Saturday, 22 June 2013

Rock pooling destination: White Island, Isles of Scilly

Rock pooling destination: White Island, Isles of Scilly, May 2013.

The high energy rocky shore of White Island is comprised of bedrock and boulders with gullies and rock pools. 
Yellow and green lichens occur in the uppermost 'splash zone' of the shore. The black tar lichen forms a band below in the uppershore, with periwinkles, limpets, mussels, beadlet anemones, barnacles and channeled wrack. The mid to low shore contains robust fucoids and rock pools rich in red seaweeds which as you descend to the lower shore form an understory below the thong weed. 

The shore comes under the broad biotope description: LR.HLR (High energy littoral rock).

Rocky Shore comprising bedrock and boulders.
Sea ivory (Ramalina siliquosa) and an orange lichen on the upper most part of the shore. Biotope classification: LR.FLR.Lic.(Lichens on supralittoral and littoral fringe rock).
Tar lichen (Verrucaria maura) forms a distinctive band across the littoral fringe rock. Biotope classification: LR.FLR.Lic.(Lichens on supralittoral and littoral fringe rock).
Small periwinkles(Melarhaphe neritoides) occur within cracks and divots on the upper shore rocks.
Channel wrack (Pelvetia canaliculata) within a crevice of the upper shore.
Common limpets (Patella vulgata) and Rough periwinkles (Littorina saxatilis) seek refuge form the high energy waves beneath an overhang and within crevices of the upper shore. 
Barnacle distribution is patchy; possibly the result of heavy molluscan grazing?
The rocky shore is hit by strong winter storms. Life 'on the edge' can be stressful and many fauna including this mussel (Mytilus edulis) seek refuge  and 'cling on' within rock crevices and ledges.
Beadlet anemone (Actinia equina) and barnacles.
Mussels (Mytilus edulis), Limpets (Patella vulgata) and Beadlet anemones (Actinia equina) cluster together within a crevice of a ledge corner. Aggregation can help to reduce desiccation by forming a micro climate around the group. 
The rocky shore is exposed to high energy storms that roll the boulders forming smooth bedrock gullies and boulders.
In areas of the shore green seaweed grows over the boulders.
A blenny in a mid shore pool.
Spiral wrack (Fucus spp) on the mid shore. Biotope classification: LR.HLR.FR  (Robust fucoids and/or red seaweed communities)
Spiral wrack (Fucus spp) and Limpets (Patella vulgata) on the mid shore.  
Limpets (Patella vulgata)
 (Osmundea spp). 
Serrated wrack (Fucus serratus) edges a pool of coral weed (Coralina officinalis) and the green seaweed Cladophora rupestris on the lower shore. 
Grape pip weed (Mastrocarpus stellatus) on the lower shore.  
Cladophora rupestris and grape pip weed (Mastrocarpus stellatus) on the lower shore.
A snakelocks anemone (Anemonia viridis) in a corallinacea pool of the lower shore.
A corallinacea crust. 
Chondrus crispus.  
 Biotope classification: LR.HLR.FR  (Robust fucoids and/or red seaweed communities)
Beadlet anemones (Actinia equina) and red seaweed turfs of the lower shore.
An overhang community of the lower shore comprised of beadlet anemone (Actinaia equina), sea squirts, hydrozoa, purse sponge (Grantia compressa), red seaweeds and painted topshell (Calliostoma zizyphinum).
Grey topshells (Gibbula cineraria) occur beneath boulders of the lower shore.
Isopods and amphipods forage amongst seaweed washed up in the gullies of the lower shore.
Thong weed (Himanthelia elongata) and Chondrus crispus on the extreme low shore.
Thong weed (Himanthelia elongata) and red seaweeds on the extreme low shore.
The early stages of Thong weed (Himanthalia elongata)  resemble buttons.
Furbellows (Saccorhiza polyschides)
Thong weed (Himanthalia elongata).

Sunday, 9 June 2013

Rock Pooling Destination: Porth Seal, Isles of Scilly, UK. April 2013

The rock pools at Porth Seal vary with those in the upper shore characterized by the green seaweeds Cladophora and Ulva spp; whilst mid shore pools are dominated by encrusting coralline algae and a variety of red and brown seaweeds; further down the shore brown seaweeds, such as Bifurcaria bifurcata and Himanthalia elongata, become more prolific within the coralline pools with red seaweeds occupying the understory. Above the pools is a mosaic of fucoids, osmundea, grazing molluscs and barnacles.

Spring storms had washed large quantities of seaweed up onto the shore where it formed mounds marking the successive strand lines and filled many of the higher to mid shore pools. The presence of the decomposing seaweed in the pools caused the water to become de-oxygenation and stagnant. The spring storms also deposited sand into many of the higher and mid shore pools that formed a thick layer over the pre-existing coralline algae and facilitated the growth of ephemeral green seaweeds such as Cladophora spp. In comparison to April 2012 these pools appeared to contain less mobile fauna (fewer gastropods and no sea hares were observed).

Below are photographs of some of the organisms in these pools:


Spring storms had washed large quantities of seaweed on the shore.

The washed up seaweed filled many of the higher to mid shore pools.

 The presence of the decomposing seaweed in the pools caused the water to become de-oxygenation and stagnant.

The rocky shore is comprised of bed rock and boulders interspersed with rockpools and gullies. Biotope classification:  LR.MLR (Moderate energy littoral rock).
 The mid and upper shore is charecterised by mosaics of barnacles and fucoids.
The shallow rock pools of the upper and mid shore that have not been smothered by sand or seaweed are charecterised by corallinacea crusts. Biotope classification:   
LR.FLR.Rkp.Cor (Coralline crust-dominated shallow eulittoral rockpools).

A corallinacea crust dominated rock pool with Coral weed (Corallina officinalis), Beadlet anemone (Actinia equina), Topshell (Gibbula umbilicus) and a blenny. 

A beadlet anemone (Actinia equina)
A mussel (Mytilus edulis)

A coralline pool dominated by ephemeral green seaweeds; coralline crusts can still be seen beneath the sand.

Sand covers the Corallinacea crust and the pool is dominated by ephemeral green seaweeds.

Mid shore pools are less effected by the deposition of seaweed and contain more seaweed species.

Coral weed (Corallina officinalis) 
Ceramium Spp 
Codium fragile 

Codium fragile on the mid shore.

 Bushy rainbow wrack (Cystoseira tamariscifolia).

Cladophora rupestris

Calliblepharis jubata


Daisy anemone (Cereus pedunculatus)

Gem anemone (Aulactinia verrucosa)

  Bifurcaria bifurcate dominates certain pools of the lower shoreBiotope classification: LR.FLR.Rkp.Cor.Bif Bifurcaria bifurcata in shallow eulittoral rockpools.

Serrated wrack (Fucus serratus) dominates the lower shore with red seaweeds beneath its understory. Biotope claasification: LR.MLR.BF.Fser.R (Fucus serratus and red seaweeds on moderately exposed lower eulittoral rock).
Red seaweeds form mosaics amongst the serrated wrack (Fucus serratus). Sand binder (Rhodothamniella floridula) forms a truf whilst Osmundea spp occurs within crevices and cracks of the boulders.

Osmundea spp

A limpet (Patella vulgata) and barnacles

Grape pip weed (Mastocarpus stellatus)

Corallinacea crust, Corallina officinalis , Bifurcaria bifurcata, The limpet Patella vulgata and snakelocks anemone (Anemonia viridis) occur on a boulder amongst Serrated wrack (Fucus serratus).

Corallinacea crust occurring on the lower shore.

Coral weeds (Corallina spp ) form dense turfs on the lower shore.

Dahlia anemone (Urticina felina)

Purse sponge (Grantia compressa)
Further down the shore Thong weed (Himanthalia elongata) occurs amongst red seaweeds.