Biodiversity & Conservation

Phymatolithon calcareum maerl beds with hydroids and echinoderms in deeper infralittoral clean gravel or coarse sand



Image Sarah Fowler - Maerl bed in Loch Gairloch, Highland. Image width ca 2 m in foreground.
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Distribution map

SS.SMp.Mrl.Pcal.Nmix recorded (dark blue bullet) and expected (light blue bullet) distribution in Britain and Ireland (see below)

  • EC_Habitats
  • UK_BAP

Text page icon Habitat description

Map icon Distribution of biotope in Britain and Ireland Present at locations within the photic zone all along the west coast of Scotland, including the Western Isles, Orkney, and Shetland. The biotope is almost certainly present round the Isle of Man. Localised occurrences in southern England. Also Strangford Lough in Northern Ireland. The biotope has not yet been officially recorded from Ireland but is expected to be widespread but patchily distributed around the south and west.
National importance Uncommon

Text page icon Description of biotope

For a full description of this biotope including characterizing species, distribution, survey information and references visit JNCC

Lower infralittoral maerl beds characterized by Phymatolithon calcareum in gravels and sand with a variety of associated hydroids and echinoderms. Hydroids present are typically erect colonies such as Nemertesia spp. and often occur on the maerl or attached to dead shells within the maerl. Echinoderms such as Antedon bifida, Ophiothrix fragilis, Ophiocomina nigra, Ophiura albida and Neopentadactyla mixta are occasional or frequent in IGS.Phy.HEc but do not often occur in IGS.Phy.R. Other, more ubiquitous echinoderms such as Marthasterias glacialis are found throughout IGS.Phy biotopes. (Information taken from the Marine Biotope Classification for Britain and Ireland, Version 97.06: Connor et al., 1997a, b).

Additional information icon Additional information

This review can be cited as follows:

Jackson, A. 2006. Phymatolithon calcareum maerl beds with hydroids and echinoderms in deeper infralittoral clean gravel or coarse sand. Marine Life Information Network: Biology and Sensitivity Key Information Sub-programme [on-line]. Plymouth: Marine Biological Association of the United Kingdom. [cited 24/11/2015]. Available from: <>