| Autor: |
Schöl, Andreas, Kirchesch, Volker, Bergfeld, Tanja, Schöll, Franz, Borcherding, Jost, Müller, Dieter |
| Zdroj: |
International Review of Hydrobiology; May 2002, Vol. 87 Issue: 2-3 p295-317, 23p |
| Abstrakt: |
The chlorophyll a content of the German part of the River Rhine is simulated with the aid of a deterministic water quality model (QSIM). At the upper boundary of the investigated river stretch at km 359 (Karlsruhe) low chlorophyll a concentrations (< 25 μg/l) were measured throughout the year 1990, while at the lower river region at km 865 (Bimmen) high chlorophyll a concentrations (>50130 μg/l) occurred in spring time and late summer. The model-based analysis of the algal biomass shows that beside inoculation by the main tributaries Neckar, Main, Lahn and Moselle, algal production in the Rhine itself is of major concern. The calculated losses of phytoplankton showed seasonal dependency with a maximum grazing rate of about 0.04 d1 for rotifers and 0.20.3 d1 for D. polymorpha. Depending on the algal food content, the biomass of rotifers and Dreissena polymorpha population is simulated and compared with observed rotifer abundances and estimated zebra mussel biomass derived from measured densities and size structures of local populations. In agreement with observations modelled rotifer and D. polymorpha population biomass is increasing downstream, explained by modelling as a matter of improved food supply. Nevertheless, both groups were unable to control algal development in River Rhine between km 359 and 860, due to favourable growth conditions for phytoplankton. |
| Databáze: |
Supplemental Index |
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