Rockpooling destination: Revisit West Penwith, March 2016

The rocky shore is comprised of boulders and bedrock with rockpools, crevices and gullies. Habitat classification: LR.HLR (High energy littoral rock) EUNIS: A1.1 , LR.FLR.Rkp (Rockpools) EUNIS:A1.41 and LR.FLR.Lic.(Lichens on supralittoral and littoral fringe rock) EUNIS: B3.11

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

The high energy environment of the shore leads to an extended lichen zone, that descends over much of the boulder field, which apart from Littorinids is relatively barren. Patches of lichens extend further down into the barnacle communities, which dominate from the upper to lower shore, inter-dispersed by shallow coralline rockpools in the mid shore, and deeper cobble filled rockpools on the lower shore. As the low tide mark is reached wave tolerant seaweeds lace the gullies.

Habitat classification:

Substrate	LR (Littoral rock)
Habitat	LR.HLR (High energy littoral rock)			LR.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 sp on exposed upper eulittoral rock)	LR.HLR.MusB.Sem (Semibalanus balanoides on exposed to moderately exposed or vertical sheltered eulittoral rock)		LR.FLR.Lic.Ver (Verrucaria Maura on  littoral fringe rock)	LR.FLR.Lic.YG (Yellow and grey lichens on supralittoral rock)	LR.FLR.Rkp.Cor (Coralline crust dominated shallow eulittoral rockpools)

Below are images of the organisms you may encounter in these habitats:

Among the mobile boulders of the littoral fringe are populations of rough and small periwinkles. In this high energy environment organisms are confined to crevices and nooks, where they are buffeted from the full force of the waves and potential dislodgement. Habitat classification:  LR.FLR.Lic.(Lichens on supralittoral and littoral fringe rock) EUNIS: B3.11

Small and rough periwinkles aggregate in a boulder crevice.

Wave exposure drives the distribution of many organisms on the shore. A larger boulder provides shelter from the waves and resists rolling enabling it to support a community of limpets, periwinkles and barnacles.

Waves pick up and roll boulders that lie within the gullies ‘ grinding’ away much of the epifauna. Those that survive seek refuge within crevices of the bedrock or, occur on larger boulders/bedrock that is not subjected to the same forces.

However, during winter storms even the bedrock fractures and comes away! Demonstrating the strength of the waves hitting these shores and the ability of wave exposure  to modify the environmental conditions experienced by the organisms and/or dislodge the organisms themselves!

Exposed uppershore bedrock is covered in dense barnacles, with crevices jammed by mussels, anemones and coralline seaweeds. Small periwinkles occur among the barnacles, seeking shelter within the dead barnacle tests. The black lichen Lichina pygmaea forms tufts on the upper rock. All these organisms are characteristic of the biotope: LR.HLR.MUSb.CHT (Chthamalus sp on exposed upper eulittoral rock) EUNIS: A1.112.

Mussels (M. edulis) on the edge of a coralline rockpool

                        

At this time of year the ephemeral seaweeds within rockpools, Fucoids and some patches of Lichina pygmaea have died back.

  There is also ‘New life’ as young fucoid fronds defy the elements

On areas of lower lying bedrock and boulders seaweeds, topshells and dog whelks increase in abundance. The lichen V mucosa is characteristic of this biotope, as is an increase in fucoid and red seaweeds, such as Osmundea sp with the relative abundances varying throughout the year. Topshells, dogwhelks, anemones and Patella depressa are also characteristic. Habitat classification: LR.MUSb.Sem (Semibalanus balanoides on exposed to moderately exposed or vertical sheltered eulittoral rock) EUNIS: A1.113.

Patella depressa among barnacles and limpets.

Rhodophyta

 

Shallow coralline rockpools of the upper to mod eulittoral. Habitat classification: LR.FLR.Rkp.Cor (Coralline crust dominated shallow eulittoral rockpools) EUNIS:A1.411.

Scytosiphon lomentaria is present in some of the rockpools, as the season goes on this will be one of the most common brown seaweeds in the coralline rockpools of the upper eulittoral.

At this time of year the ephemeral seaweeds within rockpools have died back, whilst the coralline and perennial brown seaweeds are beginning to show new growth. These coralline rockpools of the mid and lower eulittoral support a greater diversity of seaweeds, including Bifurcaria bifurcata, Corallina officinalis, coralinaceae crusts and the early growths of ephemeral green seaweeds, along with beadlet anemones, china limpets, flat topshells and thick topshells.

The snakelocks anemone occurs in the shallow coralline rockpools of the lower eulittoral.

Seaweeds are almost absent from the rockpools of the lower shore at this time of year. Possible due to the ‘grinding’ nature within these pools during this time of year. The only seaweed to persist is an ephemeral green.

Rockpooling Destination: Revisit West Penwith, December, 2015

The rocky shore is comprised of boulders and bedrock with rockpools, crevices and gullies. Habitat classification: LR.HLR (High energy littoral rock) EUNIS: A1.1 , LR.FLR.Rkp (Rockpools) EUNIS:A1.41 and LR.FLR.Lic.(Lichens on supralittoral and littoral fringe rock) EUNIS: B3.11

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

The high energy environment of the shore leads to an extended lichen zone, that descends over much of the boulder field, which apart from Littorinids is relatively barren. Patches of lichens extend further down into the barnacle communities, which dominate from the upper to lower shore, interdispersed by shallow coralline rockpools in the mid shore, and deeper cobble filled rockpools on the lower shore. As the low tide mark is reached wave tolerant seaweeds lace the gullies.

Habitat classification:

Substrate	LR (Littoral rock)
Habitat	LR.HLR (High energy littoral rock)			LR.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 sp on exposed upper eulittoral rock)	LR.HLR.MusB.Sem (Semibalanus balanoides on exposed to moderately exposed or vertical sheltered eulittoral rock)		LR.FLR.Lic.Ver (Verrucaria Maura on  littoral fringe rock)	LR.FLR.Lic.YG (Yellow and grey lichens on supralittoral rock)	LR.FLR.Rkp.Cor (Coralline crust dominated shallow eulittoral rockpools)

Below are images of the organisms you may encounter in these habitats:

A 'By the wind sailor' (Velella velella)  washed up high onto the shore. This is a pelagic hydrozoa that is often washed up onto shores during the winter months.

Lichens have a patchy distribution, covering the larger and more stable boulders and bedrock of the supralittoral and littoral fringe rock. Habitat classification: LR.FLR.Lic.(Lichens on supralittoral and littoral fringe rock) EUNIS: B3.11.

Many boulders are too mobile to facilitate lichen growth, in such circumstances lichen growth is restricted to areas surrounding 'protected' crevices.

The boulders of the littoral fringe support a community of  rough and small periwinkles with seasonal growths of green ephemeral seaweeds. Towards the lower extend of the littoral fringe rock, sparse barnacles are found. On the boulders where the V. maura is absent the littoral fringe is identified by the presence of other organisms, including rough (Littorina saxatilis) and small periwinkles (Melarhaphe neritoides) and sparse barnacles. The ineffective application of the JNCC and EUNIS habitat classification to the littoral fringe boulder habitat is rectified by the much broader 1993 phase 1 habitat classification which seems to capture these environments under the boulder habitat classification which is in turn is listed under the EUNIS website as comparable to the habitat classification supralittoral rock (lichen or splash zone).

On stable bedrock and larger boulders  V. maura is evident. Common limpets (Patella vulgata), sparse barnacles and an increased diversity of periwinkles (Littorina sp)are also present. The mobile organisms congregate within crevices, nooks and crannies or the leeward sides of rock in a bid to avoid wave exposure.

Littorinid identifications helped by Ian Smith..... 

Rough periwinkles (Littorina saxatilis agg)

Rough periwinkles (Littorina saxatilis agg)

Rough periwinkles (Littorina compressa)

Rough periwinkles (Littorina compressa)

Rough periwinkles (Littorina sp)

The bedrock of the upper eulittoral supports barnacle communities and shallow coralline rockpools. Patches of the lichen, Lichina pygmaea occur on certain rock faces, as does Verrucaria mucosa, whilst the crevices support mussels (Mytilus edulis), periwinkles and  beadlet anemones (Actina equina). Habitat classification: LR.HLR.MusB.Cht (Chthamalus sp on exposed upper eulittoral rock) EUNIS: A1.112 and LR.HLR.MusB.Sem (Semibalanus balanoides on exposed to moderately exposed or vertical sheltered eulittoral rock) EUNIS: A1.113.

Patches of Lichina pygmaea show seasonal die back.

Barnacles

Coralline rockpools occur throughout the bedrock of the eulittoral. During the winter months the ephemeral seaweeds of the pools have died back, as too has those corallinaceae crusts that were exposed to the sun. China limpets (Patella ulyssiponensis),  M. edulis and the seaweeds Corallinaceae crusts, Corallina officinalis, Chondrus crispus and ephemeral greens can be found within these pools. Habitat classification: LR.FLR.Rkp.Cor (Coralline crust dominated shallow eulittoral rockpools) EUNIS: A1.411.

Mid eulittoral bedrock and less stable boulders, support a more patchy distribution of barnacles, and appear 'pinker' as the granite colour can be seen. Robust fucoids cling on in this environment and between the boulders are filter feeders and robust red seaweeds and beadlet anemones (Actina equina) and among boulders in sheltered gullies are dog whelks (Nucella lapillus) and topshells. Habitat classification: LR.HLR.MusB.Sem (Semibalanus balanoides on exposed to moderately exposed or vertical sheltered eulittoral rock) EUNIS: A1.113.

A flat topshell (Littorina sp) found among the robust fucoids.

Where wave exposure and scour from pebbles and cobbles is high, faunal cover is low.

Bedrock of the lower eulittoral supports an ever increasing diversity of filter feeders, that form 'turfs' with the robust red seaweeds.Habitat classification: LR.HLR.FR (Robust fucoid and/or red seaweed communities) EUNIS: A1.12

Sponges occur beneath shaded over hangs.

Red seaweeds including, Palmaria palmata, Corallinaceae crusts and foliose reds, lace a gully of the lower eulittoral. 

Red seaweed diversity is highest on the lower eulittoral, comprising Calliblepharis sp, Fucus serratus,  Chondrus crispus, Mastrocarous stellatus, Corallinaceae crusts, Corallina officinalis,  Geldium sp and others.

The coralline rockpools of the lower eulittoral support higher densities and diversity of red seaweeds and anemones. Habitat classification: LR.FLR.Rkp.Cor (Coralline crust dominated shallow eulittoral rockpools) EUNIS: A1.411.

In those rockpools filled with coarser sediment the diversity is less.

Rockpooling Destination: Revisit Hemsby, March 2016

The intertidal sediments experience periods of erosion and deposition which in turn influence the sediments and organisms found or washed up on the shore.



In March the strandlines separate in to an upper, comprised of bryozoa (predominantly Flustra foliacea) and a lower, comprised of red seaweeds (predominantly combweed, Plocamium sp).

The sediments of the shore in March, comprise coarser elements than during the summer.

March 2016

The shore in Summer, 2014



Characterising species of the littoral fringe rock

           

The littoral fringe zone occurs between the supralittoral and eulittoral zones and in some cases is considered a terrestrial habitat i.e. within the EUNIS classification it is placed with the coastal habitats and the supralittoral and littoral fringe lichen communities come under the one broad habitat complex, Lichens or small green algae on supralittoral and littoral fringe rock B3.11. 

The littoral fringe receives the salt spray from the waves, as such, those shores experiencing greater exposure and salt spray from waves have larger littoral fringe zones. Rock altitude, angle, shade and local climate also influence the extent of the zone. These factors also effect the distinction between the supralittoral and littoral fringe communities so that sometimes they are distinct or are intermingled.

The littoral fringe zone is often characterised by rocks covered in the black tar lichen (Verrucaria maura), rough periwinkles, channel wrack, ephemeral seaweeds, sparse barnacles and pools with variable salinity and temperatures. 

Other organisms that come under the broad lichen habitat complex (LR.FLR.Lic) that are also characteristic of littoral fringe communities are green seaweeds such as Blidingia sp, Ulothrix sp and Urospora sp that can characterise areas of littoral fringe soft rock or vertical rock where there is fresh water run off. 

The organisms living in this zone are highly specialized to endure variable salinity and extended periods of air exposure.  

The littoral fringe can often be discernible from a distance by the presence of the black tar lichen (Verrucaria maura) that covers the rock, above which the rocks of the supralittoral appear light grey whilst below the rocks of the eulittoral appear beige.

High wave exposure leads to an extended splash zone enabling lichens to colonise further up the cliffs. In the photograph above two distinct bands of differing lichen communities can be seen. At the highest position on the supralittoral are yellow and grey lichens, whilst on the littoral fringe below V. maura covers the bedrock. Habitat classification: LR.FLR.Lic.YG (Yellow and grey lichens on supralittoral rock) EUNIS: B3111 and LR.FLR.Lic.Ver (Verrucaria maura on littoral fringe rock) EUNIS: B3.113.

Variations in rock altitude can lead to a mosaic like distribution of the supralittoral and littoral fringe lichen communities. Also at this altitude on the shore fluctuating temperatures and salinity lead to prolific growth of Ulva spp (formally Entomorpha spp) in some of the rockpools. Habitat classification: LR.FLR.Lic.YG (Yellow and grey lichens on supralittoral rock) EUNIS: B3111, LR.FLR.Lic.Ver (Verrucaria maura on littoral fringe rock) EUNIS: B3.113 and  LR.FLR.Rkp.G (Green seaweeds (Entomorpha spp. and Cladophora spp.) in shallow upper shore rock pools) EUNIS: A1.421. 

The lichen communities are not always present on unstable rock substrates, and this can make the distinction between the the supralittoral and littoral fringe difficult. On the shore above the supralittoral and littoral fringe rock is distinguishable by its 'white colour' as these boulders do not experience daily submergence. The yellow and grey lichens of the supralittoral are able to grow on the boulders of the most upper shore that have been thrown up during storms and are only rolled during the most extreme storms, however the remaining boulders of the supralittoral and littoral fringe are rolled just enough during periodic storms to prevent their growth.

On the shore above the boulders are larger and more stable allowing for a more established and diverse lichen community to develop. The black tar lichen (V. maura) is still absent from many of the boulders that would occupy the altitude of the littoral fringe but does occur on the bedrock of this height. On the boulders where the V. maura is absent the littoral fringe is identified by the presence of other organisms, including rough (Littorina saxatilis) and small periwinkles (Melarhaphe neritoides) and sparse barnacles. The ineffective application of the JNCC and EUNIS habitat classification to the littoral fringe boulder habitat is rectified by the much broader 1993 phase 1 habitat classification which seems to capture these environments under the boulder habitat classification which is in turn listed under the EUNIS website as comparable to the habitat classification supralittoral rock (lichen or splash zone).

On stable bedrock the black lichen, V. maura is one of the most characteristic species of the littoral fringe. Living among this lichen you may also encounter L. saxatilis, ephemeral seaweeds and sparse barnacles. Because of the extended period of exposure the organisms tend to aggregate in crevices or shaded areas in order to reduce desiccation. The rockpools of the littoral fringe are species poor. Fluctuating temperatures and salinity lead to prolific growth of Ulva spp (formally Entomorpha spp) in some of the rockpools whilst others support the occassional amphipod. Habitat classification: LR.FLR.Lic.Ver (Verrucaria maura on littoral fringe rock) EUNIS: B3.113 and  LR.FLR.Rkp.G (Green seaweeds (Entomorpha spp. and Cladophora spp.) in shallow upper shore rock pools) EUNIS: A1.421. 

A characteristic species of the lower littoral fringe rock of some shores is channel wrack (Pelvetia canaliculata) and on moderately exposed shores an accompanying spare barnacle community. Habitat classification: LR.MLR.BF.PelB (Pelvetia canaliculata and barnacles on moderately exposed littoral fringe rock) EUNIS: A1.211.

P. canaliculata cover increases on sheltered shores and the there is no associated barnacle community. Habitat classification: LR.LLR.F.Pel (Pelvetia canaliculata on sheltered littoral fringe rock) EUNIS: A1.321.

Rockpooling destination: Hemsby, March 2016

During the months of February and March the eggcases of a variety of rays, skates and catshark are washed up onto the Norfolk shores. Common eggcases that can be found include the Thornback and Spotted ray and the curly ended eggcases of the catshark. Sometimes you can find the larger Blonde ray eggcases.

A walk along the shore turned up some nice mermaid purses and lots of the bryozoan, Flustra foliacea.

Unexpected creatures of the intertidal: Featherstar

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