Brain cooling marginally increases acute upper thermal tolerance in Atlantic cod

Jutfelt, Fredrik; Roche, Dominique G.; Norin, Tommy; Binning, Sandra A.; Speers‐Roesch, Ben; Amcoff, Mirjam; Morgan, Rachael; Andreassen, Anna H.; Sundin, Josefin

doi:10.1242/jeb.208249

Cited by 39 publications

(49 citation statements)

References 19 publications

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“…Thus, in addition to TRPs, there appear to be other more nuanced pathways whereby cells and tissues can compensate for the temperature effects at a local level. Reduced absolute brain temperature increased thermal tolerance in Atlantic cod, but the effect was minor and it is not clear whether it is of ecological significance (Jutfelt et al ., 2019).…”

Section: Signalling Pathwaysmentioning

confidence: 99%

What do warming waters mean for fish physiology and fisheries?

Little

Loughland

Seebacher

2020

Journal of Fish Biology

139

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Environmental signals act primarily on physiological systems, which then influence higher-level functions such as movement patterns and population dynamics. Increases in average temperature and temperature variability associated with global climate change are likely to have strong effects on fish physiology and thereby on populations and fisheries. Here we review the principal mechanisms that transduce temperature signals and the physiological responses to those signals in fish. Temperature has a direct, thermodynamic effect on biochemical reaction rates. Nonetheless, plastic responses to longer-term thermal signals mean that fishes can modulate their acute thermal responses to compensate at least partially for thermodynamic effects. Energetics are particularly relevant for growth and movement, and therefore for fisheries, and temperature can have pronounced effects on energy metabolism. All energy (ATP) production is ultimately linked to mitochondria, and temperature has pronounced effects on mitochondrial efficiency and maximal capacities. Mitochondria are dependent on oxygen as the ultimate electron acceptor so that cardiovascular function and oxygen delivery link environmental inputs with energy metabolism.

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Section: Signalling Pathwaysmentioning

confidence: 99%

What do warming waters mean for fish physiology and fisheries?

Little

Loughland

Seebacher

2020

Journal of Fish Biology

139

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“…The physiological mechanisms of oxygen-independent CT max are not understood and may be linked to effects of acute warming on membrane integrity and nerve function. These points have all been raised to argue against the universality of the OCLTT framework (Ern et al, 2014(Ern et al, , 2016(Ern et al, , 2017Jutfelt et al, 2019;Wang et al, 2014). By contrast, the CT swim protocol specifically targets metabolic constraints caused by warming.…”

Section: Discussionmentioning

confidence: 99%

“…Although the CT max does not cause mortality, LOE is an incipient lethal threshold because, in the wild, the animal would be unable to escape from the thermal conditions and so its survival would be threatened (Lutterschmidt and Hutchison, 1997). It has also proven rather difficult to understand what causes LOE at CT max in fishes (Ern et al, 2016(Ern et al, , 2017Jutfelt et al, 2019;Wang et al, 2014). It is essential to understand the physiological mechanisms that underlie tolerance of warming because this will greatly improve the ability to model and project the effects of global warming on fish populations and communities (Jørgensen et al, 2012;McKenzie et al, 2016).…”

Section: Introductionmentioning

confidence: 99%

Using aerobic exercise to evaluate sub-lethal tolerance of acute warming in fishes

Blasco

Esbaugh²,

Killen

et al. 2020

Journal of Experimental Biology

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We investigated whether fatigue from sustained aerobic swimming provides a sub-lethal endpoint to define tolerance of acute warming in fishes, as an alternative to loss of equilibrium (LOE) during a critical thermal maximum (CT max) protocol. Two species were studied, Nile tilapia (Oreochromis niloticus) and pacu (Piaractus mesopotamicus). Each fish underwent an incremental swim test to determine gait transition speed (U GT), where it first engaged the unsteady anaerobic swimming mode that preceded fatigue. After suitable recovery, each fish was exercised at 85% of their own U GT and warmed 1°C every 30 min, to identify the temperature at which they fatigued, denoted as CT swim. Fish were also submitted to a standard CT max , warming at the same rate as CT swim , under static conditions until LOE. All individuals fatigued in CT swim , at a mean temperature approximately 2°C lower than their CT max. Therefore, if exposed to acute warming in the wild, the ability to perform aerobic metabolic work would be constrained at temperatures significantly below those that directly threatened survival. The collapse in performance at CT swim was preceded by a gait transition qualitatively indistinguishable from that during the incremental swim test. This suggests that fatigue in CT swim was linked to an inability to meet the tissue oxygen demands of exercise plus warming. This is consistent with the oxygen and capacity limited thermal tolerance (OCLTT) hypothesis, regarding the mechanism underlying tolerance of warming in fishes. Overall, fatigue at CT swim provides an ecologically relevant sub-lethal threshold that is more sensitive to extreme events than LOE at CT max .

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“…This could indicate accumulation of physiological effects of stress in the fish due to confinement, as well as a starvation effect. While loss of equilibrium during CTmax trials seem to be controlled by neural failure ( Jutfelt et al, 2019 ), the end-point of ILOS generally occurs when adenosine triphosphate (ATP) levels in the brain are depleted ( Speers-Roesch et al , 2013 ). As ATP production is highly dependent on glycogen stores, a fish that has not fed for 2 weeks will likely have lower glycogen stores, leading to LOE sooner at higher oxygen concentrations.…”

Section: Discussionmentioning

confidence: 99%

Physiological resilience of pink salmon to naturally occurring ocean acidification

Frommel

Carless

Hunt

et al. 2020

Conservation Physiology

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Pacific salmon stocks are in decline with climate change named as a contributing factor. The North Pacific coast of British Columbia is characterized by strong temporal and spatial heterogeneity in ocean conditions with upwelling events elevating CO2 levels up to 10-fold those of pre-industrial global averages. Early life stages of pink salmon have been shown to be affected by these CO2 levels, and juveniles naturally migrate through regions of high CO2 during the energetically costly phase of smoltification. To investigate the physiological response of out-migrating wild juvenile pink salmon to these naturally occurring elevated CO2 levels, we captured fish in Georgia Strait, British Columbia and transported them to a marine lab (Hakai Institute, Quadra Island) where fish were exposed to one of three CO2 levels (850, 1500 and 2000 μatm CO2) for 2 weeks. At ½, 1 and 2 weeks of exposure, we measured their weight and length to calculate condition factor (Fulton’s K), as well as haematocrit and plasma [Cl−]. At each of these times, two additional stressors were imposed (hypoxia and temperature) to provide further insight into their physiological condition. Juvenile pink salmon were largely robust to elevated CO2 concentrations up to 2000 μatm CO2, with no mortality or change in condition factor over the 2-week exposure duration. After 1 week of exposure, temperature and hypoxia tolerance were significantly reduced in high CO2, an effect that did not persist to 2 weeks of exposure. Haematocrit was increased by 20% after 2 weeks in the CO2 treatments relative to the initial measurements, while plasma [Cl−] was not significantly different. Taken together, these data indicate that juvenile pink salmon are quite resilient to naturally occurring high CO2 levels during their ocean outmigration.

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Brain cooling marginally increases acute upper thermal tolerance in Atlantic cod

Cited by 39 publications

References 19 publications

What do warming waters mean for fish physiology and fisheries?

What do warming waters mean for fish physiology and fisheries?

Using aerobic exercise to evaluate sub-lethal tolerance of acute warming in fishes

Physiological resilience of pink salmon to naturally occurring ocean acidification

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