Contrasting effects of climate change in continental vs. oceanic environments on population persistence and microevolution of Atlantic salmon

• Published in: Global Change Biology
• Main Authors: Piou, Cyril, Prévost, Etienne
• Other Authors: Ecologie Comportementale et Biologie des Populations de Poissons (ECOBIOP), Institut National de la Recherche Agronomique (INRA)-Université de Pau et des Pays de l'Adour (UPPA), Centre de Coopération Internationale en Recherche Agronomique pour le Développement (Cirad), This work was financed under a grant from the French Ministry of Ecology and Sustainable Development ‘Programme GICC2: Gestion et Impact du Changement Climatique’ and a funding from ONEMA (French national office of water and aquatic environments) under the ONEMA-INRA 2008–2010 conventions.
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2013
• Subjects: diadromous fish; ecogenetic modelling; evolutionary demography; extinction risk; life-history strategy; phenotypic plasticity; river flow management; population dynamic; salmo salar; [SDE.MCG]Environmental Sciences/Global Changes; [SDE.BE]Environmental Sciences/Biodiversity and Ecology; Atlantic salmon; Salmo salar
• Online Access: https://hal.inrae.fr/hal-02645331; https://doi.org/10.1111/gcb.12085

International audience Facing climate change (CC), species are prone to multiple modifications in their environment that can lead to extinction, migration or adaptation. Identifying the role and interplay of different potential stressors becomes a key question. Anadromous fishes will be exposed to both river and oceanic habitat changes. For Atlantic salmon, the river water temperature, river flow and oceanic growth conditions appear as three main stressing factors. They could act on population dynamics or as selective forces on life-history pathways. Using an individual-based demo-genetic model, we assessed the effects of these factors (1) to compare risks of extinction resulting from CC in river and ocean, and (2) to assess CC effects on life-history pathways including the evolution of underlying genetic control of phenotypic plasticity. We focused on Atlantic salmon populations from Southern Europe for a time horizon of three decades. We showed that CC in river alone should not lead to extinction of Southern European salmon populations. In contrast, the reduced oceanic growth appeared as a significant threat for population persistence. An increase in river flow amplitude increased the risk of local extinction in synergy with the oceanic effects, but river temperature rise reduced this risk. In terms of life-history modifications, the reduced oceanic growth increased the age of return of individuals through plastic and genetic responses. The river temperature rise increased the proportion of sexually mature parr, but the genetic evolution of the maturation threshold lowered the maturation rate of male parr. This was identified as a case of environmentally driven plastic response that masked an underlying evolutionary response of plasticity going in the opposite direction. We concluded that to counteract oceanic effects, river flow management represented the sole potential force to reduce the extinction probability of Atlantic salmon populations in Southern Europe, although this might not impede changes in ...