Joint temporal trends in river thermal and hydrological conditions can threaten the downstream migration of the critically endangered European eel

• Published in: Scientific Reports
• Main Authors: Arevalo, Elorri, Drouineau, Hilaire, Tétard, Stéphane, Durif, Caroline M. F., Diserud, Ola, Poole, W. Russell, Maire, Anthony
• Other Authors: Ecosystèmes aquatiques et changements globaux (UR EABX), Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE), Laboratoire National d’Hydraulique et Environnement (EDF R&D LNHE), EDF R&D (EDF R&D), EDF (EDF)-EDF (EDF), Austevoll Research Station (IMR), Institute of Marine Research Bergen (IMR), University of Bergen (UiB)-University of Bergen (UiB), NORWEGIAN INSTITUTE FOR NATURE RESEARCH TRONDHEIM NOR, Partenaires IRSTEA, Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA), MARINE INSTITUTE FURNACE NEWPORT CO MAYO IRELAND GBR
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2021
• Subjects: [SDV]Life Sciences [q-bio]; Anguilla anguilla; European eel
• Online Access: https://hal.inrae.fr/hal-03347372; https://hal.inrae.fr/hal-03347372/document; https://hal.inrae.fr/hal-03347372/file/Arevalo2021.pdf; https://doi.org/10.1038/s41598-021-96302-x

International audience Climate change is modifying the hydrological and thermal regimes of rivers worldwide, threatening the triggering of organisms’ key life-cycle processes. European eel ( Anguilla anguilla ) is a critically endangered fish species that migrates over several thousand kilometres between its rearing habitats in continental waters of Europe and North Africa and its spawning area in the Sargasso Sea. Downstream migration of adult eels occurs during periods of decreasing river water temperature associated with high discharge but changes in these environmental cues may affected eel migratory conditions. An innovative multivariate method was developed to analyse long-term datasets of daily water temperature, discharge and eel passage in two European rivers. Over the past 50 years, water temperature and discharge increased in both rivers during the downstream migration period from August to November. Silver eels preferentially migrated at temperatures between 10 and 20 °C combined with high discharge. Environmental changes have resulted in the migration of silver eels under warmer water temperatures. This example illustrates how the changes in environmental cues have led to a growing mismatch between the migratory conditions preferentially selected and those actually used, which may threaten the completion of the eel’s life cycle and ultimately the persistence of this already critically endangered species.