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Concept: Polychaetes in littoral fine sand in the eunishabitats vocabulary

Concept URI http://eunis.eea.europa.eu/eunishabitats/A2.231
Preferred label Polychaetes in littoral fine sand
Definition 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]. The Po biotope is split into three sub-biotopes, between which there can be a large degree of overlap. The bivalve [Angulus tenuis] dominates the Po.Aten sub-biotope, which is characterised by slightly more stable and fine sediments than the other two sub-biotopes. Situation: The Po biotopes may be present below the AmSco communities or Ol.FS on moderately exposed shores. BarSa may occur on the upper part of the shore if it is subject to drying in between tides. The strandline biotope Tal 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.
Notation A2.231
Status Valid
Status Modified 2014-01-31
Accepted Date 2014-01-31
Not Accepted Date
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