Can Polar fish get out of breath? Hypoxia tolerance and aerobic scope of Polar cod, Boreogadus saida

Felix.Christopher.Mark [ at ]


The effects of climate change are projected to be most severe changes in Arctic environments. Warming has already caused various environmental changes, including a loss of almost 50% Arctic sea-ice coverage since the 1980s. Sea-ice loss strengthens summer stratification and, consequently, hypoxic zones in the deep-water layers may form. The deep fjord systems of the Svalbard archipelago are particularly at risk from this long-lasting stratification. Thus, the present study investigates the hypoxia tolerance in the Arctic key species Polar cod, Boreogadus saida. We measured respiratory capacity (standard, routine and maximum metabolic rates, SMR, RMR, MMR) and swim performance under progressive hypoxia (100% to 5% air saturation) via intermittent-flow and swim-tunnel respirometry. The calculated SMR for Polar cod accounted 0.44 µmol O2∙g-1∙h-1 at full oxygen saturation. RMR followed an oxygen regulating pattern and never fell below SMR until the fish lost equilibrium at about 3% O2 saturation. Under exercise, Polar cod were able to retain a steady MMR until a threshold of 45% PO2 was reached, after which MMR decreased linearily, reaching SMR at about 5% oxygen saturation. Ugait was not significantly affected by hypoxia, albeit the total number of anaerobic bursts and total active swimming time decreased significantly with progressive hypoxia. Despite the common paradigm that polar organisms are not hypoxia tolerant, our study revealed that Polar cod can handle very low oxygen saturations down to a Pcrit of 4.81% air saturation. The loss of anaerobic metabolic capacity under hypoxia however may endanger this species with regard to predator-prey-interactions and loss of escape-reactions.

Item Type
Conference (Talk)
Primary Division
Primary Topic
Helmholtz Cross Cutting Activity (2021-2027)
Publication Status
Event Details
SEB Annual Main Meeting, 29 Jun 2021 - 08 Jul 2021, Online.
Eprint ID
Cite as
Mark, F. C. , Kempf, S. , Neven, C. J. and Claireaux, G. (2021): Can Polar fish get out of breath? Hypoxia tolerance and aerobic scope of Polar cod, Boreogadus saida , SEB Annual Main Meeting, Online, 29 June 2021 - 8 July 2021 .

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HE > 500-519 > 519
HE > 560-579 > 560

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