Biodiversity & Conservation

Ceramium sp. and piddocks on eulittoral fossilized peat



Image Rohan Holt - Piddock bored rock with red algae. Image width ca 1 m (foreground).
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Distribution map

LR.MLR.R.RPid 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

  • Barnea candida
  • Petricola pholadiformis
Community Importance Species name Common Name
Important characterizing Barnea candida White piddock
Important characterizing Petricola pholadiformis American piddock
Important structural Ceramium virgatum A red seaweed
Important structural Ulva intestinalis Gut weed


The most significant feature for identification of this biotope is the fossilized peat substratum. In the absence of peat the biotope would not be recognized. All species of the community can occur elsewhere, on and in other substrata. The most faithful species to the MLR.RPid biotope are the piddocks, Barnea candida and Petricola pholadiformis, and these species have been assessed to be important characterizing species. The surface of the peat is covered by a mat of predominantly red seaweed, Ceramium sp., but also ephemeral green seaweeds such as Ulva and Ulva. These species are included as important structural species as they provide a habitat for small invertebrates.

Additional information

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This review can be cited as follows:

Budd, G.C. 2008. Ceramium sp. and piddocks on eulittoral fossilized peat. Marine Life Information Network: Biology and Sensitivity Key Information Sub-programme [on-line]. Plymouth: Marine Biological Association of the United Kingdom. [cited 29/11/2015]. Available from: <>