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 CO₂ 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 CO₂ (\(p_{{\rm{CO}}_{2}}\)) conditions projected for 2100. These changes are driven by \(p_{{\rm{CO}}_{2}}\) 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.

海洋酸化（OA）将影响从生物到生态系统水平的海洋生物区系。然而，对于生物碳泵的后果以及由此向大气汇入大气中的CO ₂的后果尚不清楚。在这里，我们表明OA大大改变了有机物出口的C / N比（C / N_出口），这是决定生物泵效率的关键因素。通过综合来自不同海洋生物群落的原位mesocosm研究的沉积物陷阱数据，我们发现了OA对C / N_出口的独特但变化多端的影响，在CO ₂分压下可达20％的增加/减少（\（p_ {{\ rm {CO}} _ {2}} \））条件预计在2100年进行。这些更改由\（p _ {{{\ rm {CO}} _ {2}} \\驱动对各种浮游生物类群的影响以及食物网结构的相应变化。值得注意的是，我们的发现表明，异养过程在控制C / N_出口到OA的反应中起着关键作用，因此与主要生产者作为对海洋变化的生物地球化学反应的主要驱动力的范式相矛盾。