Sound of Barra
Strong tidal currents flow through the Sound of Barra, and its clear, shallow waters and sandy sea floor provide an ideal habitat for the eelgrass Zostera marina. The eelgrass beds, together with beds of maerl, are home to many species of small animals. Such rich, current-swept communities in this part of Scotland are threatened by the building of rock causeways across the sounds, which cut off the nutrient-bearing currents that are essential for healthy growth. Eelgrass also grows in nearby brackish lagoons, together with the tasselweed Ruppia maritima, which is regarded by some scientists as a type of seagrass. Forests of the kelp Laminaria hyperborea grow on rocks at the edges of the sound, and these are home to abundant sea squirts and sponges.