Skip to Content

Marine Habitat Classification


6 results for 'SS.SCS.CCS.MedLumVen'

   SS.SCS.CCS.MedLumVen  Mediomastus fragilis, Lumbrineris spp. and venerid bivalves in circalittoral coarse sand or gravel

Circalittoral gravels, coarse to medium sands, and shell gravels, sometimes with a small amount of silt and generally in relatively deep water (generally over 15-20 m), 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 Spirobranchus lamarcki. In sand wave areas this biotope may also contain elements of the SS.SSa.IMuSa.FfabMag biotope, particularly Magelona species. This biotope has previously been described as the 'Deep Venus Community' and the 'Boreal Off-Shore Gravel Association' (Ford 1923; Jones 1950) and may also be part of the Venus community described by Thorson (1957) and in the infralittoral stage described by Glemarec (1973). SS.SCS.CCS.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). In the presence of pebbles, cobbles or shell, in coarse sandy gravel sediment, the biotope may support encrusting fauna such as hydroids, Sertularia cupressina and Hydrallmania falcata, bryozoa including Disporella hispida, Schizomavella spp., and Escharella immersa and encrusting polychaetes, Spirobranchus triqueter and instances of Sabellaria spinulosa. In the presence of these encrusting forms, and with the transition of sediment types to more tidally swept circalittoral mixed sediment, the biotope may form a transition to SS.SMx.CMx.FluHyd. Other variants in gravel, sands and stones in circalittoral waters, from records in the east English Channel, show this biotope may support high densities of polychaetes and copepods, Nematoda and Nemertea. The biotope may be represented in moderately exposed, shallower areas, with muddy mixed gravel or sand with shell sediments and maerl (Hapalidiaceae), supporting the characteristic fauna of Mediomastus and Hilbigneris gracilis, but absence of venerid bivalves. Furthermore, in impoverished variants of the biotopes, there may be a reduced component of Mediomastus and Hilbigneris gracilis.

   SS.SCS.CCS.Blan  Branchiostoma lanceolatum in circalittoral coarse sand with shell gravel

Gravel and coarse sand with shell gravel often contains communities of robust venerid bivalves (SS.SCS.CCS.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 the 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. Variants to this biotope may occur in deeper, circalittoral waters, with slightly muddy or gravelly sediments. These transitional forms of the biotope to muddier, or more gravelly sediments may be characterised by polychaetes such as Notomastus latericeus, and the amphipod Urothoe marina. 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 associated with the 'Venus fasciata' community of Cabioch (Glemarec 1973). This biotope may be an epibiotic overlay of the biotope SS.SCS.ICS.MoeVen or SS.SCS.CCS.MedLumVen.

   SS.SCS.OCS.GlapThyAmy  Glycera lapidum, Thyasira spp. and Amythasides macroglossus in offshore gravelly sand

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 Hilbigneris gracilis and occasional numbers of the bivalve Timoclea ovata. This biotope bears some resemblance to the shallow SS.SCS.ICS.Glap and to the circalittoral and offshore venerid biotopes (SS.SCS.CCS.MedLumVen and SS.SMx.OMx.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.

   SS.SCS.CCS.Nmix  Neopentadactyla mixta in circalittoral shell gravel or coarse sand

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 SS.SCS.CCS.MedLumVen.

   SS.SMx.CMx.FluHyd  Flustra foliacea and Hydrallmania falcata on tide-swept circalittoral mixed sediment

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 ramosa, occur where suitably stable hard substrata is found. The anemone Urticina felina and the soft coral Alcyonium digitatum may also characterise this biotope. Barnacles Balanus crenatus and tube worms Spirobranchus 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. In offshore areas, such as in the Greater Gabbard North Sea Area, where there is circalottoral mixed sediment, with pebbles and gravels, the biotope may further support rich encrusting fauna, including bryozoans, Spirobranchus lamarcki, and the barnacle Verruca stroemia, and occasionally Sabellaria spinulosa. Alongside these encrusting fauna, infauna such as Lumbrinerids (Hilbigneris gracilis), Glycera lapidum, Echinocyamus pusillus, Amphipholis squamata, Caulleriella alata may be present, and may represent a transitionary form between SS.SMx.CMx.FluHyd and SS.SCS.CCS.MedLumVen.

   SS.SMx.OMx.PoVen  Polychaete-rich deep Venus community in offshore mixed sediments

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, Hilbigneris gracilis, Pseudomystides limbata, Protomystides bidentata and syllid species and bivalves such as Timoclea ovata, Glycymeris glycymeris, Spisula elliptica and Goodallia triangularis. Some examples of this biotope may have abundant juvenile Modiolus modiolus. Several echinoderms including Amphipholis squamata, Echinocyamus pusillus are present in many locations. In coarser variations of the biotope, with gravelly sediment and the presence of pebbles or cobbles, the biotope may support encrusting fauna such as hydroids, Sertularia cupressina and Hydrallmania falcata, bryozoans and Spirobranchus triqueter. Mobile crustacea including the long-clawed porcelain crab Pisidia longicornis and amphipod Nototropis vedlomensis can also be highly abundant. This biotope has been recorded in the Irish Sea and English Channel and collectively with SS.SCS.CCS.MedLumVen comprise the 'Deep Venus Community' and the 'Boreal Off-Shore Gravel Association' as defined by other workers (Ford 1923; Jones 1950).
Back to top