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Lookup NU author(s): Emeritus Professor Steve Juggins
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Restoration goals for damaged freshwater habitats can be defined according to ecological as well as to chemical criteria. For disturbed lakes, the sediment microfossil record can be used to select potential modern analogue sites as possible restoration target ecosystems. Fossil diatom assemblages in two acidified lakes (Round Loch of Glenhead and Loch Dee) in Galloway, Scotland, were compared floristically with modern surface sediment samples from ca. 200 lakes in Britain, Ireland, Sweden and Norway using numerical techniques. Mean squared Chi-squared dissimilarity (SCD) values based on between sample Chi-square distance measures were used to compare samples. 'Space-for-time substitution' using diatom assemblage matching techniques identified several modern analogue sites with Hebridean Loch Teanga and Irish Lough Claggan possessing modern diatom floras most similar to those which existed at the Round Loch of Glenhead and Loch Dee before acidification. From the point of view of atmospheric pollution, the most closely matching modern analogue sites were not necessarily in the most pristine regions. Some analogues occurred in UK regions of moderate or low acid deposition and modern diatom assemblages in atmospherically cleaner mid Norway were generally less similar floristically. It is argued that identification of modern analogue sites raises the possibility of using time-space substitution of closely matched modern and fossil samples to infer whole lake ecosystems. Diatoms are however poor indicators of some water chemistry variables and the two closest matched modern analogue sites have too high calcium concentrations making faunistic comparisons questionable. Identification of good modern analogue lakes can be improved by using selection criteria, other than diatoms, to pre-select sites. Screening inappropriate sites according to water chemistry and basin features combined with a larger biological database of modern and fossil samples offers a promising way of refining the selection processes. Despite necessary refinements, modern analogue matching can potentially identify whole lake ecosystems that can serve as biological target communities for currently disturbed sites. Being based on biological rather than chemical criteria, this approach does not rely on species-water chemistry transfer functions. It is therefore directly relevant to lake conservation and restoration objectives and offers an alternative method for reconstructing lake palaeo-environments. © 1997 Kluwer Academic Publishers.
Author(s): Flower R, Juggins S, Battarbee R
Publication type: Article
Publication status: Published
Print publication date: 01/01/1997
ISSN (print): 0018-8158
ISSN (electronic): 1573-5117
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