Effects of experimentally elevated egg cortisol on offspring traits in two species of wild Pacific salmon
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In fishes, elevated levels of cortisol in eggs can have carry-over effects on phenotypic and performance traits early in life. How responses to elevations in egg cortisol differ among species remains poorly understood. Using wild populations of chum salmon (Oncorhynchus keta) and sockeye salmon (O. nerka), we investigated whether experimentally-elevated concentrations of cortisol in newly fertilized eggs had effects on offspring morphology and/or burst swimming capacity. Immediately following fertilization, eggs were incubated for 2 h with water dosed with 0 ng/mL or 1000 ng/mL of cortisol. Embryos were reared to the fry life stage (complete yolk sac absorption). Morphology and burst swimming performance of fry were then assessed. Sockeye salmon fry reared from cortisol-treated eggs were smaller overall (i.e., smaller body, fins and eyes) compared to conspecifics reared from untreated eggs. In contrast, the morphology of chum salmon fry was not affected by the experimental elevation of egg cortisol. In both species, burst swimming duration was unaffected by egg cortisol treatment, while offspring reared from the cortisol-treated eggs initiated fewer bouts of burst swimming. Our results demonstrate that closely-related species can respond differently to elevations in egg cortisol, and not all offspring traits may be affected by these elevations in cortisol. Further efforts to establish links among offspring quality, maternal stress, and egg composition need to consider the potential for divergent responses among species and examine multiple measures of phenotype and performance throughout development.
KeywordsGlucocorticoid Oncorhynchus Swimming Morphology Fish Survival
Research conformed to protocols approved by UBC’s Committee on Animal Care (#A11 0215) and met the Canadian Council on Animal Care guidelines. We thank members of UBC’s Pacific Salmon Ecology and Conservation Lab, DFO Environmental Watch, DFO Stock Assessment, J. Burke and undergraduate volunteers for fish collection and offspring rearing, J. Hills and A. Faure for egg cortisol extraction, and anonymous reviewers for constructive feedback on earlier versions of this manuscript. SGH is funded by a Natural Sciences and Engineering Research Council of Canada (NSERC) Discovery, Strategic and Network (Ocean Tracking Network Canada) grant. NMS and GDR were funded by NSERC graduate scholarships, and SJH was funded by an NSERC undergraduate student research award (USRA).
- Beamish FWH (1978) In: Hoar WS, Randall DJ (eds) Swimming capacity. Fish Physiology, Vol VII Academic Press, New York, pp. 101–187Google Scholar
- Birtwell IK, Nassichuk MD, Beune H (1987) Underyearling sockeye salmon (Oncorhynchus nerka) in the estuary of the Fraser River. Canadian Special Publication of Fisheries and Aquatic Sciences 9:a25–a35Google Scholar
- Burgner RL (1991) Life history of sockeye salmon (Oncorhynchus nerka). In Groot C, Margolis L (eds). Pacific salmon life histories. UBC press. Vancouver:1–117Google Scholar
- Chadwick JG, Nislow KH, McCormick SD (2015) Thermal onset of cellular and endocrine stress responses correspond to ecological limits in brook trout, an iconic cold-water fish. Conserv Phys 3:cov017Google Scholar
- DFO (Fisheries and Oceans Canada) (2005) Canada’s policy for conservation of wild Pacific salmon. Available online - http://www.pac.dfo-mpo.gc.ca/publications/pdfs/wsp-eng.pdf (accessed 23/02/14)
- Hruska KA, Hinch SG, Healey MC, Patterson DA, Larsson S, Farrell AP (2010) Influences of sexual status and behavior on physiological changes among individual adult sockeye salmon during rapid senescence. Physiol Biol Chem 83:663–676Google Scholar
- Jeffrey JD, Gilmour KM (2016) Programming of the hypothalamic-pituitary-interrenal axis by maternal social status in zebrafish (Danio rerio). J Exp Biol 219:1734–1743Google Scholar
- Pikulkaew S, Benato F, Celeghin A, Zucal C, Skobo T, Colombo L, Dalla Valle L (2011) The knockdown of maternal glucocorticoid receptor mRNA alters embryo development in zebrafish. Dev Dynam 240:874–889Google Scholar
- Salo EO (1991) Life history of chum salmon (Oncorhynchus keta). In Groot C, Margolis L (eds). Pacific salmon life histories. UBC press. Vancouver:213–310Google Scholar