Natural England - Moderate energy intertidal rock

Moderate energy intertidal rock

Rocky seashores, with some shelter from waves and currents

Moderate energy intertidal rock © JNCC

Moderate energy intertidal rock -
© JNCC

The movement of the sea across moderate energy rocky shores is strong enough to prevent much sand or mud accumulating, but these shores are not subject to the full forces of the waves and tides, so many different seashore animals and seaweeds live here.

On these shores, there are places where plants and animals can find shelter from the waves – the landward sides of boulders, in cracks and crevices, and in rock pools. Brown seaweeds are usually common everywhere on the shore, with different species occupying different zones according to how long they spend uncovered by the tide. They do not, however, form such complete blanket coverage as is the case on more sheltered rocky shores. Red seaweeds are also found on the lower shore, where they are only exposed to the air for relatively short periods. Where freshwater streams cross the shore or the rock is scoured as sand is washed across it, the plant communities will tend to be dominated by red and green seaweeds, which come and go.

Barnacles and blue mussels are common on these rocky shores, as are limpets, whelks and periwinkles

Brief description of European distribution

Moderately exposed rocky and boulder shores are found on the south-west and west coasts of Britain, where they are exposed to the prevailing south-westerly wind. They are also found on the north-east English coast. In mainland Europe, they are associated with south and west facing coastlines, where there are rocky cliffs.

Further information sources

Moderate energy littoral rockexternal link (JNCC)

Interesting fact

It isn’t easy living in a rock pool. Rock pool creatures must contend with the water becoming more salty as it evaporates, less salty when it rains and with large fluctuations in temperature.