Changing carbon-to-nitrogen ratios of organic-matter export under ocean acidification

• Published in: Nature Climate Change
• Main Authors: Taucher, J, Boxhammer, T, Bach, LT, Paul, AJ, Schartau, M, Stange, P, Riebesell, U
• Format: Article in Journal/Newspaper
• Language: English
• Published: Nature Publishing Group 2021
• Subjects: Earth Sciences; Oceanography; Biological oceanography; Ocean acidification
• Online Access: https://doi.org/10.1038/s41558-020-00915-5; http://ecite.utas.edu.au/141467

Ocean acidification (OA) will affect marine biotas from the organism to the ecosystem level. Yet, the consequences for the biological carbon pump and thereby the oceanic sink for atmospheric CO 2 are still unclear. Here we show that OA considerably alters the C/N ratio of organic-matter export (C/N export ), a key factor determining efficiency of the biological pump. By synthesizing sediment-trap data from in situ mesocosm studies in different marine biomes, we find distinct but highly variable impacts of OA on C/N export , reaching up to a 20% increase/decrease under partial pressure of CO 2 effects on a variety of plankton taxa and corresponding shifts in food-web structure. Notably, our findings suggest a pivotal role of heterotrophic processes in controlling the response of C/N export to OA, thus contradicting the paradigm of primary producers as the principal driver of biogeochemical responses to ocean change.