Description of biotope or habitat type
Semibalanus balanoides on exposed to moderately exposed or vertical sheltered eulittoral rock
Habitat (physical) description
|Salinity||Full (30-35 ppt)|
|Wave exposure||Exposed, Moderately exposed|
|Substratum||Bedrock; large boulders|
|Zone||Eulittoral - mid, Eulittoral - upper|
|Depth Band||Mid shore, Upper shore|
|Other Features||Also on sheltered vertical bedrock|
Download comparative physical and biological data. The comparative tables enable a rapid comparison of the species composition and principal physical characteristics between a given set of biotopes.
- Records used to define the biotope (core records)
- Other records assigned to this biotope, marked as 'certain'
- Other records assigned to this biotope, marked as 'uncertain'
Point data based on records in the UK Marine Recorder Snapshot.
Exposed to moderately exposed mid to upper eulittoral bedrock and large boulders characterised by dense barnacles Semibalanus balanoides and the limpet Patella vulgata. The community has a relatively low diversity of species though occasional cracks and crevices in the rock can provide a refuge for small individuals of the mussel Mytilus edulis, the winkle Littorina saxatilis and the whelk Nucella lapillus. Seaweeds are usually not found in high numbers though fissures and crevices in the bedrock can hold a sparse algal community including the green seaweed Enteromorpha intestinalis. On some shores the olive green lichen Verrucaria mucosa can be present in some abundance (Frequent). Three variants have been described: A S. balanoides and P. vulgata dominated community on bedrock (Sem.Sem); S. balanoides and sparse Fucus vesioculosus and red seaweeds (Sem.FvesR); and barnacles and L. littorea eulittoral boulders and cobbles (Sem.LlitX).
On very exposed to exposed shores Chthamalus spp. (see Cht for geographical variation) often forms a distinct white band above a darker band of S. balanoides in the mid eulittoral zone. Alternatively, the black lichen Verrucaria maura dominated biotopes (Ver.Ver or Ver.B) may be found above Sem. In the lower eulittoral and the sublittoral fringe a community dominated by the wrack Himanthalia elongata and various red seaweeds such as Corallina officinalis, Mastocarpus stellatus and Osmundea pinnatifida (Him; Coff; Osm) often occurs. Sem may also occur on steep and vertical faces on more sheltered shores, while fucoids dominate the flatter areas (FvesB; Sem.FvesR).
Periods with little scour or calmer weather can allow a seaweed community to develop, creating a more diverse biotope (i.e. Fves or FvesB). This is a dynamic process, which will change individual sites over time. More information is required to determine the exact nature of this process.
|Taxon||Relative importance of taxon for defining this community (%)||Typical abundance - SACFOR scale||% of core records where taxon was recorded|
|Semibalanus balanoides||38||Abundant||81-100 %|
|Patella vulgata||18||Common||61-80 %|
|Littorina saxatilis||5||Frequent||21-40 %|
|Nucella lapillus||5||Frequent||41-60 %|
|Mytilus edulis||9||Occasional||61-80 %|
|Enteromorpha intestinalis||2||Occasional||21-40 %|
|Verrucaria mucosa||2||Frequent||21-40 %|
Not applicable or unknown.