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

Text page icon Habitat description

Map icon Distribution of biotope in Britain and Ireland Present on the Orkney and Shetland Isles, north east coast of Britain, the south west, the Welsh coast and the west coast of Scotland. Also present on the west coast of Ireland.
National importance Common

Text page icon Description of biotope

For a full description of this biotope including characterizing species, distribution, survey information and references visit JNCC

Exposed to moderately exposed lower eulittoral bedrock may be characterized by buttons and straps of the thong weed Himanthalia elongata (at least frequent) with a dense turf of red algae beneath. The predominant red algae are usually Mastocarpus stellatus, Osmundea pinnatifida, Corallina officinalis and Palmaria palmata which tend to grow over a crust of pink coralline algae. Any patches between the algal turf may be colonised by barnacles Semibalanus balanoides, or Balanus perforatus in the south-west, and limpets Patella vulgata. Pits and crevices in the rock often provide a refuge for anemones, gastropods (Nucella lapillus and Littorina neglecta) and small mussels Mytilus edulis. This biotope generally characterises those shores which are too exposed for Fucus serratus to form a dense canopy, often occurring as large patches within the Fucus serratus / red algal turf zone (MLR.Fser.R). Consequently, Fucus serratus plants frequently occur amongst the Himanthalia elongata and red algae (Fucus serratus common or less). On some shores this biotope may occur as a distinct zone between the Fucus serratus/ red algal turf (MLR.Fser.R) and the Alaria esculenta / Laminaria digitata zone (EIR.Ala.Ldig). In the south and south-west Bifurcaria bifurcata may replace Himanthalia elongata, and can sometimes form a distinct band on the lower shore. Himanthalia elongata may occur on tide-swept, sheltered shores in sea lochs (e.g. Loch Maddy). (Information taken from the Marine Biotope Classification for Britain and Ireland, Version 97.06: Connor et al., 1997a, b).

Additional information icon 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 29/11/2015]. Available from: <>