An expanded weighted-averaging model for inferring past total phosphorus concentrations from diatom assemblages in eutrophic British Columbia (Canada) lakes |
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| Authors: | Euan D Reavie Roland I Hall John P Smol |
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| Institution: | (1) Paleoecological Environmental Assessment & Research Lab (PEARL), Department of Biology, Queen's University, K7L 3N6 Kingston, Ontario, Canada;(2) Present address: Science & Technology Branch, Aquatic Science Section, Ontario Ministry of Environment & Energy, Bellwood Acres Rd., P.O. Box 39, P0A 1E0 Dorset, Ontario, Canada |
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| Abstract: | Eighteen lakes were added to a published training set of 46 British Columbia (BC) lakes in order to expand the original range of total phosphorus (TP) concentrations. Canonical correspondence analysis (CCA) was used to analyze the relationship between diatom assemblages and environmental variables. Specific conductivity and TP] each explained significant (P 0.05) directions of variance in the distribution of the diatoms. The relationship between diatom assemblages and TP] was sufficiently strong to warrant the development of a weighted-averaging (WA) regression and calibration model that can be used to infer past trophic status from fossil diatom assemblages.The relationship between observed and inferred TP] was not improved by the addition of more eutrophic lakes, however the TP] range and the number of taxa used in the transfer function are now superior to the original model. Diatom species assemblages changed very little in lakes with TP concentrations greater than 85 µg 1–1, so we document the development of a model containing lakes with TP85 µg 1–1. The updated model uses 59 training lakes and covers a range of species optima from 6 to 41.9 µg 1–1 TP, and a total of 150 diatom taxa.The updated inference model provided a more realistic reconstruction of the anthropogenic history of a highly eutrophic BC lake. The model can now be used to infer past nutrient conditions in other BC lakes in order to assess changes in trophic status. |
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| Keywords: | diatoms eutrophication lake management paleolimnology British Columbia lakes phosphorus training sets |
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