Rosero-Lopez D. auteur aut IRD Walter M. T. auteur aut IRD Flecker A. S. auteur aut IRD De Bievre B. auteur aut IRD Osorio R. auteur aut IRD Gonzalez-Zeas D. auteur aut IRD Cauvy-Fraunie S. auteur aut IRD Dangles Olivier auteur aut IRD text journalArticle eng text/pdf reformatted digital access The growing threat of abrupt and irreversible changes to the functioning of freshwater ecosystems compels robust measures of tipping point thresholds. To determine benthic cyanobacteria regime shifts in a potable water supply system in the tropical Andes, we conducted a whole ecosystem-scale experiment in which we systematically diverted 20 to 90% of streamflow and measured ecological responses. Benthic cyanobacteria greatly increased with a 60% flow reduction and this tipping point was related to water temperature and nitrate concentration increases, both known to boost algal productivity. We supplemented our experiment with a regional survey collecting > 1450 flow-benthic algal measurements at streams varying in water abstraction levels. We confirmed the tipping point flow value, albeit at a slightly lower threshold (40-50%). A global literature review broadly confirmed our results with a mean tipping point at 58% of flow reduction. Our study provides robust in situ demonstrations of regime shift thresholds in running waters with potentially strong implications for environmental flows management. Experimental stream manipulation in a mountain river system in the tropical Andes initiates a regime shift of benthic cyanobacteria. This whole-ecosystem experiment in conjunction with a global synthesis reveal regime shift tipping points dependent upon freshwater streamflow. specialized EQUATEUR ANDES ZONE TROPICALE MONDE CAYAMBE COCA PARC NATIONAL CHALPI GRANDE BASSIN VERSANT 036 034 021 5 1 420 [8 p.] 2022 https://www.documentation.ird.fr/hor/fdi:010084756 10.1038/s42003-022-03345-5 [F B010084756] https://www.documentation.ird.fr/hor/fdi:010084756 https://horizon.documentation.ird.fr/exl-doc/pleins_textes/2022-06/010084756.pdf IRD - Base Horizon / Pleins textes 2022-06-03 2025-02-24 fdi:010084756 fre