Impact of Short- and Long-Term Exposure to Elevated Seawater Pco on Metabolic Rate and Hypoxia Tolerance in .

AbstractMuch of the CO released by human activity into the atmosphere is dissolving into the oceans, making them more acidic. In this study we provide the first data on the short- and long-term impacts of ocean acidification on octopuses. We measured routine metabolic rate (RMR) of at elevated CO pressure (Pco) with no prior acclimation and 1 or 5 wk of acclimation and critical oxygen pressure (P) after 5 wk of acclimation. Our results show that with no prior acclimation, octopuses had significantly higher RMRs in 1,500-μatm Pco environments than octopuses in 700- or 360-μatm environments. However, after both 1 and 5 wk of acclimation there was no significant difference in RMRs between octopuses at differing Pco, indicating that octopuses acclimated rapidly to elevated Pco. In octopuses acclimated for 5 wk at 1,500 μatm Pco, we observed impaired hypoxia tolerance, as demonstrated by a significantly higher P than those acclimated to 700 μatm Pco. Our findings suggest that experiences short-term stress in elevated Pco but is able to acclimate over time. However, while this species may be able to acclimate to near-term ocean acidification, compounding environmental effects of acidification and hypoxia may present a physiological challenge for this species.