Rock pooling destination: Bay of Laig, Eigg May 2013

The rocky shore at the Bay of Laig: Shelving bed rock juts out into the sand. Habitat classification: LR.FLR.Eph Ephermeral green or red seaweeds (Fresh water or sand influenced), LR.MLR.BF (Barnacles and fucoids on moderately exposed shores) and LR.FLR.Rkp (Rock pools).

The shore comprises shelving bedrock and boulders with shallow rock pools and narrow gullies  below which sand extends to the low water mark.

The top of the rocky shore is influenced by fresh water runoff, whilst the lower extremity is influenced by sand scour. Both these factors interact to determine the communities present.

Ephermeral green seaweed characterises areas of the upper shore where there is fresh water influx, elsewhere on the upper shore channel wrack, barnacles and periwinkles occur. As you extend further down the shore fucoids increasingly dominate the available hard substrate, until the lower rocky shore is reached and sand resistant species form bands with Fucus serratus perpendicular to the shore in relation to the shelving bedrock.

Habitat classifications:

Substrate	LR (Littoral rock)
Habitat	MLR (Moderate energy littoral rock)				FLR (Features of ilttoral rock)
Biotope complex	BF (Barnacles and fucoids on moderately exposed shores)				Eph (Ephemeral green or red seaweed communities		Rkp (Rockpools)
Biotope	LR.LMR.BF.Pel (Pelvetia canaliculata and barnacles on moderately exposed shores)	LR.MLR.BF.FspiB (Fucus spiralis on full salinity exposed to moderately exposed upper eulittoral rock)	LR.MLR.BF.Fser (Fucus serratus on moderately exposed mid eulittoral rock)	LR.MLR.BF.Rho (Rhodothamniella floridula on sand scoured lower eulittoral rock)	LR.FLR.Eph (Ephermeral green or red seaweeds (Fresh water or sand influenced)	LR.FLR.Eph.EntPor (Porphyra purpurea and Entomorpha spp. on sand scoured lower eulittoral rock)

Below are images of these habitats and the organisms you may encounter whilst rock pooling within it:

Ephermeral green seaweed characterises areas of the upper shore where there is fresh water influx. Habitat classification: LR.FLR.Eph Ephermeral green or red seaweeds (Fresh water or sand influenced).

Channel wrack (Pelvetia canaliculata), Spiral wrack (Fucus spiralis), Common blue mussel (Mytilus edulis) and barnacles on the upper shore.  Pelvetia canaliculata characterises the biotope LR.LMR.BF.Pel (Pelvetia canaliculata and barnacles on moderately exposed shores) that occurs within the broader biotope complex of LR.MLR.BF (Barnacles and fucoids on moderately exposed shores). The band of channel wrack delimits the upper extent of the biotope complex.

Channel wrack (Pelvetia canaliculata) in its reproductive phase with swollen ends to the frond known as receptacles that contain the conceptacles from which gametes are released.

Habitat classification: LR.LMR.BF.Pel (Pelvetia canaliculata and barnacles on moderately exposed shores).

 The rough and small periwinkles (Littorina spp and Melarhaphe neritoides) seek refuge within a depression of a boulder that has also been colonised by a group of barnacles. Habitat classification: LR.LMR.BF.Pel (Pelvetia canaliculata and barnacles on moderately exposed shores).

Spiral wrack (Fucus spiralis), barnacles and Limpets (Patella vulgata).  Fucus spiralis characterises the biotope LR.MLR.BF.FspiB (Fucus spiralis on full salinity exposed to moderately exposed upper eulittoral rock) that occurs within the broader biotope complex of LR.MLR.BF (Barnacles and fucoids on moderately exposed shores).

Within the crevices of the bed rock, barnacles, common blue mussels (Mytilus edulis) and rough periwinkles (Littorina saxatilis and L. Compressa) occur. Habitat classification LR.MLR.BF.FspiB (Fucus spiralis on full salinity exposed to moderately exposed upper eulittoral rock).

Fucoids exhibit a patchy distribution across the shore. Habitat classification: LR.MLR.BF (Barnacles and fucoids on moderately exposed shores).

A gully of the lower shore edged by serrated wrack (Fucus serratus). Fucus serratus characterises the biotope LR.MLR.BF.Fser (Fucus serratus on moderately exposed mid eulittoral rock) that occurs within the broader biotope complex of LR.MLR.BF (Barnacles and fucoids on moderately exposed shores).

Serrated wrack (Fucus serratus) in its reproductive phase with swollen and mottled areas on the frond known as conceptacles from which gametes are released. Habitat classification: LR.MLR.BF.Fser (Fucus serratus on moderately exposed mid eulittoral rock).

Dog whelks (Nucella lapillus) are predatory among the barnacles that comprise a mixed aged population. Habitat classification: LR.MLR.BF.Fser (Fucus serratus on moderately exposed mid eulittoral rock).

Barnacles and the common blue mussel (Mytilus edulis) occur on the ridge of a gully on the lower rocky shore. Habitat classification: LR.MLR.BF.Fser (Fucus serratus on moderately exposed mid eulittoral rock).

Barnacles on the lower shore. Habitat classification: LR.MLR.BF.Fser (Fucus serratus on moderately exposed mid eulittoral rock).

Lower down the shore the influence of the surrounding sand increases, with deposits on top of the bed rock that cause a patchy distribution of Fucus serratus and sand tolerant ephemeral green and red seaweeds. Habitat classification: LR.MLR.BF (Barnacles and fucoids on moderately exposed shores) and LR.MLR.BF.Rho (Rhodothamniella floridula on sand scoured lower eulittoral rock).

Sand binder (Rhodothamniella floridula) and Porphyra spp. are sand tolerant species associated with the biotope LR.MLR.BF.Rho (Rhodothamniella floridula on sand scoured lower eulittoral rock) that occurs within the biotope complex LR.MLR.BF (Barnacles and fucoids on moderately exposed shores).

The edges of the rocky shelves are colonized by seaweeds, each distributed within distinct bands.

Serrated wrack (Fucus serratus) occurs at the top, beneath which are the sand tolerant Mastocarpus stellatus,  porphyra and then cladophora sp. Habitat classification: LR.MLR.BF.Rho (Rhodothamniella floridula on sand scoured lower eulittoral rock).

 Sand resistant species form alternating bands with fucus serratus perpendicular to the shore in relation to the shelving bedrock and driven by exposure to sand scour. Habitat classification: LR.MLR.BF.Rho (Rhodothamniella floridula on sand scoured lower eulittoral rock) and LR.MLR.BF.Fser (Fucus serratus on moderately exposed mid eulittoral rock).

The sand tolerant Porphyra occurs on the lowest extreme of the rocky shore where sand scour is greatest and represents its own biotope LR.FLR.Eph.EntPor (Porphyra purpurea and Entomorpha spp. on sand scoured lower eulittoral rock).