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Mitochondrial acclimation potential to ocean acidification and warming of Polar cod ( Boreogadus saida ) and Atlantic cod ( Gadus morhua )

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ABSTRACT

Background: Ocean acidification and warming are happening fast in the Arctic but little is known about the effects of ocean acidification and warming on the physiological performance and survival of Arctic fish.

Results: In this study we investigated the metabolic background of performance through analyses of cardiac mitochondrial function in response to control and elevated water temperatures and PCO2 of two gadoid fish species, Polar cod (Boreogadus saida), an endemic Arctic species, and Atlantic cod (Gadus morhua), which is a temperate to cold eurytherm and currently expanding into Arctic waters in the wake of ocean warming. We studied their responses to the above-mentioned drivers and their acclimation potential through analysing the cardiac mitochondrial function in permeabilised cardiac muscle fibres after 4 months of incubation at different temperatures (Polar cod: 0, 3, 6, 8 °C and Atlantic cod: 3, 8, 12, 16 °C), combined with exposure to present (400μatm) and year 2100 (1170μatm) levels of CO2.

Results: OXPHOS, proton leak and ATP production efficiency in Polar cod were similar in the groups acclimated at 400μatm and 1170μatm of CO2, while incubation at 8 °C evoked increased proton leak resulting in decreased ATP production efficiency and decreased Complex IV capacity. In contrast, OXPHOS of Atlantic cod increased with temperature without compromising the ATP production efficiency, whereas the combination of high temperature and high PCO2 depressed OXPHOS and ATP production efficiency.

Conclusions: Polar cod mitochondrial efficiency decreased at 8 °C while Atlantic cod mitochondria were more resilient to elevated temperature; however, this resilience was constrained by high PCO2. In line with its lower habitat temperature and higher degree of stenothermy, Polar cod has a lower acclimation potential to warming than Atlantic cod.

No MeSH data available.


Related in: MedlinePlus

Complex IV (Cytochrome c Oxidase) capacity. Panel a: permeabilised heart muscle fibres of Polar cod (B. saida). Panel b: permeabilised heart muscle fibres of NEAC (G. morhua). Different letters within the panels indicate significant differences (p <0.05) between temperature treatments; lower case letters: control PCO2 (400μatm), upper case letters: high PCO2 (1170μatm). All values are reported as means ± S.E.M. (for n refer to Table 1). Open symbols: control PCO2 (400μatm), filled symbols: high PCO2 (1170μatm). Circles: Polar cod, Squares: NEAC. Blue box: cold shared incubation temperature (3 °C), Red box: warm shared incubation temperature (8 °C) between the two species
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Fig5: Complex IV (Cytochrome c Oxidase) capacity. Panel a: permeabilised heart muscle fibres of Polar cod (B. saida). Panel b: permeabilised heart muscle fibres of NEAC (G. morhua). Different letters within the panels indicate significant differences (p <0.05) between temperature treatments; lower case letters: control PCO2 (400μatm), upper case letters: high PCO2 (1170μatm). All values are reported as means ± S.E.M. (for n refer to Table 1). Open symbols: control PCO2 (400μatm), filled symbols: high PCO2 (1170μatm). Circles: Polar cod, Squares: NEAC. Blue box: cold shared incubation temperature (3 °C), Red box: warm shared incubation temperature (8 °C) between the two species

Mentions: The thermal sensitivity of Complex IV also differed between the two species (Fig. 5). In Polar cod, Complex IV capacity rose from 0 to 6 °C (control PCO2: F = 67.29, p <0.001) and decreased between 6 °C and 8 °C (control PCO2: p <0.001). This trajectory was only present as a non-significant trend in the groups incubated under high PCO2 (F = 3.88, p = 0.10) because of the non-significant decrease of the mean capacity of Complex IV at 6 °C/high PCO2 compared to control PCO2 at the same temperature (p = 0.09). In NEAC, Complex IV capacity increased with increasing temperatures in the groups incubated under control PCO2 (F = 3.25, p = 0.05), but not in the groups incubated under high PCO2 (F = 2.18, p = 0.12). At 16 °C, the capacity of NEAC Complex IV was lower under high PCO2 (p =0.099) than under control PCO2. Comparing the two species, the capacity of Complex IV was similar (non-significant differences) in all shared treatments (3 °C/control CO2, 8 °C/control CO2 and 8 °C/high CO2: p >0.05, Fig. 5 blue and red boxes).Fig. 5


Mitochondrial acclimation potential to ocean acidification and warming of Polar cod ( Boreogadus saida ) and Atlantic cod ( Gadus morhua )
Complex IV (Cytochrome c Oxidase) capacity. Panel a: permeabilised heart muscle fibres of Polar cod (B. saida). Panel b: permeabilised heart muscle fibres of NEAC (G. morhua). Different letters within the panels indicate significant differences (p <0.05) between temperature treatments; lower case letters: control PCO2 (400μatm), upper case letters: high PCO2 (1170μatm). All values are reported as means ± S.E.M. (for n refer to Table 1). Open symbols: control PCO2 (400μatm), filled symbols: high PCO2 (1170μatm). Circles: Polar cod, Squares: NEAC. Blue box: cold shared incubation temperature (3 °C), Red box: warm shared incubation temperature (8 °C) between the two species
© Copyright Policy - OpenAccess
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC5391599&req=5

Fig5: Complex IV (Cytochrome c Oxidase) capacity. Panel a: permeabilised heart muscle fibres of Polar cod (B. saida). Panel b: permeabilised heart muscle fibres of NEAC (G. morhua). Different letters within the panels indicate significant differences (p <0.05) between temperature treatments; lower case letters: control PCO2 (400μatm), upper case letters: high PCO2 (1170μatm). All values are reported as means ± S.E.M. (for n refer to Table 1). Open symbols: control PCO2 (400μatm), filled symbols: high PCO2 (1170μatm). Circles: Polar cod, Squares: NEAC. Blue box: cold shared incubation temperature (3 °C), Red box: warm shared incubation temperature (8 °C) between the two species
Mentions: The thermal sensitivity of Complex IV also differed between the two species (Fig. 5). In Polar cod, Complex IV capacity rose from 0 to 6 °C (control PCO2: F = 67.29, p <0.001) and decreased between 6 °C and 8 °C (control PCO2: p <0.001). This trajectory was only present as a non-significant trend in the groups incubated under high PCO2 (F = 3.88, p = 0.10) because of the non-significant decrease of the mean capacity of Complex IV at 6 °C/high PCO2 compared to control PCO2 at the same temperature (p = 0.09). In NEAC, Complex IV capacity increased with increasing temperatures in the groups incubated under control PCO2 (F = 3.25, p = 0.05), but not in the groups incubated under high PCO2 (F = 2.18, p = 0.12). At 16 °C, the capacity of NEAC Complex IV was lower under high PCO2 (p =0.099) than under control PCO2. Comparing the two species, the capacity of Complex IV was similar (non-significant differences) in all shared treatments (3 °C/control CO2, 8 °C/control CO2 and 8 °C/high CO2: p >0.05, Fig. 5 blue and red boxes).Fig. 5

View Article: PubMed Central - PubMed

ABSTRACT

Background: Ocean acidification and warming are happening fast in the Arctic but little is known about the effects of ocean acidification and warming on the physiological performance and survival of Arctic fish.

Results: In this study we investigated the metabolic background of performance through analyses of cardiac mitochondrial function in response to control and elevated water temperatures and PCO2 of two gadoid fish species, Polar cod (Boreogadus saida), an endemic Arctic species, and Atlantic cod (Gadus morhua), which is a temperate to cold eurytherm and currently expanding into Arctic waters in the wake of ocean warming. We studied their responses to the above-mentioned drivers and their acclimation potential through analysing the cardiac mitochondrial function in permeabilised cardiac muscle fibres after 4 months of incubation at different temperatures (Polar cod: 0, 3, 6, 8&nbsp;&deg;C and Atlantic cod: 3, 8, 12, 16&nbsp;&deg;C), combined with exposure to present (400&mu;atm) and year 2100 (1170&mu;atm) levels of CO2.

Results: OXPHOS, proton leak and ATP production efficiency in Polar cod were similar in the groups acclimated at 400&mu;atm and 1170&mu;atm of CO2, while incubation at 8&nbsp;&deg;C evoked increased proton leak resulting in decreased ATP production efficiency and decreased Complex IV capacity. In contrast, OXPHOS of Atlantic cod increased with temperature without compromising the ATP production efficiency, whereas the combination of high temperature and high PCO2 depressed OXPHOS and ATP production efficiency.

Conclusions: Polar cod mitochondrial efficiency decreased at 8&nbsp;&deg;C while Atlantic cod mitochondria were more resilient to elevated temperature; however, this resilience was constrained by high PCO2. In line with its lower habitat temperature and higher degree of stenothermy, Polar cod has a lower acclimation potential to warming than Atlantic cod.

No MeSH data available.


Related in: MedlinePlus