title: Increased mitochondrial coupling and anaerobic capacity minimizes aerobic costs of trout in the sea.
abstract: Anadromy is a distinctive life-history strategy in fishes that has evolved independently many times. In an evolutionary context, the benefits of anadromy for a species or population must outweigh the costs and risks associated with the habitat switch. The migration of fish across the freshwater-ocean boundary coincides with potentially energetically costly osmoregulatory modifications occurring at numerous levels of biological organization. By integrating whole animal and sub-cellular metabolic measurements, this study presents significant findings demonstrating how an anadromous salmonid (i.e. rainbow trout, Oncorhynchus mykiss) is able to transform from a hyper- to hypo-osmoregulatory state without incurring significant increases in whole animal oxygen consumption rate. Instead, underlying metabolic mechanisms that fuel the osmoregulatory machinery at the organ level (i.e. intestine) are modulated, as mitochondrial coupling and anaerobic metabolism are increased to satisfy the elevated energetic demands. This may have positive implications for the relative fitness of the migrating individual, as aerobic capacity may be maintained for locomotion (i.e. foraging and predator avoidance) and growth. Furthermore, the ability to modulate mitochondrial metabolism in order to maintain osmotic balance suggests that mitochondria of anadromous fish may have been a key target for natural selection, driving species adaptations to different aquatic environments.
authors.affiliation: Department of Biological and Environmental Sciences, University of Gothenburg, Gothenburg, Sweden.
authors.forename: Jeroen
authors.initials: J
authors.lastname: Brijs
authors.affiliation: Department of Biological and Environmental Sciences, University of Gothenburg, Gothenburg, Sweden.
authors.forename: Erik
authors.initials: E
authors.lastname: Sandblom
authors.affiliation: Department of Biological and Environmental Sciences, University of Gothenburg, Gothenburg, Sweden.
authors.forename: Henrik
authors.initials: H
authors.lastname: Sundh
authors.affiliation: Department of Animal Environment and Health, Swedish University of Agricultural Sciences, Skara, Sweden.
authors.forename: Albin
authors.initials: A
authors.lastname: Gräns
authors.affiliation: Department of Biological and Environmental Sciences, University of Gothenburg, Gothenburg, Sweden.
authors.forename: James
authors.initials: J
authors.lastname: Hinchcliffe
authors.affiliation: Department of Biological and Environmental Sciences, University of Gothenburg, Gothenburg, Sweden.
authors.forename: Andreas
authors.initials: A
authors.lastname: Ekström
authors.affiliation: Department of Biological and Environmental Sciences, University of Gothenburg, Gothenburg, Sweden.
authors.forename: Kristina
authors.initials: K
authors.lastname: Sundell
authors.affiliation: Department of Biological and Environmental Sciences, University of Gothenburg, Gothenburg, Sweden.
authors.forename: Catharina
authors.initials: C
authors.lastname: Olsson
authors.affiliation: Department of Biological and Environmental Sciences, University of Gothenburg, Gothenburg, Sweden.
authors.forename: Michael
authors.initials: M
authors.lastname: Axelsson
authors.affiliation: Département de chimie et biochimie, Université de Moncton, Moncton, NB, Canada.
authors.forename: Nicolas
authors.initials: N
authors.lastname: Pichaud
mesh_terms: D000064:Acclimatization; D000693:Anaerobiosis; D025041:Animal Migration; D000818:Animals; D005260:Female; D007413:Intestinal Mucosa / Q000378:metabolism; D008297:Male; D008928:Mitochondria / Q000378:metabolism*; D017686:Oncorhynchus mykiss / Q000378:metabolism*; D064587:Osmoregulation; D010101:Oxygen Consumption; D012623:Seawater