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The inland waters of the Outer Hebrides

Published online by Cambridge University Press:  05 December 2011

A. R. Waterston ,
A. V. Holden ,
R. N. Campbell  and
P. S. Maitland
A. R. Waterston
Affiliation:
Royal Scottish Museum, Edinburgh
A. V. Holden
Affiliation:
Freshwater Fisheries Laboratory, Pitlochry
R. N. Campbell
Affiliation:
Nature Conservancy Council, Inverness
P. S. Maitland
Affiliation:
Institute of Terrestrial Ecology, Edinburgh
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Synopsis

The Outer Hebrides comprise approximately 1·3% of the land area but 15·8% of the area of standing waters of Great Britain. Streams there are generally small and only three are as large as fifth order. The majority of the lochs occur below 200 m altitude and are less than 25 ha in area. A total of 1375 stream systems enter the sea, and drain the land mass through 9240 stream segments. There are just over 6000 lochs, of which less than half are connected to these networks. Most of the water systems are on geologically base-poor rock or soil, and less than 3%, situated on machair, are base-rich and eutrophic. The islands, due to their situation, receive precipitation in the form of very dilute sea water (with some non-marine sulphate probably derived from fossil fuel combustion) and this leads to unusual concentrations of chloride in the inland waters. Metamorphic rocks are resistant to weathering, so there is usually little variation in the composition of fresh waters except in the machair areas, where calcareous sands affect calcium concentrations and alkalinities.

The flora and fauna reflect the aqueous conditions and there are some unique successions of species from high to low salinities even in the same water body. The lochs provide a wide range of habitats for aquatic vegetation, ranging from the rich machair lochs to the oligotrophic peaty lochs (which show marked similarities with their counterparts on the mainland). Three broad categories can be delineated on the basis of their water quality and vegetation: brackish lochs with varying degrees of marine influence, calcareous machair lochs which may also be affected by sea connections, and the peaty lochans of low alkalinity. A few brackish water animals are sufficiently euryhaline to exist in the machair lochs, which are otherwise dominated by freshwater species. The occurrence of chloride in inland waters enables some crustaceans, e.g. Neomysis integer, Gammarus duebeni and Diaptomus wierzejskii to extend into what are poor freshwater habitats. The main constituents of the freshwater fauna are molluscs and arthropods, and a few species of euryhaline fishes, i.e. salmon, sea and brown trout, three-spined and ten-spined sticklebacks and eels. There are some populations of non-migratory charr. No amphibians are present.

Type
Research Article
Information
Proceedings of the Royal Society of Edinburgh, Section B: Biological Sciences , Volume 77: The Natural Environment of the Outer Hebrides , 1979 , pp. 329 - 351
Copyright
Copyright © Royal Society of Edinburgh 1979

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References

Annandale, N., 1908. Notes on some freshwater sponges collected in Scotland. J. Linn. Soc. Zool., 30, 244–250.CrossRefGoogle Scholar
Balfour-Browne, F., 1914. Field Notebook, vol. 6. In: Library, Royal Scottish Museum, Edinburgh.Google Scholar
Balfour-Browne, F., 1915. The aquatic Coleoptera of the Outer Hebrides. Scott. Nat., 1915, 13–20, 59–67, 89–92, 106–111.Google Scholar
Balfour-Browne, F., 1938. The aquatic Coleoptera of the Outer Hebrides. 2nd Paper. Scott. Nat., 1938, 33–46.Google Scholar
Balfour-Browne, F., 1953. The aquatic Coleoptera of the western Scottish islands with a discussion of their sources of origin and means of arrival. Entomologist's Gaz., 4, 79–127.Google Scholar
Campbell, R. N., 1971. The growth of brown trout Salmo trutta L. in northern Scottish lochs with special reference to the improvement of fisheries. J. Fish. Biol., 3, 1–28.CrossRefGoogle Scholar
Campbell, R. N. and Williamson, R. B., 1979. The fishes of inland waters in the Outer Hebrides. Proc. Roy. Soc. Edinb., 77B, 377–393.Google Scholar
Elton, C., 1937. Notes on freshwater animals in the Isle of Lewis, Outer Hebrides. Proc. Zool. Soc. Lond., 1937, 939–944.CrossRefGoogle Scholar
Fleming, K. M. G., 1936. Turbellaria and Nematomorpha. In: The natural history of Barra, Outer Hebrides, pp. 262–265. (Forrest, J. E. et al. , 1936, see below.)Google Scholar
Forrest, J. E., Waterston, A. R. and Watson, E. V., 1936. The natural history of Barra, Outer Hebrides. Proc. Roy. Phys. Soc. Edinb., 22, 241–296.Google Scholar
Gurney, R., 1931. The British Freshwater Copepoda, 1. London.CrossRefGoogle Scholar
Hamilton, J. D., 1963. The freshwater fauna of Hirta, St Kilda. Glasg. Nat., 18, 233–241.Google Scholar
Hewitt, J., 1910. Some distinctive characters in the freshwater plankton from various islands off the north and west coasts of Scotland. Rep. Scient. Results Bathymetr. Surv. Scot. Freshw. Lochs, 1, 335–353, 6 pls.Google Scholar
Holden, A. V., 1961. Concentration of chloride in freshwaters and rain water. Nature, Lond., 192, 961–962.CrossRefGoogle Scholar
Holden, A. V., 1966. A chemical study of rain and stream waters in the Scottish Highlands. Freshwat. Salm. Fish. Res., No. 37, 17 pp.Google Scholar
Horton, R. E., 1945. Erosional development of streams and their drainage basins: hydrophysical approach to quantitative morphology. Bull. Geol. Soc. Am., 56, 275–370.CrossRefGoogle Scholar
Hunter, W. R. and Warwick, T., 1957. Records of Potamopyrgus jenkinsi (Smith) in Scottish fresh waters over fifty years (1905–56). Proc. Roy. Soc. Edinb., 66B, 360–373.Google Scholar
Lewis, J. R., 1957. An introduction to the intertidal ecology of the rocky shores of a Hebridean island. Oikos, 8, 130–160.CrossRefGoogle Scholar
Lind, E. M., 1952. The phytoplankton of some lochs in South Uist and Rhum. Trans. Bot. Soc. Edinb., 36, 37–47.CrossRefGoogle Scholar
Lindroth, C. H., 1957. The Faunal Connections Between Europe and North America. New York.CrossRefGoogle Scholar
Maitland, P. S., 1976. Fish in the large freshwater lochs of Scotland. J. Scott. Wildl., 12, 13–17.Google Scholar
Mason, O., 1977. Gazetteer of Britain. Edinburgh: Bartholomew.Google Scholar
McIntosh, W. C., 1866. Observations on the marine zoology of North Uist. Proc. Roy. Soc. Edinb., 5, 600–614.Google Scholar
Monro, D., 1774. A Description of the Western Islands of Scotland. Edinburgh.Google Scholar
Murray, James 1905. On the distribution of the pelagic organisms in Scottish lakes. Proc. Roy. Phys. Soc. Edinb., 16, 51–62.Google Scholar
Murray, John and Pullar, L., 1910. Bathymetrical survey of the Scottish freshwater lochs. Rep. Scient. Results Bathymetr. Surv. Scot. Freshw. Lochs., 2, 183–221; 6, pls. 68–89.Google Scholar
Nicol, E. A. T., 1936a. The Brackish-water lochs of North Uist. Proc. Roy. Soc. Edinb., 56, 169–195.CrossRefGoogle Scholar
Nicol, E. A. T., 1936b. The fauna of Loch Bee. Scott. Nat., 1936, 131–134.Google Scholar
OECD, 1977. Long-range Transport of Air Pollutants. Measurements and Findings. Paris: OECD.Google Scholar
Reynoldson, T. B., 1958. The quantitative ecology of lake-dwelling triclads in northern Britain. Oikos, 9, 94–138.CrossRefGoogle Scholar
Scott, T., 1894a. Diaptomus serricornis, Lilljeborg in lochs in Barra and North Uist. Ann. Scot. Nat. Hist., 3, 258–259.Google Scholar
Scott, T., 1894b. Neomysis (Mysis) vulgaris J. V. Thompson in Barra, Outer Hebrides. Ann. Scot. Nat. Hist., 3, 259.Google Scholar
Scott, T., 1895. The invertebrate fauna of the inland waters of Scotland. Part 5. Rep. Fishery Bd Scotl., 13 (3), 237–245.Google Scholar
Smith, I. R. 1978. An index of British lakes and reservoirs. (In preparation.)Google Scholar
Spence, D. H. N., 1960. Studies on the vegetation of Shetland. III. Scrub in Shetland and in South Uist, Outer Hebrides. J. Ecol., 48, 73–95.CrossRefGoogle Scholar
Spence, D. H. N., Allen, E. D., and Fraser, J., 1979. Macrophytic vegetation of fresh and brackish waters in and near the Loch Druidibeg National Nature Reserve, South Uist. Proc. Roy. Soc. Edinb., 77B, 307–328.Google Scholar
Stephen, A. C., 1935. Notes on the intertidal fauna of North Uist. Scott. Nat., 1935, 137–142.Google Scholar
Stephens, J., 1912. Freshwater Porifera. Proc. Roy. Ir. Acad. (Clare Is. Surv., 60), 31, 1–18.Google Scholar
Sutcliffe, D. W., 1967. A re-examination of observations on the distribution of Gammarus duebeni Lilljeborg in relation to the salt content in fresh water. J. Anim. Ecol., 36, 579–597.CrossRefGoogle Scholar
Van Someren, V. C., 1939. Trout in Barra. Game and Gun and the Angler's Monthly. April 1939, 3 pp. (separate.)Google Scholar
Walton, G. A., 1942. The aquatic Hemiptera of the Hebrides. Trans. Roy. Ent. Soc. Lond., 92, 417–456.CrossRefGoogle Scholar
Waterston, A. R. and Lyster, I. H. J., 1979. The macrofauna of brackish and fresh waters of the Loch Druidibeg National Nature Reserve and its neighbourhood, South Uist. Proc. Roy. Soc. Edinb., 77B, 353–376.Google Scholar
West, G. S., 1905. Notes on some Scottish freshwater Rhizopoda and Heliozoa. Ann. Scot. Nat. Hist., 14, 89–94.Google Scholar
West, W. and West, G. S., 1903. Scottish freshwater plankton. J. Linn. Soc. Bot., 35, 519–556.CrossRefGoogle Scholar