Biodiversity & Conservation

Ascophyllum nodosum, sponges and ascidians on tide-swept mid eulittoral rock


<i>%Ascophyllum nodosum%</i>, sponges and ascidians on tide-swept mid eulittoral rock
Distribution map

LR.HLR.FT.AscT recorded (dark blue bullet) and expected (light blue bullet) distribution in Britain and Ireland (see below)

  • UK_BAP

Text page icon Habitat description

Map icon Distribution of biotope in Britain and Ireland This biotope is not recorded from the east coasts of Britain and Ireland. In England and Wales, the only recorded sites were on the Isles of Scilly and in the Menai Strait respectively. In Scotland, the biotope is found in Shapinsay Sound, Orkney and in various location in the Inner and Outer Hebrides and on the north west coast of the Scottish mainland. Irish survey data has not been analyzed to identify biotopes although it seems likely that the biotope will occur in tidal sounds and rapids such as occur in Strangford Lough.
National importance Not available

Text page icon Description of biotope

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

Very sheltered to extremely sheltered areas of mid eulittoral rock that are subject to strong to moderate tidal streams, such as the narrows in sea lochs, and characterized by the wrack Ascophyllum nodosum. The wracks Fucus vesiculosus and Fucus serratus are occasionally present. The increased water movement encourages a rich associated fauna including several filter-feeding groups. These include the sponges Leucosolenia spp., Grantia compressa, Halichondria panicea and Hymeniacidon perleve which frequently occur on steep and overhanging faces of boulders and bedrock. It also includes the sea squirts Dendrodoa grossularia and Ascidiella scabra, which occur on steep surfaces and beneath boulders. Hydroids such as the pink Clava multicornis can form colonies on Ascophyllum nodosum while Dynamena pumila is more often found on Fucus vesiculosus or Fucus serratus. Underneath the canopy formed by the brown seaweeds is a diverse community of the red seaweeds Gelidium pusillum, Chondrus crispus, Lomentaria articulata, Membranoptera alata and coralline crusts, but the green seaweeds Enteromorpha intestinalis, Ulva lactuca and Cladophora rupestris can be present. The filamentous red seaweed Polysiphonia lanosa can usually be found growing on Ascophyllum nodosum. On the rock beneath are the limpet Patella vulgata and the barnacle Semibalanus balanoides, while the crab Carcinus maenas and a variety of winkles including Littorina littorea, Littorina mariae and Littorina obtusata can be found on or among the boulders. The whelk Nucella lapillus can either be found in cracks and crevices or preying on the barnacles. (Information taken from the revised Marine Biotope Classification, Version 04.06, Connor et al., 2004).

Additional information icon Additional information

This review can be cited as follows:

Marshall, C.E. 2005. Ascophyllum nodosum, sponges and ascidians on tide-swept 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 01/12/2015]. Available from: <>