Diatom-inferred trophic history of IJsselmeer (The Netherlands) |
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Authors: | Holger Cremer Frans P M Bunnik Emiliya P Kirilova Eddy H R R Lammens André F Lotter |
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Institution: | (1) TNO Built Environment and Geosciences, Geological Survey of the Netherlands, Princetonlaan 6, 3584 CB Utrecht, The Netherlands;(2) Institute of Environmental Biology, Laboratory of Palaeobotany and Palynology, Utrecht University, Budapestlaan 4, 3584 Utrecht, The Netherlands;(3) Rijkswaterstaat Waterdienst, P. O. Box 17, 8200 Lelystad, The Netherlands |
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Abstract: | IJsselmeer was formed in 1932 through the closure of the Afsluitdijk that separated the artificial lake from the former Zuiderzee
estuary. The palaeoecology of IJsselmeer was studied on a 63-cm-long sediment core. Lithology and microfossil data, particularly
the diatom flora, clearly show the transition from the marine Zuiderzee into the freshwater IJsselmeer. Trophic conditions
in IJsselmeer since 1932 have been inferred by qualitative and quantitative diatom-based approaches: by plotting the distribution
of trophic categories based on published trophic indicator values, by a canonical correspondence analysis (CCA) yielding relative
total phosphorus (TP) changes and by applying a transfer function in order to calculate TP concentrations. All three approaches
indicate that IJsselmeer initially was meso- to eutrophic. A first hypertrophic period is indicated for the mid-1940s, likely
due to internal loading. After 1960, the phosphorus load steadily increased and TP in IJsselmeer reached highest concentrations
(ca. 150 μg l−1) in the 1980s as confirmed by monitoring data since 1975. The monitored data show that the TP concentration continuously
decreased after 1985 due to successful environmental protection measures. This trend is not (or not yet) evidenced by the
diatom data and thus, the diatom-inferred TP concentration.
Guest editors: K. Buczkó, J. Korponai, J. Padisák & S. W. Starratt
Palaeolimnological Proxies as Tools of Environmental Reconstruction in Fresh Water |
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Keywords: | Palaeolimnology Lake sediments Diatoms Phosphorus Eutrophication |
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