Is oxygen limitation in warming waters a valid mechanism to explain decreased body sizes in aquatic ectotherms?

Asta Audzijonyte (Corresponding Author), Diego R. Barneche, Alan R. Baudron, Jonathan Belmaker, Timothy D. Clark, C. Tara Marshall, John R. Morrongiello, van Rijn Itai

Research output: Contribution to journalArticlepeer-review

93 Citations (Scopus)
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The negative correlation between temperature and body size of ectothermic animals (broadly known as a temperature-size rule or TSR) is a widely observed pattern, especially in aquatic organisms. Studies have claimed that TSR arises due to decreased oxygen solubility and increasing metabolic costs at warmer temperatures, whereby oxygen supply to a large body becomes increasingly difficult. However, mixed empirical evidence has led to a controversy about the mechanisms affecting species’ size and performance under different temperatures. We review the main competing genetic, physiological and ecological explanations for TSR and suggest a roadmap to move the field forward.




Aquatic ectotherms

Time period

1980 – Present


We show that current studies cannot discriminate among alternative hypotheses and none of the hypotheses can explain all TSR related observations. To resolve the impasse we need experiments and field-sampling programs that specifically compare alternative mechanisms and formally consider energetics, such as costs of growth, oxygen supply and behaviour. We highlight the distinction between evolutionary and plastic mechanisms, and suggest that the oxygen limitation debate should separate processes operating on short, decadal and millennial timescales.


Despite decades of research, we remain uncertain whether TSR is an adaptive response to temperature-related physiological (enzyme activity) or ecological changes (food, predation, other mortality), or a response to constraints operating at a cellular level (oxygen supply and associated costs). To make progress, ecologists, physiologists, modellers and geneticists should work together to develop a cross-disciplinary research program that integrates theory and data, explores time scales over which TSR operates, and assesses limits to adaptation or plasticity. We identify four questions for such a program. Answering these questions is crucial given the widespread impacts of climate change and reliance of management on models that are highly dependent on accurate representation of ecological and physiological responses to temperature.
Original languageEnglish
Pages (from-to)64-77
Number of pages14
JournalGlobal Ecology and Biogeography
Issue number2
Early online date16 Nov 2018
Publication statusPublished - Jan 2019

Bibliographical note

The authors would like to acknowledge funding from Australian Research Council (grant No. DP170104240) and the Kone Foundation (to AA), Horizon 2020 European research projects ClimeFish (grant No. 677039) (to ARB) and Australian Academy of Science (to JRM)


  • adaptation
  • alternative mechanisms
  • climate change
  • growth
  • poikilotherm
  • energy budget
  • geometric biology
  • temperature size rule


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