Characterising species of the supralittoral zone

The supralittoral zone marks the upper extent of the intertidal and in some cases is considered a terrestrial habitat i.e within the EUNIS classification it is placed with the coastal habitats.

The supralittoral or 'splash zone' is the area at the top of the shore that receives the salt spray from the waves, as such, those shores experiencing greater exposure and salt spray from waves have larger supralittoral zones. Rock angle, shade and local climate also influence the extent of the zone.

The supralittoral zone is characterised by rocks covered in lichens, salt tolerant angiosperm and pools with variable salinity and temperatures. The organisms are highly specialized to endure variable salinity, periods of exposure and occasional immersion during storms. 

Lichens are one of the characteristic species of the supralittoral and often come to dominate the available rock. Concordantly the presence of lichens is a key component in the habitat classification of supralittoral rock and is captured by the habitat description: LR.FLR.Lic.YG (Yellow and grey lichens on supralittoral rock) EUNIS: B3.111.

One of the few mobile species to extend up into the supralittoral from the intertidal is the rough periwinkle (Littorina saxatilis).   

A variety of grey and yellow lichens can be found in the supralittoral.

The seaslater (Ligia oceanica) can also be observed.

Salt tolerant plants can also occur.

The distinction between the lichen and plant communities of the supralittoral and the terrestrial vegetation is often unclear. 

Rockpools within the supralittoral experience variable salinity and temperature making them inhospitable for many species. Habitat classification: EUNIS A1.42 (Communities of rockpools in supralittoral zone).

In this example tadpoles are found in the supralittoal rockpools of the shore.

Rock pooling destination: White Island, Isles of Scilly

Rock pooling destination: White Island, Isles of Scilly, May 2013.

The high energy rocky shore of White Island is comprised of bedrock and boulders with gullies and rock pools. 

Yellow and green lichens occur in the uppermost 'splash zone' of the shore. The black tar lichen forms a band below in the uppershore, with periwinkles, limpets, mussels, beadlet anemones, barnacles and channeled wrack. The mid to low shore contains robust fucoids and rock pools rich in red seaweeds which as you descend to the lower shore form an understory below the thong weed. 

The shore comes under the broad biotope description: LR.HLR (High energy littoral rock).

Rocky Shore comprising bedrock and boulders.

Sea ivory (Ramalina siliquosa) and an orange lichen on the upper most part of the shore. Biotope classification: LR.FLR.Lic.(Lichens on supralittoral and littoral fringe rock).

Tar lichen (Verrucaria maura) forms a distinctive band across the littoral fringe rock. Biotope classification: LR.FLR.Lic.(Lichens on supralittoral and littoral fringe rock).

Small periwinkles(Melarhaphe neritoides) occur within cracks and divots on the upper shore rocks.

Channel wrack (Pelvetia canaliculata) within a crevice of the upper shore.

Common limpets (Patella vulgata) and Rough periwinkles (Littorina saxatilis) seek refuge form the high energy waves beneath an overhang and within crevices of the upper shore. 

Barnacle distribution is patchy; possibly the result of heavy molluscan grazing?

The rocky shore is hit by strong winter storms. Life 'on the edge' can be stressful and many fauna including this mussel (Mytilus edulis) seek refuge  and 'cling on' within rock crevices and ledges.

Beadlet anemone (Actinia equina) and barnacles.

Mussels (Mytilus edulis), Limpets (Patella vulgata) and Beadlet anemones (Actinia equina) cluster together within a crevice of a ledge corner. Aggregation can help to reduce desiccation by forming a micro climate around the group. 

The rocky shore is exposed to high energy storms that roll the boulders forming smooth bedrock gullies and boulders.

In areas of the shore green seaweed grows over the boulders.

A blenny in a mid shore pool.

Spiral wrack (Fucus spp) on the mid shore. Biotope classification: LR.HLR.FR  (Robust fucoids and/or red seaweed communities)

Spiral wrack (Fucus spp) and Limpets (Patella vulgata) on the mid shore.  

Limpets (Patella vulgata)

 (Osmundea spp). 

Serrated wrack (Fucus serratus) edges a pool of coral weed (Coralina officinalis) and the green seaweed Cladophora rupestris on the lower shore. 

Grape pip weed (Mastrocarpus stellatus) on the lower shore.  

Cladophora rupestris and grape pip weed (Mastrocarpus stellatus) on the lower shore.

A snakelocks anemone (Anemonia viridis) in a corallinacea pool of the lower shore.

A corallinacea crust. 

Chondrus crispus.  

 Biotope classification: LR.HLR.FR  (Robust fucoids and/or red seaweed communities)

Beadlet anemones (Actinia equina) and red seaweed turfs of the lower shore.

An overhang community of the lower shore comprised of beadlet anemone (Actinaia equina), sea squirts, hydrozoa, purse sponge (Grantia compressa), red seaweeds and painted topshell (Calliostoma zizyphinum).

Grey topshells (Gibbula cineraria) occur beneath boulders of the lower shore.

Isopods and amphipods forage amongst seaweed washed up in the gullies of the lower shore.

Thong weed (Himanthelia elongata) and Chondrus crispus on the extreme low shore.

Thong weed (Himanthelia elongata) and red seaweeds on the extreme low shore.

The early stages of Thong weed (Himanthalia elongata)  resemble buttons.

Furbellows (Saccorhiza polyschides)

Thong weed (Himanthalia elongata).

Common Lichens of the sea shore

Lichens are symbiotic fungi that occur throughout the terrestrial environment and into the intertidal zone where they colonise suitable hard substrates of the upper shore and splash zone.

They are often the defining species of splash zone habitats and come in a variety of forms and colours.

Below are images of the common lichens you may encounter whilst rock pooling around the UK:

  

An orange lichen (Xanthoria parietina).

An orange lichen (Xanthoria parietina).

Black lichen (Lichina pygmaea).

Tar lichen (Verrucaria maura) and an orange lichen.

Tar lichen  (Verrucaria maura) forms a thin black crust over the rock



Above the high tide mark Sea ivory (Ramalina siliquosa) and the orange lichen, Xanthoria parietina occur.

Sea ivory (Ramalina siliquosa)

Sea ivory (Ramalina siliquosa)

Sheep are partial to sea ivory!

Possible Parelle (Ochrolechia parella).



Anaptychia spp.