Influence of CO2-induced acidification on the reproduction of a key Arctic copepod Calanus glacialis

The Arctic Ocean is facing rapid changes in seawater carbonate chemistry due to the uptake of atmospheric carbon dioxide (CO2). In the current study, the effects of different seawater pH levels (8.2, 7.6 and 6.9) on the reproduction of Calanus glacialis, an Arctic shelf-water copepod, have been quantified. Results indicated that CO2-induced seawater acidification had no significant effect on C. glacialis egg production. However, a reduction in pH to 6.9 significantly delayed hatching and possibly reduced overall hatching success. The results of the current study are in agreement with previous studies on other copepod species and would indicate that copepods, as a group, may be well equipped to deal with the chemical changes associated with ocean acidification. However, all previous studies have been over relatively short exposure periods and most have only considered the isolated impacts of elevated CO2. Long-term exposures examining the synergistic effects of ocean acidification with other climate stressors, particularly warming on population viability and success, have yet to be conducted.

► We studied the impact of decreasing pH on the reproduction of a key Arctic copepod.
► Calanus glacialis seem resilient to predicted levels of seawater acidification.
► However, an extreme pH delayed its hatching and reduced hatching success.
► Synergistic effects of acidification and warming may impact Arctic ecosystems.