Fucus distichus and Fucus spiralis f. nana on extremely exposed upper eulittoral rock
|EUNIS habitat type||code MA1231|
|Relation to||Resolution 4 habitat type (used for designation of Emerald sites)|
Extremely exposed gently or steeply sloping upper shore bedrock which supports a mixture of the wracks Fucus distichus and Fucus spiralis f. nana, the latter often at the top of the zone. On some sites F. distichus dominates and F. spiralis is not present. Other seaweeds normally found on exposed coasts are common in this biotope. These include ephemeral species such as the foliose red Porphyra umbilicalis and the green Enteromorpha spp. The winkles Melarhaphe neritoides and Littorina saxatilis can be found grazing on the bedrock or on the fucoids, while red crusts of Hildenbrandia rubra and the mussel Mytilus edulis are restricted to moist cracks and crevices. A sparse covering of the black lichens Verrucaria maura and Verrucaria mucosa can be found in the upper part of this biotope competing for space with barnacle Semibalanus balanoides and the limpet Patella vulgata. This biotope is very rare and restricted to the far north and west coasts.
Situation: This mixed band of F. distichus and F. spiralis f. nana is generally found between the Verrucaria maura and Porphyra spp. zone (MA1-2131 or MA1-2132) above, and the M. edulis and barnacle zone below (MA1-221). It may also occur above a red algal zone consisting of Mastocarpus stellatus as recorded on Barra (Scotland).
Temporal variation: Due to the occurrence of this biotope on very exposed coasts a certain amount of fluctuation between this biotope and unit MA1-2131 from year to year is to be expected. More information is required to validate this hypothesis. There can be seasonal fluctuations in the density of ephemeral green algae.
Source: EUNIS habitat classification
Relation to other habitat types mentioned in legal instruments
Relation to vegetation types (syntaxa)Not available
Species mentioned in habitat description
|Species scientific name||English common name||Species group|
|Classification||Code||Habitat type name||Relationship type|
|EUNIS Habitat Classification 2007 (revised descriptions 2012)||A1.121||Fucus distichus and Fucus spiralis f. nana on extremely exposed upper eulittoral rock||same|
|Classification||Code||Habitat type name||Relationship type||Comment|
|EUNIS Habitat Classification 200410||A1.121||Fucus distichus and Fucus spiralis f. nana on extremely exposed upper eulittoral rock||same|
|EUNIS Habitat Classification 200308||A1.121||Fucus distichus and Fucus spiralis f. nana on extremely exposed upper eulittoral rock||same|
|EUNIS Habitat Classification 200202||A1.121||Fucus distichus subsp. anceps and Fucus spiralis f. nana on extremely exposed upper eulittoral rock||same|
|EUNIS Habitat Classification 199910||A1.121||Fucus distichus subsp. anceps and Fucus spiralis f. nana on extremely exposed upper eulittoral rock||same|
|MNCR BioMar 97.06 (Britain & Ireland)||ELR.FR.Fdis||Fucus distichus subsp. anceps and Fucus spiralis f. nana on extremely exposed upper eulittoral rock||same|