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Thermal windows and metabolic performance curves in a developing Antarctic fish

Abstract

For ectotherms, temperature modifies the rate of physiological function across a temperature tolerance window depending on thermal history, ontogeny, and evolutionary history. Some adult Antarctic fishes, with comparatively narrow thermal windows, exhibit thermal plasticity in standard metabolic rate; however, little is known about the shape or breadth of thermal performance curves of earlier life stages of Antarctic fishes. We tested the effects of acute warming (− 1 to 8 °C) and temperature acclimation (2 weeks at − 1, 2, 4 °C) on survival and standard metabolic rate in early embryos of the dragonfish Gymnodraco acuticeps from McMurdo Sound, Ross Island, Antarctica. Contrary to predictions, embryos acclimated to warmer temperatures did not experience greater mortality and nearly all embryos survived acute warming to 8 °C. Metabolic performance curve height and shape were both significantly altered after 2 weeks of development at − 1 °C, with further increase in curve height, but not alteration of shape, with warm temperature acclimation. Overall metabolic rate temperature sensitivity (Q 10) from − 1 to 8 °C varied from 2.6 to 3.6, with the greatest thermal sensitivity exhibited by embryos at earlier developmental stages. Interclutch variation in metabolic rates, mass, and development of simultaneously collected embryos was also documented. Taken together, metabolic performance curves provide insight into the costs of early development under warming temperatures, with the potential for thermal sensitivity to be modified by dragonfish phenology and magnitude of seasonal changes in temperature.

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Abbreviations

ANOVA:

Analysis of variance

CTmax:

Critical thermal maxima

GAMM:

General additive mixed modeling

TPC:

Thermal performance curve

SMR:

Standard metabolic rate

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Acknowledgements

We thank the United States Antarctic Program and Lockheed Martin for logistical and field support at McMurdo Station, Antarctica, including SCUBA divers Rob Robbins and Steve Rupp. Brittany Davis and Dr. Nathan Miller provided invaluable experimental assistance, and Prof. Nann Fangue contributed helpful discussion and feedback to the writing of this paper. This work was supported by the National Science Foundation (NSF ANT-1142122) to A.E.T.

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Correspondence to Anne E. Todgham.

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The authors declare that they have no conflict of interest.

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Communicated by G. Heldmaier.

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Flynn, E.E., Todgham, A.E. Thermal windows and metabolic performance curves in a developing Antarctic fish. J Comp Physiol B 188, 271–282 (2018). https://doi.org/10.1007/s00360-017-1124-3

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  • DOI: https://doi.org/10.1007/s00360-017-1124-3

Keywords

  • Temperature
  • Metabolism
  • Performance curves
  • Embryos
  • Polar fish
  • Gymnodraco acuticeps