Wednesday 20 August 2014

Rockpooling destination: Mousehole May, 2014

The shore comprises bedrock with gullies, crevices and rockpools. The variability in the bedrock topography results in a patchy distribution of habitats. Ephemeral green seaweeds characterise many of the upper and lower shore rockpools, while the mid shore is characterised by coralline seaweeds. The only seaweed to occur outside the rockpools is a band of channel wrack in the upper-mid shore, elsewhere the rock is bare. Gastropods occur across the shore.

Habitat classification:

Substrate
LR (Littoral rock)
Habitat
LR.MLR (Moderate energy littoral rock)
LR.FLR (Features of ilttoral rock)
Biotope complex
LR.MLR.BF (Barnacles and fucoids on moderately exposed shores)
LR.FLR.Rkp (Rockpools)
Biotope
LR.LMR.BF       (Pelvetia canaliculata and barnacles on moderately exposed shores)
LR.FLR.Rkp.Cor (Corallina officinalis, coralline crusts and brown seaweeds in 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 rockpooling in this habitat:

The rocky shore comprises bedrock with gullies, crevices and rockpools. Habitat classification: LR.ML (Moderate energy littoral rock), LR.FLR.Lic (Lichens on supralittoral and littoral fringe rock) and LR.FLR.Rkp (Rockpools).

A rock pipit forages stands amongst Lichens of the splash zone. Habitat classification: LR.FLR.Lic.YG (Yellow and grey lichens on supralittoral rock).

The rockpools of the upper shore experience fluctuations in salinity and temperature which restricts gastropod density, thus 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.

Thick topshells (Osilinus lineatus) aggregate above the rockpools of the upper shore.
A lichen, probably Ochrolechia parella

Due to the topographic variability of the bedrock the distribution of lichens is patchy; with yellow and green lichens simultaneously above and below tar lichen (Verrucaria Maura). However the proile of the shore reveals that the Verrucaria Maura does indeed occur at a lower altitude, and that its the bedrock that dips and then rises again. Habitat classification: LR.FLR.Lic.YG (Yellow and grey lichens on supralittoral rock) and LR.FLR.Lic.Ver (Verrucaria Maura on littoral fringe rock) both of which occur within the broader habitat LR.FLR.Lic.(Lichens on supralittoral and littoral fringe rock).



As you go further down the shore ephemeral green seaweed decreases in abundance and corallinacea crusts begin to cover the rockpool floor. Habitat classification: LR.FLR.Rkp.Cor (Coralline crust dominated shallow eulittoral rockpools).

A white blaze marks a previous lower water mark within the rockpool when the corallinacea crust became exposed and bleached by the sun.

Ephemeral green seaweed (Ulva sp) 

Channel wrack (Pelvetia canaliculata) and sparse barnacles. Habitat classification: LR.LMR.BF.PelB (Pelvetia canaliculata and barnacles on moderately exposed shores).
Channel wrack  (Pelvetia canaliculata) occurs as a band across a certain height on the shore.
Channel wrack (Pelvetia canaliculata) in its reproductive phase with swollen receptacles at the end of their fronds.
Barnacles and Small periwinkles (Melarhaphe neritoides) which seek refuge within the dead barnacle tests occur on the upper shore.

A flat periwinkle (Gibbula umbilicus) within a coralline rockpool.


A rockpool on the lower shore with ephemeral green seaweed (Ulva sp) and edible periwinkles (Littorina littorea). Habitat classification: LR.FLR.Rkp (Rockpools)
An edible periwinkle (Littorina littorea)
An edible periwinkle (Littorina littorea) and thick topshell (Osilinus lineatus).


Dead bryozoan washed up on the shore.

Dead bryozoan washed up on the shore.

The bedrock of the lower shore is bare with ephemeral green seaweeds restricted to those crevices or those areas that will become rockpools as the tide reseeds

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