Near-future ocean acidification does not alter the lipid content and fatty acid composition of adult Antarctic krill

• Published in: Scientific Reports
• Main Authors: Ericson, JA, Hellessey, N, Kawaguchi, S, Nichols, PD, Nicol, S, Hoem, N, Virtue, P
• Format: Article in Journal/Newspaper
• Language: English
• Published: Nature Publishing Group 2019
• Subjects: Biological Sciences; Ecology; Ecological Physiology; Antarctic; Southern Ocean; Antarc*; Antarctic Krill; Euphausia superba; Ocean acidification
• Online Access: https://doi.org/10.1038/s41598-019-48665-5; http://www.ncbi.nlm.nih.gov/pubmed/31451724; http://ecite.utas.edu.au/134669

Euphausia superba (Antarctic krill) is a keystone species in the Southern Ocean, but little is known about how it will respond to climate change. Ocean acidification, caused by sequestration of carbon dioxide into ocean surface waters ( p CO 2 ), alters the lipid biochemistry of some organisms. This can have cascading effects up the food chain. In a year-long laboratory experiment adult krill were exposed to ambient seawater p CO 2 levels (400 μatm), elevated p CO 2 levels mimicking near-future ocean acidification (1000, 1500 and 2000 μatm) and an extreme p CO 2 level (4000 μatm). Total lipid mass (mg g −1 DM) of krill was unaffected by near-future p CO 2 . Fatty acid composition (%) and fatty acid ratios associated with immune responses and cell membrane fluidity were also unaffected by near-future p CO 2 , apart from an increase in 18:3n-3/18:2n-6 ratios in krill in 1500 μatm p CO 2 in winter and spring . Extreme p CO 2 had no effect on krill lipid biochemistry during summer. During winter and spring, krill in extreme p CO 2 had elevated levels of 18:2n-6 (up to 1.2% increase), 20:4n-6 (up to 0.8% increase), lower 18:3n-3/18:2n-6 and 20:5n-3/20:4n-6 ratios, and showed evidence of increased membrane fluidity (up to three-fold increase in phospholipid/sterol ratios). These results indicate that the lipid biochemistry of adult krill is robust to near-future ocean acidification.