Poor correlation between large-scale environmental flow violations and freshwater biodiversity: Implications for water resource management and the freshwater planetary boundary

Date

2022

Authors

Mohan, Chinchu
Gleeson, Tom
Famiglietti, James S.
Virkki, Vili
Kummu, Matti
Miina, Porkka
Wang-Erlandsson, Lan
Huggins, Xander
Gerten, Dieter
Jähnig, Sonja C.

Journal Title

Journal ISSN

Volume Title

Publisher

Hydrology and Earth System Sciences

Abstract

The freshwater ecosystems around the world are degrading, such that maintaining environmental flow^1 (EF) in river networks is critical to their preservation. The relationship between streamflow alterations (subsequent EF violations^2) and the freshwater biodiversity response is well established at the scale of stream reaches or small basins ( ~< 100 km^2). 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^3 for freshwater. Therefore, this study intends to conduct 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, probability of shifting to a violated state, and probability of staying 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. These findings imply the need for a holistic bio-geo-hydro-physical approach in determining the environmental flows. While our results thus suggest that streamflow and EF may not be the 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.

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Citation

Mohan, C., Gleeson, T., Famiglietti, J. S., Virkki, V., Kummu, M., Porkka, M., . . . Jähnig, S. C. (2022). “Poor correlation between large-scale environmental flow violations and freshwater biodiversity: Implications for water resource management and the freshwater planetary boundary.” Hydrology and Earth System Sciences, 26, 6247-6262. https://doi.org/10.5194/hess-26-6247-2022