Rockpooling destination: St. Martins Flats, Isles of Scilly April 2014

The shore comprises outcrops of bedrock and boulders amongst vast expanses of sandon the lower shore.

Fucoids form a blanket across the rock, with dense ephemeral green alga and the occasional fucoid on the small cobbles toward the edges of the outcrops.

Periwinkles, limpets and topshells occur across the outcrop with anemones, crabs, spirorbid polychaetes and red seaweeds beneath the fucoid understorey.

Habitat classification:     

Substrate	LR (Littoral rock)					LS (Littoral substrate)
Habitat	LLR (Low energy littoral rock)			FLR (Features of littoral rock)		LS.LSa (Littoral sand)
Biotope complex	LR.LLR.F (Fucoids on sheltered marine shores)			Eph.FLR.Eph (Ephemeral green or red seaweed communities	Rkp (Rockpools)
	LR.MLR.BF.Fser.Bo (Fucus serratus and under boulder fauna on lower eulittoral boulders).	LR.LLR.F.Asc .FS (Ascophyllum nodosum on full salinity rock)	LR.LLR.F.Fserr (Fucus serratus on sheltered lower eulittoral rock).

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

The rocky shore is comprised of outcropping bedrock and boulders covered by fucoids and ephemeral green alga. Habitat classification: LR.LLR.F (Fucoids on sheltered marine shores) and LS.LSa (Littoral sand).

Rough periwinkles (Littorina saxatilis) occur on the higher rock of the outcrop. 

Bladder wrack (Fucus vesiculosus) characterises the mid shore, whilst a mix of seaweeds can be found in rockpools. Habitat classification: LR.LLR.F (Fucoids on sheltered marine shores) and LR.FLR.Rkp (Rockpools).

Lower down Limpests (Patella vulgata) and Egg wrack (Ascophyllum nodosum) with its epiphyte Polysiphonia sp occur.

Eventually the Egg wrack (Ascophyllum nodosum) and occasional serrated wrack (Fucus serratus) comes to cover the rocks. Habitat classification:  LR.LLR.F.Asc .FS (Ascophyllum nodosum on full salinity rock)

Carefully lifting the seaweed reveals the understorey community of red seaweeds, anemones, gastropods, crustaceans, spirorbid polychaetes and encrusting epifauna.

An understorey red seaweed.

An understorey red seaweed.

Corallinaceae crusts cover much of the understorey rock.

Breadcrumb sponge (Halichondria (Halichondria) panicea).

Further down serrated wrack (Fucus serratus) comes to dominate. Here the young growth of f. serratus amongst the understorey reds can be seen. Habitat classification:    LR.LLR.F.Fserr (Fucus serratus on sheltered lower eulittoral rock).

Serrated wrack (Fucus serratus).

Amongst the F. serratus and beneath the boulders is a rich faunal community, comprising an increased number of filter feeding species.  Habitat classification: LR.MLR.BF.Fser.Bo (Fucus serratus and under boulder fauna on lower eulittoral boulders).

A Montagu's crab (Xantho hydrophilus) amongst seaweed and boulders of the lower shore.

An anemone and painted topshell (Calliostoma zizyphinum)

A seaspider carrying its eggs. 

A seaspider carrying its eggs. 

A Broad-clawed porcelain crab (Porcellana platycheles) on the underside of a boulder of the lower shore.

A wart barnacle (Verruca stroemia) on the underside of a boulder on the lower shore.

Encrusting epifauna, spirorbid polychaetes and wart barnacles (Verruca stroemia) on the underside of a boulder on the lower shore.

Encrusting epifauna, including spirorbid polychaetes and bryozoa, on the underside of a boulder on the lower shore.

An anemone on the side of a boulder on the lower shore.

A capitellid polychaete.

Ephemeral green algae and brown seaweed grow on the mixed substrate surrounding the outcrop

At the low water mark, Thong weed (Himanthalia elongata) and red seaweeds come to dominate. 

Boulders at the low tide mark are colonised by a variety of seaweed species including Serrated wrack (Fucus serratus), Chondus crispus , Osmoundea sp, Thong weed (Himanthalia elongata), Lomentaria articulata and sandbinder (Rhodothamniella floridula)

A red seaweed

Red seaweeds including,Chondus crispus and Ulva sp.

Serrated wrack (Fucus serratus), Chondus crispus , Osmoundea sp and sandbinder (Rhodothamniella floridula)

Osmoundea sp

Lomentaria articulata 

Harpoon weed (Asparagopsis armata)

A close up of the epiphytic filamentous brown seaweed shows its fine frond structure.

Ceranium sp.

Ceranium sp

Creep horn (Chondracanthus acicularis)

A snakelocks anemone (Anemonia viridis)

Anemone

Away from the rocky shore outcrop great swaths of sand extend across the bay. Lugworm characterise areas of this sand habitat with their presence inferred from their casts.

Sand mason tubes also occur throughout the lower shore sand habitat.

Netted dog whelks (Nassarius reticulatus) aggregate to feed on the remains of a green shore crab (Carcinus maenas).

The Netted dog whelk (Nassarius reticulatus) uses its siphon to ‘sniff’ out food.

A necklace shell 

A necklace shell 

Majiidae crab washed up on the shore.

Rockpooling destination: Mousehole area, April 2014

The shore consists of a shelving bedrock platform with crevices and rock pools. Lichens occur in the splash zone and extend into the upper shore. Ephemeral green seaweeds occur in crevices and upper shore pools; whilst the mid and lower shore is characterised by barnacles and robust fucoids.

Habitat classifications:

Substrate	LR (Littoral rock)
Habitat	LR.HLR (High energy littoral rock)	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)	LR.FLR.Rkp.G        (Green seaweeds (Entomorpha spp. and Cladophora spp.) in shallow upper shore rock pools)

Below are images of organisms you may encounter whilst rock pooling in this habitat:

The rockyshore comprises bedrock with crevices and rockpools. Habitat classification: LR.HLR. MusB (Mussel and/or barnacle communities), LR.FLR.Lic.(Lichens on supralittoral and littoral fringe rock) and LR.FLR.Rkp (Rockpools).

Lichens occur throughout the splash zone. Habitat classification: LR.FLR.Lic.YG (Yellow and grey lichens on supralittoral rock).

Lichens in the splash zone, include the spiky Sea ivory (Ramalina siliquosa).

Lichen

Lichens

Common orange lichen (Xanthoria parietina)

Those rock pools just below the splash zone are too hostile to support ephemeral seaweeds and instead gammarid amphipods are the obvious macrofauna. Habitat classification: LR.FLR.Rkp (Rockpools).

A gammarid amphipod in an uppershore rockpool.

The rockpools of the upper shore experience fluctuations in salinity and temperature that restrict gastropod density allowing the prolific growth of ephemeral green seaweeds: Habitat classification: LR.FLR.Rkp.G  (Green seaweeds (Entomorpha spp. and Cladophora spp.) in shallow upper shore rock pools).

Ulva sp (previously Entomorpha sp) growth is restricted to the rockpools and crevices.

Ulva sp dominated rock pool of the upper shore. The edges of the rock pool appear white from the Ulva sp becoming bleached from the sun as the water level of the rock pool decreases.

Tar lichen (Verrucaria Maura) covers the rocks of the upper shore. Habitat classification: LR.FLR.Lic.Ver (Verrucaria Maura on littoral fringe rock).

Small periwinkles (Melarhaphe neritoides) occur within the V. maura biotope.

The shore exhibits a gradient in barnacle density, increasing toward the low water mark. Patches of the lichen, Lichina pygmaea occur throughout the mid shore. Habitat classification: LR.HLR. MusB (Mussel and/or barnacle communities).

The lichen, Lichina pygmaea provides refuge for small periwinkles (Melarhaphe neritoides).

Spiral wrack (Fucus spiralis) and barnacles on the mid shore.

Spiral wrack (Fucus spiralis) grows amongst the barnacles.

The spiral wrack (Fucus spiralis) exhibits a thickened stipe to resist wave action.

The density of the spiral wrack (Fucus spp) increases toward sheltered platforms of the mid and lower shore.

Small individuals of common mussels (Mytilus edulis) also find refuge with the small periwinkles (Melarhaphe neritoides) amongst the barnacles.

The dead tests of barnacles provide a refuge for limpets (Patella sp), Small periwinkles (Melarhaphe neritoides) and the young growth stages of Spiral wrack (Fucus spp).

A Dog whelk (Nucella lapillus) and Limpet (Patella sp) occur amongst barnacles whilst small periwinkles (Melarhaphe neritoides) seek refuge within the dead barnacle tests.

Beadlet anemones (Actinia equina), Dog whelks (Nucella lapillus) and limpets (Patella sp) occur within a small coralline pool with coral weed (Corallina officinalis) and Corallinaceae crusts. Habitat classification: LR.FLR.Rkp.Cor (Coralline crust dominated shallow eulittoral rockpools).

A coralline dominated rock pool with coral weed (Corallina officinalis), Corallinaceae crusts, Limpets (Patella sp) and ephemeral seaweeds.

Ephemeral green seaweeds grow on the shells of limpets, where they avoid grazing from other limpets!