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Poor correlation between large-scale environmental flow violations and freshwater biodiversity: implications for water resource management and water planetary boundary
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  • Chinchu Mohan,
  • Tom Gleeson,
  • James S. Famiglietti,
  • Vili Virkki,
  • Matti Kummu,
  • Miina Porkka,
  • Xander Huggins,
  • Lan Wang-Erlandsson,
  • Dieter Gerten,
  • Sonja C. Jähnig
Chinchu Mohan
University of Saskatchewan, University of Saskatchewan

Corresponding Author:[email protected]

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Tom Gleeson
University of Victoria, University of Victoria
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James S. Famiglietti
University of Saskatchewan, University of Saskatchewan
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Vili Virkki
Aalto University, Aalto University
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Matti Kummu
Aalto University, Aalto University
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Miina Porkka
Aalto University, Aalto University
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Xander Huggins
University of Victoria, University of Victoria
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Lan Wang-Erlandsson
Stockholm University, Stockholm University
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Dieter Gerten
Potsdam Institute for Climate Impact Research, Potsdam Institute for Climate Impact Research
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Sonja C. Jähnig
Leibniz Institute of Freshwater Ecology and Inland Fisheries (IGB), Leibniz Institute of Freshwater Ecology and Inland Fisheries (IGB)
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Abstract

The freshwater ecosystems around the world are degrading, such that maintaining environmental flow (EF) in river networks is critical to their preservation. The relationship between streamflow alterations and, respectively, EF violations, and freshwater biodiversity is well established at the scale of stream reaches or small basins (~<100 km²). However, it is unclear if this relationship is robust at larger scales even though there are large-scale initiatives to legalize the EF requirement. Moreover, EFs have been used in assessing a planetary boundary for freshwater. Therefore, this study intends to carry out an exploratory evaluation of the relationship between EF violation and freshwater biodiversity at globally aggregated scales and for freshwater ecoregions. Four EF violation indices (severity, frequency, the probability to shift to violated state, and probability to stay violated) and seven independent freshwater biodiversity indicators (calculated from observed biota data) were used for correlation analysis. No statistically significant negative relationship between EF violation and freshwater biodiversity was found at global or ecoregion scales. While our results thus suggest that streamflow and EF may not be an only determinant of freshwater biodiversity at large scales, they do not preclude the existence of relationships at smaller scales or with more holistic EF methods (e.g., including water temperature, water quality, intermittency, connectivity etc.) or with other biodiversity data or metrics.