Biodiversity & Conservation

Himanthalia elongata and red seaweeds on exposed lower eulittoral rock



Image Keith Hiscock - Himanthalia elongata and Laminaria digitata on lower shore bedrock. Image width ca XX cm.
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Distribution map

LR.HLR.FR.Him 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.

Species found especially in this biotope

  • Himanthalia elongata
  • Semibalanus balanoides
  • Patella vulgata
Community Importance Species name Common Name
Important characterizing Himanthalia elongata Thongweed
Important characterizing Palmaria palmata Dulse
Important characterizing Chondrus crispus Carragheen
Important characterizing Corallina officinalis Coral weed
Important characterizing Patella vulgata Common limpet
Important characterizing Semibalanus balanoides An acorn barnacle
Important other Nucella lapillus Dog whelk
Important other Mytilus edulis Common mussel


Himanthalia elongata is the characterizing brown algae in this biotope as it is more tolerant of wave exposure than Fucus serratus, which would otherwise form a patchy but often dense canopy amongst red algal turfs in the lower eulittoral zone. A turf of red foliose and encrusting algae is particularly characteristic of this biotope and Palmaria palmata and Chondrus crispus are included as important characterizing species representative of themselves and other foliose red algae, such as Mastocarpus stellatus. Corallina officinalis is included as a representative of turf forming calcareous species. Semibalanus balanoides and Patella vulgata are species which typically colonize patches occurring in the turf. Species such as Nucella lapillus, Littorina neglecta and Mytilus edulis are not especially faithful to the biotope but may occasionally occur in the biotope, exploiting damp pits and crevices in the rock, their presence therefore may have some bearing on the sensitivity of the biotope and are included as important others.

Additional information

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This review can be cited as follows:

Budd, G.C. 2002. Himanthalia elongata and red seaweeds on exposed 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: <>