The macrofauna of intertidal sand in the Outer Hebrides

The abundance and composition of the macrofauna of Outer Hebridean beaches is determined mainly by the degree of exposure to wave action. Most of the beaches are on the western seaboard, many without any form of shelter, and thus receive the full force of the Atlantic swell.

Twenty principal sites in Lewis and Harris were sampled for intertidal macrofauna.

Beaches of open aspect are populated by amphipods and Eurydice pulchra with very low densities of polychaetes. The sands of the Minch coast and some of the western beaches which are sheltered by islands or headlands usually have a Tellina–Nephtys association, with a tendency for Tellina tenuis to be replaced by Donax vittatus with increasing shelter. Very sheltered inlets and the fords of the Uists have a well-developed Cerastoderma-Macoma association, while Traigh Mhor in Barra, dominated by Cerastoderma edule, has the richest fauna of any beach in the Outer Hebrides.