Biodiversity & Conservation

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Littoral sandy mud and mud in sheltered, often estuarine, conditions with a community of polychaetes together with the bivalve Macoma balthica. The most abundant large polychaete is typically Hediste (Nereis) diversicolor, which can be readily seen when digging over the sediment. Other smaller polychaetes include Eteone longa, Nephtys hombergii, Aphelochaeta marioni, Pygospio elegans, Arenicola marina and Manayunkia aestuarina. Oligochaete worms (e.g. Tubificoides benedii, Tubificoides pseudogaster and enchytraeids) are common or abundant and the amphipod Corophium volutator may be abundant. The mud snail Hydrobia ulvae is often common, with individuals or their fine tracks visible on the mud surface. The bivalve Macoma balthica may be accompanied by Cerastoderma edule, Abra tenuis and Mya arenaria. The surface of the mud may be covered with green algae such as Ulva spp. or Ulva lactuca. There is usually a black anoxic layer close to the sediment surface. LMU.HedStr is a similar biotope that is associated with muddier sediment in reduced salinity conditions with Streblospio shrubsolii, Manayunkia aestuarina or Tharyx killariensis and with fewer bivalves. Three variations of this biotope are recognised: LMU.HedMac.Are, LMU.HedMac.Pyg and LMU.HedMac.Mare. (Information taken from the Marine Biotope Classification for Britain and Ireland, Version 97.06: Connor et al., 1997a, b).