How does rising atmospheric CO2 affect marine organisms?

Click to locate material archived on our website by topic

Antarctic Krill Show Resilience to Ocean Acidification

Paper Reviewed
Ericson, J.A., Hellessey, N., Kawaguchi, S., Nicol, S., Nichols, P.D., Hoem, N. and Virtue, P. 2018. Adult Antarctic krill proves resilient in a simulated high CO2 ocean. Communications Biology 1: 190, DOI: 10.1038/s42003-018-0195-3.

Antarctic krill (Euphausia superba) play a key role in the food web of the Southern Ocean, serving as the primary prey of numerous predators. Any change in their abundance could potentially have disastrous consequences for the ecology of this important ocean region. Therefore, it is important for scientists to investigate the possible impacts of climate change, including so-called ocean acidification, on krill. And that is exactly what the research team of Ericson et al. (2018) set out to do. More specifically, the seven scientists conducted a long-term laboratory experiment in which they subjected samples of adult krill species collected from the Southern Ocean in 2015 to a range of seawater pCO2 levels (control at 400 µatm, 1000 µatm, 1500 µatm, 2000 µatm and 4000 µatm, corresponding to pH levels of 8.1, 7.8, 7.6, 7.4 and 7.1, respectively) for a period of 46 weeks while monitoring a suite of physiological and biochemical parameters.

In reporting their findings, Ericson et al. state that "the measured physiological processes in adult Antarctic krill were robust to near-future ocean acidification (1000-2000 µatm pCO2)." In particular, they note that "the survival rate of krill subject to near-future pCO2 increased by up to 11%" and that such pCO2 levels "did not affect the size of adult krill," nor their ability to moult, grow, store fat or mature. Such positive findings, according to the researchers, is "likely to be directly linked to their ability to maintain acid-base balance and respiration rates at these [higher] pCO2 levels." Consequently, in light of all these findings, Ericson et al. conclude their results "suggest that adult Antarctic krill are resilient to ocean acidification, and may not be affected by pCO2 levels predicted for the next 100-300 years." And that is great news of this keystone species of the Southern Ocean and the food web dependent upon it!

Posted 18 July 2019