The effects of artificial ammonium enhancement on riverine periphytic diatom communities |
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| Authors: | Joachim Hürlimann Ferdinand Schanz |
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| Institution: | (1) Present address: AquaPlus, Hauptstrasse 6, CH-8832 Wollerau, Switzerland;(2) Limnologische Station, Universität Zürich, Seestrasse 187, CH-8802 Kirchberg, Switzerland |
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| Abstract: | An experiment to ascertain the influence of artificially enhanced ammonium concentrations on riverine periphytic diatom communities was conducted during an 80 day period in winter 1988/89 (temperature: 5°C). During an initial 47 day enrichment phase, ammonium chloride at different concentrations was added to O2-saturated river water in experimental channels. Compared to a control, the addition of 1.2 mg NH
4
+
-N·l–1 resulted in only slight changes in the species composition of the diatom community. The addition of 5.1 mg NH
4
+
-N·l–1 and more ( 60 µg NH3-N·l–1) resulted in a decrease in the biomass and a drastic change in the species composition. After the 42 day enrichment period, the diatom speciesFragilaria capucina var.vaucheriae, Navicula saprophila, Navicula atomus andGomphonema parvulum, all of which are known to be tolerant to organic pollution, were found with relative abundances of 44.8%, 35.6%, 2.3% and 1.5%, respectively. Changes in species composition of the periphytic diatom communities occurred within the first two weeks of the subsequent recovery phase. After a month of recovery, all periphytic diatom communities exhibited a high degree of structural similarity with the control. |
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| Keywords: | diatoms periphyton experimental channels ammonium pollution recovery water quality |
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