Rockpooling destination: West Penwith, Cornwall September 2013

The rocky shore is a high energy environment comprised of boulders and bedrock with rock pools and gullies on the lower shore.

Fauna are relatively sparse amongst the boulder field, with the upper most shore characterised by lichens, below which periwinkles seek refuge amongst boulder crevices. Further down the shore barnacles increase in abundance and anemones and mussels occur within crevices with damper crevices and shallow rockpools characterised by coralline algae. At the low water mark deeper rockpools and gullies are characterised by a variety of wave tolerant seaweeds. 

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.FLR.Lic.(Lichens on supralittoral and littoral fringe rock).		LR.FLR.Rkp (Rockpools)
Biotope		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)
SubBiotope				LR.FLR.Rkp.Cor.Bif (Bifurcaria bifurcata in shallow eulittoral rockpools)

Below are images of the organisms you may encounter in this habitat:

The rocky shore is comprised of boulders and bedrock with rock pools and gullies in the lower shore. Habitat Classification: LR.HLR (High energy littoral rock) and LR.FLR.Rkp (Rockpools).

The supralittoral shore is characterised by yellow and green lichens. Habitat classification: LR.FLR.Lic.YG (Yellow and grey lichens on supralittoral rock).

Sea ivory (Ramalina siliquosa) and common orange lichen (Xanthoria parietina).

Orange and Tar lichens (Verrucaria Maura) form a sparse covering over a boulder in the upper shore. The presence of Verrucaria Maura characterises the habitat LR.FLR.Lic.Ver (Verrucaria Maura on littoral fringe rock).

Fauna in the upper shore is relatively sparse. 

In this high energy environment fauna seek refuge within crevices or depressions of the boulders. Rough periwinkles (Littorina saxatilis agg.) and the small periwinkle (Melarhaphe neritoides) seek refuge within a crevice. 

Rough periwinkles (Littorina saxatilis agg.) and the small periwinkle (Melarhaphe neritoides) seek refuge within a crevice.

Small periwnkles (Melarhaphe neritoides) seek refuge within a depression of a boulder. 

Small periwnkles (Melarhaphe neritoides) seek refuge within a depression of a boulder. 

The distribution of barnacles is patchy and sparse. 

A Rough periwinkle (Littorina saxatilis agg.).

The mid shore is characterised by an increased abundance of barnacles with patches of Lichina pygmaea Habitat classification: LR.HLR. MusB (Mussel and/or barnacle communities

Small periwinkles (Melarhaphe neritoides) aggregated amongst the Lichina pygmaea. 

Barnacles and limpets (Patella vulgata) are characteristic of barnacle communities.

Barnacles, Small periwinkles (Melarhaphe neritoides), Rough periwinkles (Littorina compressa var. nigrolineata) and limpets (Patella vulgata) occur together in the mid shore.

The distribution of fauna reflects the high energy regime of the shore. Limpets show an aggregated distribution on the leeward side of boulders where they gain shelter from wave exposure. 

Limpets (Patella vulgata), anemones (Actinia equina) and thick topshells (Osilinus lineatus) occur in crevices and pits of the bed rock. Barnacles are less prolific due to increased predation of settling juveniles by grazing molluscs. Habitat classification: LR.HLR. MusB (Mussel and/or barnacle communities).

A damp crevice provides suitable habitat for coral weed (Corallina officinalis), Common mussels (Mytilus edulis), Rough periwinkles (Littorina sp), limpets and barnacles.

Dog whelks (Nucella lapillus) predate barnacles and mussels on the shore. 

Rock pools occur throughout the bedrock of the lower shore, but their altitude makes environmental conditions more like mid shore rock pools. Habitat classification: LR.FLR.Rkp (Rockpools).

These small shallow rock pools are dominated by coralline crusts. Habitat classification: LR.FLR.Rkp.Cor (Coralline crust dominated shallow eulittoral rockpools).

Small common mussels (Mytilus edulis) and beadlet anemones (Actinia equina) occur in crevices of larger coralline rock pools. Limpets and gastropods graze the coralline rock pool so that foliose seaweeds are restricted; ephemeral green seaweeds are able to grow by using limpet shells as a refuge from predation. 

A coralline dominated rock pool.

Deeper coralline pools support a wider variety of seaweeds, including ephemeral green seaweeds, foliose reds and an increased abundance of Coral weed (Corallina officinalis),Common mussel (Mytilus edulis) and limpets.

Lower down the shore the brown seaweed Bifurcaria bifurcata comes to co- dominate the coralline rockpools. A variant of the coralline biotope called LR.FLR.Rkp.Cor.Bif (Bifurcaria bifurcata in shallow eulittoral rockpools).

Rock pools on the lower shore Habitat classification. LR.FLR.Rkp (Rockpools).

 A rockpooling trip in July enabled further exploration of the lower shore rock pools.

July 2013

The lower shore rock pools are deeper accommodating more seaweed species Corallinaceae crusts still blankets the rock pools, becoming bleached white when exposed to the air as the water level of the rock pools drop. Habitat classification: LR.FLR.Rkp.Cor.Bif (Bifurcaria bifurcata in shallow eulittoral rockpools).

 Corallinacea crusts cover the rock surface of the coralline rock pools. Habitat classification: LR.FLR.Rkp.Cor.Bif (Bifurcaria bifurcata in shallow eulittoral rockpools).

Bifurcaria bifurcata in a  coraline rock pool. Habitat classification: LR.FLR.Rkp.Cor.Bif (Bifurcaria bifurcata in shallow eulittoral rockpools).

Corallina officinalis forms dence turfs in the rockpools. Habitat classification: LR.FLR.Rkp.Cor.Bif (Bifurcaria bifurcata in shallow eulittoral rockpools).

Corallina officinalis forms dence turfs amongst which emphermal green algae grows. Habitat classification: LR.FLR.Rkp.Cor.Bif (Bifurcaria bifurcata in shallow eulittoral rockpools).

Corallina officinalis, emphermal green algae Ulva sp, jap weed (Sargassum muticum) and Bifurcaria bifurcata within a coralline rockpool. Habitat classification: LR.FLR.Rkp.Cor.Bif (Bifurcaria bifurcata in shallow eulittoral rockpools).

Thick top shells (Osilinus lineatus) graze within the rock pools. Habitat classification: LR.FLR.Rkp.Cor.Bif (Bifurcaria bifurcata in shallow eulittoral rockpools).

Land’s End Peninsula, England, August 2012

Rock pooling destination: Land’s End Peninsula, England, 2012

The bay experiences a dynamic regime, alternating between periods of erosion and deposition. The underlying substrate is boulders, 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.

At the time of visitation the beach was mainly sand with boulders exposed in the region of the river and amongst out cropping bedrock in the mid to lower shore.

The highest abundances of organism are encountered on the most persistent substrate, which is the hard substrate that does not experience sand deposition, mainly the steep sloping bedrock that forms the base of the cliff and represents the upper shore. This environment is dominated by barnacles, with limpets, periwinkles, whelks and the coral weed Corallina officnalis all of which are characteristic of a high energy regime environment.

The lower shore is more characteristic of a moderate energy regime with focuids and the red seaweed Mastocarpus stellatus covering boulders and bedrock, additionally Rhodothamniella floridula is present where sand scours the boulders.

The hard substrate of the upper shore can broadly be characterised under the habitat classification: LR.HLR.MusB (Mussel and/or barnacle communities) and the hard substrate of the mid and lower shore can be broadly characterised under the habitat classification: LR.MLR.BF (Barnacles and fucoids on moderately exposed shores); whilst the sand can be characterised as LS.LSa (Sublittoral sand).

Below are photographs of some of the organisms

encountered whilst rock pooling in this habitat.

Fresh water influx to the shore.

The sediment type of the beach varies temporally between sand and boulders; the river
has washed away the superficial layer of sand to reveal the boulders that occur across the bay beneath the sand.

Barnacles and Lipets (Patella vulgata).
Habitat classification: LR.HLR.MusB (Mussel and/or barnacle communities)

Dog whelk (Nucella lapillus).

Mastocarpus stellatus

Coralline algae are confined to the crevise where water seeps from a rock pool above.

Limpets (Patella vulgata) attach themselves to a boulder that has been covered by sand.

Strand line of kelp and Ulva spp.

Barnacles and Limpets (Patella vulgata).



Serrated wrack (Fucus serratus). Habitat classification: LR.MLR.BF
(Barnacles and fucoids on moderately exposed shores).

Serrated wrack (Fucus serratus).

Mastrocarpus stellatus and sand binder (Rhodothamniella floridula).
Biotope classification: LR.MLR.BF.Rho (Rhodothamniella floridula on sand scoured
lower eulittoral rock).

Mastrocarpus stellatus and serrated wrack (Fucus serratus).

Codium spp in shallow sand pool of the lower shore.

Beadlet anemone (Actinia equina).



Ulva spp and Cladophora in a sand scoured pool of the lower shore.
These species are able to grow quickly and can persist during the alternating regimes.



Ulva spp and Cladophora in a sand scoured pool of the lower shore.

Grey Atlantic Seals frequent the bay.