Integration of Gill and Intestinal Osmoregulatory Functions to Assess the Smoltification Window in Atlantic Salmon
The transfer time of Atlantic salmon smolts from freshwater to seawater remains a challenge in aquaculture, with the “smolt window” referring to the optimal timeframe for seawater readiness. Our study monitored Atlantic salmon osmoregulatory adaptations during smoltification under continuous light (...
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2025-03-01
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| author | Jonás I. Silva-Marrero Floriana Lai Sigurd O. Handeland Cindy Pedrosa Virginie Gelebart Pablo Balseiro Juan Fuentes Ivar Rønnestad Ana S. Gomes |
| author_facet | Jonás I. Silva-Marrero Floriana Lai Sigurd O. Handeland Cindy Pedrosa Virginie Gelebart Pablo Balseiro Juan Fuentes Ivar Rønnestad Ana S. Gomes |
| author_sort | Jonás I. Silva-Marrero |
| collection | DOAJ |
| description | The transfer time of Atlantic salmon smolts from freshwater to seawater remains a challenge in aquaculture, with the “smolt window” referring to the optimal timeframe for seawater readiness. Our study monitored Atlantic salmon osmoregulatory adaptations during smoltification under continuous light (LL) and winter signal regime (6 weeks LD 12:12) followed by 6 or 8 weeks of constant light. Fish were subsequently reared in seawater for 8 weeks and subjected to a stress event of cyclic hypoxia at the conclusion of the trial. Significant differences in growth trajectories were observed between the LL and LD groups, with fish receiving the winter signal showing compensatory growth after seawater transfer. Gill Na<sup>+</sup>/K<sup>+</sup>-ATPase (NKA) activity, plasma ions, glucose, and cortisol levels confirmed the importance of the winter signal for seawater adaptation. Molecular markers, including <i>nka</i> isoforms, Na<sup>+</sup>-K<sup>+</sup>-2Cl<sup>−</sup> cotransporter (<i>nkcc</i>), cystic fibrosis transmembrane conductance regulator (<i>cftr</i>), and Na<sup>+</sup>/HCO<sub>3</sub><sup>−</sup> cotransporter (<i>nbc</i>), showed distinct temporal expression patterns, particularly in gills and midgut. Notably, the LD group with delayed seawater transfer exhibited enhanced growth and improved hypo-osmoregulatory capacity. These findings underscore the advantages of a winter signal in smoltification and suggest that delaying seawater transfer for up to 8 weeks could be beneficial. |
| format | Article |
| id | doaj-art-4652db21fb8f4c19a27c5ee0c8edf6dc |
| institution | Kabale University |
| issn | 2410-3888 |
| language | English |
| publishDate | 2025-03-01 |
| publisher | MDPI AG |
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| series | Fishes |
| spelling | doaj-art-4652db21fb8f4c19a27c5ee0c8edf6dc2025-08-20T03:43:11ZengMDPI AGFishes2410-38882025-03-0110311910.3390/fishes10030119Integration of Gill and Intestinal Osmoregulatory Functions to Assess the Smoltification Window in Atlantic SalmonJonás I. Silva-Marrero0Floriana Lai1Sigurd O. Handeland2Cindy Pedrosa3Virginie Gelebart4Pablo Balseiro5Juan Fuentes6Ivar Rønnestad7Ana S. Gomes8Department of Biological Sciences, University of Bergen, 5020 Bergen, NorwayDepartment of Biological Sciences, University of Bergen, 5020 Bergen, NorwayDepartment of Biological Sciences, University of Bergen, 5020 Bergen, NorwayDepartment of Biological Sciences, University of Bergen, 5020 Bergen, NorwayDepartment of Biological Sciences, University of Bergen, 5020 Bergen, NorwayDepartment of Biological Sciences, University of Bergen, 5020 Bergen, NorwayInstituto de Ciencias Marinas de Andalucía, Consejo Superior de Investigaciones Científicas (ICMAN-CSIC), 11519 Cádiz, SpainDepartment of Biological Sciences, University of Bergen, 5020 Bergen, NorwayDepartment of Biological Sciences, University of Bergen, 5020 Bergen, NorwayThe transfer time of Atlantic salmon smolts from freshwater to seawater remains a challenge in aquaculture, with the “smolt window” referring to the optimal timeframe for seawater readiness. Our study monitored Atlantic salmon osmoregulatory adaptations during smoltification under continuous light (LL) and winter signal regime (6 weeks LD 12:12) followed by 6 or 8 weeks of constant light. Fish were subsequently reared in seawater for 8 weeks and subjected to a stress event of cyclic hypoxia at the conclusion of the trial. Significant differences in growth trajectories were observed between the LL and LD groups, with fish receiving the winter signal showing compensatory growth after seawater transfer. Gill Na<sup>+</sup>/K<sup>+</sup>-ATPase (NKA) activity, plasma ions, glucose, and cortisol levels confirmed the importance of the winter signal for seawater adaptation. Molecular markers, including <i>nka</i> isoforms, Na<sup>+</sup>-K<sup>+</sup>-2Cl<sup>−</sup> cotransporter (<i>nkcc</i>), cystic fibrosis transmembrane conductance regulator (<i>cftr</i>), and Na<sup>+</sup>/HCO<sub>3</sub><sup>−</sup> cotransporter (<i>nbc</i>), showed distinct temporal expression patterns, particularly in gills and midgut. Notably, the LD group with delayed seawater transfer exhibited enhanced growth and improved hypo-osmoregulatory capacity. These findings underscore the advantages of a winter signal in smoltification and suggest that delaying seawater transfer for up to 8 weeks could be beneficial.https://www.mdpi.com/2410-3888/10/3/119<i>Salmo salar</i>smolt windowgillsintestineosmoregulationNa<sup>+</sup>/K<sup>+</sup>-ATPase |
| spellingShingle | Jonás I. Silva-Marrero Floriana Lai Sigurd O. Handeland Cindy Pedrosa Virginie Gelebart Pablo Balseiro Juan Fuentes Ivar Rønnestad Ana S. Gomes Integration of Gill and Intestinal Osmoregulatory Functions to Assess the Smoltification Window in Atlantic Salmon Fishes <i>Salmo salar</i> smolt window gills intestine osmoregulation Na<sup>+</sup>/K<sup>+</sup>-ATPase |
| title | Integration of Gill and Intestinal Osmoregulatory Functions to Assess the Smoltification Window in Atlantic Salmon |
| title_full | Integration of Gill and Intestinal Osmoregulatory Functions to Assess the Smoltification Window in Atlantic Salmon |
| title_fullStr | Integration of Gill and Intestinal Osmoregulatory Functions to Assess the Smoltification Window in Atlantic Salmon |
| title_full_unstemmed | Integration of Gill and Intestinal Osmoregulatory Functions to Assess the Smoltification Window in Atlantic Salmon |
| title_short | Integration of Gill and Intestinal Osmoregulatory Functions to Assess the Smoltification Window in Atlantic Salmon |
| title_sort | integration of gill and intestinal osmoregulatory functions to assess the smoltification window in atlantic salmon |
| topic | <i>Salmo salar</i> smolt window gills intestine osmoregulation Na<sup>+</sup>/K<sup>+</sup>-ATPase |
| url | https://www.mdpi.com/2410-3888/10/3/119 |
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