Take time to look at the fish: Behavioral response to acute thermal challenge in two Amazonian cichlids

Kochhann, Daiani; Sarmento, Carolina G.; Oliveira, Jomara Cavalcante de; Queiroz, Helder Lima de; Val, Adalberto Luís; Chapman, Lauren J.

doi:10.1002/jez.2541

Cited by 8 publications

(11 citation statements)

References 66 publications

(102 reference statements)

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“…Our finding that embryos exhibited a period of increased activity, which peaked approximately 2-3°C before CTmax, is in line with the theory that ectotherms may exhibit behavioural strategies to avoid physiological damage that occurs near their CTmax (Kochhann et al, 2021;Lutterschmidt & Hutchison, 1997). These behavioural strategies may be associated with seeking local thermal refugia or alternative habitats (Kochhann et al, 2021).…”

Section: Discussionsupporting

confidence: 88%

“…Our results are in line with other quantitative studies, for example an increase in activity was observed 6°C before CTmax in the neotropical cichlid Cichlasoma paranaense (Brandão et al 2018). In adult Amazonian cichlids Apistogramma agassizii and Mesonauta insignis, Tag was observed at 4 and 5.4°C, respectively, prior to CTmax (Kochhann et al, 2021). It is worth noting that all embryos in a trial in our study continued to be heated until no movements and no heartbeats were observed in any individuals in the trial.…”

Section: Discussionmentioning

confidence: 64%

“…These behavioural strategies may be associated with seeking local thermal refugia or alternative habitats (Kochhann et al, 2021). Kochhann et al (2021) describe the temperature at which increased activity occurs as the agitation temperature (Tag). With continued increase in warming, a period of inactivity follows, during which CTmax occurs (Kochhann et al, 2021;Lutterschmidt & Hutchison, 1997), which was also found here.…”

Section: Discussionmentioning

confidence: 99%

“…Kochhann et al (2021) describe the temperature at which increased activity occurs as the agitation temperature (Tag). With continued increase in warming, a period of inactivity follows, during which CTmax occurs (Kochhann et al, 2021;Lutterschmidt & Hutchison, 1997), which was also found here. Our results are in line with other quantitative studies, for example an increase in activity was observed 6°C before CTmax in the neotropical cichlid Cichlasoma paranaense (Brandão et al 2018).…”

Section: Discussionmentioning

confidence: 99%

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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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Section: Discussionsupporting

confidence: 88%

Section: Discussionmentioning

confidence: 64%

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

See 2 more Smart Citations

A novel method for measuring acute thermal tolerance in fish embryos

Cowan¹,

Andreassen²,

Bonville³

et al. 2023

Preprint

View full text Add to dashboard Cite

show abstract

“…For example, Pagurus bernhardus in low pH significantly reduced antennular flick rates (the ‘sniffing’ response in decapod) and movement [ 13 ]. In the increased temperature, Apistogramma agassizii and Mesonauta insignis increased both activity level and digging behavior and decreased the use of shelter [ 14 ]. Additionally, the salinity in water is always changing due to tidal action and seasonal variation, forcing aquatic animals to start osmotic regulation to reach a new equilibrium [ 15 , 16 ].…”

Section: Introductionmentioning

confidence: 99%

Salinity-Driven Changes in Behavioral Responses of Catadromous Eriocher sinensis

Shen

Wang

Feng

et al. 2022

Animals

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The effects of salinity on behavior are far-reaching, and Eriocheir sinensis showed disparate behaviors under different salinity conditions. Female crabs were more active in saline water, especially low salinity stress, which is beneficial for female crabs to escape from the low-salinity environment quickly. Then, antennal movement indicated that antennae might be the main osmoreceptors in E. sinensis, and 65 min might be a good starting time for salinity stress to analyze osmoregulation in crabs. Interestingly, E. sinensis had obvious behavioral differences in the high and low salinity stress, and behaviors were more intense in a salinity dip from salinity 18 to salinity 0. This study analyzed the osmoregulatory process of catadromous E. sinensis in different salinity from the point of osmoregulatory organ and behavioral response. These results will provide a scientific basis for the osmoregulatory mechanism of E. sinensis, which are conducive to evaluating and analyzing the impact of saltwater intrusion in the Yangtze River estuary on resource fluctuation.

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A novel method for measuring acute thermal tolerance in fish embryos

Cowan

Andreassen

Bonville

et al. 2023

Conservation Physiology

View full text Add to dashboard Cite

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 (CTmax) 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 CTmax 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 CTmax 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 CTmax. We found that, like other life stages, late-stage embryos exhibited a period of increased activity, peaking approximately 2–3°C before CTmax. Measurements of CTmax 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, CTmax 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 CTmax 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.

show abstract

Take time to look at the fish: Behavioral response to acute thermal challenge in two Amazonian cichlids

Cited by 8 publications

References 66 publications

A novel method for measuring acute thermal tolerance in fish embryos

A novel method for measuring acute thermal tolerance in fish embryos

Salinity-Driven Changes in Behavioral Responses of Catadromous Eriocher sinensis

A novel method for measuring acute thermal tolerance in fish embryos

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