Eutrophication mitigation in rivers: 30 years of trends in spatial and seasonal patterns of biogeochemistry of the Loire River (1980–2012)

Minaudo, Camille; Meybeck, Michel; Moatar, Florentina; Gassama, Nathalie; Curie, Florence

doi:10.5194/bg-12-2549-2015

Cited by 104 publications

(99 citation statements)

References 63 publications

(84 reference statements)

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“…High phosphorus concentrations during low flow are commonly interpreted as resulting from undiluted point sources (Withers et al, 2014;Bowes et al, 2014Bowes et al, , 2015Minaudo et al, 2015), and this may lead catchment managers to target point sources as a priority to reduce eutrophication risk during the summer lowflow period. However in the present study, high SRP during low flow was also observed in headwater catchments free of point-source contributions, and this phenomenon was more prominent in the headwater catchments with the presence of riparian hydromorphic soils (US-Agr and US-For).…”

Section: In-stream Processes and Point-source Contributionsmentioning

confidence: 99%

“…Thus, monitoring headwater catchments was necessary to disentangle both types of processes, as observed downstream export regimes may not describe well the dynamics of landto-stream transfer (Worrall et al, 2012;Minaudo et al, 2015;Temnerud et al, 2016;Baronas et al, 2017). Furthermore, both upstream processes (e.g., summer SRP release) and downstream contributions (e.g., point-source SRP contribution during summer) may lead to the same export regime (e.g., high SRP during low flow); this phenomenon creates epistemic uncertainty, which may lead to equifinality problems when calibrating catchment models to the data (Beven, 2013).…”

Section: Implications For Monitoring and Managementmentioning

confidence: 99%

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Carbon and nutrient export regimes from headwater catchments to downstream reaches

et al. 2017

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Abstract. Excessive amounts of nutrients and dissolved organic matter in freshwater bodies affect aquatic ecosystems. In this study, the spatial and temporal variability in nitrate (NO − 3 ), dissolved organic carbon (DOC) and soluble reactive phosphorus (SRP) was analyzed in the Selke (Germany) river continuum from three headwaters draining 1-3 km 2 catchments to two downstream reaches representing spatially integrated signals from 184-456 km 2 catchments. Three headwater catchments were selected as archetypes of the main landscape units (land use × lithology) present in the Selke catchment. Export regimes in headwater catchments were interpreted in terms of NO − 3 , DOC and SRP land-to-stream transfer processes. Headwater signals were subtracted from downstream signals, with the differences interpreted in terms of in-stream processes and contributions from point sources. The seasonal dynamics for NO − 3 were opposite those of DOC and SRP in all three headwater catchments, and spatial differences also showed NO − 3 contrasting with DOC and SRP. These dynamics were interpreted as the result of the interplay of hydrological and biogeochemical processes, for which riparian zones were hypothesized to play a determining role. In the two downstream reaches, NO − 3 was transported almost conservatively, whereas DOC was consumed and produced in the upper and lower river sections, respectively. The natural export regime of SRP in the three headwater catchments mimicked a point-source signal (high SRP during summer low flow), which may lead to overestimation of domestic contributions in the downstream reaches. Monitoring the river continuum from headwaters to downstream reaches proved effective to jointly investigate land-to-stream and instream transport, and transformation processes.

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Section: In-stream Processes and Point-source Contributionsmentioning

confidence: 99%

Section: Implications For Monitoring and Managementmentioning

confidence: 99%

Carbon and nutrient export regimes from headwater catchments to downstream reaches

et al. 2017

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“…, Minaudo et al. ) and eutrophication (Stoddard et al. ) of lakes and rivers will impact biodiversity and functionality of algae, which are an important carbon source for higher trophic levels (Finlay , Brett et al.…”

Section: Introductionmentioning

confidence: 99%

Niche dimensionality and herbivory control stream algal biomass via shifts in guild composition, richness, and evenness

Passy

Larson

2019

Ecology

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We developed a framework for the hierarchical pathways of bottom‐up (niche dimensionality) and top‐down control (herbivory) on biomass of stream algae via changes in guild composition (relative abundance of low profile, high profile, and motile guilds), species richness, and evenness. We further tested (1) the contrasting predictions of resource competition theory vs. the benthic model of coexistence on how the number of added nutrients constrains species richness, (2) the relationship between species richness and evenness, and (3) the biodiversity–ecosystem‐function paradigm. Implementing a combination of field and lab experiments that manipulated for the first time in benthic algae herbivory and/or niche dimensionality, i.e., the number of added nutrients (NAN), including nitrogen, phosphorus, iron, and manganese, we made the following discoveries. First, important predictors of guild composition were herbivory (field) and NAN (lab); of richness, NAN (field) and NAN and guild composition (lab); of evenness, guild composition (field and lab) and herbivory (field); and of biomass, guild composition, NAN, and richness + evenness (field and lab). Herbivory increased the proportions of the low profile and motile guilds but decreased the proportion of the high profile guild. In the absence of grazing, greater proportions of the high profile guild resulted in elevated richness and biomass but diminished evenness, whereas in the presence of grazing, these relationships generally disappeared. Second, both experiments confirmed the prediction of the benthic model that species richness increases with NAN, a pattern inconsistent with resource competition theory. Third, supplementation with manganese and/or iron increased algal richness, indicating that micronutrients, which have generally been overlooked in stream ecology, added dimensions to the algal niche. Fourth, the richness–evenness relationship, observed only in the absence of herbivory, depended on the size of the species pool. It was positive at richness lower than 49 species (lab), implying complementarity and facilitation, while at higher richness (field and lab), this relationship was negative, consistent with negative interspecific interactions. Finally, the greater dependence of biomass production on guild composition and NAN than on richness and evenness suggests that more comprehensive, environmentally explicit, and trait‐based approaches are necessary for the study of the biodiversity–ecosystem‐function paradigm.

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“…Eutrophication, manifested by severe algae blooms, is globally the most pervasive water quality challenge [1][2][3]. It perturbs ecosystem services of the aquatic systems and decreases biodiversity [3][4][5].…”

Section: Introductionmentioning

confidence: 99%

Spatial and Temporal Variations in Environmental Variables in Relation to Phytoplankton Community Structure in a Eutrophic River-Type Reservoir

Zhao

Jiao

et al. 2017

Water

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This study assesses spatial and temporal variation in environmental variables in relation to phytoplankton community size and composition in a typically eutrophic river reservoir (Hai River, northern China). The aim is to identify environmental parameters governing spatial and temporal differences in phytoplankton density and composition. Physicochemical parameters, including nutrient concentrations, were determined in monthly surface water samples from 2015. The average concentration of key eutrophication indexes (i.e., total phosphorous (TP: 0.24 ± 0.11 mg·L −1 ), total nitrogen (TN: 2.96 ± 1.60 mg·L −1 ), and Chlorophyll a (Chl a: 38.5 ± 11.5 mg·m −3 )) substantially exceeded threshold values for eutrophic streams. Moreover, the eutrophication increased significantly downstream along the river reservoir as a consequence of an increasing fraction of agricultural and industrial land-use in the watershed. 103 phytoplankton species were identified, of which Chlorophyta was the dominated phylum (47 species), followed by Bacillariophyta (23 species) and Cyanophyta (18 species). No spatial difference in species distribution (ANOVA, p > 0.05) were found, while the temporal differences in species composition exhibited significant heterogeneity (ANOVA, p < 0.001). Phytoplankton abundance was highest in early summer (June and July), with maximum values increasing from 1.78 × 10 8 and 2.80 × 10 8 cells·L −1 in upstream and middle reaches, respectively, to 4.18 × 10 8 cells·L −1 furthest downstream. Cyanophyta, also known as Cyanobacteria and commonly referred to as blue-green algal, are known to constitute algae bloom in eutrophic systems. Common species are Microcystis marginata, Microcystis flos-aquae, and Oscillatoria sp. This was the dominant phyla during summer months, especially in the middle and lower reaches of the stream reservoir where it accounted for 88.9% of the phytoplankton community. Shannon weaver index (H') and Pielous's evenness index (J') were extremely low (1.91-2.43 for H' and 0.39-0.45 for J') in samples collected from the lower part of the stream during the period of algal bloom, indicating an imbalance in the phytoplankton communities. Canonical correspondence analysis (CCA) indicated that water temperature (WT) and possible pH, along with nitrate (NO 3 -N) and nitrite (NO 2 -N), were the most important explanatory parameters in regard to phytoplankton composition. This research provides an understanding of the role of physicochemical water quality parameters in governing algal blooms and phytoplankton composition in river reservoirs.

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Eutrophication mitigation in rivers: 30 years of trends in spatial and seasonal patterns of biogeochemistry of the Loire River (1980–2012)

Cited by 104 publications

References 63 publications

Carbon and nutrient export regimes from headwater catchments to downstream reaches

Carbon and nutrient export regimes from headwater catchments to downstream reaches

Niche dimensionality and herbivory control stream algal biomass via shifts in guild composition, richness, and evenness

Spatial and Temporal Variations in Environmental Variables in Relation to Phytoplankton Community Structure in a Eutrophic River-Type Reservoir

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