Aspects Of the biology ofLaminaria hyperboreaI. vertical distribution

Abstract

SUMMARYProfiles of bottoms near the shore of the Isle of Man and two areas of Scotland are described, together with the vertical distribution of species of Laminariaceae. Laminaria digitata dominates over a narrow zone near lowwater springs. Unstable bottoms, providing they are sheltered enough to be habitable, support mainly L. saccharina. Stable bottoms of either boulders or solid rock support L. saccharina when sheltered (by topography or depth) from wave action and L. hyperborea when exposed. Near Port Erin, Isle of Man, the downward penetration of L. hyperborea on exposed rocks and boulders is limited by an as yet unknown factor which might possibly be associated with a slope of more than to the horizontal.