Are European sea bass as euryhaline as expected? Intraspecific variation in freshwater tolerance

• Published in: Marine Biology
• Main Authors: L'Honore, Thibaut, Farcy, Emilie, Chatain, Beatrice, Gros, Romain, Ruelle, F, Hermet, Sophie, Blondeau-Bidet, Eva, Naudet, Jeanne, Lorin-Nebel, Catherine
• Other Authors: MARine Biodiversity Exploitation and Conservation (UMR MARBEC), Centre National de la Recherche Scientifique (CNRS)-Université de Montpellier (UM)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Institut de Recherche pour le Développement (IRD), Biologie des Organismes et Ecosystèmes Aquatiques (BOREA), Université de Caen Normandie (UNICAEN), Normandie Université (NU)-Normandie Université (NU)-Muséum national d'Histoire naturelle (MNHN)-Institut de Recherche pour le Développement (IRD)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université des Antilles (UA), Université de Montpellier (UM)
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2019
• Subjects: atlantic salmon; teleost fish; gene-expression; dicentrarchus-labrax; phenotypic plasticity; molecular characterization; dna methylation; growth-hormone; messenger-rna levels; stress-response; [SDE.BE]Environmental Sciences/Biodiversity and Ecology; [SDV.EE.ECO]Life Sciences [q-bio]/Ecology; environment/Ecosystems; Atlantic salmon
• Online Access: https://hal.archives-ouvertes.fr/hal-02434225; https://doi.org/10.1007/s00227-019-3551-z

WOS:000475657500006 International audience In teleosts, the regulation of hydromineral balance has a direct impact on several physiological functions, biochemical processes, and can influence behaviour, distribution and survival. As European sea bass Dicentrarchus labrax undertake seasonal migrations from seawater (SW) to brackish, estuarine and fresh water (FW) in their habitat, this study investigates their capacity to tolerate fresh water and explores intraspecific variations in physiological responses. Juvenile D. labrax were transferred from SW to FW at various ages. Freshwater-tolerant and non-tolerant phenotypes were discriminated according to behavioural and morphological characteristics. About 30% of the fish exposed to FW were identified as freshwater intolerant following FW challenges performed at different ages. Interestingly, intolerant fish exhibited the same phenotypic traits: erratic swimming, lower speed, isolation from the shoal and darker colour. Freshwater-intolerant fish were also characterised by a significant lower blood osmolality compared to tolerant fish, and significantly lower Na+/K+-ATPase α1a expression in the posterior kidney. An imbalance in ion regulatory mechanisms was further confirmed by a blood Na+/Cl− ratio imbalance observed in some freshwater-intolerant fish. The analysis of glucocorticoid and mineralocorticoid receptor expression levels in gills and kidney revealed significant differences between freshwater-intolerant and -tolerant fish in both organs, suggesting differential stress-related responses. This study clearly shows an intraspecific difference in the responses following FW transfer with a decreased renal ion uptake capacity as a major cause for freshwater intolerance.