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Treated and highly diluted wastewater impacts diversity and energy fluxes of freshwater food webs
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  • Ioar de Guzman,
  • Arturo Elosegi,
  • Daniel von Schiller,
  • Jose González,
  • Laura Paz,
  • Benoit Gauzens,
  • Ulrich Brose,
  • Alvaro Antón,
  • Nuria Olarte,
  • Jose Montoya,
  • Aitor Larrañaga
Ioar de Guzman
University of the Basque Country Faculty of Science and Technology

Corresponding Author:[email protected]

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Arturo Elosegi
University of the Basque Country (UPV/EHU)
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Daniel von Schiller
University of Barcelona
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Jose González
Rey Juan Carlos University
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Laura Paz
Universidad Nacional del Centro de la Provincia de Buenos Aires
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Benoit Gauzens
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Ulrich Brose
German Centre for Integrative Biodiversity Research Halle-Jena-Lepizig
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Alvaro Antón
University of the Basque Country
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Nuria Olarte
University of the Basque Country
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Jose Montoya
Centre National de la Recherche Scientifique
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Aitor Larrañaga
University of the Basque Country Faculty of Science and Technology
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The implementation of Wastewater Treatment Plants (WWTPs) brought great improvement in river ecological status. However, WWTP effluents still contain a complex cocktail of pollutants whose environmental effects might go unnoticed, masked by other stressors in the receiving waters or by spatiotemporal variability. We conducted a BACI (Before-After/Control-Impact) ecosystem manipulation experiment to assess the effects of a well-treated and highly diluted effluent on diversity and food web dynamics in an unpolluted stream. Although effluent toxicity was low, it reduced diversity, increased primary production and herbivory, and reduced energy fluxes associated to terrestrial inputs. Altogether, the effluent decreased total energy fluxes in stream food webs, showing that treated wastewater can lead to important ecosystem-level changes, affecting the structure and functioning of stream communities even at high dilution rates. Our study highlights the need for further efforts to treat polluted waters to conserve aquatic food webs.
Nov 2023Published in Journal of Environmental Management volume 345 on pages 118510. 10.1016/j.jenvman.2023.118510