Sunday 7 July 2013

Rock Pooling Destination: St. Martins, Isles of Scilly, UK. April 2013



On the southern side of St. Martins stretches of the mid to lower shore comprise boulders and cobbles lying on sand or, bed rock.

Fucoid seaweeds dominate the rocky shore habitat, exhibiting zonation, whilst other organisms live and seek refuge amongst the fucoid understory, in crevices, under boulders and within rock pools.


The mosaic of boulders and cobbles on sand or, bedrock provides a variety of micro habitats which in turn enables more organisms to co-exist. For example, the organisms living on top of the boulder will vary to those living underneath.


Rocky shore dominated by fucoid seaweeds.  Biotope classification: LR.LLR.F  Fucoids on sheltered marine shores.
Green seaweed (Entermorpha spp) cover the rocks to form a band above the fucoids. Habitat classification: LR.FLR.Eph (Ephemeral green seaweed communities (Sand- influenced).


Spiral wrack (Fucus spiralis). Habitat classification:  
LR.LLR.F.Fspi (Fucus spiralis on sheltered upper eulittoral rock)

Channel wrack (Pelvetia canaliculata)  occurs occasionally within this habitat.

Spiral wrack (Fucus spiralis) and thick topshell (Osilinus lineatus).
Limpet (Patella vulgata)
Rough periwinkle (Littorina spp) and barnacles
Intertidal pools form amongst the serrated wrack (Fucus serratus) of the lower shore. Looking amongst these transitory  pools you can find a variety of fauna.
Flat periwinkle (Littorina obtusata)
Flat topshell (Gibbula umbilicus)
Gem anemone (Aulactinia verrucosa)
Seaspider
Two sea slugs congregate at the base of  seaweed on the lower shore.
Sea slug
The red seaweeds, Lomentaria articulata and Osmundea spp with Serrated wrack (Fucus serratus) on the lower shore.
Ascidiacea
Limpet (Patella vulgata) covered by an encrusting red algae.
Serrated wrack (Fucus serraus), Bladder wrack (Fucus vesiculosus) and Egg wrack (Ascophyllum nodosum) with epiphytic polysiphonia form a canopy above the boulders that support limpets (Patella vulgata) and thick topshells (Osillnus lineatus).  Habitat classification: LR.LLR.F  Fucoids on sheltered marine shores.
Below the boulders in this section of the lower shore are under boulder communities- The following photos demonstrate the variety of fauna found beneath this one boulder.
A closer look at the under boulder community shown in the previous photo reveals Grey topshells (Gibbula cineraria) and spiorbid polychaete wormtubes.
Cushionstar (Asterina gibbosa), Seasquirts (Ascideacea), Painted topshell (Calliostoma zizyphinum), Bryozoa, Broad clawed porcelain crab (Porcellana platycheles) and spiorbid worm tubes form part of the under boulder community.
A scale worm also forms part of the under boulder community.
A worm pipefish (Nerophis lumbriciformis) lies motionless below the boulder.
The edges of boulders that experience fast currents support a filter feeding assemblage of  sea squirts (Ascideacea).
A solitary sea squirt (Ascideacea).
A serpulid worm.
An ophuroidea.
Risso's crab (Xantho pilipes)
A scorpian fish lays motionless.
A scorpian fish
A worm pipefish (Nerophis lumbriciformis) is motionless amongst the weed.
A worm pipefish (Nerophis lumbriciformis)
A rockling
A rockling
A goby




























































No comments:

Post a Comment