Global ocean lipidomes show a universal relationship between temperature and lipid unsaturation

Global-scale surveys of plankton communities using “omics” techniques have revolutionized our understanding of the ocean. Lipidomics has demonstrated the potential to add further essential insights on ocean ecosystem function but has yet to be applied on a global scale. We analyzed 930 lipid samples across the global ocean using a uniform high-resolution accurate-mass mass spectrometry analytical workflow, revealing previously unknown characteristics of ocean planktonic lipidomes. Focusing on 10 molecularly diverse glycerolipid classes, we identified 1151 distinct lipid species, finding that fatty acid unsaturation (i.e., number of carbon-carbon double bonds) is fundamentally constrained by temperature. We predict substantial declines in the essential fatty acid eicosapentaenoic acid over the next century, which are likely to have serious deleterious effects on economically critical fisheries. The lipid composition of organisms will change as surrounding physicochemical conditions change to ensure that membranes and other essential biological functions stay intact, a process known as homeoviscous adaptation. Holm et al . used high-resolution mass spectrometry to analyze the lipid composition of surface layer plankton sampled largely from the Atlantic Ocean (see the Perspective by Sepúlveda and Cantarero). Although a few lipid species constitute the bulk of the plankton lipidome, organisms living in cold (−2°C) regions have threefold more unsaturated fatty acids than those in warm (29°C) waters. Declines in unsaturation of planktonic essential fatty acids under different scenarios of climate change could have negative consequences for food webs and ultimately for fisheries. —CA Climate-change-related declines in the availability of some essential fatty acids to marine food webs may affect future fisheries.