Biodiversity & Conservation

Flustra foliacea and other hydroid/bryozoan turf species on slightly scoured circalittoral rock or mixed substrata


Image David Connor - Flustra foliacea and other hydroid/bryozoan turf species on slightly scoured circalittoral rock or mixed substrata. Image width ca 10 cm.
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Distribution map

recorded (dark blue bullet) and expected (light blue bullet) distribution in Britain and Ireland (see below)

  • EC_Habitats

Species indicative of sensitivity

To assess the sensitivity of the biotope, the sensitivity of component species is reviewed. Those species that are considered to be particularly indicative of the sensitivity of the biotope, and for which research has been undertaken in detail are shown below (see selection criteria). The biology of other component species of the biotope is also taken into account wherever information is known to the researcher.

Species found especially in this biotope

  • Flustra foliacea
  • Thuiaria thuja
  • Nemertesia antennina
  • Nemertesia ramosa
  • Abietinaria abietina
  • Sertularia argentea
  • Polymastia boletiformis
  • Polymastia mamillaris
  • Tubularia indivisa
  • Jujubinus miliaris
  • Alcyonidium parasiticum
  • Chartella papyracea
  • Vesicularia spinosa
  • Eucratea loricata
  • Hyas coarctatus
Community Importance Species name Common Name
Important characterizing Flustra foliacea Hornwrack
Important characterizing Bugula turbinata An erect bryozoan
Important characterizing Nemertesia ramosa A hydroid
Important other Alcyonium digitatum Dead man's fingers
Important other Urticina felina Dahlia anemone
Important functional Echinus esculentus Edible sea urchin
Important other Molgula manhattensis A sea squirt
Important other Halichondria panicea Breadcrumb sponge


This biotope is dominated by the erect bryozoan Flustra foliacea, which if lost would result in loss of the biotope as described. The biotope is characterized by a faunal turf of hydroids and bryozoans. Although, loss of a single species may not be detrimental, loss of the bryozoan/ hydroid turf would result in degradation of the community, and potentially loss of the biotope as described. Therefore, Nemertesia ramosa has been included to represent Nemertesia species and other hydroids, while Bugula turbinata has been included to represent Bugula species and other seasonal bryozoan species. The soft coral Alcyonium digitatum is included to represent the sensitivity of large epifauna and, together with Urticina felina, the sensitivity of anthozoans. Sebens (1985, 1986) demonstrated that predators, especially by sea urchins, were an important factor structuring epifaunal communities, therefore, Echinus esculentus has been included as important functional. The sensitivity of ascidians has been represented by Molgula manhattensis and the sensitivity of sponges by Halichondria panicea.

Additional information

The Flustra foliacea dominated biotopes support a large number of sessile, interstitial, and mobile cryptofauna. The species richness varies between sub-biotopes. For example the MNCR identified 183 species in MCR.Flu, 378 species in MCR.Flu.Flu, 664 in MCR.Flu.HByS, 305 in MCR.Flu.Hocu, and 594 in MCR.Flu.SerHyd (JNCC, 1999). It should be remembered that the above numbers are probably underestimates and that not all species occur in all instances of the biotope. However, the above estimates of species richness give an indication of the biodiversity of circalittoral faunal turf habitats.

This review can be cited as follows:

Tyler-Walters, H. 2002. Flustra foliacea and other hydroid/bryozoan turf species on slightly scoured circalittoral rock or mixed substrata. Marine Life Information Network: Biology and Sensitivity Key Information Sub-programme [on-line]. Plymouth: Marine Biological Association of the United Kingdom. [cited 01/12/2015]. Available from: <>