Biodiversity & Conservation

Ulva spp. on freshwater-influenced or unstable upper eulittoral rock



Image David George - Fallen chalk blocks covered in Enteromorpha. Image width ca 4 m.
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Distribution map

LR.MLR.Eph.Ent 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

  • Ulva spp.
  • Porphyra spp.
Community Importance Species name Common Name
Important characterizing Ulva intestinalis Gut weed
Important characterizing Porphyra spp. Laver


The biotope is characterized by algal species of an ephemeral nature, whose life cycle enables them to rapidly colonize and dominate the upper shore substrata that is prone to instability and considerable freshwater runoff. Hence, Ulva intestinalis and Porphyra spp. are considered to be important characterizing species.

Additional information

The biotope is generally devoid of macrofauna, except for the occasional limpet, winkle or barnacle, but these species are not considered to be indicative of the sensitivity of the biotope. Mobile species from either adjacent terrestrial or littoral biotopes may be recorded but are likely to be transient.

This review can be cited as follows:

Budd, G.C. 2004. Ulva spp. on freshwater-influenced or unstable upper eulittoral rock. Marine Life Information Network: Biology and Sensitivity Key Information Sub-programme [on-line]. Plymouth: Marine Biological Association of the United Kingdom. [cited 26/11/2015]. Available from: <>