Variability of photosynthesis‐irradiance curves and ecosystem respiration in a small river

Uehlinger, Urs; König, Christof; Reichert, Peter

doi:10.1046/j.1365-2427.2000.00602.x

Cited by 67 publications

(56 citation statements)

References 46 publications

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“…The still relatively closed canopy in autumn and low water temperatures in winter in headwater streams most likely limited periphyton growth and consequently the rates of periphyton respiration. Such patterns have already been reported in other studies , with respiration rates usually higher during warm seasons and lower during cold seasons. The higher values for periphyton biomass recorded during autumn and winter were attributed to anamorphic organic matter (e.g., fine particulate organic matter derived from litter decomposition) trapped in the polysaccharide matrix, since the high AFDM values in the cold seasons were not companied by high Chl‐ a concentrations or high respiration rates.…”

Section: Discussionsupporting

confidence: 88%

Combined effects of water temperature and nutrients concentration on periphyton respiration – implications of global change

Rosa

Ferreira

Canhoto

et al. 2012

Internat. Rev. Hydrobiol.

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With the increase in global mean surface temperature predicted for the near future, stream water temperature will also increase. Simultaneously, water quality is likely to decrease (e.g., due to increases in nutrient and pollutant concentrations). The objective of this study was to evaluate the individual and combined effects of increases in water temperature and nutrients concentration on periphyton respiration, as a surrogate for stream metabolism. Stones naturally colonized with periphyton in an unpolluted mountain stream in Central Portugal were sampled seasonally over a year, and incubated in the laboratory under two water temperatures (ambient and 4°C elevated) and two nutrients concentration levels (ambient and ∼6× higher inorganic dissolved nitrogen, ∼2× higher soluble reactive phosphorous concentrations). Overall, increases in water temperature stimulated periphyton respiration to a larger extent than did increases in nutrients concentration. In spring, the simultaneous increase in water temperature and nutrients concentration stimulated periphyton respiration beyond expected from the individual effect of each factor. These results indicate that synergistic interactions between factors might occur under certain environmental conditions, suggesting that care should be taken when predicting the combined effect of changes in multiple factors from their individual effects. The observed stimulation of periphyton respiration promoted by increased temperature and nutrients concentration can lead to changes in streams carbon budgets, with a positive feedback for global warming, as more CO2 might be released to the atmosphere.

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Section: Discussionsupporting

confidence: 88%

Combined effects of water temperature and nutrients concentration on periphyton respiration – implications of global change

Rosa

Ferreira

Canhoto

et al. 2012

Internat. Rev. Hydrobiol.

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“…Factors describing the influence of prevailing environmental conditions were mean daily discharge ( Q ), T and I . All of these factors proved to be useful in explaining temporal variation in photosynthesis–light relationships and ER (Uehlinger, König & Reichert, 2000). To account for potential non‐linear effects such as the increase of shear stress with discharge or the relationship between light and GPP, the squares of T , I and Q were also included.…”

Section: Methodsmentioning

confidence: 99%

Resistance and resilience of ecosystem metabolism in a flood‐prone river system

2000

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1. Gross primary production (GPP) and ecosystem respiration (ER) were analysed for 18 months in two reaches of the River Thur, a prealpine river in Switzerland. The upper reach at 655 m above sea level (a.s.l.) is bedrock constrained, has a high slope (0.60%) and a catchment area of 126 km 2 . The lower reach at 370 m a.s.l. has a more extensive hyporheic zone, a lower slope (0.17%) and a catchment of 1696 km 2 . 2. In both reaches, temporal patterns of stream metabolism reflected the occurrence of bed-moving spates. Average reductions of GPP and ER by spates were 53 and 24% in the upper reach, and 37 and 14% in the lower reach, respectively. The greater resistance of ER than GPP in both reaches shifted the ecosystem metabolism towards heterotrophy (decrease of the ratio of GPP to ER (P/R)) following spates. 3. Recovery of GPP was significantly faster in the lower reach and exhibited distinct seasonal variation (positive correlation with incident light). The differences in stability (both resistance and resilience) between reaches reflected differences in geomorphic settings and disturbance regime. 4. Stepwise regression analysis was used to explore the potential influence of season, disturbance and prevailing environmental conditions on stream metabolism in each reach. Time since spate plus temperature explained 73 and 86% of variation in ER and GPP, respectively, in the upper reach and 55% of variation in ER in the lower reach. Season plus prevailing environmental conditions explained 67% of variation in GPP in the lower reach. 5. To test how the perception of stability may change with increasing scale of observation, the disturbance regimes of 12 sites were compared with the disturbance regime of the entire Thur catchment. The analysis suggests that stream metabolism at the catchment scale is far more resistant to high flow events than at the reach scale.

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“…Sediment resuspension was a major source of turbidity in our wetland, which limited light availability for algal growth, while at the same time, potentially increasing C and nutrient availability for heterotrophic bacteria, resulting in a general shift of the system towards heterotrophic metabolism (Maynard et al 2012). Additionally, bacterioplankton growth and respiration is dependent on temperature, resulting in lower rates of CR during colder months (Uehlinger et al 2000), as seen on 06 June and 13 September (Table 3). This relationship between CR and temperature was also shown in a concurrent study in this system, where CR was most strongly correlated with temperature (Maynard et al 2012).…”

Section: Effect Of Elevated Nutrient Carbon and Sediment Loads On Wmentioning

confidence: 99%

Autochthonous and Allochthonous Carbon Cycling in a Eutrophic Flow-Through Wetland

2014

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Wetland environments are important sites for the cycling and retention of terrestrially derived organic matter and nutrients. Wetland treatment of agricultural runoff has been shown to improve water quality and promote carbon sequestration. However, the potential role of eutrophic wetlands as a source of algal loading contributing to downstream hypoxia has prompted interest in understanding algal productivity and export from these systems. This study, in the San Joaquin Valley, California, quantified a mass balance of carbon and nutrients within a seasonally-saturated constructed wetland receiving agricultural runoff, as well as quantifying autochthonous carbon production on four sampling dates during a year with minimal emergent vegetation. Results from this study show that the wetland was a net-sink for nutrients and particulate/dissolved organic carbon. Despite high concentrations of inflowing nutrients and high rates of primary productivity, high respiration rates limited net organic C production and export due to high heterotrophic activity. The addition of high C loads in inflowing water and moderate retention efficiencies, however, resulted in a positive C retention during most sampling dates. This study provides valuable insight into the connection between elevated carbon and nutrient inflows, their effects on autochthonous carbon production, and resulting carbon and nutrient outflows.

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Variability of photosynthesis‐irradiance curves and ecosystem respiration in a small river

Cited by 67 publications

References 46 publications

Combined effects of water temperature and nutrients concentration on periphyton respiration – implications of global change

Combined effects of water temperature and nutrients concentration on periphyton respiration – implications of global change

Resistance and resilience of ecosystem metabolism in a flood‐prone river system

Autochthonous and Allochthonous Carbon Cycling in a Eutrophic Flow-Through Wetland

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