Monday 11 August 2014

Rockpooling destination: St. Martins, April 2014

The rocky shore occurs throughout the mid and lower shore of a large, sheltered sweeping bay, and comprises 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 rockpools.

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.

Habitat classification:

Substrate
LR (Littoral rock)
Habitat
LLR (Low energy littoral rock)
FLR (Features of littoral rock)
Biotope complex
LR.LLR.F (Fucoids on sheltered marine shores)
Rkp (Rockpools)
Biotope
LR.LLR.F.Fserr (Fucus serratus on sheltered lower eulittoral rock)

Sub Biotope
LR.MLR.BF.Fser.Bo Fucus serratus and under-boulder fauna on lower eulittoral rocks.


Below are images of organisms you may encounter whilst rock pooling in these habitats:

The rocky shore comprises boulders and cobbles on bedrock and sand. Fucoid seaweeds form a blanket covering the rock and are a characteristic feature of the different sub habitats within the broad habitat, fucoids on sheltered marine shores (LR. LLR. F).

Bladder wrack (Fucus vesiculosus) amongst serrated wrack (Fucus serratus). A blanket of fucoids covers the shore. Habitat classification: LR. LLR.F (Fucoids on sheltered marine shores).

Common limpets (Patella vulgata) with a covering of the brown encrusting seaweed, Thick topshell (Osilinus lineatus) and barnacles occur on a boulder amongst the blanket of fucoids on the lower shore. 



Turning over the boulders reveals a different group of organisms to that above including, Berthella plumula, young whelks, cushion star (Asterina gibbosa) and Broad-clawed porcelain crab (Porcellana platycheles).Habitat classification: LR.MLR.BF.Fser.Bo Fucus serratus and under-boulder fauna on lower eulittoral rocks.

An under-boulder community of young topshells, cushion star (Asterina gibbosa), Broad-clawed porcelain crab (Porcellana platycheles) and encrusting seasquirts and bryozoans.

An under-boulder community of green sea urchin (Psammechinus miliaris), grey topshell (Gibbula cineraria) and flat topshell (Gibbula umbilicus).

Green shore crab (Carcinus maenas).

Brittlestar  and spirorbid polychaetes are both filter feeders that are found amongst the under-boulder community.

A colonial seasquirt.

Anemones occur throughout the lower shore rockpools. Habitat classification: LR.FKR.Rkp (Rockpools).

Anemones occur throughout the lower shore rockpools. 

Hermit crabs can also be found foraging amongst the rockpools.


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