Tuesday, 19 May 2015

Rockpooling Destination: Lamorna, December 2014

The shore is positioned within in a small cove, with a crumbled down harbour wall. Boulders back the cove giving way to sand on the lower shore and a river runs over and under the boulders down to the sea. The harbour wall had relatively recently fallen into disrepair and where the wall has broken down, slabs of rock that were once positioned in the sublittoral have been washed up the shore, to occupy a position in the intertidal. The result is that 'at present' species usually found in the subtidal can be seen in the intertidal.






The shore is comprised of boulders that give way to sand on the lower shore.

A strandline has formed on the sandy shore. Habitat classification: LS.LSa (Littoral sand) and  LS.LSa.St (Strandline) EUNIS: A2.21.


Periwinkles and sparse barnacles aggregate within crevices and pits of the boulders of the upper shore, whilst below ephemeral algae cover boulders that experience sand scour from the adjacent sand below. 

Small periwinkles (Melarhaphe neritoides), rough periwinkles (Littorina sp) and sparse barnacles aggregate in a crevice of a boulder. 
Small periwinkles (Melarhaphe neritoides), rough periwinkles (Littorina sp) and sparse barnacles aggregate in a crevice of a boulder.
Small periwinkles (Melarhaphe neritoides) utilize the pits of the boulder.
Small periwinkles (Melarhaphe neritoides) utilize the pits of the boulder.
Ephemeral green algae covers the boulders that are adjacent to the sand and experience sand scour. Habitat classification: Eph.FLR.Eph (Ephemeral green or red seaweed communities) EUNIS A1.45.

Ephemeral green algae


The red ephemeral algae, Porphyra sp also grows on the boulders affected by sand scour.

The harbour wall provides a hard substrate upon which organisms can grow and feed.

Damp conditions at the base of the harbour wall facilitate the growth of coralline crusts, red seaweeds, polychaete worm tubes and anemones, whilst above barnacles and mussels occur.
Small periwinkles (Melarhaphe neritoides), rough periwinkles (Littorina compressa) and sparse barnacles.

Limpets (Patella spp) and barnacles are the most prominant species of the harbour wall. Habitat classification: LR.HLR. MusB (Mussel and/or barnacle communities) EUNIS A1.11.


Other organisms are restricted to crevices and damp patches at the base of the harbour wall. Here a common blue mussel (Mytilus edulis)  exploits a crevice of the harbour wall.
         

Red seaweeds occur in patches on the lower extents of the harbour wall, Mastrocarpus stellatus


Mastrocarpus stellatus




A red seaweed



Barnacle and beadlet anemone  (Actina equina) abundance reaches its highest at a height on the wall where exposure and sand scour reach a trade off.

A damp area at the base of the wall facilitates the growth of Coralline crusts and limpets increase in abundance.

Spirobid polychaete worm tubes also occur within this damp patch.


Beadlet anemones (Actina equina) also occur on the cobbles beneath the harbour wall.
On parts of the harbour wall that have been washed up, sublittoral species are now found in the intertidal. Here you can see serpulid polychaete worm tubes.



 A chiton and serpulid polychaete  (Pomatoceros triqueter).



A chiton finds protection within a depression of the rock.


Limpets

A serpulid worm tube (Pomatoceros triqueter)



Serpulid worm tubes  (Pomatoceros triqueter).
Gastropods aggregate within the protection of the serpulid  worm tube  (Pomatoceros triqueter).


Gastropods within Ulva spp.


A blue rayed limpet (Patella pellucida)



A limpet (Patella depressa)


Bryozoan


Flat topshell (Gibbula umbilicus)

Barnacles

Barnacles (Balanus perforatus)
Limpets, rough periwinkles (Littorina compressa v nigrolineata), beadlet anemone (Actina equina), barnacles (Balanus perforatus) and Lomentaria articulata..













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