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A novel method for measuring acute thermal tolerance in fish embryos

Aquatic ectotherms are vulnerable to thermal stress, with embryos predicted to be more sensitive than juveniles and adults. When examining the vulnerability of species and life stages to warming, comparable methodology must be used to obtain robust conclusions. Critical thermal methodology is common...

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Autores principales: Cowan, Zara-Louise, Andreassen, Anna H, De Bonville, Jeremy, Green, Leon, Binning, Sandra A, Silva-Garay, Lorena, Jutfelt, Fredrik, Sundin, Josefin
Formato: Online Artículo Texto
Lenguaje:English
Publicado: Oxford University Press 2023
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10410291/
https://www.ncbi.nlm.nih.gov/pubmed/37565236
http://dx.doi.org/10.1093/conphys/coad061
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author Cowan, Zara-Louise
Andreassen, Anna H
De Bonville, Jeremy
Green, Leon
Binning, Sandra A
Silva-Garay, Lorena
Jutfelt, Fredrik
Sundin, Josefin
author_facet Cowan, Zara-Louise
Andreassen, Anna H
De Bonville, Jeremy
Green, Leon
Binning, Sandra A
Silva-Garay, Lorena
Jutfelt, Fredrik
Sundin, Josefin
author_sort Cowan, Zara-Louise
collection PubMed
description Aquatic ectotherms are vulnerable to thermal stress, with embryos predicted to be more sensitive than juveniles and adults. When examining the vulnerability of species and life stages to warming, comparable methodology must be used to obtain robust conclusions. Critical thermal methodology is commonly used to characterize acute thermal tolerances in fishes, with critical thermal maximum (CT(max)) referring to the acute upper thermal tolerance limit. At this temperature, fish exhibit loss of controlled locomotion due to a temperature-induced collapse of vital physiological functions. While it is relatively easy to monitor behavioural responses and measure CT(max) in larval and adult fish, this is more challenging in embryos, leading to a lack of data on this life stage, or that studies rely on potentially incomparable metrics. Here, we present a novel method for measuring CT(max) in fish embryos, defined by the temperature at which embryos stop moving. Additionally, we compare this measurement with the temperature of the embryos’ last heartbeat, which has previously been proposed as a method for measuring embryonic CT(max). We found that, like other life stages, late-stage embryos exhibited a period of increased activity, peaking approximately 2–3°C before CT(max). Measurements of CT(max) based on last movement are more conservative and easier to record in later developmental stages than measurements based on last heartbeat, and they also work well with large and small embryos. Importantly, CT(max) measurements based on last movement in embryos are similar to measurements from larvae and adults based on loss of locomotory control. Using last heartbeat as CT(max) in embryos likely overestimates acute thermal tolerance, as the heart is still beating when loss of response/equilibrium is reached in larvae/adults. The last movement technique described here allows for comparisons of acute thermal tolerance of embryos between species and across life stages, and as a response variable to treatments.
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spelling pubmed-104102912023-08-10 A novel method for measuring acute thermal tolerance in fish embryos Cowan, Zara-Louise Andreassen, Anna H De Bonville, Jeremy Green, Leon Binning, Sandra A Silva-Garay, Lorena Jutfelt, Fredrik Sundin, Josefin Conserv Physiol Research Article Aquatic ectotherms are vulnerable to thermal stress, with embryos predicted to be more sensitive than juveniles and adults. When examining the vulnerability of species and life stages to warming, comparable methodology must be used to obtain robust conclusions. Critical thermal methodology is commonly used to characterize acute thermal tolerances in fishes, with critical thermal maximum (CT(max)) referring to the acute upper thermal tolerance limit. At this temperature, fish exhibit loss of controlled locomotion due to a temperature-induced collapse of vital physiological functions. While it is relatively easy to monitor behavioural responses and measure CT(max) in larval and adult fish, this is more challenging in embryos, leading to a lack of data on this life stage, or that studies rely on potentially incomparable metrics. Here, we present a novel method for measuring CT(max) in fish embryos, defined by the temperature at which embryos stop moving. Additionally, we compare this measurement with the temperature of the embryos’ last heartbeat, which has previously been proposed as a method for measuring embryonic CT(max). We found that, like other life stages, late-stage embryos exhibited a period of increased activity, peaking approximately 2–3°C before CT(max). Measurements of CT(max) based on last movement are more conservative and easier to record in later developmental stages than measurements based on last heartbeat, and they also work well with large and small embryos. Importantly, CT(max) measurements based on last movement in embryos are similar to measurements from larvae and adults based on loss of locomotory control. Using last heartbeat as CT(max) in embryos likely overestimates acute thermal tolerance, as the heart is still beating when loss of response/equilibrium is reached in larvae/adults. The last movement technique described here allows for comparisons of acute thermal tolerance of embryos between species and across life stages, and as a response variable to treatments. Oxford University Press 2023-08-08 /pmc/articles/PMC10410291/ /pubmed/37565236 http://dx.doi.org/10.1093/conphys/coad061 Text en © The Author(s) 2023. Published by Oxford University Press and the Society for Experimental Biology. https://creativecommons.org/licenses/by/4.0/This is an Open Access article distributed under the terms of the Creative Commons Attribution License (https://creativecommons.org/licenses/by/4.0/), which permits unrestricted reuse, distribution, and reproduction in any medium, provided the original work is properly cited.
spellingShingle Research Article
Cowan, Zara-Louise
Andreassen, Anna H
De Bonville, Jeremy
Green, Leon
Binning, Sandra A
Silva-Garay, Lorena
Jutfelt, Fredrik
Sundin, Josefin
A novel method for measuring acute thermal tolerance in fish embryos
title A novel method for measuring acute thermal tolerance in fish embryos
title_full A novel method for measuring acute thermal tolerance in fish embryos
title_fullStr A novel method for measuring acute thermal tolerance in fish embryos
title_full_unstemmed A novel method for measuring acute thermal tolerance in fish embryos
title_short A novel method for measuring acute thermal tolerance in fish embryos
title_sort novel method for measuring acute thermal tolerance in fish embryos
topic Research Article
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10410291/
https://www.ncbi.nlm.nih.gov/pubmed/37565236
http://dx.doi.org/10.1093/conphys/coad061
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