Measuring critical thermal maximum in aquatic ectotherms: A practical guide

Abstract Critical thermal limits, commonly quantified as CT max (maximum) or CT min (minimum), are core metrics in the thermal biology of aquatic ectotherms. CT max , in particular, has recently surged in popularity due to its various applications, including understanding and predicting the responses of animals to climate warming. Despite its growing popularity, there is a limited literature aimed at establishing best practices for designing, running and reporting CT max experiments. This lack of standardisation and insufficiently detailed reporting in the literature creates challenges when designing CT max studies or comparing results across studies. Here, we provide a comprehensive, practical guide for designing and conducting experiments to measure critical thermal limits, with an emphasis on CT max . Our recommendations cover 12 topic areas including apparatus design, masking (blinding), warming rates, end points, replication and reporting. We include diagrams and photos for designing and building critical thermal limit arenas for field or lab applications. We also provide a reporting checklist as a reference for researchers when carrying out experiments and preparing manuscripts. Future studies incorporating critical thermal limits would benefit from transparent reporting of warming/cooling rates (raw data, supplementary graphs) and photo/video evidence showing arena designs and critical thermal limit end points. We also provide directions for empirical research that will help further inform the measurement of critical thermal limits, including biotic factors like stress and digestion, warming/cooling rates, the effects of body mass on heat transfer and the physiological mechanisms underlying thermal tolerance.

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Publication Details

Journal
Methods in Ecology and Evolution
Published
2025-08-15
DOI
https://doi.org/10.1111/2041-210x.70103
Citations
13
Primary Topic
Physiological and biochemical adaptations
Type
article
Field-Weighted Citation Impact
22.31

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article

Measuring critical thermal maximum in aquatic ectotherms: A practical guide

Luis Kuchenmüller, Fredrik Jutfelt, León Green, Eirik R. Åsheim et al.
13 citations
Methods in Ecology and Evolution
Physiological and biochemical adaptations
22.31
article

Measuring critical thermal maximum in aquatic ectotherms: A practical guide

Luis Kuchenmüller, Fredrik Jutfelt, León Green, Eirik R. Åsheim, Tamzin A. Blewett, Erin Stewart, Zara‐Louise Cowan, Anna H. Andreassen, Rasmus Ern, Graham D. Raby, Robine H. J. Leeuwis, Jérémy De Bonville, Josefin Sundin, Rachael Morgan, Ben Speers‐Roesch, Elizabeth C. Hoots, Lauren E. Rowsey, Sandra A. Binning, Heather Bauer Reid, Robert A. Griffin, Thomas D. Clark, Sidney Martin, Moa Metz
article en
13 citations

Abstract

Abstract Critical thermal limits, commonly quantified as CT max (maximum) or CT min (minimum), are core metrics in the thermal biology of aquatic ectotherms. CT max , in particular, has recently surged in popularity due to its various applications, including understanding and predicting the responses of animals to climate warming. Despite its growing popularity, there is a limited literature aimed at establishing best practices for designing, running and reporting CT max experiments. This lack of standardisation and insufficiently detailed reporting in the literature creates challenges when designing CT max studies or comparing results across studies. Here, we provide a comprehensive, practical guide for designing and conducting experiments to measure critical thermal limits, with an emphasis on CT max . Our recommendations cover 12 topic areas including apparatus design, masking (blinding), warming rates, end points, replication and reporting. We include diagrams and photos for designing and building critical thermal limit arenas for field or lab applications. We also provide a reporting checklist as a reference for researchers when carrying out experiments and preparing manuscripts. Future studies incorporating critical thermal limits would benefit from transparent reporting of warming/cooling rates (raw data, supplementary graphs) and photo/video evidence showing arena designs and critical thermal limit end points. We also provide directions for empirical research that will help further inform the measurement of critical thermal limits, including biotic factors like stress and digestion, warming/cooling rates, the effects of body mass on heat transfer and the physiological mechanisms underlying thermal tolerance.

Methods in Ecology and EvolutionVol. 16(10)
University of New Brunswick (CA), Deakin University (AU), University of Alberta (CA), Norwegian University of Science and Technology (NO), Swedish University of Agricultural Sciences (SE), Natural Resources Institute Finland (FI), University of Bergen (NO), Trent University (CA), Université de Montréal (CA), University of Gothenburg (SE), Technical University of Denmark (DK)
Australian Government, Deakin University, Natural Sciences and Engineering Research Council of Canada, European Research Council, H2020 Marie Skłodowska-Curie Actions
Openalex Percentile: Top 0%
Physiological and biochemical adaptations
22.31
DOIOpen Access PDFOpenAlex
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