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Marine Habitat Classification


3 results for 'SS.SCS.ICS.Glap'

   SS.SCS.ICS.Glap  Glycera lapidum in impoverished infralittoral mobile gravel and sand

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

   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.SMp.SSgr.Zmar  Zostera marina/angustifolia beds on lower shore or infralittoral clean or muddy sand

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 SS.Smp.SSgr.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, Saccharina latissima, 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 SS.SCS.ICS.MoeVen, SS.SCS.ICS.SLan or SS.SCS.ICS.Glap whilst muddy sands may have infaunal populations related to SS.SSa.IMuSa.EcorEns, SS.SMu.IMuSa.AreISa and SS.SSa.IMuSa.FfabMag. Muddy examples of this biotope may show similarities to SS.SMu.ISaMu.CundAasp, SS.SMu.IFiMu.PhiVir, SS.SMu.IFiMu.Are or SS.SMu.CSaMu.AfilKurAnit. 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.
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