Ecological response of two hydro‐morphological similar pre‐dams to contrasting land‐use in the Rappbode reservoir system (Germany)

Friese, Kurt; Schultze, Martin; Boehrer, Bertram; Büttner, Olaf; Herzsprung, Peter; Koschorreck, Matthias; Kuehn, Burkhard; Rönicke, Helmut; Tittel, Jörg; Wendt‐Potthoff, Katrin; Wollschläger, Ute; Dietze, Maren; Rinke, Karsten

doi:10.1002/iroh.201301672

Cited by 38 publications

(30 citation statements)

References 46 publications

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“…The sediments were therefore, a net sink of DOC (−178 kg yr −1 ). In terms of the reservoirs carbon budget this is small compared with the DOC annual load of 15 tonnes (Friese et al ). Thus, the quantitative importance of the benthic DOC flux in terms of the total carbon budget is small.…”

Section: Discussionmentioning

confidence: 99%

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Benthic dissolved organic carbon fluxes in a drinking water reservoir

et al. 2015

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The trend of increasing dissolved organic carbon (DOC) in surface waters motivated us to gain a mechanistic understanding of DOC exchange at the sediment water interface in lakes. We quantified seasonal DOC and solute fluxes under different redox conditions, in a small drinking water reservoir using sediment core incubations. Processes governing benthic DOC exchange were microbial production of DOC and interaction with mineral surfaces. Mobilization of DOC in anoxic sediments seemed to be closely linked to reductive dissolution of ferric minerals as shown by the strong positive correlation (r 2 5 0.99) between DOC and Fe fluxes. Oxidized surface sediments were an efficient DOC trap where DOC was bound to ferric minerals. Redox conditions appeared to be the primary regulator of the DOC exchange, resulting in sedimentary uptake of DOC (21.8 mmol m 22 d 21 ) only under oxic conditions. DOC production was regulated by temperature, leading to higher DOC fluxes (up to 2.4 mmol m 22 d 21 ) in summer. The sediment was a net sink of DOC (20.2 tonnes yr 21 ) but this was small compared with the annual DOC load (15 tonnes yr 21 ) of the reservoir. However, the benthic DOC flux was about 10-20% of the dissolved carbon flux at the sediment-water interface, making it a significant process in the lake internal carbon cycle. Climate change is supposed to promote reducing conditions at the bottom of lakes, which might increase benthic DOC production in the future.

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Section: Discussionmentioning

confidence: 99%

“…Hassel pre‐dam is located in the Harz Mountains (51.74° N, 10.89° E), in central northern Germany. It is part of the Rappbode Reservoir System and was built in 1960 to reduce the sediment and phosphorus load into the Rappbode Reservoir (Rinke et al ; Friese et al ). The pre‐dam has a maximum and mean depth of 14 m and 5 m, respectively.…”

Section: Methodsmentioning

confidence: 99%

Benthic dissolved organic carbon fluxes in a drinking water reservoir

et al. 2015

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“…High-frequency observed data (every 10 min) were averaged to hourly values for the simulations. A small amount of missing values was filled with measurements from a nearby observatory at the Rappbode auxiliary reservoir [19,36] or from the German Weather Service station at Harzgerode (15 km away from the research area). The precipitation values were primarily drawn from the Harzgerode station because of sensor failures at the measurement buoy and the gaps were filled from data recorded at the Rappbode auxiliary reservoir.…”

Section: Model Setup and Input Datamentioning

confidence: 99%

Variable withdrawal elevations as a management tool to counter the effects of climate warming in Germany’s largest drinking water reservoir

Sadeghian

Rinke

2019

Environ Sci Eur

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Background: Thermal stratification in reservoirs is a significant factor affecting water quality, and can be strongly influenced by climate change and operational strategies. Reservoirs in the temperate zone react most sensitively to climate warming during winter as ice cover and inversed stratification are about to disappear in a warmer world. In this study, two well-established hydrodynamic models, the one-dimensional General Lake Model (GLM) and the twodimensional CE-QUAL-W2 (W2), were used to investigate the response of winter inversed stratification in the Rappbode Reservoir to future climate warming, combined with different water withdrawal elevations. Results: Under increased air temperature, the duration of inversed stratification is reduced and the inversion phenomenon will entirely disappear under current management if the air temperature is increased high enough (more than 4.5 K) in the future. Under strong climate warming, the Rappbode Reservoir will therefore change from a dimictic to a monomictic mixing type. Changing the reservoir management from deep withdrawal (e.g., below 350 m a.s.l.) to shallow withdrawal elevations (e.g., above 390 m a.s.l.) reduces internal heat energy stored in the reservoir in summer and prolongs the inversed stratification period in winter. This strategy can retain the dimictic behavior even under strong warming. Conclusions: Our study indicates that adjusting the withdrawal elevation is an effective management instrument to control the winter conditions and can, in fact, mitigate climate warming effects on winter hydrodynamics by stabilizing the dimictic mixing type.

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“…The water of the Rappbode Reservoir discharges into the Wendefurth Reservoir, where it is used for energy production and energy storage by a pump storage station (Friese et al, 2014). The Rappbode Reservoir is elongated in shape with a length of 8 km, a maximum surface area of 3.95 km 2 , an inflow volume of 120 9 10 6 m 3 / a and a residence time of 344 days.…”

Section: Study Sitementioning

confidence: 99%

Mechanisms preventing a decrease in phytoplankton biomass after phosphorus reductions in a German drinking water reservoir—results from more than 50 years of observation

et al. 2018

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To counteract the severe consequences of eutrophication on water quality and ecosystem health, nutrient inputs have been reduced in many lakes and reservoirs during the last decades. Contrary to expectations, in some lakes phytoplankton biomass did not decrease in response to oligotrophication (nutrient reduction). The underlying mechanisms preventing a decrease in biomass in these lakes are the subject of ongoing discussion. We used a hitherto unpublished long‐term data set ranging from 1961 until 2016 from a German drinking water reservoir (Rappbode Reservoir) to investigate the underlying mechanisms preventing a decrease in biomass. Total phosphorus (TP) concentrations in the Rappbode Reservoir dropped abruptly in 1990 from 0.163 to 0.027 mg/L within three consecutive years, as a result of banning phosphate‐containing detergents. Despite substantial reductions in TP, total annual phytoplankton biomass did not decline in the long‐run, and therefore, the yield of total phytoplankton biomass per unit phosphorus largely increased. Regression analysis revealed a positive association between the yield and potentially phagotrophic mixotrophs (R2 = .465, p < .001). We infer that by ingesting bacteria, mixotrophic species were capable of exploiting additional P sources that are not accessible to obligate autotrophic phytoplankton, eventually preventing a decrease in algal biomass after TP reductions. Long‐term epilimnetic phosphorus concentrations during the winter mixing period decreased to a greater degree than summer phosphorus concentrations. Apparently, TP losses over the season were less intense. Spring diatom biomass also markedly decreased after oligotrophication. In fact, spring diatom biomass was positively related to the TP loss over the season suggesting diatoms play an important role in P reduction. However, this intraannual P processing was not the primary factor when focusing on the average yearly yield, which remained to be fully explained by mixotrophs. Our study demonstrates this ecosystem's ability to compensate for changes in resource availability through changes in phytoplankton community composition and functional strategies. We conclude that an increase in mixotrophy and the ability to make bacterial phosphorus available for phytoplankters were the main factors that allowed the phytoplankton community of the Rappbode Reservoir to adapt to lower nutrient levels without a loss in total biomass.

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Ecological response of two hydro‐morphological similar pre‐dams to contrasting land‐use in the Rappbode reservoir system (Germany)

Cited by 38 publications

References 46 publications

Benthic dissolved organic carbon fluxes in a drinking water reservoir

Benthic dissolved organic carbon fluxes in a drinking water reservoir

Variable withdrawal elevations as a management tool to counter the effects of climate warming in Germany’s largest drinking water reservoir

Mechanisms preventing a decrease in phytoplankton biomass after phosphorus reductions in a German drinking water reservoir—results from more than 50 years of observation

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