Biodiversity & Conservation

Ascophyllum nodosum on very sheltered mid eulittoral rock.


<i>%Ascophyllum nodosum%</i> on very sheltered mid eulittoral rock.
Distribution map

LR.SLR.F.Asc recorded (dark blue bullet) and expected (light blue bullet) distribution in Britain and Ireland (see below)

  • EC_Habitats

Marine natural heritage importance

Listed under EC Habitats Directive
National importance Widespread
Habitat Directive feature (Annex 1) Reefs
Large shallow inlets and bays

Biotope importance

Fish and crustaceans migrating into the intertidal zone to feed as the tide rises, are important predators of rocky shore species. Corkwing wrasse Crenilabrus melops rely greatly on the intertidal. Juvenile wrasse are commonly found in rockpools. Shore birds also feed on the rocky shores because the invertebrates attracted to seaweed on the strandline are a particularly important food source. Rich pickings are also available under macroalgae canopies. Algal patches may also act as nursery grounds for various species including Nucella lapillus.


Ascophyllum nodosum is harvested in Ireland and Scotland for use in alginates, fertilisers and for the manufacture of seaweed meal for animal and human consumption. Around 32,000 tonnes are harvested per year. The species is also harvested in continental Europe and Canada. Poor resource management and over-exploitation have led to severely depleted populations in many regions. These factors, together with the long-recognised shortage of sporelings (David, 1943) and the failure of the species to recolonize denuded areas for decades, illustrate the need to have good management strategies and reseeding techniques.

Additional information icon Additional information

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This review can be cited as follows:

Hill, J.M. 2001. Ascophyllum nodosum on very sheltered mid 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: <>