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Nitrate availability and hydrophyte species richness in shallow lakes

Authors


  • Present addresses: Cassandra James, Murray-Darling Freshwater Research Centre, Northern Laboratory, 116 Marshall Street, Goondiwindi, Queensland 4390, Australia.
    Jane Fisher, Hydro-Ecology and Wetlands, CEH Wallingford, Crowmarsh Gifford, Wallingford, Oxfordshire, OX10 8BB, U.K.

Brian Moss, School of Biological Sciences, Jones Building, University of Liverpool, Liverpool L69 3GS, U.K.
E-mail: brmoss@liv.ac.uk

Summary

1. Submerged plant richness is a key element in determining the ecological quality of freshwater systems; it has often been reduced or completely lost.

2. The submerged and floating-leaved macrophyte communities of 60 shallow lakes in Poland and the U.K. have been surveyed and species richness related to environmental factors by general linearised models.

3. Nitrogen, and more specifically winter nitrate, concentrations were most important in explaining species richness with which they were inversely correlated. Phosphorus was subsidiary. Such an inverse relationship is consistent with findings in terrestrial communities. Polish lakes, with less intensively farmed catchments, had greater richness than the U.K. lakes.

4. The richest U.K. communities were associated with winter nitrate-N concentrations of up to about 1–2 mg L−1 and may correspond with ‘good’ ecological quality under the terms of the European Water Framework Directive. Current concentrations in European lowlands are often much higher.

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