Biodiversity & Conservation

Laminaria digitata, ascidians and bryozoans on tide-swept sublittoral fringe rock


<i>%Laminaria digitata%</i>, ascidians and bryozoans on tide-swept sublittoral fringe rock
Distribution map

IR.MIR.KR.Ldig.T recorded (dark blue bullet) and expected (light blue bullet) distribution in Britain and Ireland (see below)

  • UK_BAP

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.

Community Importance Species name Common Name
Important functional Halichondria panicea Breadcrumb sponge
Important characterizing Botryllus schlosseri Star ascidian
Important characterizing Membranipora membranacea A bryozoan
Important characterizing Corallina officinalis Coral weed
Important characterizing Palmaria palmata Dulse
Key Structuring Laminaria digitata Oarweed
Important Structural Gibbula cineraria Grey top shell
Important other Lithophyllum incrustans An encrusting coralline algae


Laminaria digitata is the major characterizing species within this biotope and is the most significant component in terms of size and dominance. It provides a substratum for important characterizing species and a habitat and refuge for many others. The breadcrumb sponge Halichondria panicea is likely to compete with and exclude bryozoans and ascidians for space and is therefore considered to be an important functional species. Coral weed Corallina officinalis and dulse Palmaria palmata are frequently found in this biotope where they can be abundant. They are included as they are representative of the associated range of foliose red seaweeds. Membranipora membranacea is the most frequently occurring bryozoan in this biotope and has been used to represent other less commonly occurring bryozoans. The encrusting coralline algae Lithophyllum incrustans has been included as an important 'other' species because, although it is not a characterizing species within this biotope, it represents the encrusting coralline algae that are likely to cover much of the rock in many of the records of MIR.Ldig.T.

Additional information

The MNCR recorded 425 species in 45 records of this biotope although not all the species occurred in all records of the biotope (JNCC, 1999).

This review can be cited as follows:

Marshall, C.E. 2005. Laminaria digitata, ascidians and bryozoans on tide-swept sublittoral fringe rock. Marine Life Information Network: Biology and Sensitivity Key Information Sub-programme [on-line]. Plymouth: Marine Biological Association of the United Kingdom. [cited 28/11/2015]. Available from: <>