Biodiversity & Conservation

Laminaria digitata and piddocks on sublittoral fringe soft rock



Image David George - View across shore showing extensive kelp beds on chalk. Image width ca 4 m.
Image copyright information

Distribution map

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

  • EC_Habitats
  • 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.

Species found especially in this biotope

  • Pholas dactylus
  • Barnea candida
Community Importance Species name Common Name
Key structural Laminaria digitata Oarweed
Key structural Pholas dactylus Common piddock
Key functional Polydora ciliata A bristleworm
Important characterizing Palmaria palmata Dulse


Laminaria digitata and Pholas dactylus are the key structuring species and also give the name to the biotope. The fronds, stipe and holdfast of the kelp plants create structural complexity within the biotope. The piddock Pholas dactylus is a key structuring species because of the refugia provided by the holes it makes. These have been known to increase species diversity (Pinn et al., in press). The burrowing polychaete Polydora ciliata is functionally important because tube building can modify the substratum and in areas of mud tubes can agglomerate, forming layers of mud that can sometimes be thick enough to eliminate the original fauna and flora, or at least can be considered as a threat to the ecological balance achieved by some biotopes (Daro & Polk, 1973). The understorey of red algae in the biotope is represented by Palmaria palmata which is frequently found both on rocks and sometimes on older Laminaria digitata stipes.

Additional information

This review can be cited as follows:

Hill, J.M. 2008. Laminaria digitata and piddocks on sublittoral fringe soft rock. Marine Life Information Network: Biology and Sensitivity Key Information Sub-programme [on-line]. Plymouth: Marine Biological Association of the United Kingdom. [cited 30/11/2015]. Available from: <>