Biodiversity & Conservation

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

SS.SMp.Mrl.Pcal.Nmix

IGS.Phy.Hec

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
  • OSPAR

Marine natural heritage importance

Listed under EC Habitats Directive
UK Biodiversity Action Plan
National importance Uncommon
Habitat Directive feature (Annex 1) Sandbanks which are slightly covered by sea water all the time
Large shallow inlets and bays

Biotope importance

The biotope is highly important for other species, with high structural complexity and biodiversity. Mobile grazers and foragers can move in and out of the biotope to feed.

Exploitation

Maerl is mainly sold dried as a soil additive but is also used in animal feed, water filtration systems, pharmaceuticals, cosmetics and bone surgery. Maerl beds are dredged for scallops (found in high densities compared with other scallop habitats) where extraction efficiency is very high. This harvesting has serious detrimental effects on the diversity, species richness and abundance of maerl beds (BIOMAERL team, 1999).

Additional information icon Additional information

Maerl beds are included within the marine habitat 'sand banks which are slightly covered by seawater at all times' listed in Annex I of the EC Habitats Directive. Phymatolithon calcareum, the key structural species of the biotope is included within Annex V(b) of the EC Habitats Directive. Annex V(b) indicates plant species that are of community interest whose taking in the wild and exploitation may be subject to management measures. This species is also on the UK Biodiversity Action Plan long list.

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 24/05/2013]. Available from: <http://www.marlin.ac.uk/habitatimportance.php?habitatid=64&code=2004>