Sex-Specific Consequences of Experimental Cortisol Elevation in Pre-Reproductive Wild Largemouth Bass

Authors

  • Constance M. O'Connor,

    Corresponding authorCurrent affiliation:
    1. Aquatic Behavioural Ecology Laboratory, Department of Psychology, Neuroscience, and Behaviour, McMaster University, 1280 Main St W, Hamilton, ON, Canada
    • FishEcology and Conservation Physiology Laboratory, Ottawa-Carleton Institute of Biology, Carleton University, Ottawa, Ontario, Canada
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  • Michael Nannini,

    1. Sam Parr Biological Station, Illinois Natural History Survey, Kinmundy, Illinois
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  • David H. Wahl,

    1. Kaskaskia Biological Station, Illinois Natural History Survey, Sullivan, Illinois
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  • Samantha M. Wilson,

    1. FishEcology and Conservation Physiology Laboratory, Ottawa-Carleton Institute of Biology, Carleton University, Ottawa, Ontario, Canada
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  • Kathleen M. Gilmour,

    1. Department of Biology, University of Ottawa, Ottawa, Ontario, Canada
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  • Steven J. Cooke

    1. FishEcology and Conservation Physiology Laboratory, Ottawa-Carleton Institute of Biology, Carleton University, Ottawa, Ontario, Canada
    2. Instituteof Environmental Science, Carleton University, Ottawa, Ontario, Canada
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Correspondence to: Constance M. O'Connor, 1280 Main St W, Hamilton, ON, Canada L8S 4L8. E-mail: coconn@mcmaster.ca

Abstract

Experimental implants were used to investigate the effect of elevated cortisol (the primary stress hormone in teleost fish) on energetic and physiological condition prior to reproduction in male and female largemouth bass (Micropterus salmoides). Fish were wild-caught from lakes in Illinois, and held in experimental ponds for the duration of the study. Between 9 and 13 days after cortisol treatment, and immediately prior to the start of the reproductive period, treated and control animals were sampled. Females exhibited lower muscle lipid content, lower liver glycogen content, and higher hepatosomatic indices than males, regardless of treatment. Also, cortisol-treated females had higher hepatosomatic indices and lower final mass than control females, whereas males showed no differences between treatment groups. Finally, cortisol-treated females had higher gonadal cortisol concentrations than control females. In general, we found evidence of reduced energetic stores in female fish relative to male fish, likely due to timing differences in the allocation of resources during reproduction between males and females. Perhaps driven by the difference in energetic reserves, our data further suggest that females are more sensitive than males to elevated cortisol during the period immediately prior to reproduction. J. Exp. Zool. 319A:23–31, 2013. © 2012 Wiley Periodicals, Inc.

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