Rockpooling Destination: Revisit to Lerwick, Shetland, April 2015

Waiting for the tide to fall reveals a world of barnacles, seaweeds and rockpools!

The exposed to moderately exposed shore is comprised of sloping bed rock and boulders with crevices, gullies and rockpools. There is freshwater influx from a small waterfall at the base of the cliffs. 

Lichen communities occur throughout the supralittoral and littoral fringe. Below which, barnacle communities 

characterise most of the shore, interspersed by rockpools.

The shore appears similar to that in September, 2014. See blog post: 

http://thesaltyscavenger.blogspot.nl/2015/01/lerwick-shetland-2014-supralittoral-to.html

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)		LR.FLR.Lic (Lichens and small green alage on suprallitoral and littoral fringe rock)
Biotope	LR.MLR.BF.FspiB (Fucus spiralis on full salinity exposed to moderately exposed upper eulittoral rock)	LR.FLR.Rkp.Cor (Coralline crust dominated shallow eulittoral rockpools)	LR.FLR.Rkp.FK (Fucoids and Kelp in deep eulittoral rockpools)	LR.FLR.Lic.Ver (Verrucaria Maura on littoral fringe rock)	LR.FLR.Lic.YG (Yellow and grey lichens on supralittoral rock)

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

Grey and yellow lichens cover the cliff tops of the supralittoral. Habitat classification: LR.FLR.Lic.YG (Yellow and grey lichens on supralittoral rock) EUNIS: B3.111.

A variety of supralittoral lichens.

Rough periwinkles (Littorina saxatilis agg) seek refuge within a crevice.

Black tar lichen (Verrucaria maura)  and red mites occur in the littoral fringe. Habitat classification: LR.FLR.Lic.Ver (Verrucaria maura on littoral fringe rock) EUNIS: B3.113. 

The littoral fringe is relatively barren of motile life, being characterised by lichens, ephemeral green algae and periwinkles.


A seasonal strandline comprised of many hundreds of crustaceans covers the rock.


Hundreds of crustaceans washed up onto the shore.

Patchy lichens, rough periwinkles (Littorina spp) and sparse barnacles. 

Sparse barnacles and  and a Rough periwinkle (Littorina spp)

Patchy lichens, sparse barnacles and Melarhaphe neritoides.

Sparse barnacles and Melarhaphe neritoides.

Patchy lichens, sparse barnacles and limpets (Patella vulgata).


Barnacles

From the littoral fringe down, the bed rock forms large sloping slabs with gullies, crevices and rockpools. Habitat classification: LR.MLR (Moderate energy littoral rock) EUNIS: A1.2 and LR.FLR.Rkp (Rockpools) EUNIS: A1.41.

Ephemeral green and red seaweeds, including Porphyra spp form seasonal coverings over the rock of the upper shore. 

Fucoids and barnacles form a patchwork across the mid shore interspersed with rockpools. Habitat classification: LR.MLR.BF (Barnacles and fucoids on moderately exposed shores)  EUNIS: A1.21 and LR.FLR.Rkp (Rockpools) EUNIS: A1.41.

Fucoids and barnacles form a patchwork across the mid shore interspersed with rockpools.

Fucus spiralis  is the dominant fucoid. Habitat classification: LR.MLR.BF.FspiB (Fucus spiralis on full salinity exposed to moderately exposed upper eulittoral rock) EUNIS: A1.212.

Dog whelks (Nucella lapillus) can be found across the barnacle community upon which they feed. Dog whelks also feed on common mussels (Mytilus edulis), small individuals of which occur on the shore.

Barnacles

Barnacles and small individuals of the common mussel (Mytilus edulis)

Limpets (Patella vulgata) and barnacles

Nucella lapillus, Mytlius edulis and Fucus spiralis.

Shallow coralline rockpools are interspersed throughout the barnacle communities. Habitat classification: LR.FLR.Rkp.Cor (Coralline crust-dominated shallow eulittoral rockpools) EUNIS: A1.411.

Larger coralline rockpools support more species of coralline seaweeds, Cholorophyta and fucoids.

In cases many Rhodophyta, Cholorphyta and even kelp occur within the coralline rockpools of the mid and lower shore:

Rhodophyta

Rhodophyta

Corallina officinalis

Rhodophyta (Polysiphonia spp) and Gastropods

Rhodophyta (Polysiphonia spp) and Gastropods

Rhodophyta (Polysiphonia spp) and Gastropods

Rhodophyta and Gastropods

Nucella lapillus with eggs (on ledge above), sea squirts, Rhodophyta and Corallinaceae crusts.

Nucella lapillus

Limpet (Patella ulyssiponensis)

Edible periwinkle (Littorina littoria)

Edible periwinkles (Littorina littoria) aggregate within a corner of the rockpool.

Dabberlocks (Alaria esculenta) grows attached to a china limpet (Patella ulyssiponensis) as does Osmundea spp, Chlorophyta and Coralinaceae crusts, the latter also encrusts the rockpool bottom encapsulating the barnacles.

The deeper rockpools of the lower shore support kelps and fucoids. Habitat classification: LR.FLR.Rkp.  (Fucoids and kelps in deep eulittoral rockpools) EUNIS: A1.412. 

Alaria esculenta

Alaria esculenta

As the tide returns Turn stones come to feed on the shore.