Seaweeds and rocky shores of the Outer Hebrides

Synopsis The Outer Hebrides are oceanic in character, bathed by comparatively warm waters derived from the North Atlantic Drift. The spring tide range is 3·5 m (west coast) and 4 m (east coast). The southern and western coasts include some of the most exposed shores in Britain and the steep rocky sh...

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Bibliographic Details
Published in:Proceedings of the Royal Society of Edinburgh. Section B. Biological Sciences
Main Authors: Norton, T. A., Powell, H. T.
Format: Article in Journal/Newspaper
Language:English
Published: Cambridge University Press (CUP) 1979
Subjects:
Online Access:http://dx.doi.org/10.1017/s0269727000012690
https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S0269727000012690
Description
Summary:Synopsis The Outer Hebrides are oceanic in character, bathed by comparatively warm waters derived from the North Atlantic Drift. The spring tide range is 3·5 m (west coast) and 4 m (east coast). The southern and western coasts include some of the most exposed shores in Britain and the steep rocky shores exhibit species and zonation patterns typical of north-west Britain. The sublittoral zone is mainly rocky and is dominated by beds of Laminaria hyperborea , which are very extensive west of the Uists. The eastern sides of the larger islands are much more sheltered and have numerous sea lochs many of which have great lengths of very sheltered rocky shore, dominated by extremely vigorous growths of fucoid algae, particularly Ascophyllum nodosum . Some of the lochs have extensive ramifications, with localized tidal tidal rapids supporting a rich and luxuriant flora and fauna. The paper reviews the literature on the ecology of the rocky shores, on the seaweeds in particular, and includes a full list of all seaweeds recorded in the islands with their distribution by island. (Two hundred and sixty-four species are recorded and this is about 38% of the British total.) Thus the seaweed flora is rich and diverse; the presence of selected species is discussed. The large brown seaweeds grow very luxuriantly in the Outer Hebrides and have been used by man there for many centuries. The history of this utilization is briefly reviewed. The fucoids and Laminaria spp. were formerly used extensively as a source of alkalis (sodium and potassium carbonates) and iodine. Nowadays very large tonnages of Ascophyllum are regularly harvested for the production of alginates; quantities of cast up Laminaria hyperborea are also used for this purpose.