Model-based analysis of oxygen budget and biological processes in the regulated rivers Moselle and Saar: modelling the influence of benthic filter feeders on phytoplankton

Schöl, Andreas; Kirchesch, Volker; Bergfeld, Tanja; Müller, Dieter G.

doi:10.1007/978-94-017-2163-9_18

Cited by 19 publications

(24 citation statements)

References 12 publications

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“…During seasonal investigations at km 422, a maximum of as many as 16 900 ind./L rotifers was reported at water temperatures above 20°C [17]. Benthic filterers, which could reduce the level of chlorophyll-a in the river -as already observed on the rivers Weser (Herbst [20]), Mosel and Rhine (Schöl et al [21], Schöl et al [22], Ietswaart et al [23]) -do not appear in high densities in the Elbe and therefore could not reduce phytoplankton biomass.…”

Section: Discussion Of the Resultsmentioning

confidence: 87%

The Effects of Nutrient Concentrations in the River Elbe

Guhr

Spott

Bormki

et al. 2003

Acta hydrochim. hydrobiol.

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The nutrient turnover and the resulting development of phytoplankton biomass were investigated during four river surveys in the free-flowing reach of the river Elbe under almost constant hydrological and meteorological conditions taking into account the transport time and the time of day.The chlorophyll-a concentration was found to increase by a factor of between 3 and 6 depending on the season, while the biomass load increased by a factor of up to 18. The concentrations of dissolved silicate and dissolved total phosphate behaved oppositely to this development, while the levels of particulate bound nutrients rose accordingly. Depending on the season, 6...23 % of the total bound nitrogen was found to be removed from the river by denitrification. The river Saale contains the highest load of nutrients of all the tributaries. At the end of the investigated reach, algae biomass accounts for as much as 75 % of the POC. Nährstoffumsatz in der ElbeMit 4 transport-und tageszeitkonformen Längsschnittbereisungen der frei fließenden Elbe bei jeweils annähernd gleichbleibenden hydrologisch-meteorologischen Bedingungen konnte der Nährstoffumsatz und die sich daraus entwickelnde Phytoplanktonbiomasse verfolgt werden. Die Chlorophyllkonzentration nimmt auf der Fließstrecke von der Grenze zu Tschechien bis nahe Geesthacht je nach Jahreszeit um das Drei-bis Sechsfache zu, die Fracht um bis zum 18fachen. Insbesondere die Konzentrationen an gelöstem Silicat und gelöstem Gesamtphosphat verhalten sich zu dieser Entwicklung gegenläufig, während die partikulär gebundenen Nährstoffgehalte entsprechend ansteigen. Je nach Jahreszeit werden durch Denitrifikation 6...23 % des gebundenen Gesamtstickstoffs aus dem Gewässer entfernt. Von den Nebenflüssen weist die Saale die höchste Nährstoffbelastung auf. Am Ende der Untersuchungsstrecke hat die Algenbiomasse einen Anteil von bis zu 75 % am POC.

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Section: Discussion Of the Resultsmentioning

confidence: 87%

The Effects of Nutrient Concentrations in the River Elbe

Guhr

Spott

Bormki

et al. 2003

Acta hydrochim. hydrobiol.

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“…These possibly abrupt changes are depicted by the large variance of the scores during summer. It is algal concentrations in summer and autumn (Schöl et al, 1999). Hence, primary production (high scores) and the growth of green algae, which are favoured by high temperatures, is probably reduced by benthic filter feeders in late summer and autumn, leading to maximum scores during May.…”

Section: The Role Of the Biological Modementioning

confidence: 99%

Processes governing river water quality identified by principal component analysis

Haag

Westrich

2002

Hydrological Processes

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Abstract:The present study demonstrates the usefulness of principal component analysis in condensing and interpreting multivariate time-series of water quality data. In a case study the water quality system of the lock-regulated part of the River Neckar (Germany) was analysed, with special emphasis on the oxygen budget. Pooled data of ten water quality parameters and discharge, which had been determined at six stations along a 200 km reach of the river between the years 1993 and 1998, were subjected to principal component analysis. The analysis yielded four stable principal components, explaining 72% of the total variance of the 11 parameters. The four components could be interpreted confidently in terms of underlying processes: biological activity, dilution by high discharge, seasonal effects and the influence of wastewater. From analysing the data of single stations separately, these processes were found to be active throughout the complete reach. Considering the oxygen budget of the river, the variance of biological activity, representing the counteracting processes of primary production and microbial degradation, was found to be most important. This principal component explained 79% of the observed variance of oxygen saturation. In contrast, the analysis of a reduced data set from the 1970s showed that oxygen saturation was then dominated by discharge and temperature variations. The findings indicate that the oxygen budget used to be governed directly by the emission of degradable matter, whereas nowadays eutrophication is most important for extreme oxygen concentrations. Therefore, controlling eutrophication has to be the primary goal, in order to mitigate the rare episodes of pronounced oxygen over-and undersaturation in the future.

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“…mussels) had clearly higher densities in the Moselle than in the Rhine and especially than in the Saar. Studies using a computerbased water quality model revealed a potential development of high algal biomass in the Moselle as a consequence of high water residence time and phosphate values (Schöl et al, 1999), but the study also pointed to a strong predatory effect of filter feeders grazing (e.g. the zebra mussel) on algae with their annual grazing maximum in late summer.…”

Section: Phytoplanktonmentioning

confidence: 90%

“…In the Saar, the temporarily low algal content had a different reason. Application of the water quality model showed that phytoplankton growth is diminished in summer due to light limitation, whereas the influence of benthic grazers is negligible (Schöl et al, 1999) coinciding with the low densities of benthic predators. The high degree of impoundment of this relatively small river resulted in a relatively high water depth (around 9 m in front of the weirs) and in a very low turbulence partly leading to a stratification of the river in summer.…”

Section: Phytoplanktonmentioning

confidence: 99%

“…The results in the Saar point to a distinct grazing impact of metazooplankton in spring and summer. Two studies applying a water quality model to Saar, Moselle and Rhine (Schöl et al, 1999;Schöl et al, 2002) show a low grazing pressure of metazooplankton on phytoplankton in former years. This low importance of metazooplankton in rivers was also found by Basu and Pick (1997), Karrasch et al (2001) and Weitere et al (2005).…”

Section: Metazooplanktonmentioning

confidence: 99%

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Comparison of the components of the planktonic food web in three large rivers (Rhine, Moselle and Saar)

Bergfeld¹,

Scherwaß²,

Ackermann³

et al. 2008

River Research & Apps

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The dynamics of phyto-, bacterio-, proto-and metazooplankton were investigated for a period of 22 months fortnightly from March 1999 until December 2000 in the rivers Moselle, Saar and Rhine. Plankton abundances reached the lowest values in the Rhine and the highest in the Saar. Protozoa and not the much more studied metazoa clearly dominate the zooplankton not only by number but also by biomass by about 90%. We show that the plankton biomass in each of the rivers is the result of the interplay of the grazing by benthic predators and of the human induced factors such as river morphology, water residence time and nutrient load. Furthermore, we compare our study with the planktonic food web of three other large European rivers. The comparison between all studies revealed a general rise of the absolute mean biomass of all heterotrophic planktonic food web components (bacteria, protozoa, metazoa) parallel to an increase of the algal biomass of the river. For the rivers Rhine, Moselle and Saar, the average biomass of all investigated plankton groups was very low compared to the values obtained in the rivers Meuse, Loire and Elbe. The relative importance of organisms of the microbial food web increased with a decrease of the algal biomass or organic carbon content, respectively, in each of the rivers. We postulate that with a sinking nutrient level in the Rhine, the microbial food web components will become even more important within the plankton than they already are.

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Model-based analysis of oxygen budget and biological processes in the regulated rivers Moselle and Saar: modelling the influence of benthic filter feeders on phytoplankton

Cited by 19 publications

References 12 publications

The Effects of Nutrient Concentrations in the River Elbe

The Effects of Nutrient Concentrations in the River Elbe

Processes governing river water quality identified by principal component analysis

Comparison of the components of the planktonic food web in three large rivers (Rhine, Moselle and Saar)

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