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.

Rockpooling destination: Revisit Land's End peninsular: Scour tolerant and robust fucoid/red seaweed habitats

Steep cliffs surround the bay, the lower craggy edges covered in lichens. The cliff bases and steeper bedrock transition between the lichen and barnacle communities with limpets, periwinkles and whelks. Boulders and bedrock of the mid and lower shore host a similar barnacle community plus a variety of seaweeds, including where sand scour is event, ephemeral seaweeds. Rockpools occur throughout the shore, and a river flows downs from the cliffs.

The bay experiences a dynamic regime, alternating between periods of erosion and deposition. The underlying substrate is boulders and bedrock, however, variable amounts of sand may be deposited on top, sourced from the sand bar situated offshore. The communities encountered reflect the alternation between these regimes.


The shore alternates between periods of deposition (sandy)  and erosion (stony).

April 2015

September 2013                    January 2014
The overlaying sand has been eroded to reveal the boulders beneath.

At the time of visitation the cove was comprised of boulders and bedrock with an occasional thin veneer of sand.

Habitat classification:

Substrate	LR (Littoral rock)
Habitat	LR.HLR (High energy littoral rock)	LR.MLR (Moderate energy littoral rock)		LR.FLR (Features of ilttoral rock)
Biotope complex	LR.  HLR.MusB (Mussels and/or barnacles on high energy littoral rock)	LR.MLR.BF (Barnacles and fucoids on moderately exposed shores)		LR.FLR.Lic.(Lichens on supralittoral and littoral fringe rock).	LR.FLR.Rkp (Rockpools)		LR.FLR.Eph (Ephemeral green or red seaweed communities		LR.FLR.CvoV (Littoral caves and overhangs).
Biotope		LR.MLR.BF.Fser (Fucus serratus on   moderately exposed eulittoral rock)	LR.MLR.BF.Rho (Rhodothamniella floridula on sand scoured lower eulittoral rock)	LR.FLR.Lic.Ver (Verrucaria Maura on littoral fringe rock)	LR.FLR.Rkp.Cor (Coralline crust-dominated shallow eulittoral rockpools)	LR.FLR.Rckp.SwSed (Seaweeds in sediment- floored eulittoral rockpools).	LR.FLR.Eph (Ephermeral green or red   seaweeds (Fresh water or sand influenced)	LR.FLR.Eph.EntPor (Porphyra purpurea and Entomorpha spp. on sand scoured mid to  lower eulittoral rock)
Sub Biotope		LR.MLR.BF.Fser.R (Fucus serratus and red seaweeds on moderately exposed lower eulittoral rock)			LR.FLR.Rkp.Cor.Cor (Corallina officinalis and coralline crusts in shallow eulittoral rockpools)

Below are images of organisms you may encounter whilst rockpooling among the lower shore habitats:

The influences of subtidal sand scour increases on the lower shore, influencing the species found. Sand scour tolerant  seaweeds flourish, including the red seaweed, sand binder (Rhodothamniella floridula) and the ephemeral green Cladophora spp.

Sand binder (Rhodothamniella floridula) can attain high abundance on the shore. Habitat classification: LR.MLR.BF.Rho (Rhodothamniella floridula on sand scoured lower eulittoral rock)

Among the sandbinder covered rock are rockpools filled with sand . These sediment filled rockpools support a variety of  red and ephemeral green seaweeds  including, Corallina officinalis, Ahnfeltia plicata and Lomentaria articulata.  LR.FLR.Rkp.SwSed (Seaweeds in sediment-floored eulittoral rockpools) EUNIS:A1.413.

Rhodophtya within a sand filled rockpool of the lower shore.

Rhodophtya within a sand filled rockpool of the lower shore.

Rhodophtya (Polyides rotundus) within a sand filled rockpool of the lower shore.

Ulva spp

A sea hare (Aplysiomorpha) and anemone within a sand filled rockpool of the lower shore.

The green seaweed, Bryopsis spp

A juvenile crab

Anemonia viridis

The ephemeral green seaweed, Cladophora rupestris.

Seaweed abundance within the sediment filled rockpools, especially that of ephemeral greens is not as extensive as observed in October, 2014. (See blog post  http://thesaltyscavenger.blogspot.co.uk/2015/03/rockpooling-destination-revisit-of.html )

Where sand scour is reduced  serrated wrack and red seaweeds increase in abundance to form patches among the sand binder. Habitat classification: LR.MLR.BF.Fser.R (Fucus serratus and red seaweeds on moderately exposed lower eulittoral rock) and LR.MLR.BF.Rho (Rhodothamniella floridula on sand scoured lower eulittoral rock.

 The seaweeds of  LR.MLR.BF.Fser.R (Fucus serratus and red seaweeds on moderately exposed lower eulittoral rock)  include Lomentaria articulata, Mastocarpus stellatus, Fucus serratus, Chondrus crispus, Rhodothamniella floridula and Osmundea Spp.

Grey topshell (Gibbula cineraria)

Eventually Fucus cover gives way to robust reds and Himanthalia elongata. Habitat classification: LR.HLR.FR (Robust fucoids and/or red seaweed communities) EUNIS: A1.12.

Corallina officinalis forms a turf on the bedrock with robust reds, Himanthalia elongata and Laminaria spp.

Corallina officinalis forms a turf on the bedrock.

Mastrocarpus stellatus,  Rhodothamniella floridula, Laminaria spp and Himnathlia elongata.

Osmundea spp, Corallina spp  and Himnathlia elongata.

Rhodophyta

Rhodophyta

Bifurcaria bifurcata

Chondracanthus acicularis

A turf of robust reds, dominated by Mastrocarpus stellatus,  Laminaria spp and Himnathlia elongata.

Himnathlia elongata.

Edible crab (Cancer pagurus)

Sea caves on the shore provide shade allowing species who are more sensitive to sunlight  to extend their occurrence beyond that of the rockpools. Habitat classification: LR.FLR.CvoV (Littoral caves and overhangs) EUNIS: A1.44.

Corallinaceae crusts occur within and extend beyond the rockpools of the cave entrance due to the shade provided by the overhanging cliff.

Cladophora spp and Coralinaceae crusts live in the shaded entrance of the sea cave.

Corallinaceae crusts occur within a rockpool of the cave cliff edge.