Brain dysfunction during warming is linked to oxygen limitation in larval zebrafish

Andreassen, Anna H.; Hall, Petter; Khatibzadeh, Pouya; Jutfelt, Fredrik; Kermen, Florence

doi:10.1073/pnas.2207052119

Cited by 32 publications

(16 citation statements)

References 69 publications

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“…For example, environmental oxygen level does not seem to have a marked influence on CT MAX in red drum (Sciaenops ocellatus) or marine lumpfish (Cyclopterus lumpus) (Ern et al, 2016), suggesting that the limitation may not be linked to the oxygen diffusion capacity across gill epithelium in these species. In European perch (Perca fluviatilis) and zebrafish (Danio rerio) environmental hyperoxia increased the CT MAX (Ekström et al, 2016;Andreassen et al, 2022), but reducing the hematocrit, i.e. reducing the oxygen carrying capacity of blood, had only a minor reducing effect on the CT MAX in European seabass (Dicentrarchus labrax) in the study by Wang et al (2014).…”

Section: Introductionmentioning

confidence: 72%

Cardiovascular oxygen transport and peripheral oxygen extraction capacity contribute to acute heat tolerance in European seabass

Anttila

Mauduit

Kanerva

et al. 2023

Comparative Biochemistry and Physiology Part A: Molecular &

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Section: Introductionmentioning

confidence: 72%

Cardiovascular oxygen transport and peripheral oxygen extraction capacity contribute to acute heat tolerance in European seabass

Anttila

Mauduit

Kanerva

et al. 2023

Comparative Biochemistry and Physiology Part A: Molecular &

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“…Following Andreassen et al (2022), larvae were continuously visually monitored and the temperature at which individual larvae failed to respond to five consecutive touches (using a dissection probe modified with 2 mm plastic cannula tubing to make a flexible and blunt end) at 3 sec intervals was defined as their CTmax. Upon reaching their CTmax, larvae were removed from the test chamber and placed in ~20°C water to recover.…”

Section: Larvae Ctmaxmentioning

confidence: 99%

A novel method for measuring acute thermal tolerance in fish embryos

Cowan¹,

Andreassen²,

Bonville³

et al. 2023

Preprint

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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.

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“…Indeed, many studies including multiple life stages have not found differences in CT max (e.g. Ospina and Mora, 2004 ; Recsetar et al, 2012 ; Andreassen et al, 2022 ); however, including a full range of life stages within a singular study is challenging, as most studies are lacking the very earliest life stages or validated reproducing adults ( Johnson, 1976 ; Ospina and Mora, 2004 ; Recsetar et al, 2012 ; Andreassen et al, 2022 ).…”

Section: Discussionmentioning

confidence: 99%

The upper thermal limit of epaulette sharks (Hemiscyllium ocellatum) is conserved across three life history stages, sex and body size

Wheeler

Lang

Mandelman

et al. 2022

Conservation Physiology

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Owing to climate change, most notably the increasing frequency of marine heatwaves and long-term ocean warming, better elucidating the upper thermal limits of marine fishes is important for predicting the future of species and populations. The critical thermal maximum (CTmax), or the highest temperature a species can tolerate, is a physiological metric that is used to establish upper thermal limits. Among marine organisms, this metric is commonly assessed in bony fishes but less so in other taxonomic groups, such as elasmobranchs (subclass of sharks, rays and skates), where only thermal acclimation effects on CTmax have been assessed. Herein, we tested whether three life history stages, sex and body size affected CTmax in a tropical elasmobranch, the epaulette shark (Hemiscyllium ocellatum), collected from the reef flats surrounding Heron Island, Australia. Overall, we found no difference in CTmax between life history stages, sexes or across a range of body sizes. Findings from this research suggest that the energetically costly processes (i.e. growth, maturation and reproduction) associated with the life history stages occupying these tropical reef flats do not change overall acute thermal tolerance. However, it is important to note that neither embryos developing in ovo, neonates, nor females actively encapsulating egg cases were observed in or collected from the reef flats. Overall, our findings provide the first evidence in an elasmobranch that upper thermal tolerance is not impacted by life history stage or size. This information will help to improve our understanding of how anthropogenic climate change may (or may not) disproportionally affect particular life stages and, as such, where additional conservation and management actions may be required.

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Brain dysfunction during warming is linked to oxygen limitation in larval zebrafish

Cited by 32 publications

References 69 publications

Cardiovascular oxygen transport and peripheral oxygen extraction capacity contribute to acute heat tolerance in European seabass

Cardiovascular oxygen transport and peripheral oxygen extraction capacity contribute to acute heat tolerance in European seabass

A novel method for measuring acute thermal tolerance in fish embryos

The upper thermal limit of epaulette sharks (Hemiscyllium ocellatum) is conserved across three life history stages, sex and body size

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