Description of biotope or habitat type
Sargassum muticum in eulittoral rockpools
Habitat (physical) description
|Salinity||Full (30-35 ppt)|
|Wave exposure||Exposed, Moderately exposed, Sheltered|
|Zone||Eulittoral - lower, Eulittoral - mid|
|Depth Band||Lower shore, Mid shore|
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.
Shallow rockpools throughout the eulittoral zone on exposed to moderately exposed shores dominated by the brown seaweed Sargassum muticum and the red seaweed Corallina officinalis. Other brown seaweeds, including the kelp Laminaria saccharina, Laminaria digitata and the wrack Fucus serratus may occur along with Dictyota dichotoma, but S. muticum always dominates. Underneath the canopy is a rich red seaweed community which includes both foliose and filamentous species such as Palmaria palmata, Chondrus crispus, Lomentaria articulata, Osmundea pinnatifida, Ceramium spp. and Dumontia contorta. Encrusting coralline algae and Hildenbrandia rubra often cover the rock surface. The foliose green seaweed Ulva lactuca is usually present in high abundance growing on the mobile gravel and boulders on the bottom of the rockpools, often along with other ephemeral green seaweeds such as Cladophora rupestris and Enteromorpha intestinalis. The winkle Littorina littorea, the limpet Patella vulgata and the top shells Gibbula cineraria and Gibbula umbilicalis can often be found grazing on the biofilm of the rock surface or the seaweeds. Crevices and fissures in the rock provide cover for anemones such as Actinia equina and Anemonia viridis, cover while the prawn Palaemon serratus often can be found in large numbers hiding underneath the seaweed canopy or along the boulders on the bottom. Some sand scour can affect these rockpools.
Rockpools throughout the eulittoral zone in bedrock on exposed and moderately exposed shores. The non-native S. muticum is an opportunistic alga which has spread extensively around the south-west coast of Britain since its introduction to UK waters in the early 1970s from the northern Pacific ocean. It is spreading to other parts of the UK. It can dominate rockpools (and other habitats), often to the exclusion of other native species such as Laminaria spp. and fucoids.
As all the available records are from the south-west of Britain some changes in the species composition can be expected from more northern sites.
|Taxon||Relative importance of taxon for defining this community (%)||Typical abundance - SACFOR scale||% of core records where taxon was recorded|
|Actinia equina||2||Occasional||61-80 %|
|Anemonia viridis||1||Occasional||41-60 %|
|Palaemon serratus||2||Occasional||41-60 %|
|Gibbula cineraria||1||Frequent||41-60 %|
|Gibbula umbilicalis||2||Occasional||61-80 %|
|Patella vulgata||2||Occasional||41-60 %|
|Littorina littorea||3||Frequent||61-80 %|
|Palmaria palmata||1||Occasional||41-60 %|
|Hildenbrandia rubra||1||Occasional||21-40 %|
|Corallina officinalis||10||Common||81-100 %|
|Calliblepharis jubata||1||Frequent||41-60 %|
|Dumontia contorta||2||Frequent||41-60 %|
|Chondrus crispus||4||Frequent||61-80 %|
|Lomentaria articulata||1||Occasional||41-60 %|
|Osmundea pinnatifida||1||Occasional||41-60 %|
|Dictyota dichotoma||2||Occasional||41-60 %|
|Laminaria digitata||1||Occasional||41-60 %|
|Laminaria saccharina||1||Occasional||41-60 %|
|Fucus serratus||3||Occasional||61-80 %|
|Sargassum muticum||14||Abundant||81-100 %|
|Enteromorpha intestinalis||3||Frequent||41-60 %|
|Ulva lactuca||9||Common||81-100 %|
|Cladophora rupestris||1||Occasional||41-60 %|