B3.1131 or B3.1132) above, and the [M. edulis] and barnacle zone below (A1.111). It may also occur above a red algal zone consisting of [Mastocarpus stellatus] as recorded on Barra (Scotland).

Temporal variation: Due to the occurrence of this biotope on very exposed coasts a certain amount of fluctuation between this biotope and unit B3.1131  from year to year is to be expected. More information is required to validate this hypothesis. There can be seasonal fluctuations in the density of ephemeral green algae.


HabitatName:
[Corallina officinalis] on exposed to moderately exposed lower eulittoral rock

HabitatDescription:
Very exposed to moderately exposed lower eulittoral rock that supports a dense turf of the red seaweed [Corallina officinalis], often on wave surged rocky slopes. There is usually a low abundance of other turf-forming red seaweeds including [Lomentaria articulata], [Mastocarpus stellatus], [Palmaria palmata] and [Osmundea] [pinnatifida]. Other seaweeds that occur in low abundance includes the wrack [Himanthalia elongata], [Laminaria digitata] while the brown seaweed [Leathesia difformis] can be found growing on and around the other seaweeds. The green seaweeds [Enteromorpha intestinalis], [Ulva lactuca] and [Cladophora rupestris] are present as well. A number of invertebrates are present on the bedrock underneath the coralline turf, including the barnacle [Semibalanus balanoides], the mussel [Mytilus edulis], the sponges [Halichondria panicea] and [Hymeniacidon perleve], the anemone [Actinia equina] and the limpets [Patella ulyssiponensis] and [Patella vulgata]. The brown seaweed [Bifurcaria bifurcata] and the barnacle [Balanus perforatus] may occur in the extreme south-west. Two variants have been described: [C. officinalis] and kelp (A1.1221) and [C. officinalis], [H. elongata] and the limpet [P. ulyssiponensis] (A1.1222).
Situation: This community usually forms a distinct band just above the kelp zone (A3.111, A3.1112 or A3.211). It can be found below the barnacle and [P. vulgata] dominated biotopes (A1.112; A1.113; A1.1132).


HabitatName:
[Corallina officinalis] and [Mastocarpus stellatus] on exposed to moderately exposed lower eulittoral rock

HabitatDescription:
Exposed lower eulittoral rock or moderately exposed lower eulittoral vertical rock that supports a dense turf of the red seaweed [Corallina officinalis], often on wave surged rocky slopes. There is usually a low abundance of other turf-forming red seaweeds such as [Lomentaria articulata], [Mastocarpus stellatus], [Palmaria palmata] and [Osmundea pinnatifida]. Other seaweeds that occur in low abundance includes the wrack [Himanthalia elongata] and the kelp [Laminaria digitata], while the brown seaweed [Leathesia difformis] can be found growing on and around the other seaweeds. Green seaweeds such as [Enteromorpha intestinalis], [Ulva lactuca] and [Cladophora rupestris] are also present. The coralline turf creates a micro-habitat for small animals such as the colonial tube building polychaete [Pomatoceros] sp. and the barnacle [Semibalanus balanoides]. The mussel [Mytilus edulis] is often found in small cracks and crevices while the sponges [Halichondria panicea] and [Hymeniacidon perleve] can be found in shaded areas or on overhangs. The limpets [Patella ulyssiponensis] and [Patella vulgata] can be found on the bedrock underneath the turf. The brown seaweed [Bifurcaria bifurcata] and the barnacle [Balanus perforatus] may occur in the extreme south-west.

Situation: This community usually forms a distinct band just above the kelp zone (A3.111, A3.1112 or A3.211). It can be found below the barnacle and [P. vulgata] dominated biotopes (A1.112; A1.1131; A1.1132).

Temporal variation: If there are many of the characteristic [H. elongata] buttons present in early spring careful comparison with unit A1.123  should be made (See Similar biotopes).


HabitatName:
[Corallina officinalis], [Himanthalia elongata] and [Patella ulyssiponensis] on very exposed lower eulittoral rock

HabitatDescription:
Very exposed to exposed lower eulittoral bedrock shores in the south-west can support a dense turf of the red seaweed [Corallina officinalis] found underneath the long erect fronds of the wrack [Himanthalia elongata]. The rock surface is pitted with the limpet [Patella ulyssiponensis]. Also found on the bedrock is the barnacle [Chthamalus stellatus] or the limpet [Patella vulgata], while numerous cracks and crevices provide shelter for anemones such as [Actinia equina] or the mussel [Mytilus edulis]. Other turf-forming red seaweeds include [Lomentaria articulata], [Mastocarpus stellatus], [Palmaria palmata, Gastroclonium ovatum, Ceramium] spp. and [Osmundea] [pinnatifida] which can be found along with the kelp [Laminaria digitata]. Foliose green seaweeds such as [Enteromorpha intestinalis] and [Ulva lactuca] may also be present along with siphonous [Codium] spp. Sponges such [as Grantia compressa], [Halichondria panicea] and [Hymeniacidon perleve] may be present in shaded areas. The brown seaweed [Bifurcaria bifurcata] and the barnacle [Balanus perforatus] may occur in the extreme south-west.

Situation: This community usually forms a distinct band just above the kelp zone (A3.111, A3.1112 or A3.211). It can be found below the barnacle and [P. vulgata] dominated biotopes (A1.112; A1.113 or A1.1132).

Temporal variation: There might be some fluctuations in the abundance of the individual species from year to year, which reverts this biotope into either  A1.1221 or  A1.123 .


HabitatName:
[Himanthalia elongata] and red seaweeds on exposed lower eulittoral rock

HabitatDescription:
Exposed to moderately exposed lower eulittoral bedrock characterised by the wrack [Himanthalia elongata] with a dense turf of red seaweeds beneath. [H. elongata] may occur on tide-swept, sheltered shores in sea lochs (e.g. Loch Maddy). The wrack [Fucus serratus] is normally present as well. The predominant red seaweeds are usually [Mastocarpus stellatus], [Osmundea pinnatifida], [Corallina officinalis] and [Palmaria palmata] that tend to grow over a crust of the pink coralline algae [Lithothamnion] spp. Any patches between the algal turf may be colonised by barnacles [Semibalanus balanoides], or [Balanus perforatus] in the south-west, and by the limpet [Patella vulgata]. Pits and crevices in the rock often provide a refuge for the whelk [Nucella lapillus], the winkle [Littorina] spp. and small individuals of the mussel [Mytilus edulis]. Besides the dominant seaweeds there are a number of other red, brown and green seaweeds present. These include species such as the red seaweeds [Dumontia contorta], [Lomentaria articulata, Porphyra] spp., the kelp [Laminaria digitata] and the green seaweeds [Enteromorpha intestinalis], [Ulva lactuca] and [Cladophora rupestris].

Situation: On some shores this biotope may occur as a distinct zone between a [Fucus serratus] and red algal turf (A1.2141) and the kelp [Alaria esculenta] and [L. digitata] community (A3.1112). This biotope generally characterises those shores which are too exposed for [F. serratus] to form a dense canopy, often occurring as large patches within the [F. serratus] / red seaweed turf zone (A1.2141). Consequently, [F. serratus] plants frequently occur amongst the [H. elongata] and red seaweed turf.

Temporal variation: In early spring only characteristic [H. elongata] buttons are present, while the long erect parts of the thalli appears later in the season. This biotope may therefore appear very similar to A1.1221 in the spring and care should be taken when assessing these biotopes in early spring (See Similar biotopes).


HabitatName:
[Palmaria palmata] on very exposed to moderately exposed lower eulittoral rock

HabitatDescription:
Very exposed to moderately exposed lower eulittoral rock which supports a pure stand of dulse [Palmaria palmata] as a dense band or in large patches above the main kelp zone. [P. palmata] favours shaded or overhanging rock and often forms a band at the top of overhanging rock. Relatively low abundance of other seaweeds, such as the red seaweed [Porphyra umbilicalis] or the green seaweeds [Enteromorpha intestinalis], [Ulva lactuca] and [Cladophora rupestris] may also occur in this biotope although [P. palmata] always dominates. On the rock underneath the seaweed turf are the barnacle [Semibalanus balanoides] and the limpet [Patella vulgata and the olive-green lichen] Verrucaria mucosa. Sites should only be recorded as A1.124 where [P. palmata] forms a distinct band or occurs in large patches on the shore.

Situation: This biotope is found below the biotopes dominated by the [P. vulgata, S. balanoides], the wrack [Fucus distichus] or [E. intestinalis] (A1.113; A1.121; A1.451). It is found above biotopes dominated by the kelp [Alaria esculenta] and [Laminaria digitata] (A3.1112; A3.2111).

Temporal variation: It is likely that the [P. palmata] biotope represents an opportunistic assemblage of fast-growing species which occupy gaps within or between the canopies of long lived perennials such as the wrack [Fucus serratus].


HabitatName:
[Mastocarpus stellatus] and [Chondrus crispus] on very exposed to moderately exposed lower eulittoral rock

HabitatDescription:
Exposed to moderately exposed lower eulittoral vertical to almost horizontal bedrock characterised by a dense turf of [Mastocarpus stellatus] and [Chondrus crispus] (either together or separately). Beneath these foliose seaweeds the rock surface is covered by encrusting coralline algae and the barnacle [Semibalanus balanoides], the limpet [Patella vulgata] and spirorbid polychaetes. Other seaweeds including the red [Lomentaria articulata] and [Osmundea pinnatifida], [Palmaria palmata], [Corallina officinalis] and coralline crusts. The wrack [Fucus serratus] and the green seaweeds [Enteromorpha intestinalis] and [Ulva lactuca] may also be present though usually at a low abundance[]. Although both [M. stellatus] and [C. crispus] are widespread in the lower eulittoral and the sublittoral fringe, they occur only infrequently in a distinct band, or in large enough patches, to justify separation from A1.2141. Consequently, where only small patches of these species occur within a larger area of mixed red algal turf, then records should be assigned to more general mixed red algal turf biotope (A1 122; A1.123). [M. stellatus] can be present in high abundance in a number of biotopes (A1 122: A1.123; A1.2141 etc.) found on the shore. At least one other species normally co-dominates and records should be assigned to the appropriate biotope. Caution should be taken regarding the characterising species list due to the low number of records. More information needed to validate this description.

Situation: This biotope can form a band above the main kelp zone, above [Alaria esculenta] (A3.111) or the mussel [Mytilus edulis] (A1.111) or within a [F. serratus]-red algal mosaic (A1.2141).

Temporal variation: [M. stellatus] is more resistant to wave action than [C]. [crispus] and may therefore dominate more exposed shores; it can dominate vertical rock at very exposed sites (e.g. Mingulay, Outer Hebrides). On more sheltered shores, especially in the south-west, [M. stellatus] may give way to [C. crispus] which has a faster growth rate.


HabitatName:
[Osmundea pinnatifida] on moderately exposed mid eulittoral rock

HabitatDescription:
Exposed to moderately exposed lower eulittoral rock characterised by extensive areas or a distinct band of [Osmundea pinnatifida] and [Gelidium pusillum] (either together or separately). This community usually occurs on shores on which a fucoid canopy is reduced in extent, or even absent. Other turf-forming red seaweeds, such as [Corallina officinalis, Mastocarpus stellatus], [Ceramium] spp. and [Callithamnion hookeri] may be present, although [O. pinnatifida] always dominate. On flatter, more sheltered shores, [Osmundea hybrida] may also occur. Small patches of bare rock amongst the algal turf are occupied by barnacles [Semibalanus balanoides], the limpet [Patella vulgata], the whelk [Nucella lapillus] and small individuals of the mussel [Mytilus edulis]. The winkles [Littorina littorea] and [Littorina saxatilis] can be present on the rock or among the seaweeds. A variation of this biotope has been described for the chalk platforms in Kent where extensive turfs of [G. pusillum] occur in the mid eulittoral above the main [O. pinnatifida] zone.
Situation: This biotope can be found below barnacles [S. balanoides] or red seaweed dominated community, which includes the species [Palmaria palmata], [C. officinalis] or [M. stellatus] (A1.112; A1 122; A1.411). It is found above biotopes dominated by the wrack [Fucus serratus] and red seaweeds (A1.12; A1.222; A1.2141) or above biotopes dominated by the kelp [Laminaria digitata] (A3.2111).


HabitatName:
[Ceramium] sp. and piddocks on eulittoral fossilised peat

HabitatDescription:
Outcrops of fossilised peat in the eulittoral are soft enough to allow a variety of piddocks such as [Barnea candida] and [Petricola pholadiformis] to bore into them. The surface of the peat can be characterised by a dense algal mat, predominantly the red seaweed [Ceramium] spp. and with the green seaweeds [Ulva lactuca] and [Enteromorpha intestinalis]. Damp areas in the algal mat are covered by aggregations of the polychaetes [Lanice conchilega] and [Polydora] sp. The crabs [Carcinus maenas] and [Cancer pagurus] occur in crevices in the peat. Small pools on the peat may contain hydroids, such as [Obelia longissima] and [Kirchenpaueria pinnata], the brown alga [Dictyota dichotoma] and the crustacean [Crangon crangon]. Description derived largely from sites in north Norfolk and this community could possibly be found on other "soft" substrata. Further records of this community are required in order to validate the description.


HabitatName:
Mediterranean and Black Sea communities of upper mediolittoral rock

HabitatDescription:
The distributions and types of species in this habitat are profoundly affected by the submersion variability determined by wave action, and by irregularities in the sea level caused by atmospheric pressure and wind.


HabitatDescription:
This facies is characterised by a continuous belt of the red alga [Bangia atropurpurea]. This facies is also present in the mediolittoral zone of the western Black Sea during winter.


HabitatDescription:
This facies is characterised by a continuous belt of the red alga [Porphyra leucosticta]. This facies is also present in the mediolittoral zone of the western Black Sea during winter.


HabitatName:
Association with [Nemalion helminthoides] and [Rissoella verruculosa]

HabitatDescription:
This facies is characterised by a continuous belt of the two red algae species [Nemalion helminthoides] and [Rissoella verruculosa].


HabitatName:
Association with [Lithophyllum papillosum] and [Polysiphonia] spp.

HabitatDescription:
This facies is characterised by a continuous belt of the red algae species [Lithophyllum papillosum] and [Polysiphonia] spp.


HabitatName:
Mediterranean and Black Sea communities of lower mediolittoral rock very exposed to wave action

HabitatDescription:
These communities are located in the lower horizon of the mediolittoral rock and result from the concomitance of three components: high waves, variations in atmospheric pressure, and variations in wind and tide. The dominant aspect, however, is the constant humidity of the substratum.


HabitatDescription:
This association is characterised by the red alga species [Lithophyllum byssoides] (ex [Lithophyllum lichenoides]). This is one of the most important bio-constructors of the Mediterranean "trottoir", particularly important because of its high aesthetic interest and its conservation value.


HabitatDescription:
This facies is very rare in Mediterranean. The characteristic species is the Cirriped (Barnacle) [Pollicipes pollicipes] ([Pollicipes cornucopiae]), living on rocky walls in areas with pure waters exposed to extremely rough waves.


HabitatName:
Association with [Titanoderma trochanter ]

HabitatDescription:
This association is characterised by the red alga [Titanoderma trochanter ] (ex [Lithophyllum trochanter]).


HabitatDescription:
This association is characterised by the red alga [Lithophyllum tortuosum] (ex [Tenarea undulosa]).


HabitatName:
[Mytilus galloprovincialis] facies in presence of moderately polluted waters


HabitatDescription:
Fucoid seaweeds in tide-swept conditions on sheltered to extremely sheltered mid eulittoral to lower eulittoral rocky shores, such as narrow channels in sea lochs. The middle shore can be dominated by the wrack [Ascophyllum nodosum] (A1.151), while [Fucus serratus] is dominating the lower shore (A1.152, A1.153). The high levels of water movement encourages a rich associated fauna including several filter-feeding groups. These include the sponges [Grantia compressa, Halichondria panicea] and [Hymeniacidon perleve] which frequently occur on steep and overhanging faces of boulders and bedrock. It also includes the sea squirts [Dendrodoa grossularia] and [Ascidiella scabra], which occur on steep surfaces and beneath boulders. Hydroids such as the pink [Clava multicornis] can form colonies on [A. nodosum] while [Dynamena pumila] is more often found on [Fucus vesiculosus] or [F. serratus]. Underneath the canopy formed by the brown seaweeds is a diverse community of the red seaweeds [Gelidium pusillum], [Chondrus crispus], [Lomentaria articulata], [Membranoptera alata] and coralline crusts, but the green seaweeds [Enteromorpha intestinalis], [Ulva lactuca] and [Cladophora rupestris] can be present. The filamentous red seaweed [Polysiphonia lanosa] can usually be found growing on [A. nodosum]. On the rock beneath are the limpet [Patella vulgata] and the barnacle [Semibalanus balanoides], while the crab [Carcinus maenas] and a variety of winkles including [Littorina littorea], [Littorina mariae] and [Littorina obtusata] can be found on or among the boulders. The whelk [Nucella lapillus] can either be found in cracks and crevices.
Situation: Sheltered tide-swept shores (i.e. estuaries and sea lochs) below the [Fucus spiralis] and [F. vesiculosus] band and above the kelp dominated zone in the sublittoral.


HabitatName:
[Ascophyllum nodosum], sponges and ascidians on tide-swept mid eulittoral rock

HabitatDescription:
Very sheltered to extremely sheltered areas of mid eulittoral rock that are subject to strong to moderate tidal streams, such as the narrows in sea lochs, and characterised by the wrack [Ascophyllum nodosum]. The wracks [Fucus vesiculosus] and [Fucus serratus] are occasionally present. The increased water movement encourages a rich associated fauna including several filter-feeding groups. These include the sponges [Leucosolenia] spp., [Grantia compressa, Halichondria panicea] and [Hymeniacidon perleve] which frequently occur on steep and overhanging faces of boulders and bedrock. It also includes the sea squirts [Dendrodoa grossularia] and [Ascidiella scabra], which occur on steep surfaces and beneath boulders. Hydroids such as the pink [Clava multicornis] can form colonies on [A. nodosum] while [Dynamena pumila] is more often found on [F. vesiculosus] or [F. serratus]. Underneath the canopy formed by the brown seaweeds is a diverse community of the red seaweeds [Gelidium pusillum], [Chondrus crispus], [Lomentaria articulata], [Membranoptera alata] and coralline crusts, but the green seaweeds [Enteromorpha intestinalis], [Ulva lactuca] and [Cladophora rupestris] can be present. The filamentous red seaweed [Polysiphonia lanosa] can usually be found growing on [A. nodosum]. On the rock beneath are the limpet [Patella vulgata] and the barnacle [Semibalanus balanoides], while the crab [Carcinus maenas] and a variety of winkles including [Littorina littorea], [Littorina mariae] and [Littorina obtusata] can be found on or among the boulders. The whelk [Nucella lapillus] can either be found in cracks and crevices or preying on the barnacles.

Situation: This biotope occurs lower on the shore than the [Fucus spiralis] biotope (A1.212) although on some shores a narrow zone of [F. vesiculosus] (unit A1.313) may occur immediately above the [A. nodosum]. A1.151 is found above the tide-swept [F. serratus] dominated biotope (unit A1.152).

Temporal variation: [A. nodosum] can reach an age of 25 years and the communities are usually very stable. [F. vesiculosus] or [F. serratus] can occur in patches where the [A. nodosum] has been removed.


HabitatName:
[Fucus serratus], sponges and ascidians on tide-swept lower eulittoral rock

HabitatDescription:
Sheltered to extremely sheltered lower eulittoral bedrock, boulders and cobbles that are subject to increased tidal water movement and characterised by the wrack [Fucus serratus] and a rich assemblage of filter-feeding fauna. This community is encouraged by the increased water movement. It includes species such as the sponges [Halichondria panicea] and [Hymeniacidon perleve], which occur frequently on steep and overhanging faces. Underneath the [F. serratus] canopy is a diverse flora of foliose red seaweeds including [Mastocarpus stellatus], [Lomentaria articulata], [Membranoptera alata] and [Chondrus crispus]. The green seaweeds [Cladophora] spp., [Enteromorpha intestinalis] and [Ulva lactuca] and the wrack [Ascophyllum nodosum] are present though usually in small numbers. On the rock underneath the seaweed canopy, species such as the limpet [Patella vulgata], the barnacles [Semibalanus balanoides] and [Balanus crenatus] and the whelk [Nucella lapillus] can be found though in lower abundance than higher up the shore. Also present on the rock are the tube-forming polychaetes [Pomatoceros triqueter] and spirorbids and more mobile species such as the winkles [Littorina mariae] and [Littorina littorea], the top shell [Gibbula cineraria] and the crab [Carcinus maenas]. Lastly, several species of bryozoans are usually present including [Electra pilosa] and [Alcyonidium gelatinosum], all competing for space with the hydroid [Dynamena pumila], which can form dense populations on the [F. serratus] fronds.
Situation: Areas where increased tidal movement influences such a community are in the narrows and/or intertidal sills of Scottish sea lochs and the rias in south-west England. In the few cases where the rock is also subject to variable salinity, an impoverished community results and records should be classified as A1.326 rather than the present biotope.


HabitatName:
[Fucus serratus] with sponges, ascidians and red seaweeds on tide-swept lower eulittoral mixed substrata

HabitatDescription:
Sheltered lower shore boulders, cobbles and pebbles on muddy sediments that are subject to enhanced tidal water movement and characterised by a species rich community. Dominant species include the sponges [Halichondria panicea] and [Hymeniacidon perleve], the sea squirts [Ascidiella aspera], [Ascidiella scabra], [Styela clava] and [Botryllus schlosseri]. A number of filamentous red seaweeds including [Halurus flosculosus], [Ceramium] spp., [Gracilaria gracilis, Polysiphonia fucoides] and foliose seaweeds [Mastocarpus stellatus] and [Chondrus crispus] are usually present. The brown seaweed [Dictyota dichotoma] and the wrack [Fucus serratus] with colonies of the hydroid [Dynamena pumila], and [Ectocarpus] sp. may be found on more stable substrata. Boulders and large cobbles provide substrata for the top shell [Gibbula cineraria], the whelk [Nucella lapillus] and barnacles such as [Semibalanus balanoides, Balanus crenatus], or in areas with variable salinity [Elminius modestus], and the tube-forming polychaete [Pomatoceros triqueter]. Patches of sand or mud are often characterised by the polychaete [Lanice conchilega] and the polychaete [Sabella pavonina]. Aggregations of the mussel [Mytilus edulis] and, in southern and eastern England the limpet [Crepidula fornicata], may be found attached to cobbles and pebbles. Sites in Scottish sea lochs may support maerl [Lithothamnion] spp. and bivalves [Venerupis senegalensis] (see also A5.433).
Situation: This biotope is found above a community dominated by kelp such as [Laminaria digitata] (A3.1112) or seagrass beds dominated by [Zostera marina] (A5.5331) depending on the substrata found below. It is found below biotopes dominated by wrack [Fucus vesiculosus] (A1.313) or [M. edulis] beds (A2.212).


HabitatName:
Pontic communities of exposed mediolittoral rock


HabitatName:
Pontic upper shore with [Chthamalus], [Ligia], [Melaraphe],  [Rivularia] (cyanophites)


HabitatName:
Pontic upper mediolittoral with [Mytilaster] spp, [Mytilus] spp., [Enteromorpha minima], [Enteromorpha compressa]


HabitatName:
Pontic ephemeral patchwork of green and red algae with [Mytilaster] and [Mytilus]


HabitatName:
Pontic association with encrusting algae and [Lepidochitona caprearum]


HabitatName:
Pontic [Corallina] turfs on exposed to moderately exposed mediolittoral rock


HabitatName:
Pontic mediolittoral barren rock scoured by sand


HabitatDescription:
Moderately exposed shores (bedrock, boulders and cobbles) characterised by mosaics of barnacles and fucoids on the mid and upper shore; with fucoids and red seaweed mosaics on the lower shore. Where freshwater or sand-scour affects the shore ephemeral red or green seaweeds can dominate. Other shores support communities of mussels and fucoids in the mid to lower shore. Two biological subtypes have been described: barnacles and fucoids (A1.21) and mussels and fucoids (A1.22).


HabitatDescription:
Moderately exposed rocky shores characterised by a mosaic of fucoids and barnacles on bedrock and boulders, where the extent of the fucoid cover is typically less than the blanket cover associated with sheltered shores. Other species are normally present as well in this habtat including the winkle [Littorina littorea], the whelk [Nucella lapillus] and the red seaweed [Mastocarpus stellatus]. Beneath the band of yellow and grey lichens at the top of the shore is a zone dominated by the wrack [Pelvetia canaliculata], scattered barnacles, while the black lichen [Verrucaria maura] covers the rock surface (A1.211). Below, on the mid shore the wrack [Fucus vesiculosus] generally forms a mosaic with the barnacle [Semibalanus balanoides] and the limpet [Patella vulgata] (A1.213). Finally, the wrack [Fucus serratus], dominates the lower shore, while a variety of red seaweeds can be found underneath the[F. serratus] canopy (A1.214). A number of variants have been described: lower shore bedrock and boulders characterised by mosaics of [F. serratus] and turf-forming red seaweeds (A1.2141); where the density of [F. serratus] is greater (typically Common - Superabundant) and the abundance of red seaweeds less A1.3151 should be recorded. The presence of boulders and cobbles on the shore can increase the micro-habitat diversity, which often results in a greater species richness. Although the upper surface of the boulders may bear very similar communities to A1.3151 there is often an increase in fauna (crabs, tube-forming polychaetes, sponges and bryozoans) and A1.2142 should be recorded. Sand-influenced exposed to moderately exposed lower shore rock can be characterised by dense mats of [Rhodothamniella floridula] (A1.215).
Situation: Mid and lower eulittoral moderately exposed bedrock with a lichen zone above and a kelp dominated community below in the sublittoral zone.


HabitatName:
[Pelvetia canaliculata] and barnacles on moderately exposed littoral fringe rock

HabitatDescription:
Exposed to moderately exposed steep, lower littoral fringe rock and mixed substrata characterised by the wrack [Pelvetia canaliculata] and sparse barnacles [Chthamalus montagui] and [Semibalanus balanoides]. On sheltered shores the biotope is restricted to vertical faces. The limpet [Patella vulgata] and the wrack [Fucus spiralis] are usually present as well. [P. canaliculata] typically overgrows a crust of the black lichen [Verrucaria maura] or on occasion [Verrucaria mucosa], in contrast to the red crust [Hildenbrandia rubra] on very sheltered shores. The winkle [Littorina saxatilis] is frequently present underneath the fronds of [P. canaliculata]. Some geographical variation are present and southern and western shores are typically characterised by the barnacle [C. montagui] or [Chthamalus stellatus] while [S. balanoides] dominates on northern and eastern shores. On mixed substrata the barnacle [Elminius modestus] may be present.
Situation: This unit is generally found below the [V. maura] and barnacle zone (B3.1131; B3.1132). On exposed shores it is found above the biotope dominated by [F. spiralis] (unit A1.312) or the mussel [Mytilus edulis] and barnacles biotope (unit A1.111) or the barnacles and [P. vulgata] biotopes (unit A1.113). In addition, patches of lichen [Lichina pygmaea] with the barnacle [Chthamalus montagui] (unit A1.1122) may also occur at the same level or above this biotope, particularly on southern shores. On sheltered to extremely sheltered shores this biotope is limited to very steep or vertical faces.


HabitatName:
[Fucus spiralis] on full salinity exposed to moderately exposed upper eulittoral rock

HabitatDescription:
Exposed to moderately exposed upper eulittoral bedrock characterised by a band of the spiral wrack [Fucus spiralis] overlying the black lichen [Verrucaria maura] and the olive green lichen [Verrucaria mucosa]. Underneath the fronds of [F. spiralis] is a community consisting of the limpet [Patella vulgata], the winkles [Littorina saxatilis] and [Littorina littorea], the mussel [Mytilus edulis] and the barnacle [Semibalanus balanoides]. The whelk [Nucella lapillus] can be found in cracks and crevices preying on the mussels and barnacles. During the summer months ephemeral green seaweeds such as [Enteromorpha intestinalis] can be common. The insect [Anurida maritima] can be present in this zone taking shelter in cracks and crevices when the tide comes in.
Situation: This zone usually lies below a zone dominated by the wrack [Pelvetia canaliculata] (unit A1.211), but occasional clumps of [P. canaliculata] may be present (usually less than common) amongst the [F. spiralis]. This unit occurs above the wrack [Fucus vesiculosus] (A1.213) zones. Vertical surfaces in this zone, especially on moderately exposed shores, often lack the fucoids and are characterised by a barnacle-limpet dominated community (unit A1.113).


HabitatName:
[Fucus vesiculosus] and barnacle mosaics on moderately exposed mid eulittoral rock

HabitatDescription:
Exposed to moderately exposed mid eulittoral bedrock and boulders are frequently characterised by a mosaic of the barnacle [Semibalanus balanoides] and the wrack [Fucus vesiculosus]. The limpet [Patella vulgata] and the whelk [Nucella lapillus] are typically present, whilst the anemone [Actinia equina] and small individuals of the mussel [Mytilus edulis] are confined to crevices. Underneath the [F. vesiculosus] is a community of red seaweeds, including [Corallina officinalis, Mastocarpus stellatus] and [Osmundea pinnatifida], usually with the winkles [Littorina littorea] and [Littorina] spp. present. Opportunistic seaweeds such as [Enteromorpha intestinalis] may occur in patches recently cleared on the rock or growing on the [M. edulis].

Situation: On exposed shores this unit is found below the black lichen [Verrucaria maura] and sparse barnacles biotope (unit B3.1131) and/or below the [Chthamalus] spp. and [P. vulgata] biotopes (A1.1121). It is found above the biotope dominated by the wrack [Himanthalia elongata] (A1.123) or the red seaweed biotopes (A1 122; A1.2141). This unit  forms an intermediate along the wave exposure gradient between the exposed shore barnacle-[P]. [vulgata] biotopes (unit A1.1132) and the sheltered shore [F. vesiculosus] biotope (A1.313). Vertical surfaces tend to be dominated by the barnacle-[P. vulgata] biotope (A1.112).

Temporal variation: On some shores, particularly those, which are moderately exposed to wave action, temporal fluctuations in the abundance of limpets, barnacles and fucoid seaweeds may occur. As a result, over a number of years, a single shore may cycle between the barnacle-[P. vulgata] dominated biotope (A1.1132), through this mosaic (A1.213) to a [F. vesiculosus]-dominated biotope (A1.313).


HabitatName:
[Fucus serratus] on moderately exposed lower eulittoral rock

HabitatDescription:
Lower eulittoral bedrock and stable boulders on moderately exposed to sheltered shores with a canopy of the wrack [Fucus serratus] and an associated fauna consisting of the limpet [Patella vulgata], the barnacle [Semibalanus balanoides], the whelk [Nucella lapillus], the anemone [Actinia equina] and the sponge [Halichondria panicea]. Green seaweeds such as [Enteromorpha intestinalis] and [Ulva lactuca] are usually present among/beneath the [F. serratus] canopy. Three variants of this biotope are described. These are: [F. serratus] with red seaweeds (A1.2141) and [F. serratus] with under-boulder communities (A1.2142) with sponges. Lastly, a [F. serratus] and piddocks community on soft rock has been identified (A1.2143). Dense [F. serratus] with fewer red seaweeds occurs on more sheltered shores (unit A1 315).
Situation: Above the [F. serratus] biotope on moderately exposed bedrock shores is the [Fucus vesiculosus] and/or [S. balanoides] and [P. vulgata] dominated biotopes (A1.113; A1.1132; A1.213). On more sheltered shores are biotopes dominated by the wracks [F. vesiculosus] and [Ascophyllum nodosum] (A1.313; A1.3141). On moderately exposed shores, the sublittoral fringe below Fser is dominated by the kelp [Laminaria digitata] and on vertical faces the kelp [Alaria esculenta] may be present (A3.2112; A3.1112). On more sheltered shores the kelp [Laminaria saccharina] is found among the [L. digitata] (A3.3131; A3.3132).


HabitatName:
[Fucus serratus] and red seaweeds on moderately exposed lower eulittoral rock

HabitatDescription:
Moderately exposed lower eulittoral bedrock characterised by mosaics of the wrack [Fucus serratus] and turf-forming red seaweeds including [Osmundea pinnatifida], [Mastocarpus stellatus] or [Corallina officinalis]. The hydroid [Dynamena pumila] can occur in dense populations on the [F. serratus] fronds whilst the sponge [Halichondria panicea] can cover the bedrock beneath. Underneath the canopy a number of other red seaweeds may be present including [Palmaria palmata], [Lomentaria articulata],[Membranoptera alata] and [Chondrus crispus]. Green seaweeds such as [Cladophora rupestris], [Enteromorpha intestinalis] and [Ulva lactuca] are present though usually in small numbers. In addition, such shores provide a greater number of permanently damp refuges between the stones and underneath the seaweed canopy. Within these micro-habitats species such as the limpet [Patella vulgata], the barnacle [Semibalanus balanoides] or the whelk [Nucella lapillus] can be found in lower abundance than higher up the shore. If a few boulders are present then the winkle [Littorina littorea] and the crab [Carcinus maenas] can be found on or underneath the boulders.

Situation: Above the [F. serratus] biotope on moderately exposed bedrock shores are the wrack [Fucus vesiculosus] and/or [S. balanoides] and [P. vulgata] dominated biotopes (A1.113; A1.1132; A1.213). The sub littoral fringe below on moderately exposed shores is dominated by the kelp [Laminaria digitata] and on vertical faces the kelp [Alaria esculenta] (A3.2112; A3.1112). On uneven bedrock [F. serratus] and red seaweeds often dominate the upper-facing surfaces, while steep or vertical rock is characterised by [S. balanoides] and [P. vulgata] dominated biotopes (see above).

Temporal variation: Fluctuations from year to year in the abundance of the [F. serratus] and the red seaweeds due to factors such as severe storms may convert this biotope into either A1.3151 or into a red seaweed dominated biotope. The [C. maenas] population may migrate offshore during the winter.


HabitatName:
[Fucus serratus] and under-boulder fauna on exposed to moderately exposed lower eulittoral boulders

HabitatDescription:
Exposed to moderalety exposed lower eulittoral boulders with the wrack [Fucus serratus] community of a high species richness as the presence of the boulders increases the micro-habitat diversity. The upper surfaces of the boulders are colonised by a very similar fauna to the other [F. serratus] biotopes, including species such as the limpet [Patella vulgata], the whelk [Nucella lapillus], the anemone [Actinia equina] and the barnacle [Semibalanus balanoides]. The shaded sides of the boulders are, depending on environmental conditions, often colonised by a variety of foliose red seaweeds, including [Mastocarpus stellatus], [Lomentaria articulata], [Osmundea pinnatifida], [Palmaria palmata] and [Chondrus crispus]. Coralline algae such as [Corallina officinalis] and coraline crusts, as well as the green seaweeds [Enteromorpha intestinalis] and [Ulva lactuca], can be found underneath the [F. serratus] canopy or in patches on the boulders. The species composition underneath the boulders varies considerably depending on the underlying substratum. On muddy shores the fauna living under the boulders may be limited to a few infaunal species, such as the polychaete [Cirratulus cirratus]. Where more space is available beneath the boulders there may be a rich assemblage of animals. Characteristic mobile species include the crabs [Porcellana platycheles] and [Carcinus maenas]. Also present on and beneath the boulders are the tube-forming polychaete [Pomatoceros triqueter], spirorbid polychaetes and a few winkles such as [Littorina obtusata/mariae] and [Littorina littorea] or even the top shell [Gibbula cineraria]. Encrusting colonies of the sponge [Halichondria panicea] are also typical of the undersides of boulders, while the hydroid [Dynamena pumila] colonies can be found on the [F. serratus] fronds. The richest examples of this biotope also contain a variety of brittlestars, ascidians and small hydroids.
Situation: This biotope usually occurs immediately below a [Fucus vesiculosus]-barnacle mosaic (unit A1.213) on moderately exposed shores or a dense canopy of [F. vesiculosus] (A1.313) or [Ascophyllum nodosum] (A1.3141) on sheltered shores. The sublittoral fringe below on moderately exposed shores is dominated by the kelp [Laminaria digitata] (A3.211; A3.2112), while the kelp [Laminaria saccharina] may co-dominate on sheltered shores (A3.3131;A3.3121). Low abundance of these kelp may also occur in this biotope.


HabitatName:
[Fucus serratus] and piddocks on lower eulittoral soft rock

HabitatDescription:
The lower eulittoral zone on soft rock shores (e.g. chalk) characterised by the wrack [Fucus serratus]. Much of the community associated with this biotope is the same as the biotope Fserr.FS, but certain taxa are specific to the soft underlying substrata. Rock-boring fauna including the piddocks [Barnea] spp., [Pholas dactylus] and [Hiatella arctica] can occur in dense aggregations. Burrowing polychaetes such as [Polydora] spp. can also occur in high numbers only visible due to their long, slender palps waving in the water as they occupy holes in the top few centimetres of the rock. A dense red algal turf occurs beneath the [F. serratus] and includes [Gelidium pusillum], [Osmundea pinnatifida, Palmaria palmata], [Lomentaria articulata] and [Rhodothamniella floridula], but also calcareous algae such as [Corallina officinalis] and coralline crusts including the red-violet encrusting algae [Phymatolithon lenormandii] are present. Infaunal taxa such as various amphipods may be common amongst the seaweeds. The empty piddock holes may provide a refuge for species such as the anemone [Actinia equina] and the mussel [Mytilus edulis] while the barnacle [Semibalanus balanoides], the limpet [Patella vulgata] can be present on the surface of the soft rock. The whelk [Nucella lapillus], the winkles [Littorina littorea] and [Littorina mariae] and the top shell [Gibbula cineraria] are all present on the soft rock among the seaweeds. The high number of characterising species is partly caused by the low number of records used to define this biotope. The high % frequency of occurrence is partly a result of the low number of records. More data is needed to validate this biotope description.
Situation: This biotope usually occurs immediately below either a [Fucus vesiculosus]-barnacle mosaic (unit A1.213) or a [Mytilus edulis] and piddocks-dominated biotope (A1.223) on moderately exposed shores or a dense canopy of [F. vesiculosus] (A1.313) or [Ascophyllum nodosum] (A1.3141) on sheltered shores. The littoral fringe below are on moderately exposed shores dominated by the kelp [Laminaria digitata] (A3.2113), while the kelp [Laminaria saccharina] may co-dominate on sheltered shores (A3.3131; A3.3132).


HabitatName:
[Rhodothamniella floridula] on sand-scoured lower eulittoral rock

HabitatDescription:
Lower eulittoral and sublittoral fringe bedrock and boulders subject to mild sand-scouring characterised by a canopy of the wracks [Fucus serratus] or [Fucus vesiculosus], beneath which a mat of the sand-binding red seaweed [Rhodothamniella floridula] occurs. These mats can form distinct areas without [F. serratus]. The small hummocks of [R. floridula] also contain a diversity of other red seaweeds tolerant of sand scour, e.g. [Palmaria palmata, Chondrus crispus], coralline crusts and [Mastocarpus stellatus]. The brown seaweed [Cladostephus spongiosus] or the ephemeral green seaweed [Enteromorpha intestinalis], [Ulva lactuca] or [Cladophora rupestris] may occur. The hydroid [Dynamena pumila] can form colonies on the [F. serratus] fronds. The barnacle [Semibalanus balanoides], the limpet [Patella vulgata], the anemone [Actinia equina] and the polychaete [Pomatoceros triqueter] may be present where bedrock are available along with a few winkles such as [Littorina littorea]. In addition, polychaetes and amphipods may burrow into the [R. floridula] mat, while the mussel [Mytilus edulis] is restricted to small crevices in the bedrock. The species diversity of this biotope is normally low and there can be much variation in the species composition from site to site.

Situation: Above this biotope in sand influenced areas are a community dominated by [M. edulis] and [F. vesiculosus] or where the sand scour is more severe, is a biotope dominated by ephemeral seaweeds such as [Enteromorpha] spp. and the red seaweed [Porphyra] spp. (unit A1.452). Below this biotope are biotopes dominated by [F. serratus] and/or red seaweeds (see subunits of A1.214) or biotopes dominated by kelp such as [Alaria esculenta] and/or [Laminaria digitata] (A3.1112).

Temporal variation: Where sand scour is more severe, fucoids and [R. floridula] may be rare or absent and green ephemeral seaweeds dominate the substratum (unit A1.452).


HabitatDescription:
Mid and lower eulittoral exposed to moderately exposed bedrock, often with nearby sediment, may be densely covered by large individuals of the mussel [Mytilus edulis]. Three biotopes have been described: In the mid eulittoral, the mussels may form a band or large patches with scattered bladder wrack [Fucus vesiculosus] (A1.221). In the lower eulittoral a range of red seaweeds including [Mastocarpus stellatus] and [Palmaria palmata] occur amongst the mussels (in higher abundance than the mid eulittoral) (A1.222). Clay outcrops in the mid to lower eulittoral may be bored by a variety of piddocks including [Pholas dactylus], [Barnea candida] and [Petricola pholadiformis], while the surface is characterised by small clumps of the mussel [M. edulis], the barnacle [Elminius modestus] and the winkle [Littorina littorea] (A1.223). Ephemeral green seaweeds such as [Enteromorpha intestinalis] and [Ulva lactuca] commonly occur on the shells of the mussels. Barnacles are common on both the mussel valves and on patches of bare rock, where the limpet [Patella vulgata] is found as well, often at high abundance. The whelk [Nucella lapillus] and a range of littorinids also occur within the mussel bed. A dense [M. edulis] community may be found on more sheltered coasts on mixed substrata (A2.721).
Situation: Above this habitat type is a [M. edulis] and [S. balanoides] dominated zone or a [F. vesiculosus] dominated biotope (A1.213). In the lower eulittoral zone below is a zone dominated by the wrack [Fucus serratus, M. edulis] and a variety of red seaweeds (A1.21) while kelp dominate the sublittoral fringe.


HabitatName:
[Mytilus edulis] and [Fucus vesiculosus] on moderately exposed mid eulittoral rock

HabitatDescription:
Mid eulittoral exposed to moderately exposed bedrock, often with nearby sediment, covered by a dense band or large patches of the mussel [Mytilus edulis]. The community often supports scattered [Fucus vesiculosus] and occasional foliose red seaweeds such as [Porphyra umbilicalis, Osmundea pinnatifida, Mastocarpus stellatus], [Palmaria palmata] or the calcareous algae [Corallina officinalis] . The ephemeral green seaweeds [Enteromorpha intestinalis] and [Ulva lactuca] commonly occur on the shells of the mussels. The barnacle [Semibalanus balanoides] is common on both the mussel valves and on patches of bare rock, where the limpet [Patella vulgata] also can be found. The whelk [Nucella lapillus] and the winkle [Littorina littorea] can be found within the mussel bed.
Situation: Above this biotope is a [M. edulis] and [S. balanoides] dominated biotope (unit A1.113) or a [F. vesiculosus] dominated biotope (unit A1.213). In the lower eulittoral zone below A1.221 is a biotope dominated by the wrack [Fucus serratus, M. edulis] and a higher diversity of red seaweeds (units A1.222; A1.2141).


HabitatName:
[Mytilus edulis], [Fucus serratus] and red seaweeds on moderately exposed lower eulittoral rock

HabitatDescription:
Lower eulittoral moderately exposed bedrock covered by a dense community of large individuals of the mussel [Mytilus edulis], often with a scarce covering of the wrack [Fucus serratus] and red seaweeds. The red seaweeds may include [Palmaria palmata], [Mastocarpus stellatus], [Ceramium] spp., [Audouinella] spp. and [Chondrus crispus]. Ephemeral green seaweeds such as [Enteromorpha intestinalis] and [Ulva lactuca] commonly occur on the shells of the mussels. The barnacle [Semibalanus balanoides] is common on both the mussel valves and on patches of bare rock, where the limpet [Patella vulgata] is also found, often at high abundance. The whelk [Nucella lapillus] and the winkle [Littorina littorea] occur within the mussel bed, as well as the polychaete [Pomatoceros triqueter] and the crab [Carcinus maenas]. The anemone [Actinia equina] is present in cracks and crevices. These moist areas can be overgrown by coralline crusts.
Situation: Above this biotope on sand influenced shores is a [M. edulis] and [F. vesiculosus] dominated biotope (unit A1.221). In the sublittoral fringe below A1.222 is a biotope dominated by the kelp [Laminaria digitata] (A3.2111).


HabitatName:
[Mytilus edulis] and piddocks on eulittoral firm clay

HabitatDescription:
Clay outcrops in the mid to lower eulittoral which are bored by a variety of piddocks including [Pholas dactylus], [Barnea candida] and [Petricola pholadiformis]. The surface of the clay is characterised by small clumps of the mussel [Mytilus edulis], the barnacle [Elminius modestus] and the winkle [Littorina littorea]. Seaweeds are generally sparse on the clay, although small patches of the red seaweeds [Mastocarpus stellatus], [Halurus flosculosus] and [Ceramium] spp. can occur, usually attached to loose-lying cobble or mussel shells. Also the green seaweeds [Enteromorpha] spp. and [Ulva lactuca] may be present. The sand mason [Lanice conchilega] can sometimes be present in the clay, while the shore crab [Carcinus maenas] is present as well. More data are required to validate this description.

Situation: This unit can usually be found beneath a [M. edulis] or barnacle and [Littorina] spp.-dominated biotope (A2.721; A2.431). It is found above a [Laminaria digitata] and piddocks-dominated biotope (unit A3.2113).

Temporal variation: The [C. maenas] population may migrate offshore during the winter season.


HabitatName:
Mediterranean communities of lower mediolittoral rock moderately exposed to wave action

HabitatDescription:
These communities are located in the lower horizon of the mediolittoral rock and result from the concomitance of three components: moderate waves, variations in atmospheric pressure and wind and tide, if present. The dominant aspect, however, is the constant humidity of the substratum.


HabitatName:
Association with [Ceramium ciliatum] and [Corallina elongata]

HabitatDescription:
This association is characterised by the red algae [Ceramium ciliatum] and [Corallina elongata].


HabitatDescription:
The characteristic species of this biocoenosis is the red alga [Neogoniolithon brassica-florida]. When present, this biocoenosis occupies the borders of the lower mediolittoral where the action of waves is very strong.


HabitatDescription:
This association is characterised by the dominance of red algae belonging to the genus [Gelidium].


HabitatName:
Pools and lagoons sometimes associated with [Vermetus] spp. (infralittoral enclave)

HabitatDescription:
This habitat is characterised by a high variability in ecological conditions. It is sometimes characterised by facies with sessile gastropod vermetids located in the middle level of the sea water. It forms well-developed vermetid platforms in Sicily, Corsica and in the eastern Mediterranean basin.


HabitatName:
Pontic communities of lower mediolittoral rock moderately exposed to wave action


HabitatName:
Pontic association with [Enteromorpha intestinalis]


HabitatName:
Pontic association with [Cladophora vagabunda]


HabitatName:
Pontic association with [Ceramium rubrum]


HabitatDescription:
Sheltered to extremely sheltered rocky shores with very weak to weak tidal streams are typically characterised by a dense cover of fucoid seaweeds which form distinct zones (the wrack [Pelvetia canaliculata] on the upper shore through to the wrack [Fucus serratus] on the lower shore). Where salinity is reduced (such as at the head of a sea loch or where streams run across the shore) [Fucus ceranoides] may occur. Fucoids also occur on less stable, mixed substrata (cobbles and pebbles on sediment) although in lower abundance and with fewer associated epifaunal species; beds of mussels [Mytilus edulis] are also common. In summer months, dense blankets of ephemeral green and red seaweeds can dominate these mixed shores. Two biological subtypes have been described: Dense blankets of fucoid seaweeds dominating sheltered, fully marine littoral rocky shores (A1.31) and fucoids dominating variable salinity rocky shores (A1.32).


HabitatDescription:
Dense blankets of fucoid seaweeds dominating sheltered to extremely sheltered rocky shores and/or in locally sheltered patches on exposed to moderately exposed rocky shores. Typically, the wrack [Pelvetia canaliculata] (A1.311) occurs on the upper shore, with the wrack [Fucus spiralis] (A1.312) below. The middle shore is dominated by vast areas of the wrack [Ascophyllum nodosum] or the wrack [Fucus vesiculosus] (A1.313, A1.314) or a mixture of both. The wrack [Fucus serratus] covers lower shore bedrock and boulders (A1.315). Sheltered to very sheltered mixed substrata (pebbles and cobbles overlying muddy sand and gravel) shores can support fucoid communities (A1.3122; A1.3132; A1.3142; A1.3152).
Situation: Sheltered shores (i.e. estuaries and sea lochs) below the lichen dominated zone and above the kelp dominated zone in the sublittoral or sheltered patches on more wave exposed shores.


HabitatName:
[Pelvetia canaliculata] on sheltered littoral fringe rock

HabitatDescription:
Lower littoral fringe bedrock or stable boulders and mixed substrata in sheltered to extremely sheltered conditions characterised by a dense cover of the wrack [Pelvetia canaliculata]. The biotope may be present in localised sheltered patches on moderately exposed shores. [P. canaliculata] overgrows a crust of black lichens [Verrucaria maura] or the non-calcified red algae [Hildenbrandia rubra] on very sheltered shores. Individuals of the wrack [Fucus spiralis] can usually be found among the [P. canaliculata] and/or in lower part of the biotope. This biotope lacks the density of barnacles found amongst the [P. canaliculata] on more exposed shores. The winkle [Littorina saxatilis] occurs, as do a variety of amphipods. The red alga [Catenella caespitosa] can be present especially in more shaded areas while the green seaweed [Enteromorpha] spp. can be present in moist areas.
Situation: This biotope is found in the lower littoral fringe on sheltered shores below biotopes dominated by [V. maura] (unit B3.1132) and above biotopes dominated by [F. spiralis] (unit A1.212). Though not typical, this biotope may occur on moderately exposed shores where local topography provides shelter.


HabitatName:
[Fucus spiralis] on sheltered upper eulittoral rock

HabitatDescription:
Sheltered upper eulittoral bedrock is typically characterised by a band of the spiral wrack [Fucus spiralis] overlying the black lichen [Verrucaria maura]. Underneath the fronds of [F. spiralis] and the occasional [Pelvetia canaliculata] is a community consisting of the limpet [Patella vulgata], the winkles [Littorina saxatilis] and [Littorina littorea] and the barnacle [Semibalanus balanoides]. The rock surface can often be covered by the red crust [Hildenbrandia rubra]. During the summer months the ephemeral green seaweed [Enteromorpha intestinalis] can be common. Two variants have been described: Upper eulittoral bedrock characterised by [F. spiralis], the black lichen [Verrucaria maura] and the olive green lichen [Verrucaria mucosa] (unit A1.3121). Upper eulittoral mixed substrata characterised by [F. spiralis] with occasional clumps of the wrack [Pelvetia canaliculata] (unit A1.3122). Note that a [F. spiralis] biotope in variable salinity conditions (A1.322) has also been descibed.
Situation: This zone usually lies below a zone dominated by the wrack [Pelvetia canaliculata] (units A1.211: A1.311), but occasional clumps of [P. canaliculata] may be present (usually less than common) amongst the [F. spiralis]. In areas of extreme shelter, such as in Scottish sea lochs, the [P. canaliculata] and [F. spiralis] zones often merge together forming a very narrow band. A1.312 occurs above the wracks [Ascophyllum nodosum] (A1.314) and/or [Fucus vesiculosus] (A1.313) zones and these two fucoids may also occur, although [F. spiralis] always dominates. Vertical surfaces in this zone, especially on moderately exposed shores, often lack the fucoids and are characterised by a barnacle-limpet dominated community (A1.113).


HabitatName:
[Fucus spiralis] on full salinity sheltered upper eulittoral rock

HabitatDescription:
Sheltered upper eulittoral bedrock characterised by a band of the spiral wrack [Fucus spiralis] overlying the black lichen [Verrucaria maura] and the olive green lichen [Verrucaria mucosa]. Underneath the fronds of [F. spiralis] is a community consisting of the limpet [Patella vulgata], the winkles [Littorina saxatilis] and [Littorina littorea] and sparse individuals of the barnacle [Semibalanus balanoides] while the mussel [Mytilus edulis] can be found attached in cracks and crevices. A variety of red algae including [Hildenbrandia rubra] may be present underneath the fronds. During the summer months ephemeral green seaweeds such as [Enteromorpha intestinalis] can be common.
Situation: This zone usually lies below a zone dominated by the wrack [Pelvetia canaliculata] (units A1.211; A1.311), but occasional clumps of [P. canaliculata] may be present (usually less than common) amongst the [F. spiralis]. In areas of extreme shelter, such as in Scottish sea lochs, the [P. canaliculata] and [F. spiralis] zones often merge together forming a very narrow band. A1.3121 occurs above the wracks [Ascophyllum nodosum] (A1.314) and/or [Fucus vesiculosus] (A1.313) zones and these two fucoids may also occur, although [F. spiralis] always dominates. Vertical surfaces in this zone, especially on moderately exposed shores, often lack the fucoids and are characterised by a barnacle-limpet dominated community (Sem).


HabitatName:
[Fucus spiralis] on full salinity upper eulittoral mixed substrata

HabitatDescription:
Moderately exposed to sheltered full salinity upper eulittoral mixed substrata characterised by a band of the wrack [Fucus spiralis]. Occasional clumps of the wrack [Pelvetia canaliculata] can be overgrowing the black lichen [Verrucaria maura] and the olive green lichen [Verrucaria mucosa]. On the more stable boulders underneath the fronds the red crust [Hildenbrandia rubra] can be found along with the barnacle [Semibalanus balanoides] and the limpet [Patella vulgata]. The winkles [Littorina littorea] and [Littorina saxatilis] can be found on and among the boulders and cobbles, while amphipods and the crab [Carcinus maenas] can be present either underneath the boulders or among the brown seaweeds. The green seaweed [Enteromorpha intestinalis] can occur in some abundance especially during the summer.

Situation: This zone usually lies below a zone dominated by the wrack [P. canaliculata] (units A1.211; A1.311). Vertical surfaces in this zone, especially on moderately exposed shores, often lack the fucoids and are characterised by a barnacle-limpet dominated community (A1.113).In areas of extreme shelter, such as in Scottish sea lochs, the [P. canaliculata] and [F. spiralis] zones often merge together forming a very narrow band. A1.3122 occur above the wracks [Ascophyllum nodosum] (A1.3142) and/or [Fucus vesiculosus] (A1.3132) zones. These two fucoids may also occur among the [F. spiralis], although [F. spiralis] always dominates. Fspi.X can also be found above a barnacle [S. balanoides] and winkle [L. littorea] dominated biotope (A2.431).

Temporal variation: Ephemeral green seaweeds such as [E. intestinalis] can occur in some abundance during the summer when the growth conditions are optimal.


HabitatName:
[Fucus vesiculosus] on moderately exposed to sheltered mid eulittoral rock

HabitatDescription:
Moderately exposed to very sheltered mid eulittoral bedrock and large boulders characterised by a dense canopy of the wrack [Fucus vesiculosus] (Abundant to Superabundant). Beneath the seaweed canopy the rock surface has a sparse covering of the barnacle [Semibalanus balanoides] and the limpet [Patella vulgata]. The mussel [Mytilus edulis] is confined to pits and crevices. A variety of winkles including [Littorina littorea] and [Littorina saxatilis] can be found grazing on the fucoid fronds. The whelk [Nucella lapillus] is found beneath the seaweed canopy. In areas of localised shelter the wrack [Ascophyllum nodosum] may occur, though never at high abundance. The crab [Carcinus maenas] may be present in pools or among the boulders. Two variants have been described: Bedrock and large boulders (unit A1.3131) and mixed substrata (unit A1.3132). Please notice that a [F. vesioculosus] biotope subject to variable salinity (unit A1.323) has been identified.

Situation: This biotope usually occurs between the wrack [Fucus spiralis] (A1.312) and the [Fucus serratus] (A1 315) zones; both of these fucoids may be present in this biotope, though never at high abundance (typically less than Frequent). In some sheltered areas [F. vesiculosus] forms a narrow zone above the [A. nodosum] zone (A1.314). Where freshwater runoff occurs on more gradually sloping shores [F. vesiculosus] may be replaced by the wrack [Fucus ceranoides] (A1.327).

Temporal variation: On some shores, particularly those which are moderately exposed to wave action, temporal fluctuations in the abundance of limpets, barnacles and fucoid seaweeds may occur. As a result, over a number of years, a single shore may cycle between the barnacle-[P. vulgata] dominated biotope (A1.1132), through this mosaic (A1.213) to a [F. vesiculosus]-dominated biotope (A1.313).


HabitatName:
[Fucus vesiculosus] on full salinity moderately exposed to sheltered mid eulittoral rock

HabitatDescription:
Moderately exposed to sheltered mid eulittoral bedrock and large boulders characterised by a dense canopy of the wrack [Fucus vesiculosus] (Abundant to Superabundant). Beneath the seaweed canopy the rock surface has a sparse covering of the barnacle [Semibalanus balanoides] and the limpet [Patella vulgata]. The mussel [Mytilus edulis] is confined to pits and crevices. A variety of winkles including [Littorina littorea, Littorina saxatilis] and the whelk [Nucella lapillus] are found beneath the seaweeds, whilst [Littorina obtusata/mariae] graze on the fucoid fronds. The calcareous tube-forming polychaete [Spirorbis spirorbis] may also occur epiphytically on the fronds. In areas of localised shelter the wrack [Ascophyllum nodosum] may occur, though never at high abundance. Damp cracks and crevices often contain patches of the red seaweed [Mastocarpus stellatus] and even the wrack [Fucus serratus] may be present. The crab [Carcinus maenas] may be present in pools or among the boulders.

Situation: This biotope usually occurs between the wrack [Fucus spiralis] (A1.312) and the [F. serratus] (A1 315) zones; both of these fucoids may be present in this biotope, though never at high abundance (typically less than Frequent). In some sheltered areas [F. vesiculosus] forms a narrow zone above the [A. nodosum] zone (A1.314). Where freshwater runoff occurs on more gradually sloping shores [F. vesiculosus] may be replaced by the wrack [Fucus ceranoides] (A1.327).

Temporal variation: On some shores, particularly those which are moderately exposed to wave action, temporal fluctuations in the abundance of limpets, barnacles and fucoid seaweeds may occur. As a result, over a number of years, a single shore may cycle between the barnacle-[P. vulgata] dominated biotope (A1.1132), through this mosaic (A1.213) to a [F. vesiculosus]-dominated biotope (A1.313).


HabitatName:
[Fucus vesiculosus] on mid eulittoral mixed substrata

HabitatDescription:
Sheltered and very sheltered mid eulittoral pebbles and cobbles lying on sediment in fully marine conditions typically characterised by the wrack [Fucus vesiculosus]. The wrack [Ascophyllum nodosum] can occasionally be found on larger boulders while the barnacle [Semibalanus balanoides] and the limpet [Patella vulgata] also can be present on the cobbles with the whelk [Nucella lapillus] preying on the barnacles and on the mussel [Mytilus edulis]. Winkles, particularly [Littorina littorea] and [Littorina obtusata], commonly graze the biofilm on the seaweeds, while [Littorina saxatilis] can be found in crevices. Ephemeral seaweeds such as [Enteromorpha intestinalis] may be present in this biotope. The sediment between patches of hard substrata often contains the polychaete [Arenicola marina] or the polychaete [Lanice conchilega], while a variety of gastropods and the crab [Carcinus maenas] occur on and under cobbles.

Situation: This unit can be found below the biotope dominated by the wrack [Fucus spiralis] (unit A1.3122) or a community dominated by [S. balanoides], [P. vulgata] and [L. littorea] (unit A2.431). It is found above a community dominated by [M. edulis] beds (A1.111) or the wrack [Fucus serratus] (A1.3152).

Temporal variation: Some variation in the ephemeral seaweeds and their abundance depending on season is likely.


HabitatName:
[Ascophyllum nodosum] on very sheltered mid eulittoral rock

HabitatDescription:
Sheltered to extremely sheltered mid eulittoral rock with the wrack [Ascophyllum nodosum]. The red seaweed [Polysiphonia lanosa] is often found growing as an epiphyte on the [A. nodosum] fronds while disturbed areas among the [A. nodosum] is colonised by the wrack [Fucus vesiculosus] and the green seaweed [Enteromorpha intestinalis].e barnacle [Semibalanus balanoides], the limpet [Patella vulgata] and [Littorina littorea] can all be found on the bedrock underneath the [A. nodosum] canopy along with coralline crusts. The whelk [Nucella lapillus] can be found preying on the barnacles and limpets. Three variants of this biotope are described. These are: full salinity (unit A1.3141), mixed substrata (unit A1.3142) and the loose lying growth form [A. nodosum] ecad [mackaii] found on very sheltered shores (A1.325). Two other biotopes has been identified as well tide-swept (A1.151) and variable salinity (A1.324).

Situation: This biotope is usually found between the wrack [Fucus spiralis] (A1.312) and [F. serratus] dominated biotopes (A1 315), although on some shores a narrow zone of [F. vesiculosus] (A1.313) may occur immediately above the [A. nodosum]. With increasing wave exposure the [A. nodosum] canopy is replaced by [F. vesiculosus] (A1.213; A1.313). Unit A1.314 can occur on more exposed shores, where there is localised shelter.

Temporal variation: [A. nodosum] communities are generally very stable communities with individual plants reaching ages of more than 25 years on shores with little wave-action.


HabitatName:
[Ascophyllum nodosum] on full salinity mid eulittoral rock

HabitatDescription:
Bedrock, stable boulders and cobbles in the mid-eulittoral zone of moderately exposed to extremely sheltered shores, in fully marine conditions, characterised by a dense canopy of the wrack [Ascophyllum nodosum]. Another wrack [Fucus vesiculosus] may in some places co-dominate the canopy. The hydroid [Dynamena pumila] can form colonies on the wracks [F. vesiculosus] and [Fucus serratus]. Variations in the ratio of [A. nodosum] and [F. vesiculosus] in the overlying canopy have little effect on the under-storey species. Beneath the canopy are a diverse array of filamentous and foliose red seaweeds, including [Mastocarpus stellatus, Chondrus crispus, Gelidium pusillum] and coralline crusts. The filamentous red seaweed [Polysiphonia lanosa] is usually present on [A. nodosum] as an epiphyte. A few green seaweeds including [Cladophora rupestris] and [Enteromorpha] spp. are also present in moderate to low densities. On the bedrock and boulders beneath the seaweed canopy is a fauna including the barnacle [Semibalanus balanoides], the limpet [Patella vulgata], tube-forming spirorbid polychaetes and the anemone [Actinia equina]. The latter can be present in damp cracks and crevices. On and among the seaweeds are mobile species including the winkles [Littorina littorea] and [Littorina obtusata], the whelk [Nucella lapillus] or even the crab [Carcinus maenas]. At the top of the [A. nodosum] zone there might be the occasional presence of the olive green lichen [Verrucaria mucosa].

Situation: This biotope is usually found between the wrack [Fucus spiralis] (unit A1.312) and [F. serratus] dominated biotopes (A1 315), although on some shores a narrow zone of [F. vesiculosus] (A1.313) may occur immediately above the [A. nodosum]. With increasing wave exposure the [A. nodosum] canopy is replaced by [F. vesiculosus] (A1.213; A1.313). This unit  can occur on more exposed shores, where there is localised shelter.

Temporal variation: [A. nodosum] can reach an age of 25 years on sheltered shores and the communities are, once established, usually very stable. [F. vesiculosus] or [F. serratus] can occur in patches where the [A. nodosum] has been removed.


HabitatName:
[Ascophyllum nodosum] on full salinity mid eulittoral mixed substrata

HabitatDescription:
Sheltered to extremely sheltered full salinity mixed substrata (cobbles, boulders and pebbles on sediment) characterised by a canopy formed by a mosaic of the wracks [Ascophyllum nodosum] and [Fucus vesiculosus]. The red seaweed [Polysiphonia lanosa] can often be found as an epiphyte on the [A. nodosum]. The mussel [Mytilus edulis] often occurs in clumps, and provides further suitable substrata for the attachment of fucoids and red and green seaweeds such as [Polysiphonia] spp. and [Enteromorpha intestinalis] or the barnacle [Semibalanus balanoides]. Winkles are common and [Littorina littorea] and [Littorina obtusata/mariae] may occur in high densities, while species such as the limpet [Patella vulgata], the crab [Carcinus maenas] and the whelk [Nucella lapillus] may occur on and around the boulders. Gammarids can be found underneath the boulders or among the seaweeds, while tube-forming spirorbids are found on the boulders, shells or on the [F. vesiculosus]. Infaunal species including the polychaetes [Arenicola marina] and [Lanice conchilega] may occur in the sediment between the cobbles.

Situation: A sparse [S. balanoides], [P. vulgata] and [L. littorea] community (unit A2.431) can occur above this biotope. On shores with a proportion of smaller cobbles and boulders, large [A. nodosum] plants become uncommon and [F. vesiculosus] dominates the canopy (A1.3132). [F. vesiculosus] also tends to replace [A. nodosum] in areas with freshwater influence. Below this biotope are either a [Fucus serratus] dominated biotope (A1.3152) or a [M. edulis] dominated biotope (A1.111).

Temporal variation: [A. nodosum] communities tend to be stable due to longevity of the individual [A. nodosum], but because of the mixed substrata some variation in the densities of [F. vesiculosus] and [A. nodosum] can be expected.


HabitatName:
[Fucus serratus] on sheltered lower eulittoral rock

HabitatDescription:
Sheltered to extremely sheltered lower eulittoral rock with [Fucus serratus] (for detailed description of the rich associated community please see unit A1.3151). Two variants of this biotope have been described; - Fully marine conditions (A1.3151) and mixed substrata (A1.3152). Please notice that three other biotopes with a [F. serratus] dominance have been described: Variable salinity (A1.326), tide-swept (A1.152) and tide-swept on mixed substrata (A1.153).
Situation: This biotope usually occurs immediately below a dense canopy of [Fucus vesiculosus] (A1.313) on sheltered shores or an [Ascophyllum nodosum] zone (A1.3141) on sheltered shores; consequently low densities of these species may occur in this biotope. The sublittoral fringe below is dominated by the kelps [Laminaria saccharina] and [Laminaria digitata] on sheltered shores (A3.3131; A3.3121).


HabitatName:
[Fucus serratus] on full salinity sheltered lower eulittoral rock

HabitatDescription:
Sheltered lower eulittoral rock subject to fully marine conditions characterised by a dense canopy of the wrack [Fucus serratus]. There is a wide range of associated species found on the surface of the rock underneath the canopy, including the barnacle [Semibalanus balanoides], limpets [Patella vulgata], winkles [Littorina littorea], and even mussels [Mytilus edulis] can be present in cracks and crevices. These species are usually found in higher abundance further up on the shore. There may also be a number of other seaweeds present, including the red [Corallina officinalis] and [Mastocarpus stellatus], the wrack [Fucus vesiculosus] and the green [Enteromorpha intestinalis], [Ulva lactuca] or [Cladophora rupestris], though these usually are present in low numbers if present at all. The sponge [Halichondria panicea] can be present underneath the [F. serratus] canopy in moist cracks or minor overhangs. Polychaetes such as [Pomatoceros triqueter] and [Spirorbis] spp. are present in their white calcareous tubes on the rock.

Situation: This biotope usually occurs immediately below a [Fucus vesiculosus]-barnacle mosaic (unit A1.213) on moderately exposed shores or a dense canopy of [F. vesiculosus] (A1.313) or [Ascophyllum nodosum] (A1.3141) on sheltered shores; consequently low densities of these species (typically less than Frequent) may also occur in this biotope. The sub littoral fringe below on moderately exposed shores is dominated by the kelp [Laminaria digitata] (A3.211; A3.2112), while the kelp [Laminaria saccharina] may co-dominate on sheltered shores (A3.3131; A3.3121).

Temporal variation: Fluctuations from year to year in the abundance of the [F. serratus] and the red seaweeds due to e.g. severe storms may convert this biotope into either A1.2141 or into a red seaweed dominated biotope on moderately exposed shores.


HabitatName:
[Fucus serratus] on full salinity lower eulittoral mixed substrata

HabitatDescription:
Sheltered to extremely sheltered full salinity lower eulittoral mixed substrata with dense stands of the wrack [Fucus serratus]. The crab [Carcinus maenas] and a large number of winkles such as [Littorina littorea] and [Littorina obtusata/mariae] can be found amongst the pebbles and cobbles as well as large individuals of the mussel [Mytilus edulis], commonly occurring in clumps. On these mussels and on larger cobbles are the barnacle [Semibalanus balanoides] and the limpet [Patella vulgata]. Red algae such as coralline crusts including [Lithothamnion] spp. and the tube-forming polychaetes [Pomatoceros triqueter] and [Spirorbis] spp. can be found on cobbles and boulders. [Spirorbis] spp. can also be found on the [F. serratus] fronds. Sediment in the spaces between the loose substrata may support infauna including the polychaete [Arenicola marina]. The red seaweed [Mastocarpus stellatus] and the wrack [Ascophyllum nodosum] can occur in patches, while the green seaweeds [Enteromorpha intestinalis] and [Cladophora] spp. can be found among the mussels and underneath the [F. serratus] canopy.
Situation: This unit occurs in the lower eulittoral below the biotopes dominated by the wrack [Fucus vesiculosus] and [A. nodosum] (A1.3132 or A1.3142) on mixed substrata shores, or on sediment shores where mixed substrata occurs in discrete patches on the lower shore. A1.3132 occurs above biotopes dominated by the kelp [Laminaria digitata] or [Laminaria saccharina] (A3.2111; A3.3131; A3.3121) depending on the substrata.


HabitatDescription:
The characteristic species of this association is the brown alga [Fucus virsoides]. When present, this assemblage occupies the entire mediolittoral zone. Its presence is related to significant tides and relatively cool, unsalted, eutrophic waters and it is peculiar to areas with these characteristics.


HabitatDescription:
Blankets of fucoid seaweeds dominating sheltered to extremely sheltered rocky shores with variable salinity. The wrack [Pelvetia canaliculata] (A1.321) occurs on the upper shore, with the wrack [Fucus spiralis] (A1.322) below. The middle shore is dominated by vast areas of the wrack [Ascophyllum nodosum] or the wrack [Fucus vesiculosus] (A1.323, A1.324) or a mixture of both. The wrack [Fucus serratus] covers lower shore bedrock and boulders (A1.326). Fucus ceranoides can be found on extremly sheltered shores with variable or low salinity (A1.327). The variable salinity communities are species impoverished compared to fucoids in full salinity or in tide-swept conditions as red seaweeds and sponges are usually absent. Underneath the canopy are a few green seaweeds including [Enteromorpha intestinalis] and [Cladophora] spp., while the red seaweed [Polysiphonia lanosa] can be found as an epiphyte on [A. nodosum]. On the rock and among the boulders are the winkles [Littorina littorea] and [Littorina saxatilis], the crab [Carcinus maenas], the barnacles [Semibalanus balanoides] and [Elminius modestus] and even the occasional mussel [Mytilus edulis.
Situation: On sheltered eulittoral rocky shores with variable salinity conditions, such as sea loch or estuaries.


HabitatName:
[Pelvetia canaliculata] on sheltered variable salinity littoral fringe rock

HabitatDescription:
Lower littoral fringe bedrock or stable boulders and mixed substrata on very sheltered to extremely sheltered variable salinity shores characterised by a dense cover of the wrack [Pelvetia canaliculata], which often overgrows a crust of black lichens [Verrucaria maura]. The wrack [Fucus spiralis] can be present among the [P. canaliculata]. This biotope lacks the density of barnacles found among the [P. canaliculata] on more exposed shores though the occasional [Semibalanus balanoides] or [Elminius modestus] can be found. The winkle [Littorina saxatilis] occurs, as do a variety of amphipods. The red alga [Catenella caespitosa] can be present in more shaded areas as well as the green seaweed [Enteromorpha intestinalis].
Situation: This biotope are found in the lower littoral fringe on sheltered shores below biotopes dominated by [V. maura] (unit B3.1132) and above biotopes dominated by [F. spiralis] (A1.312).


HabitatName:
[Fucus spiralis] on sheltered variable salinity upper eulittoral rock

HabitatDescription:
Sheltered to extremely sheltered upper eulittoral bedrock or mixed substrata (boulders, large cobbles or shells on mud) in variable salinity conditions characterised by a band of the spiral wrack [Fucus spiralis]. The ephemeral green seaweed [Enteromorpha intestinalis] is usually found in this species poor biotope. The barnacles [Semibalanus balanoides] and [Elminius modestus] can be found where suitable substrata are available, while gammarids can be found underneath the fronds of [F. spiralis] and/or underneath the boulders and cobbles. Also found underneath the fronds and among the boulders are the winkles [Littorina saxatilis] and [Littorina littorea] and the crab [Carcinus maenas].

Situation: This zone usually lies below a zone dominated by the wrack [Pelvetia canaliculata] (unit A1.311) and occasional clumps of [P. canaliculata] may be present (usually less than common) amongst the [F. spiralis]. In areas of extreme shelter and variable salinity conditions (e.g. in Scottish sea lochs), the [P. canaliculata] and [F. spiralis] zones often merge together forming a very narrow band. This unit occurs above the wracks [Ascophyllum nodosum] (A1.324) and/or [Fucus vesiculosus] (A1.323) zones and these two fucoids may also occur, although [F. spiralis] always dominates. It can also be found above a zone dominated by the wrack [Fucus ceranoides] (A1.327).

Temporal variation: During the summer months ephemeral green seaweeds such as [E. intestinalis] can be common.


HabitatName:
[Fucus vesiculosus] on variable salinity mid eulittoral boulders and stable mixed substrata

HabitatDescription:
Sheltered to extremely sheltered mid eulittoral pebbles and cobbles lying on sediment subject to variable salinity and characterised by the wrack [Fucus vesiculosus]. The wrack [Ascophyllum nodosum] can occasionally be found on larger boulders, while the barnacles [Semibalanus balanoides] and [Elminius modestus] and the mussel [Mytilus edulis] can be present on cobbles. Winkles, particularly [Littorina littorea], commonly graze on the seaweeds, while [Littorina saxatilis] can be found in crevices. Ephemeral seaweeds such as [Enteromorpha intestinalis] can occupy available space. Patches of sediment found between the hard substrata often contains the lugworm [Arenicola marina] or the sand mason [Lanice conchilega], while the crab [Carcinus maenas], gammarids and amphipods occur on and under cobbles.

Situation: This unit can be found below the biotope dominated by the wracks [Fucus spiralis] or [Fucus ceranoides] (units A1.3122; A1.327) or a community dominated by [S. balanoides], [P. vulgata] and [L. littorea] (A2.431). It is found above a community dominated by [M. edulis] (A1.111) or the wrack [Fucus serratus] (A1.326).

Temporal variation: Some variation in the ephemeral seaweeds and their abundance depending on the season is likely.


HabitatName:
[Ascophyllum nodosum] and [Fucus vesiculosus] on variable salinity mid eulittoral rock

HabitatDescription:
Very sheltered to extremely sheltered mid eulittoral bedrock, boulders or cobbles subject to variable salinity characterised by an impoverished community dominated by a mixture of the wracks [Ascophyllum nodosum] and [Fucus vesiculosus]. Underneath the canopy are a few green seaweeds including [Enteromorpha intestinalis] and [Cladophora] spp., while the red seaweed [Polysiphonia lanosa] can be found as an epiphyte on [A. nodosum]. On the rock and among the boulders are the winkles [Littorina littorea] and [Littorina saxatilis], the crab [Carcinus maenas], the barnacles [Semibalanus balanoides] and [Elminius modestus] and even the occasional mussel [Mytilus edulis]. Among the seaweeds and underneath the boulders a variety of gammarids can be found.

Situation: This biotope usually lies below the [Fucus spiralis] biotope (unit A1.322) or the [Fucus ceranoides] dominated biotopes (A1.327) and above the variable salinity [F. serratus] dominated biotope (A1.326), although on some shores a narrow zone of [F. vesiculosus] (A1.313) may occur immediately above the [A. nodosum]. With increasing wave exposure the [A. nodosum] canopy can be more dense (A1.3141).

Temporal variation: [A. nodosum] can reach an age of 25 years and the communities are usually stable. [F. vesiculosus] or [F. serratus] can occur in patches where the [A. nodosum] has been removed.


HabitatName:
[Ascophyllum nodosum] ecad. [mackaii] beds on extremely sheltered mid eulittoral mixed substrata

HabitatDescription:
Extremely sheltered mid shore mixed substrata, usually subject to variable salinity due to freshwater runoff, which support beds of the non-attached growth form of the wrack [Ascophyllum nodosum] ecad [mackaii]. Cobbles and other hard substrata are often characterised by the normal form of [A. nodosum] with the red seaweed [Polysiphonia lanosa] growing as an epiphyte and other fucoids such as [Fucus vesiculosus]. The loose mats of [A. nodosum] ecad [mackaii] provide a cryptic and humid habitat for mobile species including gammarids, the crab [Carcinus maenas] and the winkles [Littorina littorea, Littorina obtusata] and [Littorina saxatilis]. The barnacle [Semibalanus balanoides] and the mussel [Mytilus edulis] are commonly attached to pebbles and cobbles on the sediment, while the infauna may contain the polychaetes [Arenicola marina] and [Lanice conchilega]. NB: This biotope is a BAP-habitat.

Situation: Occurs in extremely sheltered conditions at the heads of Scottish sea lochs (but is also known from other sheltered areas).

Temporal variation: [A. nodosum ecad mackaii] develops initially from broken fragments of [A. nodosum] and can in sheltered conditions grow in unattached, often bladderless, wig-shaped masses in the mid to upper tide zone. Note: "Ecad" has no official status in International Code of Botanical Nomenclature, but the terminology has been applied to the free-living form of [A. nodosum] since the beginning of the 19th century. The term was first employed by Clements (1905) to denote a form which results from adaptation or a change in morphology due to a new habitat - phenotypic variation.


HabitatName:
[Fucus serratus] and large [Mytilus edulis] on variable salinity lower eulittoral rock

HabitatDescription:
Areas of very sheltered lower eulittoral rock or mixed substrata subject to variable salinity, which support an impoverished community dominated by the wrack [Fucus serratus]. The hydroid [Dynamena pumila] can form colonies on the [F. serratus] and clumps of large individuals of the mussel [Mytilus edulis] 

may be present on the bedrock beneath. The canopy of [F. serratus] is not usually as dense as in the other [F. serratus] dominated biotopes due the presence of the wracks [Ascophyllum nodosum] and [Fucus vesiculosus], which are better adapted to the variable salinity. A few red seaweeds are present which includes the species [Mastocarpus stellatus], [Chondrus crispus] and coralline crusts. Underneath the canopy is a sparse fauna consisting of barnacles [Semibalanus balanoides, Balanus crenatus]

 and [Elminius modestus], the limpet [Patella vulgata] or the occasional presence of the winkles [Littorina obtusata] and [Littorina mariae] and the crab [Carcinus maenas]. The tube-forming polychaetes [Pomatoceros triqueter] or spirorbid polychaetes can be found. In areas (such as the Scottish sea lochs) where variable salinity water passes through tide-swept narrows and the associated biota is impoverished such records should be classified as A1.326 rather than A1.152.



Situation: This biotope may be found below the variable salinity [F. vesiculosus] dominated biotope or [A. nodosum] dominated biotope (A1.324; A1.323), particularly in Scottish sea lochs. It can be found above the biotopes dominated by the kelp [Laminaria saccharina](units  A3.322; A3.323).



Temporal variation: The canopy of [F. serratus] is not as dense as in the other [F. serratus] dominated biotopes due the presence of the wracks [A. nodosum] and [F. vesiculosus], which are better adapted to the variable salinity. 

They will therefore out-compete [F. serratus] on the lower shore and an ecological shift can occur (In the Baltic Sea [F. vesiculosus] is the dominant sublittoral brown seaweed). Due to the variable or low salinity conditions the individual red seaweeds may not be as large as specimens found in fully marine conditions and they can lack sexually reproductive structures.


HabitatName:
[Fucus ceranoides] on reduced salinity eulittoral rock

HabitatDescription:
Very sheltered to extremely sheltered bedrock and stable boulders in the eulittoral zone that are subject to reduced salinity and characterised by the wrack [Fucus ceranoides]. Species richness is typically low in this biotope. The green seaweeds [Enteromorpha intestinalis] and [Ulva lactuca] may be present together with the crab [Carcinus maenas] and the occasional barnacle [Elminius modestus] and [Semibalanus balanoides].
Situation: As [F. ceranoides] is more tolerant of reduced salinity than the other fucoids, [F. ceranoides] tends to replace the wracks [Fucus spiralis], [Fucus vesiculosus] and [Ascophyllum nodosum] towards the upper reaches of estuaries and sea lochs or in areas with freshwater influence. This biotope may, however, still contain other fucoids, although [F. ceranoides] always dominates. This biotope is often found on artificial substrata such as sea defences or bridge supports.


HabitatName:
Red algal turf in lower eulittoral, sheltered from wave action

HabitatDescription:
Proposed new level 4 unit. More information required.


HabitatName:
Mediterranean communities of lower mediolittoral rock sheltered from wave action

HabitatDescription:
These communities are located in the sheltered lower horizon of the mediolittoral rock and result from the concomitance of three components: little wave action, variations in atmospheric pressure and wind and tide. The dominant aspect is the constant humidity of the substratum.


HabitatDescription:
'This is an association of polluted waters characterised by the green alga species [Ulva compressa] (ex [Enteromorpha compressa]).


HabitatDescription:
Littoral rock features include rockpools (A1.41, A1.42), ephemeral algae (A1.45) and caves (A1.44) in the intertidal zone (the area of the shore between high and low tides). These features are present throughout the littoral rock zone from the upper limit at the top of of the lichen zone and the lower limit by the top of the laminarian kelp zone. These features can be found on most rocky shores regardless of wave exposure. Lichens can be found in the supralittoral zone on shores with suitable substratum. The lichen band is wider and more distinct on more exposed shores. Rockpools occur where the topography of the shore allows seawater to be retained within depressions in the bedrock producing 'pools' on the retreat of the tide. As these rockpool communities are permanently submerged they are not directly affected by height on the shore and normal rocky shore zonation patterns do not apply allowing species from the sublittoral to survive. Ephemeral seaweeds occur on disturbed littoral rock in the lower to upper shore. The shaded nature of caves and overhangs diminishes the amount of desiccation suffered by biota during periods of low tides which allows certain species to proliferate. In addition, the amount of scour, wave surge, sea spray and penetrating light determines the unique community assemblages found in upper, mid and lower shore caves, and on overhangs on the lower shore. Non-tidal areas irregularly exposed by wind action (hydrolittoral) with hard substrata are also included here. Note that lichens and algae crusts in the supralittoral zone are coastal habitats (B3.11).


HabitatDescription:
Rockpools occur where the topography of the shore allows seawater to be retained within depressions in the bedrock producing 'pools' on the retreat of the tide. As these rockpool communities are permanently submerged they are not directly affected by height on the shore and normal rocky shore zonation patterns do not apply. For this reason rockpools have been dealt with as a separate habitat type, apart from the scheme of wave exposure and shore height. Four main rockpool biotopes have been described, and although it is accepted that an enormous variety of rockpool communities exist, it is hoped that these biotope descriptions are broad enough to adequately encompass most types. It would be meaningless to include the characterising species in a description at the habitat type level. Rockpools on the upper shore which are subject to rainwater influence and wide fluctuations in temperature are included in A1.42. Shallow rockpools in the mid to upper shore characterised by encrusting coralline algae and [Corallina officinalis] (A1.411); several variants of these coralline pools occur in south-west Britain and Ireland (A1.4112, A1.4113 and A1.4114). Deeper rockpools on the mid to lower shore can support fucoids and some sublittoral species such as kelp (A1.412). Those rockpools influenced by the presence of sand are characterised by sand-tolerant seaweed such as [Furcellaria lumbricalis] and [Polyides rotundus] (A1.413). Where more stable sand occurs in the base of the rockpool sea-grass beds can occur. Shallow rockpools on mixed cobbles, pebbles, gravel and sand may be characterised by hydroids (A1.414). A very rough guideline to the terms "shallow" and "deep" rockpools: "shallow" rockpools do not support kelp, whereas "deep" rockpools do. A1.41 does not include shallow standing water on compacted sediment or mixed substrata.

Situation: Rockpools occur in the littoral zone where the topography of the shore allows seawater to be retained within depressions in the bedrock producing 'pools' on the retreat of the tide.


HabitatDescription:
Shallow and smaller rockpools throughout the eulittoral zone in a wide range of wave exposures characterised by a covering of encrusting coralline algae on which [Corallina officinalis] often forms a dense turf. The bottom of these pools can be covered in coarse gravel and cobbles. These 'coralline' pools have a striking appearance as they are dominated by red seaweeds. Foliose red seaweeds found in these pools include [Mastocarpus stellatus, Chondrus crispus] and the filamentous [Ceramium nodulosum]. The ephemeral green seaweeds [Cladophora rupestris, Ulva lactuca] and [Enteromorpha] spp. can also occur in high abundance. The pools may hold large numbers of grazing molluscs, particularly the winkle [Littorina littorea] (which often occur in exceptionally high densities in upper shore pools) and the limpet [Patella vulgata]. Gastropods may graze these pools to such an extent that they is devoid of any foliose red seaweeds, and the flora are reduced to encrusting coralline algae and large numbers of gastropods. Large brown seaweeds are generally absent. Within the pools, pits and crevices are often occupied by the anemone [Actinia equina] and small individuals of the mussel [Mytilus edulis]. The whelk [Nucella lapillus] can be found on the rock surface preying on the barnacles and mussels. A number of variants have been identified. Pools dominated by coralline algae and foliose red seaweeds with a distribution throughout the UK (see unit  A1.4111). In Ireland, the sea urchin [Paracentrotus lividus] can dominate these shallow coralline pools (see A1.4112). In south-west Britain, the brown seaweed [Bifurcaria bifurcata] (A1.4113) or [Cystoseira] spp. (A1.4114) can be regionally dominant.

Situation: Rockpools throughout the eulittoral and lower littoral fringe on rocky shores.


HabitatName:
Coralline crusts and [Corallina officinalis] in shallow eulittoral rockpools

HabitatDescription:
Shallow and smaller rockpools throughout the eulittoral zone in a wide range of wave exposures characterised by a covering of encrusting coralline algae on which [Corallina officinalis] often forms a dense turf. The bottom of these pools can be covered in coarse gravel and cobbles. These 'coralline' pools have a striking appearance as they are dominated by red seaweeds. Foliose red seaweeds found in these pools include [Mastocarpus stellatus, Chondrus crispus] and the filamentous [Ceramium nodulosum]. The ephemeral green seaweeds [Cladophora rupestris, Ulva lactuca] and [Enteromorpha] spp. can also occur in high abundance. The pools may hold large numbers of grazing molluscs, particularly the winkle [Littorina littorea] (which often occurs in exceptionally high densities in upper shore pools), the limpet [Patella vulgata] and top shell [Gibbula cineraria]. Gastropods may graze these pools to such an extent that they is devoid of any foliose red seaweeds, and the flora are reduced to encrusting coralline algae and large numbers of gastropods. Large brown seaweeds are generally absent. Within the pools, pits and crevices are often occupied by the anemone [Actinia equina] and small individuals of the mussel [Mytilus edulis], while the barnacle [Semibalanus balanoides] can be found on the rock surface. The whelk [Nucella lapillus] can be found on the rock surface preying on the barnacles and mussels.

Situation: Rockpools throughout the eulittoral and lower littoral fringe rocky shores.

Temporal variation: The ephemeral green seaweeds [Enteromorpha intestinalis] and [Ulva lactuca] can occur during the summer.


HabitatName:
Coralline crusts and [Paracentrotus lividus] in shallow eulittoral rockpools

HabitatDescription:
Shallow and relatively small rockpools throughout the eulittoral zone on very exposed to exposed shores, characterised by a covering of encrusting coralline algae on which [Corallina officinalis] forms a dense turf. The bottom of these pools can be covered in coarse gravel and cobbles. In south and west Ireland these coralline pools may be dominated by the sea urchin [Paracentrotus lividus] and the seaweed diversity is generally low due to the grazing pressure of [P. lividus], the top shells [Gibbula cineraria] and [Gibbula umbilicalis], and winkles such as [Littorina littorea]. Within the pools, pits and crevices are often occupied by the anemone such as [Actinia equina] and [Anemonia viridis] and small individuals of the mussel [Mytilus edulis]. The siphonous green seaweed [Codium] spp. can also be present along with the wrack [Himanthalia elongata] and the brown seaweed [Leathesia difformis] and the filamentous red seaweed [Ceramium] spp. The barnacle [Semibalanus balanoides] is either absent or occurs at low abundance in these rockpools, presumably due to the grazing pressure on the larval stage and the predation pressure from the whelk [Nucella lapillus]. Soft bedrock, such as limestone, allows [P. lividus] to bore into the rock.

Situation: Rockpools throughout the eulittoral and lower littoral fringe in bedrock on very exposed to exposed shores.

Temporal variation: The ephemeral green seaweeds [Enteromorpha intestinalis] and [Ulva lactuca] can occur during the summer.


HabitatName:
[Bifurcaria bifurcata] in shallow eulittoral rockpools

HabitatDescription:
Eulittoral rockpools in south-west Britain on very exposed to moderately exposed shores dominated by the brown seaweed [Bifurcaria bifurcata] and encrusting coralline algae and [Corallina officinalis]. Kelps are present and include the species [Laminaria digitata], [Laminaria saccharina] and the wrack [Himanthalia elongata]. Underneath the canopy formed by these species is a high diversity of red seaweeds including the foliose species [Chondrus crispus], [Palmaria palmata], [Osmundea pinnatifida] and [Mastocarpus stellatus]. Other red seaweeds include [Gastroclonium ovatum], [Ceramium nodulosum], [Calliblepharis jubata] and [Mesophyllum lichenoides]. The green seaweeds [Ulva lactuca] and [Enteromorpha intestinalis] occur where space allows. Often found in small cracks and crevices are the anemones [Actinia equina] and [Anemonia viridis], while the limpet [Patella vulgata] can be found on the rock surface. Coarse gravel, cobbles and mobile boulders often cover the bottom of these rockpools, where [Gibbula umbilicalis] can be found.

Situation: Rockpools throughout the eulittoral to the upper littoral fringe in bedrock on very exposed to moderately exposed shores. [B. bifurcata] is at the edge of its range in Britain; in France it occurs in deeper lower shore pools where the alga forms a noticeable band in the mid pool level, below a band of [C. officinalis] and coralline crusts.

Temporal variation: The ephemeral green seaweeds [Enteromorpha intestinalis] and [Ulva lactuca] can occur during the summer.


HabitatName:
[Cystoseira] spp. in eulittoral rockpools

HabitatDescription:
Eulittoral rockpools on exposed to moderately exposed south-western shores dominated by the brown alga [Cystoseira] spp. (including [Cystoseira tamariscifolia]), coralline crusts and [Corallina officinalis]. These pools generally support dense red algal growth comprising: [Ceramium] spp., [Calliblepharis jubata], [Chondrus crispus], [Osmundea pinnatifida] and [Gelidium latifolium]. Wracks such as [Himanthalia elongata] and the epiphytic brown seaweed [Colpomenia peregrina] are present while the kelp [Laminaria digitata] can occupy the deeper parts of the pool. The green seaweeds [Enteromorpha intestinalis] and [Ulva lactuca] are usually present as well. The pools usually contain some sand and pebbles at the base of the pool while spirorbid polychaetes and [Pomatoceros] spp. build their tubes on any small boulders present. In addition, these pools can support high numbers of grazing gastropods including the top shells [Gibbula cineraria] and [Gibbula umbilicalis] but also the limpet [Patella vulgata], while sponges such [Hymeniacidon perleve] and [Halichondria panicea] can be found overgrowing the small boulders or on and around the seaweeds. The shanny [Lipophrus pholis] is present hiding underneath boulder and cobbles, while the anemone [Actinia equina] is found in cracks and crevices. number of available records and care should be taken not to interpret this solely as a very high species richness.
Situation: Rockpools throughout the eulittoral zone in bedrock on very exposed to moderately exposed south-western shores.


HabitatDescription:
Deep or larger rockpools in the mid to lower eulittoral zone on exposed to moderately exposed shores characterised by the wrack [Fucus serratus] and the kelp [Laminaria digitata] and the red seaweed [Corallina officinalis] while encrusting coralline algae cover the rock surface. Other large brown seaweeds, including the kelp [Laminaria saccharina] and [Halidrys siliquosa] may also occur. A wide variety of filamentous and foliose seaweeds occur beneath the brown algal canopy. The species includes the red seaweeds [Palmaria palmata], [Chondrus crispus, Mastocarpus stellatus, Ceramium nodulosum] and [Dumontia contorta], but green seaweeds such as [Enteromorpha intestinalis], [Ulva lactuca] and [Cladophora rupestris] can be present as well. Algal-free vertical and overhanging faces often support the sponge [Halichondria panicea] and anemones including [Actinia equina] and [Urticina felina]. Grazing molluscs including the limpet [Patella vulgata], the top shell [Gibbula cineraria] and the winkle [Littorina littorea] are present on the rock surface while the mussel [Mytilus edulis] can be found in cracks and crevices. The whelk [Nucella lapillus] can be found preying on the mussels. Where boulders occur in these pools they provide a greater variety of micro-habitats which support a variety of fauna. Mobile crustaceans including the crabs [Pagurus bernhardus] and [Carcinus maenas], brittlestars such as [Ophiothrix fragilis] and [Amphipholis squamata], encrusting bryozoans and ascidians are typically found beneath and between boulders.

Situation: Rockpools throughout the eulittoral zone in bedrock on exposed and moderately exposed shores.

Temporal variation: The abundance of grazing molluscs can vary considerably both spatially and temporally, resulting in fluctuations in algal diversity and abundance.


HabitatName:
[Sargassum muticum] in eulittoral rockpools

HabitatDescription:
Shallow rockpools throughout the eulittoral zone on exposed to moderately exposed shores dominated by the brown seaweed [Sargassum muticum] and the red seaweed [Corallina officinalis]. Other brown seaweeds, including the kelp [Laminaria saccharina, Laminaria digitata] and the wrack [Fucus serratus] may occur along with [Dictyota dichotoma], but [S. muticum] always dominates. Underneath the canopy is a rich red seaweed community which includes both foliose and filamentous species such as [Palmaria palmata], [Chondrus crispus], [Lomentaria articulata], [Osmundea pinnatifida], [Ceramium] spp. and [Dumontia contorta]. Encrusting coralline algae and [Hildenbrandia rubra] often cover the rock surface. The foliose green seaweed [Ulva lactuca] is usually present in high abundance growing on the mobile gravel and boulders on the bottom of the rockpools, often along with other ephemeral green seaweeds such as [Cladophora rupestris] and [Enteromorpha intestinalis]. The winkle [Littorina littorea], the limpet [Patella vulgata] and the top shells [Gibbula cineraria] and [Gibbula umbilicalis] can often be found grazing on the biofilm of the rock surface or the seaweeds. Crevices and fissures in the rock provide cover for anemones such as [Actinia equina] and [Anemonia viridis], cover while the prawn [Palaemon serratus] often can be found in large numbers hiding underneath the seaweed canopy or along the boulders on the bottom. Some sand scour can affect these rockpools.

Situation: Rockpools throughout the eulittoral zone in bedrock on exposed and moderately exposed shores. The non-native [S. muticum] is an opportunistic alga which has spread extensively around the south-west coast of Britain since its introduction to UK waters in the early 1970s from the northern Pacific ocean. It is spreading to other parts of the UK. It can dominate rockpools (and other habitats), often to the exclusion of other native species such as [Laminaria] spp. and fucoids.

Temporal variation: As all the available records are from the south-west of Britain some changes in the species composition can be expected from more northern sites.


HabitatDescription:
Rockpools with sediment (mud, sand, gravel) floors support distinct communities of scour-tolerant seaweeds. Deep pools with sediment are similar to unit A1.412, and are typically dominated by fucoids and kelp ([Fucus serratus], [Laminaria digitata], [Laminaria saccharina] and [Saccorhiza polyschides]). Areas of hard substrata near to the interface with the sediment are, however, characterised by a range of sand-tolerant seaweeds such as [Furcellaria lumbricalis], [Polyides rotundus], [Ahnfeltia plicata] and [Rhodochorton purpureum] (compare with unit A1.412). [Chorda filum] may occur attached to pebbles and shells embedded within the sediment while the top shell [Gibbula cineraria] can be found underneath or among the pebbles. In pools with large areas of sand, infaunal species such as [Arenicola marina] and [Lanice conchilega] often occur. The seagrass [Zostera] spp. may occur in some pools where stable sand is present. Shallow rockpools with cobble and pebble floors, often with an underlying layer of sediment, support red algal tufts consisting of coralline crust, [Corallina officinalis], [Chondrus crispus], [Mastocarpus stellatus] mixed with [Ceramium] spp. and the green seaweeds [Cladophora] spp. and [Enteromorpha intestinalis]. The long list of characterising species is partly due to low similarity between the available records and care should be taken not to interpret this solely as a very high species richness.

Situation: Rockpools throughout the eulittoral zone in bedrock on exposed to sheltered shores.

Temporal variation: Seasonal fluctuations in the abundance of ephemeral seaweeds will occur.


HabitatName:
Hydroids, ephemeral seaweeds and [Littorina littorea] in shallow eulittoral mixed substrata pools

HabitatDescription:
Shallow pools on mixed cobbles, pebbles, gravel and sand characterised by abundant hydroids. Species present may include [Obelia geniculata], [O. dichotoma], [O. longissima], [Sertularia cupressina], [Tublaria indivisa] and [Thuiaria thuja]. The difficulty in identifying hydroids suggests many more species may be also be present. Other species typically found in this biotope include ephemeral green algae ([Enteromorpha] spp. and [Ulva] sp.), red algae ([Chondrus crispus] and Coralline algae) and the winkle [Littorina littorea]. Within the pools, patches of sand may be occupied by the lugworm [Arenicola marina] and sand mason worms [Lanice conchilega]. These pools are often associated with mussel beds (unit A2.7211), with [Mytilus edulis] frequently recorded within the pools. Barnacles ([Semibalanus balanoides] and [Elminius modestus]) and the keel worm [Pomatoceros triqueter] may be attached to shells and small stones. Mobile species typical of rock pool habitats, such as [Crangon crangon] and [Pomatoschistus minutus] will also be found within the pool.


HabitatName:
Pontic eulittoral rockpools with green seaweeds ([Cladophora], [Ulva], [Enteromorpha]), [Mytilus], [Mytilaster], [Polybius], [Pachygrapsus] and small fish


HabitatName:
Communities of rockpools in the supralittoral zone

HabitatDescription:
Rockpools in the littoral fringe or upper eulittoral zone subject to widely fluctuating temperatures and salinity due to rainwater influence are characterised by ephemeral green alga of the genus [Enteromorpha], along with [Cladophora] spp. and [Ulva lactuca].


HabitatDescription:
Rockpools in the littoral fringe or upper eulittoral zone subject to widely fluctuating temperatures and salinity are characterised by ephemeral green alga of the genus [Enteromorpha], along with [Cladophora] spp. and [Ulva lactuca]. Due to the physical stress imposed on these upper shore pools, grazing molluscs such as the limpet [Patella vulgata] and the winkles [Littorina littorea] and [Littorina saxatilis] are generally in lower abundance than eulittoral pools, allowing the green seaweeds to proliferate under reduced grazing pressures. The bright orange copepod [Tigriopus fulvus] is tolerant of large salinity fluctuations and may occur in large numbers in these upper shore pools, along with gammarid amphipods.

Situation: Rockpools throughout the upper eulittoral and lower littoral fringe in bedrock.

Temporal variation: Fluctuations especially in the abundance of the green seaweeds will occur due to marked changes in salinity and temperature during the year. [Enteromorpha intestinalis] can often be bleached during the summer.


HabitatName:
Pontic deep upper shore rockpools with [Mytilus] and [Pachygrapsus] juveniles


HabitatName:
Brackish permanent pools in the geolittoral zone


HabitatName:
Eutrophic brackish permanent pools in the geolittoral zone


HabitatName:
Mesotrophic brackish permanent pools in the geolittoral zone


HabitatName:
Oligotrophic brackish permanent pools in the geolittoral zone


HabitatName:
Communities of littoral caves and overhangs

HabitatDescription:
Where caves and overhangs occur on rocky shores, the shaded nature of the habitat diminishes the amount of desiccation suffered by biota during periods of low tides which allows certain species to proliferate. In addition, the amount of scour, wave surge, sea spray and penetrating light determines the unique community assemblages found in upper, mid and lower shore caves and overhangs on the lower shore. Biotopes from the surrounding shore such as A1.111, A1.113 or any of the fucoid communities occasionally extend into cave entrances. A1.113 often extends some way into the cave. Other open shore biotopes may also be found within caves, such as the green seaweed [Prasiola stipitata] on cave roofs where birds roost (B3.112), and localised patches of green algae where freshwater seepage influences the rock (A1.451). Rockpools containing encrusting coralline algae (A1.411), fucoids and kelp (A1.412) and hydroids and littorinid molluscs may occur also on the floor of cave entrances. The cave biotope descriptions are largely based on data obtained from surveys of Berwickshire caves (ERT,2000), chalk caves from the Thanet coast (Tittley et al., 1998; Tittley & Spurrier 2001) and data from Wales (CCW Phase 1 data). In general, the biomass and diversity of algal species found in upper and mid-shore littoral caves decreases with increasing depth into the cave as the light levels diminish. Fucoids are usually only found at the entrances to caves, but red algae, and filamentous and encrusting green algae are able to penetrate to lower light intensities towards the back of the cave, and mats of the turf forming red seaweed [Audouinella purpurea] and/or patches of the green seaweed [Cladophora rupestris] may occur on the upper walls (A1.444). Brownish velvety growths of the brown algae [Pilinia maritima] occurring in mats with the red alga [A. purpurea] on cave walls and upper littoral levels of cliffs (A1.443) should not be confused with the green (A1.442) or golden brown algal stains often found above this zone on the ceilings of the caves (A1.443; A1.441). Below is a zone of [Verrucaria mucosa] and/or [Hildenbrandia rubra] on the inner and outer reaches (A1.445). Fauna usually only occur on the lower and mid walls of the caves and generally comprise barnacles, anemones and tube-forming polychaetes (A1.448; A1.449) depending on the level of boulder scour or wave surge. Where the floors of caves consist of mobile cobbles and small boulders, little algae and fauna occur due to the effects of scouring (A1.44A). Vertical or steeply sloping cave walls and overhangs on the mid and lower shore, subject to wave-surge but without scour, support a rich biota of sponges, hydroids, ascidians and shade-tolerant red algae (A1.447, A1.446 or A1.4461).

Situation: Caves and overhangs in the littoral zone in hard rock and limestone (including chalk).


HabitatDescription:
Orange, brownish or blackish gelatinous bands of algae at high tide and supralittoral levels on open cliff faces and on upper walls and ceilings at entrances and to the rear of upper and mid-shore hard and soft rock (chalk) caves. This dark brown band consists of an assemblage of Haptophyceae such as [Apistonema] spp., [Pleurochrysis carterae] and the orange [Chrysotila lamellosa], but other genera and species of Chrysophyceae, Haptophyceae and Prasinophyceae are likely to be present as well. Species such as [Entodesmis maritima] and [Thallochrysis littoralis] and the filamentous green alga [Epicladia perforans] are often associated with [Apistonema] spp. and the latter can form a green layer beneath the [Apistonema] spp. Associated with this splash zone algal community is an assemblage of animals of terrestrial origin, with red mites, insects and centipedes commonly found. These species descend into the community as the tide falls and retreat as the tide rises. The most common truly 'marine' species is the small winkle [Melarhaphe neritoides].

Situation: This description is partly based on a Thanet intertidal survey (Tittley & Spurrier 2001). More information is needed to identify the species composition and dominant species of this biotope.

Temporal variation: During summer the gelatinous growth dries and often peels off.


HabitatDescription:
The upper walls and ceilings of upper and mid-shore hard and soft rock (chalk) dominated by a band of green algal films (or 'stains'). Other encrusting algae including the non-calcified [Hildenbrandia rubra] may be present. In chalk caves, on the east and south-east coasts of England, a distinctive assemblage of species occurs, including the brown alga [Pilinia maritima] and the bright green algae [Pseudendoclonium submarinum] and [Entocladia perforans] that often covers the cave ceilings. Fauna is generally sparse and limited to limpets such as [Patella vulgata] and the winkle [Littorina saxatilis]. The species forming a green algal film that covers upper shore caves in Berwickshire were not identified. More information required to validate this biotope description.
Situation: This biotope is situated above the zones of units A1.444 or A1.445, extending to cover the upper walls and ceilings of caves. This unit can be found at the entrances to caves and through to the darkest areas at the back and is often found above a zone of A1.443. In hard rock caves however, the green and brown algae (A1.443) or Haptophyceae (A1.441) occur as separate zones or A1.442 may occur on its own.


HabitatName:
[Audouinella purpurea] and [Pilinia maritima] crusts on upper and mid-shore cave walls and ceilings

HabitatDescription:
Golden brown velvety growths of the brown algae [Pilinia maritima] occurring in mats with the red alga [Audouinella purpurea] forming on cave walls and upper littoral levels of cliffs. Fauna is sparse and limited to occasional individuals of the winkle [Littorina saxatilis] and spirorbid polychaetes. This assemblage is thought to be is widespread throughout Britain, although there are currently few records available. More information are needed to validate this description, which is based on information from the Thanet intertidal survey (Tittley & Spurrier 2001).

Situation: This biotope is found at the entrances and the inner reaches of caves between a band of unit A1.444 and the A1.442 zone above.

Temporal variation: Some variation in the species composition of the individual caves must be expected depending on local conditions.


HabitatName:
[Audouinella purpurea] and [Cladophora rupestris] on upper to mid-shore cave walls

HabitatDescription:
Vertical and steeply-sloping upper walls at the entrances and inner reaches of upper to mid-shore caves that are partially sheltered from direct wave action characterised by a turf of the 'velvety' red seaweed [Audouinella purpurea]. Patches of green filamentous seaweed [Cladophora] [rupestris] can be present. The fauna is generally limited to limpets [Patella] spp., the winkle [Littorina saxatilis] and the barnacle [Semibalanus balanoides], while they usually occur in low abundance. Filamentous or crust forming brown seaweeds may occur mixed with [A. purpurea], often becoming a zone in its own right (unit A1.443) above this unit. Other shade-tolerant red seaweed such as [Catenella caespitosa] and [Lomentaria articulata] may occur (but at lower abundance), and where freshwater seepage occurs, [Enteromorpha intestinalis] can form patches. Some variation in the species composition of the individual caves must be expected depending on local conditions. [A. purpurea] can be the only seaweed present in caves on the Thanet coast in south-east England. This biotope is known to occur in hard rock caves in north-east England and chalk caves in south-east England. Received after deadline: [A. purpurea] has changed name to [Rhodochorton purpurea].

Situation: In hard rock caves, this biotope is generally found on the upper walls above units A1.449 and A1.448  and beneath the biotopes dominated by green and/or brown crusts (A1.442; A1.443). In chalk caves, this unit may cover the lower and upper walls, while it is usually found below units A1.442 and/or A1.443.


HabitatName:
[Verrucaria mucosa] and/or [Hildenbrandia rubra] on upper to mid shore cave walls

HabitatDescription:
The upper walls and ceilings of the entrances and inner reaches of upper shore caves affected by direct wave action (and therefore moistened by sea spray), characterised by a mosaic of the olive green lichen [Verrucaria mucosa] and the non-calcified encrusting red alga [Hildenbrandia rubra]. The black lichen [Verrucaria maura] and red coralline algae can be present, though not dominating. The fauna in these upper shore caves is generally limited, due to problems of desiccation. However, where conditions remain sufficiently moist, and particularly in crevices and fissures, the barnacle [Semibalanus balanoides], the limpet [Patella vulgata] and winkles [Littorina saxatilis] may occur, particularly towards the rear of the cave. Although the characterising species of this biotope also occur on the shore, they do not generally occur in a distinct band other than in moist dark caves. The turf-forming red seaweed [Audouinella purpurea] (syn  [Rhodochorton purpurea]) may occasionally occur in low abundance (where [A. purpurea] covers an extensive area, generally on softer rock such as chalk, the biotope should be recorded as unit A1.444).

Situation: This unit generally occurs on upper walls and ceilings towards the rear of dark, moist caves, but can also occur at cave entrances that are directly affected by sea-spray. Where this unit occurs at cave entrances and to approximately 5 m into the cave, it is usually found above a zone of unit A1.113 and below A1.442 or A1.444. Further into the cave A1.113 is replaced completely by A1.445. There are no records for VmucHil in soft rock caves.


HabitatDescription:
Overhanging shaded bedrock on the open lower shore and at the entrance to inner reaches of caves (where light availability permits), which is not subject to appreciable wave-surge, characterised by a shade-tolerant red seaweed community. It includes foliose species such as [Plumaria plumosa, Palmaria palmata, Mastocarpus stellatus, Membranoptera alata] and [Osmundea pinnatifida], but [Lomentaria articulata] and coralline crusts are usually present as well. The foliose green seaweed [Ulva lactuca] can be present. The rock surface often supports dense populations of calcareous tube-forming polychaetes [Spirorbis] spp. and [Pomatoceros] spp., while sponges such as [Grantia compressa], [Halichondria panicea] and [Hymeniacidon perleve] can be common. The hydroid [Dynamena pumila] (normally found on fucoids) hangs in distinct form from overhanging rock. Colonies of the ascidian [Botryllus schlosseri] can be found on the rock, along with the mussel [Mytilus edulis] and the barnacles [Semibalanus balanoides] and [Balanus perforatus] (the latter may occur at high densities in the south and west), while the anemone [Actinia equina] thrives in the permanently damp pits and crevices. The whelk [Nucella lapillus] can be found among the barnacles and mussels, preying on them. The long list of characterising species is partly due to the difference in the species composition and does not solely reflect a high species richness.
Situation: On overhangs, this biotope is generally found above the A1.447 biotope, where there is more light available. In cave environments, this unit may be found at the entrance to and inner reaches of the cave, extending from the lower walls (above the A1.447 biotope) to the upper walls (depending on the height of the cave). Further into the cave where less light is available the ascidian [Dendrodoa grossularia] can be abundant (unit A1.4461).


HabitatName:
Sponges, shade-tolerant red seaweeds and [Dendrodoa grossularia] on wave-surged overhanging lower eulittoral bedrock and caves

HabitatDescription:
Overhanging bedrock on the lower shore, at cave entrances, to and on inner walls of caves, subject to wave surge and low light levels, and characterised by a high density of small groups of the solitary ascidian [Dendrodoa grossularia]. The sponges [Grantia compressa], [Halichondria panicea] and [Hymeniacidon perleve] are common on the rock surface, while the hydroid [Dynamena pumila] (normally found on fucoids) hangs in distinct form from overhanging rock. Found on the rock surface are the calcareous tube-forming polychaetes [Spirorbis] spp. and [Pomatoceros] spp. along with the barnacles [Semibalanus balanoides]. The anemone [Actinia equina] thrives in the permanently damp pits and crevices. Where sufficient light is available a sparse community of shade-tolerant red seaweeds. These include [Membranoptera alata], [Lomentaria articulata, Audouinella] spp. and coralline crusts.

Situation: This biotope is found on lower shore overhangs and on the entrances and inner walls of lower shore caves, and usually dominates the available habitat. It is generally found above the A1.44A biotope and may extend to the upper walls of caves.

Temporal variation: Some variation in the species composition of the individual caves must be expected depending on local conditions.


HabitatDescription:
Overhanging, and shaded vertical, bedrock on the lower shore and in lower shore caves, which is not subject to appreciable wave-surge, characterised by crusts of bryozoans including [Umbonula littoralis], sponges such as [Grantia compressa], [Halichondria panicea, Scypha ciliata] and [Hymeniacidon perleve] and the ascidian [Botryllus schlosseri]. On overhangs, the hydroid [Dynamena pumila] hangs in distinct form from overhanging rock. The barnacles [Balanus crenatus], [Balanus perforatus] (sometimes at high densities) and [Semibalanus balanoides], and the calcareous tube-forming polychaetes [Spirorbis] spp. and [Pomatoceros triqueter] can be present as well. Certain species which are generally confined to the sublittoral, including the anemones [Metridium senile] and [Corynactis viridis], may be found in the lower shore caves and overhangs. Littoral species such as [Actinia equina] are also present. The only algae present are coralline crusts. The list of characterising species partly reflects the variation in the species composition between individual overhangs and caves although this biotope can have a high species richness.
Situation: This biotope is found in the lower eulittoral and sublittoral fringe in less wave-surged conditions than that of unit A1.4461.


HabitatDescription:
The inner walls of caves, predominantly in the mid shore in wave-surged conditions dominated by barnacles [Semibalanus balanoides], and [Verruca stroemia], with patches of encrusting sponges such as [Halichondria panicea] and [Grantia compressa] and occasional patches of the mussel [Mytilus edulis]. Increased moisture allows a denser faunal population than unit A1.449 to develop within the cave. The limpet [Patella vulgata] and spirorbid tube-forming polychaetes can be present. The hydroid [Dynamena pumila] and anemones such as [Metridium senile] and [Actinia equina] may occur towards the lower reaches of the cave. Where a dense faunal turf of barnacles or bryozoan crusts covers the cave walls, the biotope can also extend to cover the ceiling and may be accompanied by the bryozoan [Alcyonidium diaphanum]. Variations of this biotope may occur in mid and lower shore scoured caves in south Wales the rock is dominated by dense [Sabellaria alveolata]. In south-west England the rock can be completely covered by the barnacle [Balanus perforatus]. There may be a variation in the species composition from cave to cave, depending on local conditions.
Situation: This biotope usually occurs above the sand/pebble scoured A1.449 zone and may extend to the ceilings of the caves.


HabitatDescription:
Upper to lower shore sand- or pebble-scoured cave walls characterised by an impoverished faunal assemblage which may include bryozoan crusts, scattered sponges [Halichondria panicea], barnacles such as [Semibalanus balanoides] or often large [Balanus crenatus and] the limpet [Patella vulgata]. The isopod [Ligia oceanica] may seek refuge in crevices in the rock, and due to the decreased effect of desiccation in these damp caves, other species such as the anemone [Actinia equina] and spirorbid polychaetes are able to extend further up the shore than normally found on open rock. The lower section of the wall which is subject to greatest scour may be characterised by a band of [Pomatoceros] [triqueter] and spirorbid tube-forming polychaetes. In wave sheltered conditions, this biotope may extend to the cave ceiling. The rear of caves on the lower shore may support only sparse fauna consisting of spirorbid polychaetes and barnacles such as [Chthamalus montagui] with scattered [Pomatoceros] sp., scattered bryozoan and coralline crusts and in the south-west, occasional [Sabellaria alveolata]. Shade-tolerant red algae such as [Lomentaria articulata] may occasionally occur. Due to the low species abundance in this biotope, there may be a variation from cave to cave, depending on local conditions.

Situation: This biotope is found in caves between the barren (of macro-fauna or flora) or very species poor  zone (unit A1.44A) and the wave-surged, more densely populated zone (A1.448). On the walls above the scour and near the cave entrance the community may grade into a red algal dominated community (unit A1.444).


HabitatDescription:
Mid and upper shore mobile boulders/cobbles on cave floors and the lower reaches of cave walls which are subject to scour are generally devoid of macro-fauna and flora. However, where light is available around the cave entrances, encrusting coralline algae may cover the rock and boulder surfaces. In some instances they may support sparse fauna such as the limpet [Patella] spp. and the winkle [Littorina saxatilis].

Situation: This biotope is situated on the floor, or at the base of cave walls, often with a zone of unit A1.449 above (where the scouring effect of boulders is less). In areas of extreme wave exposure this zone will extend high up the sides of the cave and in less wave-exposed conditions where the effects of scouring are reduced, some fauna may be present. At the entrances and 2-3 metres into upper shore caves, a zone of unit A1.113 may occur above the A1.44A, becoming a zone of A1.445 further into the cave. In mid shore caves, this unit is above by a zone of unit A1.449 (sparse fauna), and in caves on the lower shore, the surge-tolerant unit A1.4461 may occur above this zone.

Temporal variation: In calmer summer months cave mouths may have some ephemeral algae (e.g. [Enteromorpha intestinalis]) and a spat-fall of barnacles or limpets.


HabitatName:
Association with [Phymatolithon lenormandii] and [Hildenbrandia rubra]

HabitatDescription:
The characteristic species of this association are the red algae [Phymatolithon lenormandii] and [Hildenbrandia rubra]. This assemblage lives under the red alga [Lithophyllum byssoides] (ex [Lithophyllum lichenoides]) edge and at the entrance to mediolittoral caves.


HabitatName:
Pontic mediolittoral caves with [Hildebrandia], [Phymatolithon], [Lithophyllum], bryozoans, [Pachygrapsus], [Eriphia]


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

HabitatDescription:
Ephemeral seaweeds on disturbed littoral rock in the lower to upper shore. Dominant green seaweeds include [Enteromorpha intestinalis], [Ulva lactuca] and the red seaweeds [Rhodothamniella floridula] and [Porphyra purpurea]. Winkles such as [Littorina littorea] and [Littorina saxatilis], the limpet [Patella vulgata] and the barnacles [Semibalanus balanoides] can occur, though usually in low abundance. The crab [Carcinus maenas] can be found where boulders are present, while the barnacle [Elminius modestus] is usually present on sites subject to variable salinity. On moderately exposed shores, the biotope is [Enteromorpha] spp. on freshwater-influenced or unstable upper shore rock (A1.451) or [P. purpurea] and/or [Enteromorpha] spp. on sand-scoured mid to lower eulittoral rock (A1.452). These are biotopes 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.

Situation: This habitat type occurs the splash zone, sometimes on cliff faces, and throughout the main intertidal zone.

Note: Connor et al (2004) classify this habitat type together with A2.43 and A2.82 as LR.ELR.Eph.


HabitatName:
[Enteromorpha] spp. on freshwater-influenced and/or unstable upper eulittoral rock

HabitatDescription:
Upper shore hard substratum that is relatively unstable (e.g. soft rock) or subject to considerable freshwater runoff is typically very species poor and characterised by a dense mat of [Enteromorpha] spp., though [Ulva lactuca] can occur as well. It occurs in a wider zone spanning from the supralittoral down to the upper eulittoral, across a wide range of wave exposures range. This biotope is generally devoid of fauna, except for occasional limpets [Patella vulgata], winkles [Littorina littorea] or [Littorina saxatilis] and barnacles [Semibalanus balanoides].

Situation: This band of green seaweeds is usually found above a zone dominated by a mixture [Enteromorpha] spp. and [Porphyra] spp. (unit A1.452) or a [Fucus spiralis] or [Fucus ceranoides] zone (units A1.312; A1.327), and may replace the [Pelvetia canaliculata] zone (A1.211). It can be found below a zone dominated by yellow and grey lichens. In very sheltered areas the seagrass [Ruppia maritima] can be found above this biotope while different wracks such as [Fucus] spp. can dominate the zone below (A5.5343; A1.314; A1.312).

Temporal variation: Seasonal fluctuations in the abundance of the [Enteromorpha] spp. and the occurrence of the other green seaweeds species will occur.


HabitatName:
[Porphyra purpurea] or [Enteromorpha] spp. on sand-scoured mid or lower eulittoral rock

HabitatDescription:
Exposed and moderately exposed mid-shore bedrock and boulders occurring adjacent to areas of sand which significantly affects the rock. As a consequence of sand-abrasion, wracks such as [Fucus vesiculosus] or [Fucus spiralis] are scarce and the community is typically dominated by ephemeral red or green seaweeds, particularly the foliose red seaweed [Porphyra purpurea] and green seaweeds such as [Enteromorpha] spp. Under the blanket of ephemeral seaweeds, the barnacles [Semibalanus balanoides] or [Elminius modestus] and the limpet [Patella vulgata] may occur in the less scoured areas, along with the occasional winkles [Littorina littorea] and [Littorina saxatilis]. Few other species are present.

Situation: Usually found below the species impoverished biotope dominated by [Enteromorpha] spp. (unit A1.451) and above the [F. spiralis] zone (A1.312). It may replace the zone dominated by the wrack [Pelvetia canaliculata] (A1.211). In areas where sand abrasion is less severe, the sand-binding red alga [Rhodothamniella floridula] occurs with other sand-tolerant seaweeds and the wrack [Fucus serratus] (Rho), along with the mussel [Mytilus edulis].

Temporal variation: Seasonal fluctuations in the abundance of the [Enteromorpha] spp. and the [P. purpurea] will occur, especially as a result of storm action.


HabitatName:
Hydrolittoral soft rock: level bottoms with little or no macrophyte vegetation


HabitatName:
Hydrolittoral soft rock: level bottoms dominated by macrophyte vegetation


HabitatName:
Hydrolittoral solid rock (bedrock): level bottoms with little or no macrophyte vegetation


HabitatName:
Hydrolittoral solid rock (bedrock): level bottoms dominated by macrophyte vegetation


HabitatName:
Hydrolittoral solid rock (bedrock): reefs


HabitatName:
Hydrolittoral hard clay: level bottoms with little or no macrophyte vegetation


HabitatName:
Hydrolittoral mussel beds: with little or no macrophyte vegetation


HabitatName:
Hydrolittoral mussel beds: dominated by macrophyte vegetation


HabitatDescription:
Littoral sediment includes habitats of shingle (mobile cobbles and pebbles), gravel, sand and mud or any combination of these which occur in the intertidal zone. Littoral sediment is defined further using descriptions of particle sizes - mainly gravel (16-4 mm), coarse sand (4-1 mm), medium sand (1-0.25 mm), fine sand (0.25-0.063 mm) and mud (less than 0.063 mm) and various admixtures of these (and coarser) grades - muddy sand, sandy mud and mixed sediment (cobbles, gravel, sand and mud together). Littoral sediments support communities tolerant to some degree of drainage at low tide and often subject to variation in air temperature and reduced salinity in estuarine situations. Very coarse sediments tend to support few macrofaunal species because these sediments tend to be mobile and subject to a high degree of drying when exposed at low tide. Finer sediments tend to be more stable and retain some water between high tides, and therefore support a greater diversity of species. Medium and fine sand shores usually support a range of oligochaetes, polychaetes, and burrowing crustaceans, and even more stable muddy sand shores also support a range of bivalves. Very fine and cohesive sediment (mud) tends to have a lower species diversity, because oxygen cannot penetrate far below the sediment surface. A black, anoxic layer of sediment develops under these circumstances, which may extend to the sediment surface and in which few species can survive. Some intertidal sediments are dominated by angiosperms, e.g. eelgrass ([Zostera noltii]) beds on the mid and upper shore of muddy sand flats, or saltmarshes which develop on the extreme upper shore of sheltered fine sediment flats.

Situation: Littoral sediments are found across the entire intertidal zone, including the strandline. Sediment biotopes can extend further landwards (dune systems, marshes) and further seawards (sublittoral sediments). Sediment shores are generally found along relatively more sheltered stretches of coast compared to rocky shores. Muddy shores or muddy sand shores occur mainly in very sheltered inlets and along estuaries, where wave exposure is low enough to allow fine sediments to settle. Sandy shores and coarser sediment (gravel, pebbles, cobbles) shores are found in areas subject to higher wave exposures.

Temporal variation: Littoral sediment environments can change markedly over seasonal cycles, with sediment being eroded during winter storms and accreted during calmer summer months. The particle size structure of the sediment may change from finer to coarser during winter months, as finer sediment gets resuspended in seasonal exposed conditions. This may affect the sediment infauna, with some species only present in summer when sediments are more stable. These changes are most likely to affect sandy shores on relatively open shores. Sheltered muddy shores are likely to be more stable throughout the year, but may have a seasonal cover of green seaweeds during the summer period, particularly in nutrient enriched areas or where there is freshwater input.


HabitatDescription:
Littoral coarse sediments include shores of mobile pebbles, cobbles and gravel, sometimes with varying amounts of coarse sand. The sediment is highly mobile and subject to high degrees of drying between tides. As a result, few species are able to survive in this environment. Beaches of mobile cobbles and pebbles tend to be devoid of macroinfauna, while gravelly shores may support limited numbers of crustaceans, such as [Pectenogammarus planicrurus].

Situation: Littoral coarse sediments are found along relatively exposed open shores, where wave action prevents finer sediments from settling. Coarse sediments may also be present on the upper parts of shores where there are more stable, sandy biotopes on the lower and mid shore.

Temporal variation: The sediment particle size structure may vary seasonally, with relatively finer sediments able to settle during calmer conditions in summer. Where the sediment grain size is very large (at the interface between sediment and boulder shores), cobbles may be mobile during exposed winter conditions, but stable enough during summer months to support limited juvenile rocky shore epifauna (e.g. juvenile barnacles).


HabitatDescription:
Shores of shingle (mobile cobbles and pebbles) or coarse gravel, typically deposited as a result of onshore wave action and long-shore drift. The particle size tends to increase along the shore in the direction of the long-shore drift. As the sediment is very coarse and often quite mobile, it typically supports little marine life, other than opportunist amphipods and oligochaete worms. Summer growths of ephemeral green algae ([Enteromorpha] spp.) may develop.


HabitatDescription:
Shingle or gravel shores, typically with sediment particle size ranging from 4 - 256 mm, sometimes with some coarse sand mixed in. This biotope is normally only found on exposed open coasts in fully marine conditions. Such shores tend to support virtually no macrofauna in their very mobile and freely draining substratum. The few individuals that may be found are those washed into the habitat by the ebbing tide, including the occasional amphipod or small polychaete.

Situation: This unit often extends over the whole shore, sometimes extending into the subtidal zone. It may occur on the upper shore above A2.221, and in moderately exposed conditions, above unit A2.223 on the lower shore. Unit A2.211 may occur on the same shore as A2.111, where driftlines of algae and other debris accumulate on the upper shore.

Temporal variation: There may be a temporary cover of the green seaweeds [Enteromorpha] spp. or [Ulva] spp. during periods of stability in the summer.


HabitatName:
[Pectenogammarus planicrurus] in mid shore well-sorted gravel or coarse sand

HabitatDescription:
Shores of well-sorted gravel with a predominant particle size of 4.0 mm but ranging between 3 and 6 mm support dense populations of the amphipod [Pectenogammarus planicrurus]. Material finer than 2 mm reduces the ability of the amphipod to survive. The amphipod is tolerant of variable salinity, although a preference for a specific salinity regime has not been determined. As this habitat is regularly under-surveyed, its distribution is unclear.
Situation: The biotope is often associated with the lee side (wind or tide) of obstacles such as rock outcrops and groynes; this may be due to the deposition of algal debris, shelter from wave action or degree of sorting due to localised tidal flow around the obstacle (most likely a combination of the first and last influence).


HabitatDescription:
Shores of coarse sediments (shingle, gravels and coarse sand) in the upper reaches of estuaries and other inlets (e.g. sealochs) which are subject to variable and reduced salinity conditions. The outflow of riverine freshwater at the heads of the inlets results in the washing out of fine particulate matter, leaving coarse sediments. These are typically species-poor and characterised by oligochaete worms (cf. A2.222).


HabitatName:
Mediterranean communities of mediolittoral coarse detritic bottoms

HabitatDescription:
These biocenoses consist mainly of detritus-feeding species which draw their nourishment from decaying vegetation and miscellaneous debris caught up in the shingle. It is characterised by two crustaceans, the amphipod [Gammarus olivii] and the isopod [Sphaeroma serratum]. These communities are exposed to alternating water submersion and emersion because of variations in the water level, and they are frequently moistened by wavelets.


HabitatName:
Facies of banks of dead leaves of [Posidonia oceanica] and other phanerogams

HabitatDescription:
This facies is characterized by the accumulation of plant debris made up mostly of dead [Posidonia oceanica] leaves and/or other marine phanerogams species (e. g. [Cymodocea nodosa], [Zostera noltii], etc.)


HabitatDescription:
Shores comprising clean sands (coarse, medium or fine-grained) and muddy sands with up to 25% silt and clay fraction. Shells and stones may occasionally be present on the surface. The sand may be duned or rippled as a result of wave action or tidal currents. Littoral sands exhibit varying degrees of drying at low tide depending on the steepness of the shore, the sediment grade and the height on the shore. The more mobile sand shores are relatively impoverished (A2.22), with more species-rich communities of amphipods, polychaetes and, on the lower shore, bivalves developing with increasing stability in finer sand habitats (A2.23). Muddy sands (A2.24), the most stable within this habitat complex, contain the highest proportion of bivalves.

Situation: A strandline of talitrid amphipods (A2.211) typically develops at the top of the shore where decaying seaweed accumulates. Fully marine sandy shores occur along stretches of open coast, whilst muddy sands are often present in more sheltered lower estuarine conditions and may be subject to some freshwater influence.

Temporal variation: Littoral sandy shore environments can change markedly over seasonal cycles, with sediment being eroded during winter storms and accreted during calmer summer months. The particle size structure of the sediment may change from finer to coarser during winter months, as finer sediment gets resuspended in seasonal exposed conditions. This may affect the sediment infauna, with some species only present in summer when sediments are more stable. More sheltered muddy sand shores are likely to be more stable throughout the year, but may have a seasonal cover of green seaweeds during the summer period, particularly in nutrient enriched areas or where there is freshwater input.


HabitatDescription:
The strandline is the shifting line of decomposing seaweed and debris which is typically left behind on sediment (and some rocky shores) at the upper extreme of the intertidal at each high tide. These ephemeral bands of seaweed often shelter communities of sandhoppers. 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: Strandlines may occur in bands along the upper extreme of any sediment shore and some rocky shores.

Temporal variation: Strandlines tend to be mobile, as they consist of driftlines of decomposing seaweed and other debris, which will decompose, and be shifted by the tide. The amount of debris washed up on strandlines, and hence the extent of the strandline, may vary significantly depending on factors such as recent storms or high tides.


HabitatName:
Talitrids on the upper shore and strandline

HabitatDescription:
A community of sandhoppers (talitrid amphipods) may occur on any shore where driftlines of decomposing seaweed and other debris accumulate on the strandline. The biotope occurs most frequently on medium and fine sandy shores, but may also occur on a wide variety of sediment shores composed of muddy sediment, shingle and mixed substrata, or on rocky shores. The decaying seaweed provides cover and humidity for the sandhopper [Talitrus saltator]. In places on sand that regularly accumulate larger amounts of weed, [Talorchestia deshayesii] is often present. Oligochaetes, mainly enchytraeids, can occur where the stranded debris remains damp as a result of freshwater seepage across the shore or mass accumulation of weed in shaded situations. On shingle and gravel shores and behind saltmarshes the strandline talitrid species tend to be mainly [Orchestia] species. Abundances of the characterising species tend to be highly patchy. Two characterising species lists are presented below. They are derived from two sets of data, which were analysed separately. The first shows data from infaunal samples, the second shows data from epifaunal samples. The epifaunal lists contains no counts per square metre, as the data were collected on the SACFOR scale.

Situation: This unit may occur on the same shore as a range of sediment (especially sandy) biotopes, where driftlines of algae and other debris accumulate on the upper shore. These biotopes include units A2.111, A2.221, A2.222, A2.223, and A2.231. The biotope also occurs at the back of boulder, cobble and pebble shores, above mixed sediment and rocky biotopes.

Temporal variation: This biotope varies in its position between spring and neap tides, and as a result of changing weather. After storms, it may extend into the fore dunes, during spring tides it will occur high on the shore, and during neaps the greatest numbers of talitrids may be found at or just below MHWN level. The amount of debris washed up on strandlines, and hence the extent of this biotope, may also vary significantly depending on factors such as recent storms or high tides.


HabitatName:
[Mytilus edulis] and [Fabricia sabella] in littoral mixed sediment

HabitatDescription:
Pebbles, gravel, sand and shell debris with mud in sheltered Firths with a strandline of fucoid algae. The fauna is characterised by juvenile mussels [Mytilus edulis], often in very high numbers. The nemertean worm [Lineus] spp. may be abundant and oligochaetes are common. Polychaetes such as [Pygospio elegans], [Scoloplos armiger] and [Fabricia sabella] may be present in high densities. [Fabricia sabella] is typically found amongst algal holdfasts and between cobbles on rocky shores. The bivalves [Macoma balthica] and [Cerastoderma edule], typical of muddy sediments, characterise the community. The validity of this biotope is uncertain, as the only available data, from the Dornoch Firth and the Moray Firth, are poor. Its position within the classification, as a strandline community, is also very uncertain, but there is not enough information available for a better description or classification at this stage.
Situation: Occurs on sheltered shores of the Dornoch Firth and Moray Firth.


HabitatDescription:
Shores consisting of clean mobile sands (coarse, medium and some fine-grained), with little very fine sand, and no mud present. Shells and stones may occasionally be present on the surface. The sand may be duned or rippled as a result of wave action or tidal currents. The sands are non-cohesive, with low water retention, and thus subject to drying out between tides, especially on the upper shore and where the shore profile is steep. Most of these shores support a limited range of species, ranging from barren, highly mobile sands to more stable clean sands supporting communities of isopods, amphipods and a limited range of polychaetes. Species which can characterise mobile sand communities include [Scolelepis squamata], [Pontocrates arenarius], [Bathyporeia pelagica], [B. pilosa], [Haustorius arenarius] and [Eurydice pulchra].

Situation: Mobile sand shores are typically situated along open stretches of coastline, with a relatively high degree of wave exposure. Bands of gravel and shingle may be present on the upper shore of exposed beaches. Where the wave exposure is less, and the shore profile more shallow, mobile sand communities may also be present on the upper part of the shore, with more stable fine sand communities present lower down. A strandline of talitrid amphipods (A2.211) typically develops at the top of the shore where decaying seaweed accumulates.

Temporal variation: Mobile sand shores may show significant seasonal changes, with sediment accretion during calm summer periods and beach erosion during more stormy winter months. There may be a change in sediment particle size structure, with finer sediment grains washed out during winter months, leaving behind coarser sediments.


HabitatDescription:
Freely-draining sandy beaches, particularly on the upper and mid shore, which lack a macrofaunal community due to their continual mobility. Trial excavations are unlikely to reveal any macrofauna in these typically steep beaches on exposed coasts. Oligochaetes, probably mainly enchytraeids, and the isopod [Eurydice pulchra] may be found in extremely low abundances, but if present in any quantity should be classed as units A2.3223 or A2.2232. Burrowing amphipods ([Bathyporeia] spp.) may be present on very rare occasions. Occasionally, other species may be left behind in low abundance by the ebbing tide.
Situation: This unit may occur on the mid and/or lower shore below A2.111 in exposed conditions. In moderately exposed conditions, and where A2.221 occurs on the upper shore, a range of relatively more species-rich clean sand communities may occur on the mid and lower shore. These include A2.223, A2.222, and A2.231, depending on the degree of wave exposure and sediment mobility. Tal may occur on the same shore as A2.221, where driftlines of algae and other debris accumulate on the upper shore.


HabitatDescription:
A species-poor community of oligochaetes occurring in estuarine conditions where sands and gravel are associated with the lower shore river channel in estuaries. The sediment is relatively coarse and mobile due to strong river flow and subject to variable salinity. The biotope also occurs in fully marine conditions on open shores with mobile, medium to fine, usually clean, sand. Oligochaetes, including enchytraeid oligochaetes, constitute the infaunal assemblage. This biotope has been split into two sub-biotopes, based on the physical environment (a full-salinity and a variable salinity type).

Situation: This unit often occurs in variable salinity conditions, in channels of very fast flowing river mouths at the bottom of otherwise sheltered estuarine shores. In this situation, biotopes under the A2.31 and A2.32 biotope complexes may be present above the river channel. A2.222 also occurs on open, fully marine shores. Where it is situated on the mid shore, units A2.111 and/or A2.221 may be present on the upper shore, and lower down on the shore, A2.2231 and A2.2233 may be found. A2.222 may also occur on the upper shore, with A2.2232 present on the mid shore, and A2.2311 or A2.2312 on the lower shore. A2.211may be found on the upper shore where driftlines of wracks and debris accumulate.

Temporal variation: Wave exposure may be higher on some beaches during winter than during the summer months, leading to the disappearance of infaunal species in winter. Where this happens, the biotope may change to unit A2.221. If conditions become more sheltered, seasonally or permanently, the sediment may become colonised by a greater range of species and the area may change to A2.223.


HabitatDescription:
A species-poor community of oligochaetes occurring in fully marine conditions on open shores with mobile, medium to fine, usually clean, sand. Oligochaetes, including enchytraeid oligochaetes, constitute the infaunal assemblage. On rare occasions individuals of polychaete or crustacean species may be encountered (e.g. [Nephtys] spp., [Eurydice pulchra], [Bathyporeia] spp.), though these are not characterising for the biotope and if present in any significant abundance, the area should be classed as unit A2.223.

Situation: Where A2.2221 is situated on the mid shore, A2.111 and/or A2.221 may be present on the upper shore, and lower down on the shore, A2.2231 and A2.2233 may be found. A2.3223 may also occur on the upper shore, with A2.2232 present on the mid shore, and A2.2311 or A2.2312 on the lower shore. A2.211 may be found on the upper shore where driftlines of decomposing seaweed and other debris accumulate.

Temporal variation: Wave exposure may be higher on some beaches during winter than during the summer months, leading to the disappearance of infaunal species in winter. Where this happens, the biotope may change to A2.221. If conditions become more sheltered, seasonally or permanently, the sediment may become colonised by a greater range of species and the area may change to A2.223.


HabitatDescription:
A species-poor community of oligochaetes occurring in estuarine conditions where sands and gravel are associated with the lower shore river channel in estuaries. The sediment is relatively coarse and mobile due to strong river flow and subject to variable salinity. There is usually very little mud in the sediment. Oligochaetes, including enchytraeid oligochaetes, constitute the infaunal assemblage. Nemerteans may be present, and nematodes may be frequent.
Situation: This unit occurs in channels of very fast flowing river mouths at the bottom of otherwise sheltered estuarine shores. In this situation, biotopes under the A2.31 and A2.32 biotope complexes may be present above the river channel. Unit A2.211 may be found on the upper shore where driftlines of decomposing seaweed and other debris accumulate.


HabitatName:
Amphipods and [Scolelepis] spp. in littoral medium-fine sand

HabitatDescription:
Mobile clean sandy beaches on exposed and moderately exposed shores, with sediment grain sizes ranging from medium to fine, often with a fraction of coarser sediment. The sediment contains little or no organic matter, and usually no anoxic layer is present at all. It tends to be well-drained, retaining little water at low tide, though the sediment of the A2.2233 sub-unit may remain damp throughout the tidal cycle. These beaches usually occur under fully marine conditions, though the A2.2232 sub-unit may occur under moderately exposed lower estuarine conditions. The mobility of the sediment leads to a species-poor community, dominated by polychaetes, isopods and burrowing amphipods. [Scolelepis] spp. can tolerate well-drained conditions, and are often present in well-draining, coarser sand. Burrowing amphipods that often occur in this biotope include [Bathyporeia] spp., [Pontocrates arenarius], and [Haustorius arenarius]. The isopod [Eurydice pulchra] is also often present. On semi-exposed beaches with a moderate tide range where there is a marked high-shore berm, there can be a marked seepage at the foot of the berm that probably carries the products of the organic matter derived from strand line breakdown. Here in a narrow zone, exceptionally high populations of [Bathyporeia pilosa], sometimes above 10000 per square metre, may occur. The zone may be narrower than the strandline and could easily be missed on surveys were only a few levels are sampled. Three sub-biotopes are described for this biotope, based principally on differences in infaunal species composition.

Situation: Situated mainly on the mid and lower shore, sometimes upper shore, of exposed to moderately exposed beaches. Under more exposed conditions, it may occur below A2.221, or A2.111. Under more sheltered conditions, it may occur above the communities of unit A2.231. Unit A2.211 may be present on the same shores as A2.223, where driftlines of decomposing seaweed and other debris occur on the upper shore.

Temporal variation: Winter storms may reduce the number of or temporarily remove macroinvertebrates from exposed sandy beaches, with the sediment becoming re-colonised during the summer months.


HabitatName:
[Scolelepis] spp. in littoral mobile sand

HabitatDescription:
Exposed and moderately exposed shores of fully marine mobile clean sand, with particle sizes ranging from coarse to very fine. The sediment is not always well sorted, and may contain a subsurface layer of gravel or shell debris. Usually no anoxic layer is present. The mobility of the sediment leads to a species-poor community, dominated by the polychaetes [Scolelepis squamata] and [S. foliosa]. The amphipod [Bathyporeia pilosa] may be present. Further species that may be present in this sub-biotope include the amphipods [B. pelagica] and [Haustorius arenarius], and the isopod [Eurydice pulchra]. The lugworm [Arenicola marina] may also occur.

Situation: Situated mainly on the mid and lower shore, sometimes upper shore, of exposed to moderately exposed beaches. Under more exposed conditions, it may occur below A2.2232, A2.221, or A2.111, and on the same shores as A2.2233. Under more sheltered conditions, it may occur above the A2.231 communities. Unit A2.211may be present on the same shores, where driftlines of wrack and other debris occur on the upper shore.

Temporal variation: Winter storms may reduce the number of or temporarily remove macroinvertebrates from exposed sandy beaches, with the sediment becoming re-colonised during the summer months.


HabitatName:
[Eurydice pulchra] in littoral mobile sand

HabitatDescription:
Well-draining beaches of medium- to fine-grained mobile sand, often (but not always) well sorted. Occasionally, a small fraction of coarse sand may be present. The biotope generally occurs on exposed open coasts, but sometimes in estuarine conditions, supporting populations of the isopod [Eurydice pulchra] and burrowing amphipods which frequently include [Bathyporeia pilosa] and [Haustorius arenarius]. The degree of drainage appears to be a critical factor in determining the presence of polychaetes, with only [Scolelepis squamata] capable of tolerating the well-drained sediments of this biotope. This biotope has two facies: drying upper and mid shore sands, and highly mobile lower shore and shallow sublittoral sand bars. Where this biotope occurs in estuarine conditions, [H. arenarius] is often highly abundant.

Situation:This unit may occur on the mid and upper shore together with unit A2.2231, below A2.3223, or above A2.2233 and the A2.231 communities. Under more exposed, open conditions, this unit may be restricted to the lower part of the shore, with A2.3223, barren sand (A2.221) or barren shingle (A2.111) on the upper shore. Unit A2.211 may occur where driftlines of wracks or other debris accumulate on the upper shore.

Temporal variation: Winter storms may reduce the number of or temporarily remove macroinvertebrates from exposed sandy beaches, with the sediment becoming re-colonised during the summer months.


HabitatName:
[Pontocrates arenarius] in littoral mobile sand

HabitatDescription:
Mainly on the mid and lower shore on wave-exposed or moderately wave-exposed coasts of medium and fine sand, sometimes with a fraction of coarse sand, which remains damp throughout the tidal cycle and contains little organic matter. The sediment is often rippled and typically lacks an anoxic sub-surface layer. The infauna is dominated by burrowing amphipods, most notably [Pontocrates arenarius], as well as [Bathyporeia pelagica, Haustorius arenarius] and the isopod [Eurydice pulchra]. The polychaete fauna is poor, dominated by [Scolelepis squamata], which tolerates the exposed and mobile sediment conditions. The presence of polychaetes may be seen as coloured burrows running down from the surface of the sediment.

Situation: This biotope may be present on the lower shore, where units A2.221, A2.2232, or A2.2231 are present higher up. Where this unit occurs on the mid shore in relatively sheltered conditions, unit A2.231 may be present on the lower shore. Unit A2.211 may be present where driftlines of fucoids and other debris occur on the upper shore.

Temporal variation: This biotope may change to unit A2.2232, which is very similar in character, if [P. arenarius] decreases in abundance. Winter storms may reduce the number of or temporarily remove macroinvertebrates from exposed sandy beaches, with the sediment becoming re-colonised during the summer months.


HabitatDescription:
Shores of clean, medium to fine and very fine sand, with no coarse sand, gravel or mud present. Shells and stones may occasionally be present on the surface. The sand may be duned or rippled as a result of wave action or tidal currents. The degree of drying between tides is limited, and the sediment usually remains damp throughout the tidal cycle. Typically, no anoxic layer is present. Fine sand shores support a range of species including amphipods and polychaetes. On the lower shore, and where sediments are stable, bivalves such as [Angulus tenuis] may be present in large numbers. An exceptionally rich fine sand community has been recorded from very sheltered reduced salinity shores in Poole Harbour. Species recorded include [Anaitides maculata], [Hediste diversicolor], [Scoloplos armiger], [Pygospio elegans], [Tharyx killariensis], oligochaetes, [Gammarus locusta], [Hydrobia ulvae], [Cerastoderma edule] and [Mya truncata].

Situation: Fine sand communities may be present throughout the intertidal zone on moderately exposed beaches, or they may be present on the lower parts of the shore with mobile sand communities present along the upper shore. A strandline of talitrid amphipods (A2.211) typically develops at the top of the shore where decaying seaweed accumulates.

Temporal variation: Fine sand shores may show seasonal changes, with sediment accretion during calm summer periods and beach erosion during more stormy winter months. There may be a change in sediment particle size structure, with finer sediment grains washed out during winter months, leaving behind coarser sediments.


HabitatDescription:
Moderately exposed or sheltered beaches of medium and fine, usually clean, sand, though the sediment may on rare occasions contain a small silt and clay fraction. The sediment is relatively stable, remains damp throughout the tidal cycle, and contains little organic matter. It is often rippled and typically lacks an anoxic sub-surface layer. Where an anoxic layer is present, it occurs at a depth below 10 cm and tends to be patchy. The biotope occurs mainly on the lower part of the shore, and relatively frequently on the mid shore. It is only rarely present above mid shore level, except where coastal defences cause backwash onto the upper shore. Conditions are usually fully marine, though the biotope can also occur in open lower estuarine conditions. The infaunal community is dominated by a range of polychaete species such as [Nephtys cirrosa], [Paraonis fulgens], [Spio] spp., [Pygospio elegans], [Ophelia rathkei] and [Scoloplos armiger]. The presence of polychaetes may be seen as coloured burrows running down from the surface of the sediment, and [Arenicola marina] casts may be present on the sediment surface. The amphipods [Bathyporeia] spp. and [Pontocrates arenarius] frequently occur, and nemerteans are often present. On some North Wales shores, the presence of [Arenicola] species characterises the lowest part of the shore, with a range of species characteristic of the shallow sublittoral. These include sparsely distributed [Echinocardium], [Amphiura brachiata], [Ensis siliqua] and [Fabulina fabula]. This biotope is split into three sub-biotopes, between which there can be a large degree of overlap. The bivalve [Angulus tenuis] dominates the A2.2312 sub-biotope, which is characterised by slightly more stable and fine sediments than the other two sub-biotopes.

Situation: This unit may be present below the communities of units A2.223  or A2.2221 on moderately exposed shores. A2.221 may occur on the upper part of the shore if it is subject to drying in between tides. The strandline biotope A2.211 may be present on the same shore where driftlines of decomposing seaweed and other debris occur on the upper shore.

Temporal variation: The infauna of this biotope may be affected significantly by seasonal changes in degree of wave exposure. During stormy winters, the sediment may become de-stabilised, leading to the disappearance of some macroinfaunal species. The lugworm [A. marina] may be present occasionally, usually as a temporary recruitment and is likely to be washed out during storms.


HabitatDescription:
This biotope occurs mainly on the mid and lower shore of moderately wave-exposed coasts, with medium and fine clean sand which remains damp throughout the tidal cycle and contains little organic matter. The sediment is often rippled and typically lacks an anoxic sub-surface layer. Polychaetes make up the greater part of the community, and are dominated by [Paraonis fulgens], [Capitella capitata], [Pygospio elegans], [Ophelia rathkei] and [Eteone longa]. The presence of polychaetes may be seen as coloured burrows running down from the surface of the sediment. Nemerteans may also be present. The amphipods [Bathyporeia pilosa] and [B. sarsi] are often present.

Situation: This unit may be present higher up on the shore than unit A2.2312, or lower down than the A2.223 communities or A2.2221. The strandline community A2.211 may be present on the same shore where driftlines of decomposing seaweed and other debris occur on the upper shore.

Temporal variation: The infauna of this biotope may be reduced during winter, as increased storminess and wave action increases sediment mobility and may lead to some species migrating or being washed out of the sediment. The lugworm [Arenicola marina] may be present occasionally, usually as a temporary recruitment and is likely to be washed out during storms.


HabitatName:
Polychaetes and [Angulus tenuis] in littoral fine sand

HabitatDescription:
This biotope occurs on the mid and lower shore on moderately wave-exposed and sheltered coasts, with predominantly fine sand which remains damp throughout the tidal cycle. The sediment is often rippled, and an anoxic layer may occasionally occur below a depth of 10 cm, though it is often patchy. The infaunal community is dominated by the abundant bivalve [Angulus tenuis] together with a range of polychaetes. The presence of polychaetes may be seen as coloured burrows running down from the surface of the sediment. Polychaetes that are characterising for this biotope include [Nephtys cirrosa], [Paraonis fulgens] and [Spio filicornis]. Burrowing amphipods [Bathyporeia] spp. may occur in some samples of this biotope.

Situation: Where it occurs under moderately exposed conditions, units A2.2232, A2.2311 or A2.2221 may be present higher up on the shore than this unit. Where it occurs under more sheltered conditions, it may occur below or alongside muddy sand biotopes such as units A2.242 and A2.244.

Temporal variation: The infauna of this biotope may be reduced during winter, as increased storminess and wave action increases sediment mobility and may lead to some species migrating or being washed out of the sediment.


HabitatName:
[Nephtys cirrosa]-dominated littoral fine sand

HabitatDescription:
This biotope occurs mainly on the mid and lower shore on moderately wave-exposed and sheltered coasts, with medium to fine clean sand which remains damp throughout the tidal cycle and contains little organic matter. The sediment is not usually well sorted and may contain a fraction of coarse sand. It is often rippled and typically lacks an anoxic sub-surface layer. The polychaete infauna is dominated by [Nephtys cirrosa], [Magelona mirabilis], [Spio martinensis], [Spiophanes bombyx] and [Paraonis fulgens]. The presence of polychaetes may be seen as coloured burrows running down from the surface of the sediment. Nemertean worms may be present. The amphipods [Pontocrates] spp. and [Bathyporeia] spp., as well as [Cumopsis goodsiri] and the shrimp [Crangon crangon] are typically present. The bivalve [Angulus tenuis] is scarce or absent.

Situation: This unit may be present higher up on the shore than unit A2.2312, or lower down than A2.2232or A2.2221.

Temporal variation: The infaunal community of this biotope may change seasonally, as increased storminess during winter months may reduce sediment stability and the ability of some species to survive. Some species, such as the shrimp [C. crangon] avoid these conditions by seasonal migration to deeper water (Moore, 1991).


HabitatDescription:
Muddy sand or fine sand, often occurring as extensive intertidal flats on open coasts and in marine inlets. The sediment generally remains water-saturated during low water. The habitat may be subject to variable salinity conditions in marine inlets. An anoxic layer may be present below 5 cm of the sediment surface, sometimes seen in the worm casts on the surface. The infauna consists of a diverse range of amphipods, polychaetes, bivalves and gastropods.
Situation: Muddy sand communities are found predominantly on the mid and lower shore, though they may span the entire intertidal. Fine sand or mobile sand communities may be present on the upper shore with muddy sand communities present lower down. In sheltered mid estuarine conditions, muddy sand communities may be present on the upper part of the shore with mid estuarine muddy shore communities (A2.31) lower down.


HabitatName:
[Macoma balthica] and [Arenicola marina] in muddy sand shores

HabitatDescription:
Muddy sand or fine sand, often occurring as extensive intertidal flats both on open coasts and in marine inlets. The sediment is often compacted, with a rippled surface, areas of standing water, and generally remains water-saturated during low water. Scattered stones, cobbles and boulders with attached fucoids may be present. An anoxic layer is usually present within 5cm of the sediment surface and is often visible in worm casts. The habitat may be subject to variable salinity conditions in marine inlets. The species assemblage is characterised by the lugworm [Arenicola marina] and the Baltic tellin [Macoma balthica]. The polychaetes [Scoloplos armiger] and [Pygospio elegans] are typically superabundant and common, respectively. Oligochaetes, probably mainly [Tubificoides benedii] and [T. pseudogaster], may be common, and the cockle [Cerastoderma edule] may be abundant.
Situation: This unit has broad transition areas with units A2.242 and A2.243, which tends to occur lower down on the shore.


HabitatName:
[Cerastoderma edule] and polychaetes in littoral muddy sand

HabitatDescription:
Extensive clean fine sand or muddy sand shores with abundant cockles [Cerastoderma edule]. The community consists of the polychaetes [Eteone longa], [Scoloplos armiger], [Pygospio elegans], [Spio filicornis] and [Capitella capitata], the crustaceans [Bathyporeia sarsi], [Bodotria arenosa arenosa] and [Crangon crangon], the spire shell [Hydrobia ulvae], as well as the cockle [C. edule] and the baltic tellin [Macoma balthica]. This biotope carries commercially viable stocks of [C. edule], and it is therefore possible to find areas of this habitat where the infauna may have been changed through recent cockle dredging. Cockle dredging can result in a reduced bivalve abundance and reduced densities of some polychaete species, including [P. elegans] (Moore, 1991). At the outer edges of large flats, there may be a zone between the cockle beds and more exposed sands, where there are fewer cockles and [B. sarsi] is the commoner species.

Situation: The community is found mainly on the mid and lower shore where the sediment is water-saturated most of the time. Where it occurs in muddy sand, this unit has broad transition areas with units A2.241 and the A2.31, and where it occurs on clean sand shores, it may have broad transition areas with A2.7212. Higher on the shore, adjacent to this biotope, BatCare is found, with fewer polychaete and bivalve species due to the drier sediment found on the upper shore.

Temporal variation: A layer of mud with dense spionid polychaetes may build up on cockle beds in sheltered areas, creating a cohesive muddy layer 10-15 cm thick overlying the whole area. This may break up leaving a series of pits and patches with miniature cliffs, giving it an appearance similar to a stony shore when seen from a distance. It should be noted that where it occurs, [Hydrobia ulvae] tends to move a lot and may be highly variable in abundance.


HabitatName:
[Hediste diversicolor], [Macoma balthica] and [Eteone longa] in littoral muddy sand

HabitatDescription:
Fine to very fine muddy sand on the mid shore at the lower extreme of estuaries, and in moderately exposed and sheltered bays and marine inlets, sometimes subject to variable salinity. The infauna is characterised by the polychaetes [Eteone longa], [Hediste diversicolor] (ragworm) and [Pygospio elegans], oligochaetes (mostly [Tubificoides benedii] and [T. pseudogaster]), the crustaceans [Corophium volutator] and [Crangon crangon], the spire shell [Hydrobia ulvae] and the baltic tellin [Macoma balthica]. The cockle [Cerastoderma edule] may be abundant, and the sand gaper [Mya arenaria] may be superabundant, though these species are not always present, or may be missed in core samples due to their large size. The polychaetes [Arenicola marina], [Polydora cornuta] and [Capitella capitata], the shrimp [Crangon crangon], and the Mussel [Mytilus edulis] are sometimes present.

Situation: This unit can occur on the mid shore of sheltered, lower estuaries, with the A2.31 communities in muddier sediments on the lower shore. Under moderately exposed conditions in lower estuaries and towards open coasts, it may occur alongside other muddy sand units such as A2.242 or A2.244.

Temporal variation: [Enteromorpha] spp. or [Ulva lactuca] may form mats on the surface of the sediment during the summer months, particularly in areas of freshwater influence and/or where there is nutrient enrichment.


HabitatName:
[Bathyporeia pilosa] and [Corophium arenarium] in littoral muddy sand

HabitatDescription:
Wave-sheltered, mainly upper and mid shore flats of medium to fine sand, often muddy sand. The salinity, although predominantly recorded as variable, probably varies little from fully marine in these broad estuaries. The infauna is characterised by the amphipods [Bathyporeia pilosa], [Corophium arenarium] and [C. volutator], and the spire shell [Hydrobia ulvae]. Polychaetes and bivalves are limited in their abundance and variety, though the Baltic tellin [Macoma balthica] may occur. Tidal streams may be strong during spring tides, accounting for the presence of amphipods [B. pilosa] that are more commonly associated with open coast sandflats.

Situation: This biotope is typically found higher up the shore than sandflats with the cockle [Cerastoderma edule] (unit A2.242) in the large sandy estuaries of the west coast of England and Wales. In moderately exposed conditions,  can occur on the mid shore below units A2.211and/or A2.221. In more sheltered conditions,  may occur above unit A2.311.


HabitatDescription:
This biotope usually occurs on flats of medium fine sand and muddy sand, most often on the lower shore but sometimes also on waterlogged mid shores. The sand may contain a proportion of shell fragments or gravel. Lan can also occur on the lower part of predominantly rocky or boulder shores, where patches of sand or muddy sand occur between scattered boulders, cobbles and pebbles. Conditions may be tide-swept, and the sediment may be mobile, but the biotope usually occurs in areas sheltered from strong wave action. The sediment supports dense populations of the sand mason [Lanice conchilega]. Other polychaetes present are tolerant of sand scour or mobility of the sediment surface layers and include the polychaetes [Anaitides mucosa], [Eumida sanguinea], [Nephtys hombergii], [Scoloplos armiger], [Aricidea minuta], [Tharyx] spp. and [Pygospio elegans]. The mud shrimp [Corophium arenarium] and the cockle [Cerastoderma edule] may be abundant. The baltic tellin [Macoma balthica] may be present. On boulder shores, and where pebbles and cobbles are mixed in with lower shore tide-swept sand with dense [L. conchilega] between the cobbles, the infaunal component is rarely sampled. The infaunal community under these circumstances, provided that the cobbles are not packed very close together, is likely to be similar to that in areas without the coarse material.

Situation:This unit occurs mainly on the mid and lower shore of moderately exposed sand and muddy sand flats. Higher on the shore, other sand and muddy sand biotopes may be present, such as units A2.221 and A2.223 on the upper shore and the A2.231 communities on the mid shore. Unit A2.211 may occur where driftlines of wracks and other debris accumulate. Where Lan occurs on areas of scattered boulders and cobbles on the lower shore, there may be broad transition areas with A2.711 and other boulder shore biotopes.

Temporal variation: Where [Lanice conchilega] becomes very abundant, especially on the low shore, this can lead to the build up of sediment mounds around their tubes, thus leading to a significant alteration in the surface appearance of the biotope.


HabitatName:
Mediterranean and Pontic communities of mediolittoral sands

HabitatDescription:
Mediolittoral sands are characterised by the annelids [Ophelia radiata] and [Nerine cirratulus], the isopod crustacean [Eurydice affinis] and the pelecypod mollusc [Mesodesma corneum]. Coarse sands encourage the settlement of [Ophelia radiata], and fine sands that of [Nerine cirratulus], while [Mesodesma corneum] often avoids calcareous sands.


HabitatDescription:
This facies of the mediolittoral sands is characterised by the abundance of the annelid polychaete [Ophelia bicornis]. In the Black Sea this facies is characterised by the predominant presence of [Ophelia bicornis] and a minor amount of [Donacilla cornea] and other amphipods present in mediolittoral coarse sands.


HabitatName:
Strictly Pontic communities of mediolittoral sands


HabitatName:
[Donacilla cornea] in medium-coarse mediolittoral sands

HabitatDescription:
This facies is characterised by the predominance of Donacilla with respect to Ophelia bicornis and more medium grained sand with respect to the Ophelia bicornis facies.


HabitatName:
[Pontogammarus maeoticus] in fine mediolittoral sands

HabitatDescription:
A mediolittoral sand facies found in proximity of the Danube delta and extending until Tendrovska Bay.


HabitatDescription:
Shores of fine particulate sediment, mostly in the silt and clay fraction (particle size less than 0.063 mm in diameter), though sandy mud may contain up to 40% sand (mostly very fine and fine sand). Littoral mud typically forms extensive mudflats, though dry compacted mud can form steep and even vertical structures, particularly at the top of the shore adjacent to saltmarshes. Little oxygen penetrates these cohesive sediments, and an anoxic layer is often present within millimetres of the sediment surface. Littoral mud can support communities characterised by polychaetes, bivalves and oligochaetes. Most muddy shores are subject to some freshwater influence, as most of them occur along the shores of estuaries. Mudflats on sheltered lower estuarine shores can support a rich infauna, whereas muddy shores at the extreme upper end of estuaries and which are subject to very low salinity often support very little infauna.

Situation: Muddy shores are principally found along the shores of estuaries where there is enough shelter from wave action to allow fine sediment to settle. Muddy shores may also be present in sheltered inlets, straits and embayments which are not part of major estuarine systems.

Temporal variation: [Enteromorpha] spp. and [Ulva lactuca] may form mats on the surface of the mud during the summer months, particularly in areas of nutrient enrichment or where there is significant freshwater influence.


HabitatName:
Polychaete/bivalve-dominated mid estuarine mud shores

HabitatDescription:
Mid estuarine shores of fine sediment, mostly in the silt and clay fraction (particle size less than 0.063 mm in diameter), though sandy mud may contain up to 40% sand (mostly very fine and fine sand). Littoral mud typically forms extensive mudflats, though dry compacted mud can form steep and even vertical structures, particularly at the top of the shore adjacent to saltmarshes. Little oxygen penetrates these cohesive sediments, and an anoxic layer is often present within millimetres of the sediment surface. Most mid estuarine muddy shores are subject to some freshwater influence, though at some locations more or less fully marine conditions may prevail. Mid estuarine muds support rich communities characterised by polychaetes, bivalves and oligochaetes.

Situation: Principally along mid estuarine shores. The mid estuarine communities may also be present in sheltered inlets, straits and embayments which are not part of major estuarine systems, though usually there is some freshwater influence.

Temporal variation: [Enteromorpha] spp. and [Ulva lactuca] may form mats on the surface of the mud during the summer months, particularly in areas of nutrient enrichment or where there is significant freshwater influence.


HabitatName:
[Nephtys hombergii], [Macoma balthica] and [Streblospio shrubsolii] in littoral sandy mud

HabitatDescription:
Soft mud with a fine sand fraction, in variable salinity conditions, typically close to the head of estuaries. The infauna is dominated by the polychaete worm [Streblospio shrubsolii], the polychaete [Nephtys hombergii], oligochaetes of the genus [Tubificoides], and the Baltic tellin [Macoma balthica]. The ragworm [Hediste diversicolor] and the spire shell [Hydrobia ulvae] are often common or abundant.

Situation: This unit occurs in mid estuary conditions, usually on the low shore. Units A2.323 and A2.3223 may occur higher up the shore, as well as further towards the upper estuary.

Temporal variation: [Enteromorpha] spp. and [Ulva lactuca] may form mats on the surface of the mud during the summer months, particularly in areas of nutrient enrichment.


HabitatName:
[Hediste diversicolor] and [Macoma balthica] in littoral sandy mud

HabitatDescription:
Mainly mid and lower shore sandy mud or mud in lower estuaries, sheltered bays and marine inlets, often subject to variable salinity. The main characterising species are the ragworm [Hediste diversicolor], the baltic tellin [Macoma balthica], and the oligochaetes [Tubificoides benedii] and [T. pseudogaster]. Further polychaetes that are often common or abundant include [Pygospio elegans], [Streblospio shrubsolii], [Tharyx killariensis], [Aphelochaeta marioni], [Capitella capitata] and [Manayunkia aestuarina]. The oligochaete [Heterochaeta costata] and the mud shrimp [Corophium volutator] may be abundant. The spire shell [Hydrobia ulvae] is often common. Other species which occur in a significant proportion of samples include the polychaetes [Eteone longa] and [Nephtys hombergii], and bivalves such as the cockle [Cerastoderma edule] and [Abra tenuis]. The sand gaper [Mya arenaria] is superabundant in about a quarter of the samples for this biotope. [M. arenaria] is probably present in a higher proportion of areas of this biotope, but may be missed in core samples due to its size.

Situation: This unit may occur on the mid/lower shore of lower estuarine shores, with units A2.243 or A2.241 on the upper shore. A2.313, A2.3221, NhomAph, and A2.3222 may be present on the same shore.

Temporal variation: [Enteromorpha] spp. and [Ulva lactuca] may form mats on the surface of the mud during the summer months, particularly in areas of nutrient enrichmnent.


HabitatName:
[Hediste diversicolor], [Macoma balthica] and [Scrobicularia plana] in littoral sandy mud

HabitatDescription:
Mainly mid shore mud or sandy mud subject to variable salinity on sheltered estuarine shores. Typically, the sediment is wet in appearance and has an anoxic layer below 1 cm depth. The surface of the mud has the distinctive 'crow's foot' pattern formed by the peppery furrow shell [Scrobicularia plana]. The infauna is additionally characterised by a range of polychaete and bivalve species, including the ragworm [Hediste diversicolor], [Pygospio elegans], [Streblospio shrubsolii], [Tharyx killariensis] and the baltic tellin [Macoma balthica]. Oligochaetes, most notably [Tubificoides benedii], and the spire shell [Hydrobia ulvae] may be abundant. Other species that sometimes occur in this biotope are the cockle [Cerastoderma edule], the sand gaper [Mya arenaria] and the polychaetes [Eteone longa] and [Nephtys hombergii].

Situation: This unit may occur on the same shores as units A2.311, A2.312, NhomAph, A2.3221 and A2.3222. Higher up on the shore, and/or further towards the head of the estuary, A2.3223 may occur, changing to A2.323 at the upper extreme of the estuary.

Temporal variation: [Enteromorpha] spp. and [Ulva lactuca] may form mats on the surface of the mud during the summer months, particularly in areas of nutrient enrichment.


HabitatName:
Polychaete/oligochaete-dominated upper estuarine mud shores

HabitatDescription:
Upper estuarine sandy mud and mud shores, in areas with significant freshwater influence. Littoral mud typically forms mudflats, though dry compacted mud can form steep and even vertical structures, particularly at the top of the shore adjacent to saltmarshes. Little oxygen penetrates these cohesive sediments, and an anoxic layer is often present within millimetres of the sediment surface. The upper estuarine mud communities support few infaunal species and are principally characterised by a restricted range of polychaetes and oligochaetes.

Situation: There are three oligochaete dominated upper estuarine mud biotopes. Of these three, A2.321 occurs the furthest towards the mid estuary, and possibly lower on the shore than the other two. A2.323 is the most extreme upper estuarine biotope, occurring at the head of estuaries where there is no strong river flow and hence conditions are very sheltered, and there is a very strong freshwater influence. Further towards the mid estuary, this biotope may occur at the top of the shore, with A2.3223 and A2.321 further down the shore.

Temporal variation: [Enteromorpha] spp. and [Ulva lactuca] may form mats on the surface of the mud during the summer months, particularly in areas of nutrient enrichment.


HabitatName:
[Nephtys hombergii] and [Streblospio shrubsolii] in littoral mud

HabitatDescription:
Soft wet mud with a fine sand fraction, on the mid and lower shore of sheltered estuaries, usually with an anoxic layer present within the first 5 cm of the sediment. The infauna is relatively poor, dominated by the polychaetes [Nephtys hombergii], [Streblospio shrubsolii], and [Aphelochaeta marioni]. The oligochaete [Tubificoides benedii] is also characterising for this biotope, and [Hediste diversicolor] may be common.

Situation: This unit  may occur on the same shores as the A2.31 biotopes, A2.3222 or A2.3221. Higher up on the shore, and/or further towards the head of the estuary, A2.3223 may occur, changing to A2.323 at the upper extreme of the estuary.

Temporal variation: [Enteromorpha] spp. and [Ulva lactuca] may form mats on the surface of the mud during the summer months, particularly in areas of nutrient enrichment.


HabitatDescription:
Mud and sandy mud shores in sheltered marine inlets and estuaries subject to variable or reduced salinity. The biotope is typically found on the mid and lower shores in the upper and mid estuary. If present on the upper shore, the sediment may become firm and compacted as water drains out, though usually the biotope occurs lower on the shore and the sediment remains water saturated during low tide. An anoxic layer occurs within the upper 5 cm of the sediment. The infauna is dominated by abundant or superabundant ragworms [Hediste diversicolor]. Other species that occur in a significant number of samples include oligochaetes such as [Heterochaeta costata] and [Tubificoides] spp., polychaetes such as [Streblospio shrubsolii] and [Manayunkia aestuarina], the mud shrimp [Corophium volutator], and the spire shell [Hydrobia ulvae].

Situation: This unit  may occur on the same shores as units A2.312, A2.313r, or NhomAph. Higher up on the shore, and/or further towards the upper extreme of the estuary, A2.323 may occur.

Temporal variation: [Enteromorpha] spp. and [Ulva lactuca] may form mats on the surface of the sediment during the summer months, particularly in areas of freshwater influence and/or where there is nutrient enrichment.


HabitatName:
[Hediste diversicolor] and [Streblospio shrubsolii] in littoral sandy mud

HabitatDescription:
Mud and sandy mud shores in sheltered marine inlets and estuaries subject to variable or reduced salinity. The biotope is typically found on the mid and lower shores and is often associated with shallow layers of cobbles and pebbles in the sediment in the upper and mid estuary. The sediment is anoxic close to the surface and remains water saturated during low tide. The infaunal polychaete community is dominated by dense [Hediste diversicolor], as well as species with a limited salinity range tolerance such as [Streblospio shrubsolii] and [Manayunkia aestuarina]. Oligochaetes, including [Heterochaeta costata] and [Tubificoides benedii] are often abundant, and the amphipod [Corophium volutator] is often common.

Situation: This unit may occur on the same shores as A2.313, A2.312, NhomAph or A2.3222. Higher up on the shore, and/or further towards the head of the estuary, A2.3223 may occur, changing to Tben at the upper extreme of the estuary.

Temporal variation: [Enteromorpha] spp. or [Ulva lactuca] may form mats on the surface of the sediment during the summer months, particularly in areas of freshwater influence and/or where there is nutrient enrichment.


HabitatName:
[Hediste diversicolor] and [Corophium volutator] in littoral mud

HabitatDescription:
Sheltered estuarine shores of sandy mud, which may become firm and compacted if present in the upper shore where there is more time for drainage between high tides. An anoxic layer is usually present within the first 5 cm of the sediment. The infauna is very sparse, usually only the ragworm [Hediste diversicolor] and the amphipod [Corophium volutator] are present in any abundance. Occasionally, oligochaetes or the spire shell [Hydrobia ulvae] may be present. [Corophium multisetosum] may also be found. There may be organic pollution of the sediment.

Situation: This unit may occur on the same shores as units A2.313, A2.312, NhomAph, and A2.3221. Higher up on the shore, and/or further towards the head of the estuary, A2.3223 may occur, changing to A2.323 at the upper extreme of the estuary.

Temporal variation: [Enteromorpha] spp. or [Ulva lactuca] may form mats on the surface of the sediment during the summer months, particularly in areas of freshwater influence and/or where there is nutrient enrichment.


HabitatName:
[Hediste diversicolor] and oligochaetes in littoral mud

HabitatDescription:
A species-poor community found in mud or slightly sandy mud in low salinity conditions, typically at the head of estuaries. The infauna is dominated by the ragworm [Hediste diversicolor] which is typically superabundant. Oligochaetes, including tubificids and [Heterochaeta costata], can be abundant, as well as spionids. The peppery furrow shell [Scrobicularia plana] may be present in low abundances. The mud is often very soft and fluid, with a 'wet' surface appearance, or it may be compacted and form steep banks in the upper parts of macro-tidal estuaries and along saltmarsh creeks.

Situation: There are three oligochaete dominated upper estuarine mud biotopes. A2.323 is the most extreme upper estuarine biotope, occurring at the head of estuaries where there is a very strong freshwater influence. Further towards the mid estuary, this biotope may occur at the top of the shore, with A2.3223 further down. Unit A2.321 occurs furthest towards the mid estuary, or on the lower shore with A2.3223 and A2.323 higher up.

Temporal variation: [Enteromorpha] spp. or [Ulva lactuca] may form mats on the surface of the sediment during the summer months, particularly in areas of freshwater influence and/or where there is nutrient enrichment.


HabitatName:
[Tubificoides benedii] and other oligochaetes in littoral mud

HabitatDescription:
Extreme upper estuarine fine sandy mud, sometimes with a fine sand fraction, in very sheltered conditions and subject to reduced salinity. An anoxic layer is usually present within the upper 3 cm of the sediment. The infaunal community is extremely poor, consisting almost exclusively of oligochaetes, including [Tubificoides benedii] and, more rarely, [Heterochaeta costata]. The only polychaete species that may occur is [Capitella capitata], which may be common. The sediment may form steep banks in upper parts of macro-tidal estuaries or along saltmarsh creeks. [Vaucheria] species may form a film on the sediment surface along such creeks, and juvenile shore crabs [Carcinus maenas] may be common. At the very upper end of estuaries, the oligochaetes [Limnodrilus] spp. and [Tubifex tubifex] may be found.

Situation: There are three oligochaete dominated upper estuarine mud biotopes. This unit is the most extreme upper estuarine biotope, occurring at the head of estuaries where there is no strong river flow and hence conditions are very sheltered, and there is a very strong freshwater influence. Further towards the mid estuary, this biotope may occur at the top of the shore, with A2.3223 further down. Unit A2.321 occurs furthest towards the mid estuary, or on the lower shore with A2.3223 and A2.323 higher up.

Temporal variation: Green algae such as [Enteromorpha] spp. may form mats on the surface of the mud during the summer months.


HabitatDescription:
Proposed new unit. No description available.


HabitatName:
Pontic polychaete dominated littoral muds


HabitatName:
Pontic oligochaete and chironomid dominated littoral muds


HabitatName:
Pontic "camca" habitat of River Danube mouths


HabitatDescription:
Proposed new level 4 habitat to account for fully marine habitats in the Waddensea and elsewhere.


HabitatDescription:
Shores of mixed sediments ranging from muds with gravel and sand components to mixed sediments with pebbles, gravels, sands and mud in more even proportions. By definition, mixed sediments are poorly sorted. Stable large cobbles or boulders may be present which support epibiota such as fucoids and green seaweeds more commonly found on rocky and boulder shores. Mixed sediments which are predominantly muddy tend to support infaunal communities which are similar to those of mud and sandy mud shores.
Situation: It is probable that there are broad transition areas between areas of mudflat or sandy mudflat, and mixed sediment biotopes where the sediment consists principally of mud but has significant proportions of gravel and sand mixed in. Gravelly mud may occur in patches on mudflats. Similarly, there is unlikely to be an easily defined boundary between areas of mixed sediment with stable cobbles and boulders, and boulder fields which fall into the rocky shore category.


HabitatName:
Ragworm dominated gravelly sandy mud shores

HabitatDescription:
Sheltered gravelly sandy mud, subject to reduced salinity, mainly on the mid and lower shore. The infaunal community is dominated by abundant ragworms [Hediste diversicolor]. Other species of the infauna vary for the sub-biotopes described. They include polychaetes such as [Pygospio elegans], [Streblospio shrubsolii], and [Manayunkia aestuarina], oligochaetes such as [Heterochaeta costata] and [Tubificoides] spp., the mud shrimp [Corophium volutator], the spire shell [Hydrobia ulvae], the baltic tellin [Macoma balthica] and the peppery furrow shell [Scrobicularia plana]. Sub-biotopes described in A2.411 have equivalent communities in soft muddy sediments, but the sediment here is much firmer due to the gravel component. There are relatively few records in each sub-type, leading to uncertainty over the precise nature of the habitat, particularly regarding sediment type and salinity regime.
Situation: It is probable that there are broad transition areas between the sub-biotopes of A2.411, and the corresponding muddy sediment biotopes. The boundaries may be very indistinct, with the A2.411 groups present in patches of gravelly mud on areas of mudflat where the main biotopes are their corresponding mud or sandy mud biotopes. Given the small number of records for each of the sub-biotopes, their spatial distribution is still uncertain.


HabitatName:
[Hediste diversicolor] in littoral gravelly muddy sand and gravelly sandy mud

HabitatDescription:
Sheltered gravelly sandy mud, subject to reduced salinity, mainly on the mid and lower shore. The infaunal community is dominated by abundant ragworms [Hediste diversicolor]. Other species of the infauna vary for the sub-biotopes described. They include polychaetes such as [Pygospio elegans], [Streblospio shrubsolii], and [Manayunkia aestuarina], oligochaetes such as [Heterochaeta costata] and [Tubificoides] spp., the mud shrimp [Corophium volutator], the spire shell [Hydrobia ulvae], the baltic tellin [Macoma balthica] and the peppery furrow shell [Scrobicularia plana]. Sub-biotopes described as subunits of this unit have equivalent communities in soft muddy sediments, but the sediment here is much firmer due to the gravel component. There are relatively few records in each sub-type, leading to uncertainty over the precise nature of the habitat, particularly regarding sediment type and salinity regime.
Situation: It is probable that there are broad transition areas between the sub-biotopes of A2.411, and the corresponding muddy sediment biotopes. The boundaries may be very indistinct, with the A2.411 groups present in patches of gravelly mud on areas of mudflat where the main biotopes are their corresponding mud or sandy mud biotopes. Given the small number of records for each of the sub-biotopes, their spatial distribution is still uncertain.


HabitatName:
[Hediste diversicolor] and [Macoma balthica] in littoral gravelly mud

HabitatDescription:
Sheltered gravelly mud shores, subject to reduced salinity. The infaunal community consists of the ragworm [Hediste diversicolor], as well as the spire shell [Hydrobia ulvae] and the baltic tellin [Macoma balthica]. The presence of the gravel in the sediment is unlikely to have a large influence on the infaunal composition, which is driven mainly by the estuarine sandy mud conditions. Coarse material on the sediment surface may however enrich the biota with additional epifaunal species such as barnacles and algae. Given the low sample numbers for this biotope, more records are needed to confirm the characterising species list.
Situation: It is probable that there are broad transition areas between this biotope, and the corresponding muddy sediment biotope, unit A2.312. The boundaries may be very indistinct, with A2.4111 present in patches of gravelly mud on areas of mudflat, where the main biotope is A2.312. This biotope has been found alongside its mud equivalent in the Stour estuary.


HabitatName:
[Hediste diversicolor] and [Scrobicularia plana] in littoral gravelly mud

HabitatDescription:
Extremely sheltered gravelly mud on the mid and lower shore, containing little sand with occasional cobbles. The infaunal community includes the ragworm [Hediste diversicolor] and the peppery furrow shell [Scrobicularia plana], as well as a range of polychaetes, oligochaetes, and molluscs. Given the low sample numbers for this biotope, more records are needed to confirm the characterising species list.
Situation: It is probable that there are broad transition areas between this unit and the corresponding muddy sediment biotope A2.313. The boundaries may be very indistinct, with unit A2.4112 present in patches of gravelly mud on areas of mudflat, where the main biotope is A2.313.


HabitatName:
[Hediste diversicolor] and [Streblospio shrubsolii] in littoral gravelly sandy mud

HabitatDescription:
Extremely sheltered gravelly sandy mud, subject to variable salinity, on the mid and lower shore. The infaunal community consists of the ragworm [Hediste diversicolor], [Pygospio elegans], [Streblospio shrubsolii], and [Ampharete grubei], as well as oligochaetes and [Corophium volutator]. There are often low densities of [Scrobicularia plana]. Given the low sample numbers for this biotope, more records are needed to confirm the characterising species list.
Situation: It is probable that there are broad transition areas between this biotope and the corresponding muddy sediment biotope, unit A2.3221. The boundaries may be very indistinct, with A2.4112 present in patches of gravelly mud on areas of mudflat, where the main biotope is A2.3221. This biotope has been found along edges of tidal channels in the upper Stour estuary, below its equivalent mud biotope.


HabitatName:
[Hediste diversicolor], cirratulids and [Tubificoides] spp. in littoral gravelly sandy mud

HabitatDescription:
Sheltered gravelly sandy mud, subject to variable salinity. The infaunal community consists of the ragworm [Hediste diversicolor], [Pygospio elegans], [Streblospio shrubsolii], and cirratulid polychaetes such as [Tharyx killariensis]. Nematodes and oligochaetes occur, as well as the bivalve [Macoma balthica]. Given the low sample numbers for this biotope, more records are needed to confirm the characterising species list.
Situation: It is probable that there are broad transition areas between this biotope and the corresponding muddy sediment biotope unit A2.312. The boundaries may be very indistinct, with this unit present in patches of gravelly mud on areas of mudflat, where the main biotope is A2.312.


HabitatName:
[Hediste diversicolor] and [Corophium volutator] in littoral gravelly sandy mud

HabitatDescription:
Extremely sheltered gravelly sandy mud, subject to variable or reduced salinity. The infaunal community consists of the ragworm [Hediste diversicolor], [Streblospio shrubsolii], [Capitella capitata] and [Manayunkia aestuarina]. Oligochaetes and [Corophium volutator] are abundant. Given the low sample numbers for this biotope, more records are needed to confirm the characterising species list.
Situation: It is probable that there are broad transition areas between this biotope and the corresponding muddy sediment biotope A2.3222. The boundaries may be very indistinct, with this unit present in patches of gravelly mud on areas of mudflat, where the main biotope is A2.3222.


HabitatDescription:
Sheltered mixed sediments, usually subject to variable salinity conditions. The infauna is very diverse, dominated by a range of polychaetes including [Exogone naidina], [Sphaerosyllis taylori], [Pygospio elegans], [Chaetozone gibber], [Cirriformia tentaculata], [Aphelochaeta marioni], [Capitella capitata], [Mediomastus fragilis], and [Melinna palmata]. The oligochaete worms [Tubificoides benedii] and [T. pseudogaster] are abundant, as is the cockle [Cerastoderma edule]. A large range of amphipods may occur, including [Melita palmata], [Microprotopus maculatus], [Aora gracilis] and [Corophium volutator]. The bivalves [Abra alba] and [A. nitida] may occur. The barnacle [Elminius modestus] may be abundant where the sediment has stones on the surface.
Situation: Mid shore, lower shore, as extension of shallow sublittoral biotope.


HabitatName:
Cirratulids and [Cerastoderma edule] in littoral mixed sediment

HabitatDescription:
Sheltered mixed sediments, usually subject to variable salinity conditions. Banks of shell may be present. The infauna is very diverse, dominated by a range of polychaetes including [Exogone naidina], [Sphaerosyllis taylori], [Pygospio elegans], [Chaetozone gibber], [Cirriformia tentaculata], [Aphelochaeta marioni], [Capitella capitata], [Mediomastus fragilis], and [Melinna palmata]. The oligochaetes [Tubificoides benedii] and [T. pseudogaster] are abundant, as is the cockle [Cerastoderma edule]. A large range of amphipods may occur, including [Melita palmata], [Microprotopus maculatus], [Aora gracilis] and [Corophium volutator]. The bivalves [Abra alba] and [A. nitida] may occur. The barnacle [Elminius modestus] can be abundant where the sediment has stones on the surface. Epifaunal algae may occur attached to stable cobbles on the sediment surface.
Situation: Mid shore, lower shore, as extension of shallow sublittoral biotope.


HabitatDescription:
Eulittoral mixed substrata where the substratum is too mobile or disturbed to support a seaweed community (A2.431). 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 A2.82 as LR.FLR.Eph


HabitatName:
Barnacles and [Littorina] spp. on unstable eulittoral mixed substrata

HabitatDescription:
The eulittoral zone, particularly the mid shore zone, of sheltered to extremely sheltered mixed substrata shores is often characterised by flat banks or scards of cobbles and pebbles (on sediment) which are either too small or unstable to support a seaweed community. The boulders and larger cobbles are usually colonised by the barnacles [Semibalanus balanoides] or in areas with variable salinity [Elminius modestus] and often dense aggregations of the winkles [Littorina littorea] and [Littorina saxatilis] are present as well. Between the cobbles and pebbles the mussel [Mytilus edulis] occasionally occurs, but always at low abundance. Juvenile crabs [Carcinus maenas] and gammarids may occur between and underneath the pebbles and cobbles. Brown seaweeds are rare, although the wrack [Fucus vesiculosus] may occasionally occur on larger cobbles and small boulders in the mid and upper shore zones. Ephemeral green seaweeds such as [Enteromorpha intestinalis] may also be present. Shallow pools and patches of standing water may occur in low-lying areas and may contain amphipods and filamentous green seaweeds. Due to the unstable nature of the substratum the diversity and density of flora and fauna is characteristically low.
Situation: This biotope is found primarily on enclosed (estuarine) stony shores in wave-sheltered conditions (compare with unit A1.1133) and may be subject to variable levels of salinity. It is found predominately in the mid shore zone below or at the same level as the biotope dominated by ephemeral green seaweeds (A2.821). If it is found in the upper shore region it can be backed by salt marsh species such as [Salacornia] and [Spartina] sp. Below are biotopes dominated by the wracks [Fucus serratus] or [F. vesiculosus] (units A1.3152; A1.3132).


HabitatDescription:
Angiosperm-dominated stands of vegetation, occurring on the extreme upper shore of sheltered coasts and periodically covered by high tides. The vegetation develops on a variety of sandy and muddy sediment types and may have admixtures of coarser material. The character of the saltmarsh communities is affected by height up the shore, resulting in a zonation pattern related to the degree or frequency of immersion in seawater.


HabitatDescription:
The top level of saltmarsh, not covered by all tides. Vigorous [Atriplex] spp., [Beta vulgaris], [Elymus] spp., [Matricaria maritima] may be fertilized by drift decomposition.


HabitatName:
Atlantic saltmarsh and drift rough grass communities

HabitatDescription:
Nitrophilous tall grass communities of Atlantic saltmarshes, green beaches and beach drift accumulations, dominated by [Elymus pycnanthus] ([Agropyron pungens]), [Elymus repens], [Festuca arundinacea] or sometimes tall perennial forbs.


HabitatName:
Atlantic saltmarsh driftline annual communities

HabitatDescription:
Annual formations of pioneers colonizing driftlines forming within Atlantic saltmarshes, with [Atriplex littoralis], [Atriplex hastata], [Beta maritima], [Matricaria maritima].


HabitatDescription:
Communities of annuals forming on accumulations of organic debris in saltmarshes and saline depressions of the Mediterranean and thermo-Atlantic coasts and of endoreic (closed drainage) basins of the Mediterranean interior, in particular, of mediterranean Iberia, with [Atriplex hastata], [Suaeda splendens], [Suaeda maritima], [Bassia hirsuta], [Salsola soda], [Rumex pulcher].


HabitatName:
[Elymus pycnanthus] with [Suaeda vera] or [Inula crithmoides] saltmarsh driftlines


HabitatName:
[Suaeda vera] - [Limonium binervosum] saltmarsh driftlines


HabitatName:
[Spergularia marina] - [Puccinellia distans] saltmarsh driftlines


HabitatName:
[Frankenia laevis] - [Halimione portulacoides] saltmarsh driftlines


HabitatName:
[Sagina maritima] ephemeral salt marsh in sand


HabitatDescription:
Salt scrubs with [Arthrocnemum], [Halocnemum], [Suaeda]. Stands, sometimes rather open of [Juncus acutus], [Juncus maritimus]. Numerous other salt-tolerant species, some communities being quite species-rich.


HabitatName:
Atlantic and Baltic brackish saltmarsh communities

HabitatDescription:
Communities of saltmarshes of the Atlantic and its connected seas developed in areas of varying salinity and humidity, such as estuaries, in coastal basins with fresh water input and along brackish seashores, such as those of the inner Baltic.


HabitatDescription:
Communities of saltmarshes of the Atlantic, North Sea and Baltic coasts of Europe, from the Iberian peninsula to Scandinavia, developed in areas of varying salinity and humidity, in particular, in estuarine saltmarshes, in saltmarsh inner basins, in dike-enclsoed saltmarshes, with [Spergularia marina], [Puccinellia distans], [Puccinellia fasciculata], [Puccinellia retroflexa], [Puccinellia maritima], [Triglochin maritima], [Potentilla anserina] and [Halimione portulacoides].


HabitatDescription:
Formations of the brackish shores of the inner Baltic, dominated by [Carex paleacea], with [Eleocharis uniglumis] and [Agrostis stolonifera], accompanied by [Triglochin maritima].


HabitatDescription:
Communities of brackish lower shores of the northern and eastern Baltic dominated by [Carex mackenziei].


HabitatName:
Baltic salt basin [Agrostis]-[Triglochin] swards

HabitatDescription:
Baltic [Agrostis stolonifera]-[Triglochin palustris] formations of depressions submitted to marine salt precipitation.


HabitatDescription:
Communities of the lower levels of the brackish marshes of the Gulf of Bothnia, characteristic of exposed coasts, dominated by the endemic [Deschampsia cespitosa ssp. bottnica] ([Deschampsia bottnica]).


HabitatName:
Mediterranean [Juncus maritimus] and [Juncus acutus] saltmarshes

HabitatDescription:
Beds of tall [Juncus maritimus], [Juncus rigidus] ([Juncus maritimus var. arabicus], [Juncus arabicus]) or [Juncus acutus] of saline grounds of Mediterranean and thermo-Atlantic coastlands and of endoreic (closed drainage) interior basins of mediterranean Iberia and mediterranean North Africa, forming, in particular, in periodically inundated depressions , where they may associate with [Carex extensa], [Iris spuria], [Gladiolus communis], [Aster tripolium], [Sonchus maritimus], [Sonchus crassifolius] or other elements of units A2.523 and D6.23, and in sandy dunal depressions, where they may alternate with stands of [Schoenus nigricans] or other formations of unit A2.532.


HabitatName:
Mediterranean short [Juncus], [Carex], [Hordeum] and [Trifolium] saltmeadows

HabitatDescription:
Humid meadows of low vegetation dominated by [Juncus gerardi], [Carex divisa], [Carex extensa], [Schoenus nigricans], [Triglochin maritima], [Hordeum marinum] or [Trifolium] spp. and [Lotus] spp. of the edges of brackish lagoons of Mediterranean and thermo-Atlantic coasts of Europe, western Asia and North Africa.


HabitatName:
Mediterranean [Elymus] or [Artemisia] stands

HabitatDescription:
Formations of [Elymus] or [Artemisia] fringing Mediterranean and interior Iberian saline wetlands.


HabitatDescription:
Medium-tall [Juncus subulatus] beds, often forming facies within [Arthrocnemum] scrubs of Mediterranean and thermo-Atlantic coasts.


HabitatDescription:
Low shrubby expanses of woody glassworts, seablites, sea purslanes or [Halocnemum], characteristic of temporarily inundated saltmarshes of Mediterranean coasts, southwestern Iberian and northwestern African Atlantic coasts and interior Iberian basins. They can be further subdivided according to dominant species, generally associated with patterns of inundation. [Cistanche lutea] characterises many southern formations.


HabitatDescription:
Low shrubby carpets of prostrate [Arthrocnemum perenne] of wettest areas of coastal marshes of Mediterranean, southwestern Iberian and northwestern African Atlantic coasts.


HabitatDescription:
Stands of robust [Arthrocnemum fruticosum], capable of forming extensive low, dense thickets in coastal marshes of Mediterranean, southwestern Iberian and northwestern African Atlantic coasts.


HabitatDescription:
Shrubby formations of [Arthrocnemum glaucum]. Along northern Mediterranean shores, they often occupy somewhat drier sites such as shell banks in saline lagoons; in the North African coastal marshes of Cyrenaica, Tripolitana, Tunisia, Algeria and Morocco, they constitute the only [Arthrocnemum] formations.


HabitatDescription:
Shrubby formations of [Suaeda vera] occupying drier elevations of coastal saltmarshes of Mediterranean, southwestern Iberian and northwestern African Atlantic coasts.


HabitatDescription:
[Halimione portulacoides]-rich facies within [Arthrocnemum] communities of coastal saltmarshes of Mediterranean, southwestern Iberian and northwestern African Atlantic coasts.


HabitatDescription:
Salt scrubs of Mediterranean coastal saltmarshes dominated by [Halocnemum strobilaceum], characteristic of arid African coasts, with a few outposts on dry coasts of European peninsulas and islands.


HabitatDescription:
Sea purslane, glasswort and seablite scrubs of northern Atlantic and North Sea coasts.


HabitatDescription:
Shrubby [Halimione portulacoides] communities of middle levels of Atlantic schorres.


HabitatDescription:
[Arthrocnemum perenne]-dominated formations of the British Isles, the Atlantic coasts of France and of Iberia, except for the extreme southwest of the peninsula.


HabitatDescription:
[Suaeda vera]-dominated formations of the British Isles, where they are limited to the coast of Norfolk, and of the Atlantic coasts of France and of Iberia, except for the extreme southwest of the peninsula.


HabitatDescription:
[Arthrocnemum fruticosum]-dominated formations of the Atlantic coasts of France and of Iberia, except for the extreme southwest of the peninsula.


HabitatDescription:
Formations of often large, silver-glaucous shrubs of [Limoniastrum monopetalum] with showy pink flowers in late spring, of drier parts of Mediterranean and Iberian saltmarshes, distributed locally in North Africa, the Iberian peninsula, the southern Italian peninsula, western Sicily, Lampedusa, Sardinia and Crete.


HabitatDescription:
Low shrubby expanses of woody glassworts, seablites, sea purslanes or [Zygophyllum], characteristic of temporarily inundated saltmarshes of Canary Island coasts.


HabitatDescription:
Mediterranean humid grasslands dominated by [Juncus littoralis] and [J. maritimus] along the coast of the Black Sea, in particular in the Danube Delta.


HabitatName:
Mid-upper saltmarshes and saline and brackish reed, rush and sedge beds

HabitatDescription:
Closed saltmarsh meadows, more species-rich than in low-mid saltmarsh, dominated by graminoids [Blysmus rufus], [Carex extensa], [Festuca rubra], [Juncus gerardi], [Puccinellia] spp.; also [Armeria maritima], [Artemisia maritima], [Frankenia laevis]. Marine saline or brackish beds of [Hippuris tetraphylla], [Juncus maritimus], [Phragmites australis].


HabitatDescription:
Often relatively species-rich, grassy, flowery formations characteristic of the upper levels of the salt meadows of the Atlantic and its connected seas, with [Armeria maritima], [Glaux maritima], [Plantago maritima], [Frankenia laevis], [Artemisia maritima], [Festuca rubra], [Agrostis stolonifera], [Juncus gerardi], [Carex extensa], [Blysmus rufus], [Eleocharis] spp. Similar communities occupying the lower levels of brackish meadows, in particular of the Baltic, are included, while formations restricted to brackish conditions are listed under unit A2.521. The dominance of various species induces distinctive facies, the most important of which are individualised in subunits.


HabitatDescription:
Often species-rich, closed, flowery, upper level salt meadows of the Atlantic and its connected seas, dominated by, or rich in, [Juncus gerardi]. [Glaux maritima] can dominate facies, forming thick carpets, in particular, in pioneer situations.


HabitatDescription:
Communities of upper saltmarshes of the Atlantic, the North Sea and the Baltic, dominated by [Plantago maritima] or [Plantago maritima] and [Bupleurum tenuissimum].


HabitatName:
Atlantic [Festuca rubra]-[Agrostis stolonifera] swards

HabitatDescription:
Upper saltmarsh communities of the Atlantic and its connected seas dominated by, or rich in, [Festuca rubra] and [Agrostis stolonifera].


HabitatDescription:
Communities of salt meadows of the Atlantic and its connected seas dominated by, or rich in, [Armeria maritima].


HabitatDescription:
Communities of Atlantic salt meadows dominated by [Carex distans].


HabitatDescription:
Upper saltmarsh communities of the Atlantic and its connected seas dominated by, or rich in, [Carex extensa].


HabitatDescription:
Upper saltmarsh communities of the Atlantic and its connected seas dominated by, or rich in, [Limonium vulgare].


HabitatDescription:
Upper saltmarsh communities of the Atlantic and its connected seas dominated by, or rich in, [Blysmus rufus].


HabitatDescription:
Atlantic saltmarsh or brackish marsh communities dominated by [Eleocharis uniglumis] or [Eleocharis palustris], associated with [Agrostis stolonifera] or [Carex paleacea]. They constitute a common upper shore community in Scotland; they are also very prevalent on the lower levels of the brackish marshes of the Baltic, east and north of southeastern Sweden and Estonia; in western Scandinavia they are restricted to estuaries and fjord heads. They occur on saline littorals in Iceland.


HabitatDescription:
Saltmarsh communities of the Atlantic, the North Sea and the southern Baltic, dominated by, or rich in, [Juncus maritimus], with [Oenanthe lachenalii] and, locally, in Poland in particular, [Samolus valerandi], mostly characteristic of the upper shore, in moderately salty or brackish conditions, of the sandy-clayey transition to green beaches, also occurring, in the southern Baltic, on brackish lower shores.


HabitatDescription:
Atlantic saltmarsh communities dominated by, or rich in, [Artemisia maritima].


HabitatDescription:
Upper saltmarsh communities of the Atlantic and its connected seas dominated by, or rich in, [Potentilla anserina], including both [Potentilla anserina ssp. anserina], and, in Fennoscandia, Iceland and Greenland, [Potentilla anserina ssp. egedii].


HabitatDescription:
Atlantic upper saltmarsh communities of the English Channel and the Franco-Iberian coasts of the Atlantic, with an isolated station on Anglesey, dominated by, or rich in, [Frankenia laevis], associated with [Limonium] spp., in particular with [Limonium lychnidifolium] in France, or [Limonium vulgare] in southern England, characteristic of the sandy transition zone between saltmarshes and dunes.


HabitatDescription:
Atlantic upper schorre communities dominated by [Aster tripolium].


HabitatDescription:
Atlantic upper saltmarsh communities dominated by [Trifolium fragiferum].


HabitatDescription:
Atlantic upper saltmarsh communities dominated by [Carex nigra].


HabitatDescription:
Upper and middle saltmarsh communities of the Baltic and the northwest Atlantic, dominated by [Schoenus nigricans] or [Schoenus ferrugineus], with [Molinia caerulea] and [Campylium polygamum], developed on calcareous substrates.


HabitatDescription:
Upper shore swards of northern Norway, Iceland and the Faeroes dominated by [Agrostis stolonifera], [Festuca rubra], [Plantago maritima] and [Leontodon autumnalis].


HabitatDescription:
Upper saltmarsh tall graminoid communities of the Gulf of Bothnia and the northern Atlantic coasts of Scandinavia, south of Finnmark, dominated by [Calamagrostis stricta], [Carex aquatilis], [Carex juncella], [Eriophorum angustifolium], rich in arctic halophytes, transitional towards fens which form flood belts near fresh water. This unit is replaced northwards by the truly arctic formations of unit A2.533.


HabitatDescription:
Communities of the middle levels of exposed shores of the southern Baltic dominated by [Carex scandinavica] ([Carex serotina ssp. pulchella], "[Carex pulchellum]", [Carex oederi ssp. pulchella], [Carex viridula var. pulchella]), characteristic, in particular, of southeastern Sweden.


HabitatDescription:
Drier, dense formations of sandy soils at the foot of dunes, or between dunes and lagoons of the Mediterranean and thermo-Atlantic coasts of Europe and North Africa, and of the endoreic (closed drainage) interior basins of Mediterranean Iberia, with [Plantago crassifolia], [Schoenus nigricans], [Juncus littoralis], [Spartina versicolor] ([Spartina patens], [Spartina juncea]), [Elymus elongatus], [Inula crithmoides], all of which may dominate and form physiognomically distinct, sometimes almost monospecific, facies.


HabitatDescription:
Coastal saltmarshes of the upper shores of arctic Eurasia and Greenland submitted to winter sea ice.


HabitatDescription:
Communities of the arctic coasts of Eurasia developed in brackish water on sulphurous gleys, in particular, [Hippuris tetraphylla] beds of brackish shores of Finnmark and northern Iceland.


HabitatName:
[Juncus maritimus] mid-upper saltmarshes with [Triglochin maritima]


HabitatName:
Mid-upper saltmarshes: [Artemisia maritima] with [Festuca rubra], or open canopy of [Artemisia maritima] and [Halimione]


HabitatName:
Mid-upper saltmarshes: sub-communities of [Festuca rubra] with [Agrostis stolonifera], [Juncus gerardi], [Puccinellia maritima], [Glaux maritima], [Triglochin maritima], [Armeria maritima] and [Plantago maritima]


HabitatName:
Marine saline beds of [Phragmites australis]


HabitatName:
Geolittoral wetlands and meadows: reed, rush and sedge stands


HabitatName:
Geolittoral wetlands and meadows: reed, rush and sedge stands: natural stands


HabitatName:
Geolittoral wetlands and meadows: reed, rush and sedge stands: harvested stands


HabitatDescription:
Saltmarshes with more or less closed angiosperm vegetation. Included are grassy salt meadows dominated by [Puccinellia festuciformis] or [Aeluropus littoralis] in the Mediterranean and by [Puccinellia maritima] in northern Europe. Also characteristic are [Glaux maritima], [Halimone portulacoides], [Limonium vulgare], [Plantago maritima].


HabitatDescription:
Communities of the lower and middle schorre of the shores of the Atlantic ocean and connected seas with an overwhelming dominance of [Puccinellia maritima], often in almost monospecific stands forming bright green lawns characteristic, in particular, of pioneer stages of the lowest levels and of intensely grazed areas.


HabitatDescription:
Communities of the lower part of the coastal saltmarshes of the Atlantic and its connected seas codominated by [Puccinellia maritima] and other physiognomically important species.


HabitatDescription:
Communities of the lower part of the coastal saltmarshes of the Atlantic and its connected seas codominated by [Puccinellia maritima] and [Halimione portulacoides].


HabitatDescription:
Communities of the lower part of the coastal saltmarshes of the Atlantic and its connected seas codominated by [Puccinellia maritima] and [Aster tripolium].


HabitatDescription:
Communities of the lower part of the coastal saltmarshes of the Atlantic and its connected seas codominated by [Puccinellia maritima], annual [Salicornia] spp. and [Suaeda maritima].


HabitatDescription:
Formations dominated by the rare, threatened [Halimione pedunculata], developing very locally in the [Puccinellion maritimae] of Denmark, Germany, Poland, the Netherlands, Belgium and France, extinct in the British Isles.


HabitatDescription:
Species-poor salt meadows restricted to the shores of northern Norway and southwestern Iceland in the vicinity of the Reykjanes peninsula, codominated by [Puccinellia maritima] and the brown alga [Pelvetia canaliculata], accompanied by [Agrostis stolonifera].


HabitatDescription:
Salt meadows of Iceland and northern Norway, mostly of the lower shore, dominated by [Puccinellia maritima], with [Catabrosa aquatica], [Carex mackenziei], [Carex subspathacea], [Stellaria crassifolia], [Glaux maritima], [Gentianella detonsa].


HabitatDescription:
Communities of the lower part of the coastal saltmarshes of the Atlantic and its connected seas codominated by [Puccinellia maritima] and [Glaux maritima].


HabitatDescription:
Communities of the lower part of the coastal saltmarshes of the Atlantic and its connected seas codominated by [Puccinellia maritima] and [Plantago maritima].


HabitatDescription:
Communities of the lower part of the coastal saltmarshes of the Atlantic and its connected seas codominated by [Puccinellia maritima] and [Limonium vulgare], characteristic of undrained depressions on lightly grazed salt meadows of the Netherlands and the British Isles.


HabitatDescription:
Dense formations of perennial halophile grasses, in particular, [Puccinellia festuciformis] ([Puccinellia palustris]) or [Aeluropus littoralis], of Mediterranean coasts and their coastal lagoons.


HabitatDescription:
Species-poor communities of the lower shores of arctic Eurasia and Greenland, submitted to winter sea ice.


HabitatName:
Sub-communities of [Puccinellia maritima] saltmarsh with [Limonium vulgare] and [Armeria maritima]; [P. maritima] with [Glaux maritima] co-dominant in species-poor vegetation; [Puccinellia maritima] with [Plantago maritima] and/or [Armeria maritima]


HabitatName:
Annual [Salicornia], [Suaeda] and [Puccinellia maritima] low-mid saltmarshes


HabitatDescription:
Saltmarshes at the lowest level of non-aquatic angiosperms; vegetation open and very species-poor, typically with [Salicornia] spp. or [Spartina] spp., less often with [Arthrocnemum] spp., [Aster tripolium], [Sagina maritima], [Salsola kali] or [Suaeda] spp.


HabitatName:
[Salicornia], [Suaeda] and [Salsola] pioneer saltmarshes

HabitatDescription:
Annual glasswort ([Salicornia] spp., [Microcnemum coralloides]), seablite ([Suaeda] spp.), or sometimes saltwort ([Salsola] spp.), formations colonizing periodically inundated muds of coastal saltmarshes and inland salt-basins of the Palaearctic.


HabitatName:
Biocenosis of beaches with slowly-drying wracks under glassworts

HabitatDescription:
This biocoenosis is characterised by annual glassworts ([Salicornia] spp., [Microcnemum coralloides]), seablites ([Suaeda] spp.), or sometimes saltworts ([Salsola] spp.), formations colonizing periodically inundated muds of coastal saltmarshes and inland salt-basins of the Palaearctic.


HabitatDescription:
Mud, often consolidated with coarse sand or gravel, on the extreme upper shore with [Salicornia] spp. plants forming a pioneer saltmarsh community. This habitat typically occurs in very sheltered estuarine conditions. Usually a reduced marine fauna is present which may include the amphipod [Corophium volutator], the ragworm [Hediste (Nereis) diversicolor] and often the mud snail [Hydrobia ulvae]. The fucoid alga [Pelvetia canaliculata] may be found on hard substrata, consolidated mud or lying unattached. This community is equivalent to saltmarsh community SM8 in the British National Vegetation Classification.


HabitatDescription:
Endemic, threatened [Salicornia veneta] swards of long-inundated muds of basins of the Venice lagoon.


HabitatName:
Black Sea annual [Salicornia], [Suaeda] and [Salsola] saltmarshes

HabitatDescription:
Annual glasswort ([Salicornia] spp., [Microcnemum coralloides]), seablite ([Suaeda] spp.) and saltwort ([Salsola] spp.) solonchak formations, colonizing periodically inundated muds of Black Sea coastal saltmarshes and of inland salt-basins of central Eurasian and Irano-Anatolian steppe and cold desert zones. Annual glasswort communities of salt steppes and saltmarshes of areas of extreme continentality within the boreal zone of Siberia.


HabitatDescription:
Glasswort swards occupying long-inundated basins of coastal saltmarshes of the western Mediterranean basin, including those of Spain, southern continental France, the Gulf of Tarento, Corsica, Sardinia and Sicily, with Atlantic representatives in southwestern Europe, between southern Brittany and central Portugal, dominated by the reddening tetraploid glasswort [Salicornia emerici].


HabitatName:
Mediterranean coastal halo-nitrophilous pioneer communities

HabitatDescription:
Formations of halo-nitrophilous annuals ([Frankenia pulverulenta], [Suaeda splendens], [Salsola soda], [Cressa cretica], [Parapholis incurva], [Parapholis strigosa], [Hordeum marinum], [Sphenopus divaricatus], [Polypogon maritimus], [Spergularia] spp., [Vella annua]) colonizing salt muds of Mediterranean and thermo-Atlantic coastal regions, of Iberian and North African closed drainage basins, susceptible to temporary inundation and extreme drying; they are more species-rich or richer in non-Chenopodiaceae than the communities of unit A2.551; they are particularly developed in the Iberian peninsula, secondarily in the large Mediterranean islands, in coastal regions and endoreic basins of North Africa, in southern Italy and Mediterranean France; they occur as irradiations on thermo-Atlantic coasts, notably on the Atlantic coast of France.


HabitatDescription:
Formations of annual pioneers occupying sands subject to variable salinity and humidity, on the coasts, in the dunal systems and in the saltmarshes of the Atlantic, the North Sea and the Baltic. They are usually limited to small surfaces and best developed in the zone of contact between dune and saltmarsh. Characteristic species include [Sagina maritima], [Sagina nodosa], [Cochlearia danica], [Gentiana uliginosa], [Centaurium littorale], [Bupleurum tenuissimum].


HabitatDescription:
Perennial pioneer grasslands of coastal salt muds dominated by flat-leaved [Spartina maritima] ([Spartina stricta]), [Spartina townsendii], [Spartina anglica], [Spartina alterniflora], distributed along Atlantic and North Sea coasts of middle Europe north to Denmark and south to northwestern Iberia, with outposts on the Atlantic coast of Africa around Tangier, Rabat and Cap Blanc, extending east to the Danish archipelago and with isolated areas of occurrence in the Mediterranean basin, located in the northern Adriatic, in the Venice Lagoon and nearby coasts, from the mouth of the Po to Trieste and Slovenia, and in estuaries of the coasts of northwestern Africa.


HabitatName:
[Spartina alterniflora] with [Spartina anglica], [Puccinellia maritima] and [Aster tripolium]


HabitatDescription:
Perennial pioneer grasslands of southern Iberian coastal salt muds, dominated by the junciform-leaved [Spartina densiflora].


HabitatName:
Rayed [Aster tripolium] pioneer saltmarshes


HabitatName:
[Aster tripolium] var. [discoides] pioneer saltmarshes


HabitatName:
[Arthrocnemum perenne] pioneer saltmarshes, sometimes with [Halimione], [Puccinellia] and [Suaeda]


HabitatName:
Littoral sediments dominated by aquatic angiosperms

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


HabitatName:
Mainland Atlantic [Zostera noltii] or [Zostera angustifolia] meadows

HabitatDescription:
Formations of [Zostera noltii] or [Zostera angustifolia] of the Atlantic, North Sea and Baltic shores of continental Europe and of its continental shelf islands.


HabitatName:
[Zostera noltii] beds in littoral muddy sand

HabitatDescription:
Mid and upper shore wave-sheltered muddy fine sand or sandy mud with narrow-leafed eel grass [Zostera noltii] at an abundance of frequent or above. It should be noted that the presence of [Z. noltii] as scattered fronds does not change what is otherwise a muddy sand biotope. Exactly what determines the distribution of [Z. noltii] is not entirely clear. It is often found in small lagoons and pools, remaining permanently submerged, and on sediment shores where the muddiness of the sediment retains water and stops the roots from drying out. An anoxic layer is usually present below 5 cm sediment depth. The infaunal community is characterised by the polychaetes [Scoloplos armiger, Pygospio elegans] and [Arenicola marina], oligochaetes, the spire shell [Hydrobia ulvae], and the bivalves [Cerastoderma edule] and [Macoma balthica]. The green algae [Enteromorpha] spp. may be present on the sediment surface. The characterising species lists below give an indication both of the epibiota and of the sediment infauna that may be present in intertidal seagrass beds. The biotope is described in more detail in the British National Vegetation Classification (see the chapter on saltmarsh communities in Rodwell, 2000).

Situation: [Z. noltii]  is most frequently found on lower estuary and sheltered coastal muddy sands, together with biotopes such as unit A2.242.

Temporal variation: There may be seasonal variation in the area covered by intertidal seagrass beds, as plants die back during cold temperatures in winter. Intertidal seagrass beds may also be subject to heavy grazing by geese, which can reduce the extent of the plant cover significantly. The rhizomes of the plants will remain in place within the sediment in both situations.


HabitatDescription:
Very local [Zostera noltii] formations of Fuerteventura and Lanzarote.


HabitatName:
Pontic [Zostera marina] and [Zostera noltii] meadows

HabitatDescription:
[Zostera marina] and [Zostera noltii] formations of Black Sea shores, particularly luxuriant in the limans of the northern Black Sea and the Azov Sea. In the Black Sea, the dominant species of the [Zostera] biocenosis are [Zostera marina] and [Zostera noltii] (a total of 5 species of the genus [Zostera]) which form dense growths in bays and limans. There are 17-40 species of algae in the [Zostera] biocenosis which account for 1-30% of the phytocoenosis biomass. The most dominant of these species are: [Ulva rigida], [Chatemorpha chlorotica], [Ectocarpus confervoides], [Laurencia obtusa] and [Gracilaria verrucosa]. The total number of macrozoobenthos species varies from 24 in the Kut part of Karkinitsky Bay to 70 in Kazachey Bay (Sevastopol). In the areas with higher freshwater input, the biocoenosis contains the crabs [Macropipus holsatus] and [Rhithropanopeus harrisi tridentata], and the prawns [Palaemon adspersus] and [Palaemon elegans]. In Tendrovsky bay, other mass species are also: [Abra ovata] and Hydrobiidae. On the Crimean shelf the mass species are the gastropod molluscs [Mohrensternia parva], [Bittium reticulatum] and the bivalve mollusc [Mytilaster lineatus] (Zaitsev and Aleksandrov, 1998).


