Biodiversity & Conservation

Rhodothamniella floridula on sand-scoured lower eulittoral rock



Image Kate Northen - Sand tolerant red algae on lower shore. Image width ca 60 cm (foreground).
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Distribution map

LR.MLR.BF.Rho recorded (dark blue bullet) and expected (light blue bullet) distribution in Britain and Ireland (see below)

  • EC_Habitats

For a list of 2004 characterising species please see the JNCC website.

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 characterizing Rhodothamniella floridula A red seaweed
Important functional Patella vulgata Common limpet
Important other Fucus serratus Toothed wrack


Rhodothamniella floridula is considered to be the main characterizing species in the MLR.Rho biotope and dominates the rock surface. It is a sand scour tolerant species, which enhances stability and habitat diversity by binding sand together as a mat on the rocky substratum. In its absence the biotope would not necessarily be recognised. The dominant grazer in the biotope, Patella vulgata, is considered to be important as its grazing activity contributes to the regulation of algal patches and maintains diversity. Fucus serratus is usually abundant and provides habitat. Although the MLR.Rho biotope occurs patchily amongst fucoids, it is an important primary producer and enhances species diversity and patchiness.

Additional information

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This review can be cited as follows:

Riley, K. 2002. Rhodothamniella floridula on sand-scoured lower eulittoral rock. Marine Life Information Network: Biology and Sensitivity Key Information Sub-programme [on-line]. Plymouth: Marine Biological Association of the United Kingdom. [cited 25/11/2015]. Available from: <>