Unexpected creatures of the intertidal: Featherstar

A video of a featherstar (Antedon bifida) found on the intertidal of St. Martins, Isles of Scilly.

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.

An introduction to zonation on intertidal shores

Where the land meets the sea two worlds join, one or air and the other of sea water.

As the tide rises and falls this stretch of land, refereed to as the intertidal zone, alternates between being exposed to the air and covered by sea.

The relative environmental pressures of submergence and exposure change retrospectively throughout the intertidal zone in relation to altitude from the low water mark. Other factors such as predation and competition also act to influence the communities found. 

The combination of all these factors can often result in repeated and definable communities of species at certain altitudes and/or exposures across the intertidal zone.

Such distributions of communities in relation to altitude or, height on the rocky shore is often referred to as zonation. Zonantion is often discussed in terms of dominant seaweeds present and is best exemplified on sheltered rocky shores. 

Zonation is not always clear cut (see previous blog post: http://thesaltyscavenger.blogspot.co.uk/2014/08/rockpooling-destination-mousehole-may.html) and is affected by factors for which altitude on the shore is often correlated. 

The following posts look at some of the characterising species of the general shore 'zones'; although these can be found else where, they are often characteristic of a particular zone of the shore.

Below are images of some of the different intertidal zones found on UK rocky shores.

The different zones of the intertidal rocky shore in relation to altitude.

The communities on this exposed rocky shore in Shetland exhibit distinct distributions in relation to rock altitude and exposure. Yellow and grey lichens occur at the highest elevation of the rock and mark the supralittoral zone. Below, the rocks of the littoral fringe appear black, from the tar lichen (Verrucaria maura) which is overgrown on the more sheltered vertical rock, by a fringe of the brown channel wrack (Pelvetia canaliculata); the rocks of the upper shore become increasingly grey due to the barnacle communities which are inter-dispersed by patches of the black, Lichina pygmaea.  Habitat classification: LR.FLR.Lic.YG (Yellow and grey lichens on supralittoral rock) EUNIS: B3.111, LR.FLR.Lic.Ver (Verrucaria maura on littoral fringe rock) EUNIS: B3.113 and LR.HLR.MusB.Cht (Chthamalus spp on exposed upper eulittoral rock) EUNIS: A1.112.

The communities on this sheltered rocky shore in Shetland exhibit distinct distributions in relation to rock altitude. Yellow and grey lichens occur at the highest elevation of the rock and mark the supralittoral zone. Below, the rocks appear black, from the tar lichen (Verrucaria maura) and the eulittoral is characterised by fucoids with a green patch of ephemeral greens marking fresh water run off entering the shore. Habitat classification: LR.FLR.Lic.YG (Yellow and grey lichens on supralittoral rock) EUNIS: B3.111, LR.FLR.Lic.Ver (Verrucaria maura on littoral fringe rock) EUNIS: B3.113, LR.LLR.F (Fucoids on sheltered marine shores) EUNIS: A1.31 and  LR.FLR.Eph (Ephemeral green seaweed communities - Fresh water influenced) EUNIS: A1.45.

Regional names of common shore species

The marine animals of the shore often have a common name in addition to their Latin name. These common names can vary around the UK. 

Below are some examples:

Generic common name: Common Whelk – Shetland common name: Buckie – Latin name: Buccinum undatum

Generic common name: Three spot cowrie – Shetland common name: Grotti Buckie – Latin name: Trivia monacha

Generic common name: Edible Periwinkle – Shetland common name: Black Whelk – Latin name: Littorina litorea

Generic common name: Goose barnacles – Shetland common name: Claiks – Latin name: Lepatidae

Generic common name: Razor Shell – Shetland common name: Spoot – Latin name: Ensis sp

Generic common name: Seaslater – Cornish common name: Grammercel – Latin name: Ligia oceanica

Because of the variance in common names recorders log the organisms of the shore by their Latin names which do not change regionally.

Washed up Silver Birch is referred to as gooniemans candle is Shetland 

Deep Freeze of a winter's past

So far this year, Winter has been particularly mild but its Winters past it has not been the case....

Brackish water of the Yare estuary often becomes partially frozen in winter.......

Rockpooling Destination: Happisburgh, Artificial sea defences, August 2015

The shore at Happisburgh is comprised of mobile sands and shingle, due to high rates of coastal erosion, artificial sea defences have been erected to protect the cliffs. The defences change the dynamics of the shore and provide a hard substrate for organisms to colonise.

The hard substrate of the wooden sea defences is characterised by lichen, barnacle, gastropod and seaweeds that comprise littoral fringe and sand scour tolerant communities.

The wooden sea defences provide a stable hard substrate in an otherwise mobile sand and shingle shore. Habitat classification: LR (Littoral rock) and LS.LSa.Sh (Shingle and gravel shores) EUNIS: A2.11.

The wooden sea defences support an assemblage akin to a 'rocky shore' community that exhibits zonation in altitude. A black lichen and  small periwinkles (Melarhaphe neritoides) mark the upper vertical extent of the intertidal communities that colonise the wooden sea defences. Habitat classification: Similar to LR.FLR.Lic (Lichens or small green algae on supralittoral and littoral fringe rock) EUNIS: B3.11.

Small periwinkles (M. neritoides) aggregate in wood crevices. 

On the leeward side of the wooden defences, about 1m from their base, barnacles (Elminius modestus and Semibalanus balanoides), periwinkles (Littorina spp and M. neritoides) and occasional Fucus spiralis occur amongst a wider distributed covering of ephemeral green and red (Porphyra spp) seaweeds. Habitat classification: LR.FLR.Eph.EntPor (Porphyra purpurea and Entomorpha spp. on sand scoured mid and lower eulittoral rock) EUNIS: A1.452.

Organisms that have colonised the wooden sea defences demonstrate an aggregated distribution in accordance to their tolerance to wave exposure and sand abrasion.  Sand scour tolerant ephemeral seaweeds cover large areas of the wooden defences and extend lower than the barnacles due to their opportunistic nature, fast growth and ability to withstand the sand abrasion. Above in the leeward side of the defences F. spiralis and barnacles occur and among the barnacles and within crevices periwinkles (Littorina spp and M. neritoides) and limpets. The organisms do not extend to the lower base of the sea defences due to variability in sand movement, abrasion and potential smothering.

Rockpooling Destination: Revisit West Penwith, St. Loy September 2015

The shore is a high energy environment, comprised of boulders and bedrock, with crevices, rock pools and gullies.

Fauna are relatively sparse among the supralittoral and little fringe boulders, increasing on stable bedrock of the upper shore and within the rockpools, crevices and gullies of the mid and lower shore.

The supralittoral and littoral fringe rock is charecterised by lichen communities, whilst barnacle communities occur across the rest of the shore, inter-dispersed by rockpools. As the lower shore is reached, robust wracks and red seaweeds come to dominate.

A river flows onto the shore and beneath the boulders.

Where conditions are sheltered enough, a seasonal strandline forms.

Habitat classification:

Habitat	LR.HLR (High energy littoral rock)		FLR (Features of littoral rock)
Biotope complex	LR.HLR. MusB (Mussel and/or barnacle communities)	LR.HLR.FR (Robust fucoid and/or red seaweed   communities)	LR.FLR.Lic.(Lichens on supralittoral and littoral fringe rock).		LR.FLR.Rkp (Rockpools)
Biotope	LR.HLR.MusB.Cht (Chthamalus spp. on exposed eulittoral rock)	LR.HLR.FR.Him (Himanthalia elongata) and red seaweeds on exposed to moderately exposed lower eulittoral rock	LR.FLR.Lic.YG (Yellow and grey lichens on supralittoral rock)	LR.FLR.Lic.Ver (Verrucaria Maura on littoral fringe rock)	LR.FLR.Rkp.Cor (Coralline crust dominated shallow eulittoral rockpools)		LR.FLR.Rkp.FK (Fucoids and kelp in deep eulittoral rockpools)
Sub Biotope	LR.HLR.MusB.Cht.Cht (Chthamalus spp. on exposed upper eulittoral rock)			LR.FLR.Liv.VerB (Verrucaria maura and sparse barnacles on exposed littoral fringe rock)	LR.FLR.Rkp.Cor.Cor Coralline crusts and Corallina officinalis in shallow eulittoral rockpools	LR.FLR.Rkp.Cor.Bif (Bifurcaria bifurcata in shallow eulittoral rockpools)

Below are images of the habitats and organisms you may encounter on this shore:

The exposed nature of the shore leads to an extended lichen zone; within this zone the boulder field is comparatively barren, characterised by lichen communities and periwinkles. At the lower extent of the splash zone barnacles occur at low density. Habitat classification: Biotope complex: LR.FLR.Lic.(Lichens on supralittoral and littoral fringe rock) ENUIS: B3.11 containing the biotopes: LR.FLR.Lic.YG (Yellow and grey lichens on supralittoral rock) EUNIS: B3:111 and LR.FLR.Lic.Ver (Verrucaria maura on littoral fringe rock) EUNIS: B3:113 the latter also contains the sub biotope: LR.FLR.Liv.VerB (Verrucaria maura and sparse barnacles on exposed littoral fringe rock) EUNIS: B3:1131.

Upper shore boulders support barnacles and a range of gastropods including limpets (Patella spp), thick topshells (Osilinus lineatus) and periwinkles (Littorina spp). The seaweeds Fucus sp and Catenella caespitosa and the lichen Verrucaria mucosa occur as patches on the boulders.  Habitat classification: Biotope complex LR.HLR.MusB (Mussel and/or barnacle communities) EUNIS: A1.11.

The upper shore bedrock is covered in dense barnacles (predominantly Cthamalus spp) interspersed by limpets (Patella vulgata) and patches of Lichina pygmaea. Habitat classification: LR.HLR.MusB.Cht.Cht (Chthamalus spp. on exposed upper eulittoral rock) EUNIS: A1:1121.

Within the barnacle communities tufts of fucoids are able to grow where there is sufficient shelter from wave exposure. Seaweed species also thrive within the rockpools that punctuate the shore. Small shallow coralline rockpools are covered by pink corallinaceae crusts which are in turn overgrown by ephemeral greens (Ulva spp) and a variety of reds including, coral weed (Corallina officinalis). China limpets (Patella ulyssiponensis) and juvenile blenny (Lipophrys pholis) also occur within the rockpools.  Habitat classification: LR.FLR.Rkp.Cor.Cor (Coralline crusts and Corallina officinalis in shallow eulittoral rockpools) EUNIS: A1.4111.

Deeper coralline rockpools support a higher abundance and diversity of seaweeds. Including ephemeral greens (Ulva spp and Cladophora spp), a variety of reds including, Corallinaceae crusts, Corallina sp, Mesophyllum lichenoides and the invasive brown seaweed, Sargassum muticum. S. muticum can have detrimental effects on coralline rockpools because it grows and blocks out the light, changing the environmental conditions from that which the indigenous seaweed species are adapted. Habitat classification: Habitat classification:  LR.FLR.Rkp.Cor (Coralline crust dominated shallow eulittoral rockpools) EUNIS: A1.411.

On the mid and lower shore other seaweed species are also prolific within the coralline rockpools, including (from top right to the left) ephemeral green seaweeds such as Ulva spp and Cladophora spp, the brown forking weed (Bifurcaria bifurcata) and on the lower shore brown wracks and kelp. A range of smaller epiphyte seaweed species also occur. Habitat classification: LR.FLR.Rkp.Cor (Coralline crust dominated shallow eulittoral rockpools) EUNIS: A1.411, LR.FLR.Rkp.Cor.Bif (Bifurcaria bifurcata in shallow eulittoral rockpools) EUNIS: A1.4113 and LR.FLR.Rkp.FK (Fucoids and kelp in deep eulittoral rockpools) EUNIS: A1.412.

On the lower shore the seaweeds are no longer confined to the rockpools. Thong weed (Himanthalia elongata) and kelp cover the under-storey reds. The remaining bare rock is covered by barnacles and limpets. Habitat classification: LR.HLR.FR.Him (Himanthalia elongata) and red seaweeds on exposed to moderately exposed lower eulittoral rock EUNIS: A1.123.

Other seaweed species present include a variety of robust fucoids and reds. (Anticlockwise from  top right) Fucus serratus; kelp (Laminaria sp); Mastrocarpus stellatus and Codium spp; Cladophora rupestris, reds and Corallinaceae crusts; and Corallina officinalis. Limpets, grey topshells (Gibbula cineraria) and a variety of faunal turfs also occur. Habitat classification: Biotope complex, LR.HLR.FR (Robust fucoid and/or red seaweed communities) EUNIS: A1.12).

Anticlockwise from top right, Gelidium spp and Osmundea spp, Codium spp; Gelidium spp; and Corallina spp.

Palmaria palmata and ephemeral green seaweed (Ulva spp formally Entermorpha spp).

Where conditions allow within the broader biotope complex of robust fucoid and red seaweed habitat, the robust reds may form turfs. On the lower shore these turfs are restricted to patches on boulder edges. The turf comprises Corallinaceae crust, upon which Mastrocarpus stellatus, Chondus crispus and Corallina officinalis grow, above  Lomentaria articulata, Gelidium sp and Osmundea sp occur. That rock not covered by Corallinaceae crust supports barnacles, limpets and topshells. Habitat classification: Biotope complex, LR.HLR.FR (Robust fucoid and/or red seaweed communities) EUNIS: A1.12).

At the low tide mark the red seaweed turfs extend across the rock. Young Himanthalia elongata grow among a turfs of red seaweeds that comprise, Corallinaceae crusts, Corallina officinalis, Mastrocarpus stellatus, Chondrus crispus, Osmundea sp, Gelidium sp and Lomentaria articulata.  

The low tide mark corresponds to a dramatic increase is kelp abundance and red seaweeds turfs extend over available rock. Habitat classification: ILR (Infralittoral rock).

Looking among the kelp blades you may be lucky and spot a blue rayed limpet (Patella pellucida).

A revisit to an overhang found little change since October 2014, except it was not clear to discern the presence or absence of the fried egg anemones  (Actinothoe sphyrodeta).

The same overhang in October 2014. Such overhangs provide shade, enabling subtidal species such as, fried egg anemones (Actinothoe sphyrodeta) to occur within the rockpool and enables Coralline crusts, Serpulid polychaetes  and breadcrumb sponge (Halichondria panicea)to extend up the shaded boulder sides; Grey topshells (Gibbula cineraria) also occur.