A novel method for measuring acute thermal tolerance in fish embryos

2023 · doi:10.32942/x2v01r
Lab / animal preprint OA: closed
Full text JSON View at publisher
⚙ AI-generated deep summary by qwen3.7-flash, 2026-10-03 · read from full text ⓘ

This study introduces a novel method for determining the acute thermal tolerance limits of fish embryos by defining critical thermal maximum based on the cessation of movement. The researchers compared this behavioral endpoint to the temperature at which the embryonic heart stops beating, finding that the latter likely overestimates thermal tolerance because cardiac activity persists beyond the point of locomotory loss observed in later life stages. By demonstrating that movement cessation aligns with loss of equilibrium in juveniles and adults, the authors establish a comparable metric across different developmental phases. The paper does not explicitly discuss endometriosis or adenomyosis; it was included in the corpus via a keyword match in the upstream search index.

Read from the paper's body, not the abstract. Not a substitute for reading the paper. No clinical advice. How this works

Abstract

1. Aquatic ectotherms are particularly vulnerable to thermal stress, with certain life stages (embryos) predicted to be more sensitive than others (juveniles and adults). When examining the vulnerability of species and life stages to warming, it is particularly important to use appropriate and comparable methodology so that robust conclusions can be obtained. Critical thermal methodology (CTM) is commonly used to characterise acute thermal tolerance in fishes, with critical thermal maximum (CTmax) referring to a measured endpoint defining the upper acute thermal tolerance limit. This is the temperature at which fish exhibit loss of locomotory movements (i.e., loss of equilibrium) due to a temperature-induced collapse of vital physiological functions. While it is relatively easy to monitor behavioural responses and measure CTmax in juvenile and adult fish, this can be much more challenging in embryos. This has led to a lack of data on this life stage, or that studies rely on other, potentially incomparable, metrics.2. Here, we present a novel method for measuring acute upper thermal tolerance limits in fish embryos, where CTmax is defined by the temperature at which embryos stop moving. Additionally, we compare this measurement to the temperature at which the embryos' heart stops beating, which has previously been proposed as a method for measuring CTmax in this life stage.3. We found that, similar to other life stages, embryos exhibited a period of increased activity, which peaked approximately 2-3ºC before CTmax. Measurements of CTmax based on last movement are more conservative than measurements based on last heartbeat, additionally they are easier to record and work well with both large and small embryos. Importantly, measurements of CTmax based on last movement in embryos are similar to measurements from larval and adult stages based on loss of locomotory control.4. Using cessation of heart beats as CTmax in embryos likely overestimates acute thermal tolerance as the heart is still beating when CTmax based on loss of response/equilibrium is reached in larvae/adults. The last movement technique described here allows for comparisons of acute thermal tolerance between species, across life stages within species, and as a response variable to treatments.
Full text 2,924 characters · extracted from oa-doi-fallback · 2 sections · click to expand

Abstract

1. Aquatic ectotherms are particularly vulnerable to thermal stress, with certain life stages (embryos) predicted to be more sensitive than others (juveniles and adults). When examining the vulnerability of species and life stages to warming, it is particularly important to use appropriate and comparable methodology so that robust conclusions can be obtained. Critical thermal methodology (CTM) is commonly used to characterise acute thermal tolerance in fishes, with critical thermal maximum (CTmax) referring to a measured endpoint defining the upper acute thermal tolerance limit. This is the temperature at which fish exhibit loss of locomotory movements (i.e., loss of equilibrium) due to a temperature-induced collapse of vital physiological functions. While it is relatively easy to monitor behavioural responses and measure CTmax in juvenile and adult fish, this can be much more challenging in embryos. This has led to a lack of data on this life stage, or that studies rely on other, potentially incomparable, metrics. 2. Here, we present a novel method for measuring acute upper thermal tolerance limits in fish embryos, where CTmax is defined by the temperature at which embryos stop moving. Additionally, we compare this measurement to the temperature at which the embryos' heart stops beating, which has previously been proposed as a method for measuring CTmax in this life stage. 3. We found that, similar to other life stages, embryos exhibited a period of increased activity, which peaked approximately 2-3ºC before CTmax. Measurements of CTmax based on last movement are more conservative than measurements based on last heartbeat, additionally they are easier to record and work well with both large and small embryos. Importantly, measurements of CTmax based on last movement in embryos are similar to measurements from larval and adult stages based on loss of locomotory control. 4. Using cessation of heart beats as CTmax in embryos likely overestimates acute thermal tolerance as the heart is still beating when CTmax based on loss of response/equilibrium is reached in larvae/adults. The last movement technique described here allows for comparisons of acute thermal tolerance between species, across life stages within species, and as a response variable to treatments. DOI https://doi.org/10.32942/X2V01R Subjects Life Sciences

Keywords

Acute thermal tolerance, climate change, Critical thermal maximum, Embryo, Heatwaves, Life stage, thermal physiology, Thermal sensitivity Dates Published: 2023-02-07 09:56 Older Versions License CC BY Attribution 4.0 International Additional Metadata Conflict of interest statement: The authors have no conflict of interest to declare. Metrics Views: 1200 Downloads: 733

Text is read by the "Ask this paper" AI Q&A widget below. Extraction quality varies by source — PMC NXML preserves structure cleanly, OA-HTML may include some navigation residue, and OA-PDF can have broken hyphenation. The publisher copy (via DOI) is the canonical version.

My notes (saved in your browser only)

⚙ Ask this paper AI returns verbatim quotes from the full text · source: oa-doi-fallback ⓘ

Answers must be backed by verbatim quotes from this paper's full text. Hallucinated quotes are dropped automatically; if no verbatim passage answers the question, we say so. How this works

Citation neighborhood (no data yet)

We don't have any in-corpus citations linked to this paper yet. The paper's references may be in our DB but unresolved to ``paper_id`` (resolution happens at ingest when the cited DOI matches a row we already have). Run the cross-source citation reconcile pass to retry.

Source provenance

europepmc
last seen: 2026-05-19T01:45:01.086888+00:00