As a consequence of the growing concern about warming of the Arctic Ocean, this study quantified the thermal acclimation responses of Boreogadus saida, a key Arctic food web fish. Physiological rates for cardio-respiratory functions as well as critical maximum temperature (Tc,max) for loss of equilibrium (LOE) were measured. The transition temperatures for these events (LOE, the rate of oxygen uptake and maximum heart rate) during acute warming were used to gauge phenotypic plasticity after thermal acclimation from 0.5°C up to 6.5°C for 1 month (respiratory and Tc,max measurements) and 6 months (cardiac measurements). Tc,max increased significantly by 2.3°C from 14.9°C to 17.1°C with thermal acclimation, while the optimum temperature for absolute aerobic scope increased by 4.5°C over the same range of thermal acclimation. Warm acclimation reset the maximum heart rate to a statistically lower rate, but the first Arrhenius breakpoint temperature during acute warming was unchanged. The hierarchy of transition temperatures was quantified at three acclimation temperatures and was fitted inside a Fry temperature tolerance polygon to better define ecologically relevant thermal limits to performance of B. saida. We conclude that B. saida can acclimate to 6.5°C water temperatures in the laboratory. However, at this acclimation temperature 50% of the fish were unable to recover from maximum swimming at the 8.5°C test temperature and their cardio-respiratory performance started to decline at water temperatures greater than 5.4°C. Such costs in performance may limit the ecological significance of B. saida acclimation potential.
The authors declare no competing or financial interests.
Field work: H.E.D., A.P.F. and E.C.C.; study design: H.E.D., M.L. and A.P.F.; data collection: H.E.D., M.L. and E.C.C.; writing and revision: all authors; publication submission: H.E.D., A.P.F. and M.L.
H.E.D. was financed in part by grants from the Northern Scientific Training Programme (2011 and 2012) and the Arctic Research Foundation (2012) as support for field research and the Vancouver Aquarium Marine Science Centre for the long term laboratory space. M.L. was funded in part by a Natural Sciences and Engineering Research Council of Canada (NSERC) undergraduate research award. E.C.C. and A.P.F. were funded by NSERC. A.P.F. is funded by Canada Research Chairs.
Supplementary information available online at http://jeb.biologists.org/lookup/doi/10.1242/jeb.140194.supplemental
- Received March 7, 2016.
- Accepted July 25, 2016.
- © 2016. Published by The Company of Biologists Ltd