WFD ecological status indicator shows poor correlation with flow parameters in a large Alpine catchment

Larsen, Stefano; Bruno, M.C.; Zolezzi, Guido

doi:10.1016/j.ecolind.2018.11.047

Cited by 13 publications

(8 citation statements)

References 44 publications

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“…Although some authors (Kakouei et al, 2017; Schneider et al, 2018; Schneider & Petrin, 2017) identified one or more years before the benthic macroinvertebrate sampling, we found that 90 days revealed an adequate time span to evidence correlation between streamflow and benthos metrics in stream reaches affected by off‐stream diversion. This is in agreement with other studies (Larsen et al, 2019; Worrall et al, 2014), confirming that short‐term antecedent hydrologic conditions significantly influence benthic communities. Moreover, the streamflow metrics demonstrating higher suitability to differentiate hydrologic alterations induced by intakes or reservoirs varied by season, thus confirming the key role played by seasonality in eco‐hydraulics assessments of this kind (Krajenbrink et al, 2019; Steel et al, 2018).…”

Section: Discussionsupporting

confidence: 93%

“…The results of our investigation showed that the benthos response to the mentioned gradient of hydrological alterations (our hypothesis I) was not univocal but varied according to the adopted metrics and the statistical analysis applied. This uncertainty could hinder the development of metrics based on benthic invertebrates, specifically supporting the ecological assessment of hydrologic alterations and currently unavailable in the Alpine context (Larsen et al, 2019). Comparison of macroinvertebrate assemblages between water‐depleted monitoring reaches evidenced that seasonal dynamics were inhibited and that the relative richness of EPT was lower (but predominantly in winter), where the streamflow alterations were induced by reservoir operations, thus supporting starting assumptions.…”

Section: Discussionmentioning

confidence: 99%

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Response of benthic macroinvertebrates to different hydropower off‐stream diversion schemes

Quadroni

Salmaso

Gentili³

et al. 2020

Ecohydrology

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Despite significant advancement in environmental flow science, the release of minimum flows (MFs) still represents one of the main measures globally adopted to mitigate off‐stream diversion in regulated rivers. In the Lake Como basin (Italy), we monitored water‐depleted reaches below hydropower reservoirs and intakes and reaches unimpacted by water withdrawal. Our aim was to verify if the gradient in streamflow alterations resulted in detectable differences in the structure and functions of benthic assemblages, possibly identifying streamflow metrics explaining the observed differences. The macroinvertebrate assemblages sampled below reservoirs showed significant differences from those from unimpacted reaches, including the reduced relative richness of Ephemeroptera, Plecoptera and Trichoptera (mainly stoneflies) and the higher abundance and richness of dipterans. These differences were well explained by the corresponding streamflow pattern, characterized by a rather constant flow throughout the year, occasionally interrupted by sharp peaks related to spilling episodes. In contrast, the shift from unimpacted conditions was minor for benthic assemblages collected at reaches below intakes, where the seasonal streamflow variation was partly preserved. Our results suggest that an increase of the e‐flow released by hydropower dams during the seasons characterized by larger run‐offs could support improved benthic assemblages. Dewatered river sections below reservoirs could thus be prioritized for updating the current MF management, in the study area as well as in comparable contexts. At least to our knowledge, specific investigations are so far unavailable regarding the exploration of the different responses of benthic macroinvertebrates to intakes and reservoirs operations.

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Section: Discussionsupporting

confidence: 93%

Section: Discussionmentioning

confidence: 99%

Response of benthic macroinvertebrates to different hydropower off‐stream diversion schemes

Quadroni

Salmaso

Gentili³

et al. 2020

Ecohydrology

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“…The RCC was originally based on forested temperate high-relief basins in North America. While the Adige River conforms to these aspects, its longitudinal continuity is altered by numerous hydropower dams distributed over the basin (Chiogna et al, 2016a;Larsen et al, 2019), which are expected to alter the natural continuity of river processes (Hoenighaus et al, 2007;Humphries et al, 2014). Therefore, the present study should not be considered as a formal test of the validity of the RCC model.…”

Section: Introductionmentioning

confidence: 87%

“…dams are distributed over 1 st to 4 th order streams), mostly for hydropower generation. These dams have altered the natural flow regimes of many reaches (Larsen et al, 2019;Zolezzi et al, 2009), and likely disrupted the natural continuum of sediment and organic matter transport. Macroinvertebrate data were collected as part of the institutional monitoring programmes of the Environmental Protection Agencies of the Provinces of Trento and Bolzano.…”

Section: Study Area and Datasetmentioning

confidence: 99%

Testing the River Continuum Concept with geostatistical stream-network models

Larsen

Bruno

Vaughan

et al. 2019

Ecological Complexity

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The River Continuum Concept (RCC) provided one of the first unifying frameworks in fluvial ecosystem theory. While the RCC predictions held in many empirical tests, other research highlighted how the model overlooked sources of heterogeneity at different scales e.g. the effects of tributaries. Disentangling these effects requires an assessment of variation in key ecosystem variables over the longitudinal and lateral dimension of river networks. However, so far, no empirical tests have employed a spatially explicit statistical approach to this assessment.Here, we show how recently-developed spatially-explicit models for river networks can be used to test predictions of the RCC whilst taking into account cross-scale sources of heterogeneity. We used macroinvertebrate data from 195 monitoring sites from 1 st to 4 th order streams spread across the Adige River network (NE Italy). We compared theoretical expectations with empirical semivariograms that incorporated network topology to assess the continuity and patchiness in the proportion of invertebrates functional feeding groups (FFG) over Euclidean and in-stream distances. Geostatistical stream-network models were then used to quantify the influence of the longitudinal gradient relative to local-scale water quality and land-use drivers, while accounting for network spatial autocorrelation. Patterns in the semivariograms based on flow-connected relationships were characterised by a nested structure associated with heterogeneity at multiple scales. Therefore, the longitudinal variation in FFG was better described by a patchy discontinuum rather than a gradient, implying that both in-stream processes and landscape factors influenced stream ecosystem function. The overall shift in FFG along the longitudinal profile was generally consistent with the RCC predictions, although the best models often included water quality and local land-use predictors. Stream-network models further indicated that up to 90% of residual variation (mean=50%) was accounted for by spatial autocorrelation, especially among flow-connected communities. Accounting for such autocorrelation not only improved model performance relative to non-spatial approaches, but indicated that most flow-connected communities were spatially correlated to some extent. This has clear implications for the assessment of the RCC tenets. This is the first test of the river continuum model that explicitly accounted for stream network topology and autocorrelation. Results indicated that in the Adige River, macroinvertebrates feeding groups exhibited heterogeneity along the longitudinal gradient, which appeared punctuated by local habitat transitions. Such transitions could be associated with artificial impoundments that alter the natural continuity of river processes, and we advocate the use of spatially explicit network models to test the RCC in more natural contexts.

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“…As observed by Renöfält et al [76], in contexts highly exploited for hydropower, such as the Alps, a main challenge for river management is to identify stream reaches to prioritize for intervention (i.e., where measures involving relatively small production losses can have major ecological advantages). At the same time, advanced biomonitoring and modelling tools are required to improve quantitative prediction of the effects of hydropower [107,109], supporting a comprehensive management strategy of the water resources, aimed to sustain the production of renewable and clean energy while improving at the same time the environmental quality of exploited rivers. Moreover, water management strategies should account for the effects of current climate changes, such as the increased duration of low-flow periods [110], the increased river temperature [111] and the occurrence of catastrophic events, such as landslides increasing sediment input in regulated streams [112,113].…”

Section: Towards Environmental Flow and Sediment Managementmentioning

confidence: 99%

Monitoring and Management of Inland Waters: Insights from the Most Inhabited Italian Region

et al. 2022

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Monitoring of freshwaters allows the detection of the impacts of multiple anthropic uses and activities on aquatic ecosystems, and an eco-sustainable management of natural resources could limit these impacts. In this work, we highlighted two main issues affecting inland waters, referring to findings from the most inhabited Italian region (Lombardy, approximately 10 M inhabitants): the first issue is lake pollution by old generation pesticides, the second is river development for hydropower. In both cases, some management strategies reducing the anthropic impacts on freshwaters were discussed: organic farming and biocontrol as an alternative to diffuse pollution by agrochemicals; environmental flows and controlled sediment flushing operations to limit the hydropower impact on rivers. Although the two mentioned issues were discussed separately in this paper, the management of water resources should be carried out in a comprehensive way, accounting for the multiple impacts affecting freshwater ecosystems, including those related to the climate changes.

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WFD ecological status indicator shows poor correlation with flow parameters in a large Alpine catchment

Cited by 13 publications

References 44 publications

Response of benthic macroinvertebrates to different hydropower off‐stream diversion schemes

Response of benthic macroinvertebrates to different hydropower off‐stream diversion schemes

Testing the River Continuum Concept with geostatistical stream-network models

Monitoring and Management of Inland Waters: Insights from the Most Inhabited Italian Region

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