Definition
These are benthic marine communities that consist of coralline (calcareous) algae that form extensive beds on the seabed. Beds of maerl in coarse clean sediments of gravels and clean sands, which occur either on the open coast or in tide-swept channels of marine inlets (the latter often stony). In fully marine conditions the dominant maerl is typically Phymatolithon calcareum, whilst under variable salinity conditions in some sealochs beds of Lithothamnion glaciale may develop. (Barbera, C., Bordehore, C., Borg, J.A., Glemarec, M.,, Grall, J., Hall-Spencer, J.M., de la Huz, C., Lanfranco, E., Lastra, M., Moore, P.G., Mora, J., Pitta, M.E., Ramos-Esplá, A.A., Rizzo, M., Sánchez-Mata, A., Seva, A., Scembri, P.J., Valle, C. 2003.Conservation and management of northeast Atlantic and Mediterranean maërl beds. Aquatic Conservation: Marine and Freshwater Ecosystem, 13: S65-S76. Hall-Spencer, J.M., White, N., Gillespie, E., Gillham, K., Foggo, A., 2006. Impact of fish farm on maërl beds in strongly tidal areas. Marine Ecology Progress Series, 326: 1-9. AND Eunis habitat classification: https://eunis.eea.europa.eu/habitats/5437)