Algal blooms are hotspots of primary production in the ocean, forming the basis of the marine food web and fueling the dissolved organic matter (DOM) pool. Viruses are key players in controlling algal demise, thereby diverting biomass from higher trophic levels to the DOM pool, a process termed the “viral shunt.” To decode the metabolic footprint of the viral shunt in the environment, we induced a bloom of Emiliania huxleyi and followed its succession using untargeted exometabolomics. We show that bloom succession induces dynamic changes in the exometabolic landscape. We found a set of chlorine-iodine–containing metabolites that were induced by viral infection and released during bloom demise. These metabolites were further detected in virus-infected oceanic E. huxleyi blooms. Therefore, we propose that halogenation with both chlorine and iodine is a distinct hallmark of the virus-induced DOM of E. huxleyi, providing insights into the metabolic consequences of the viral shunt.

藻华是海洋初级生产的热点，形成海洋食物网的基础，并为溶解有机物 (DOM) 池提供燃料。病毒是控制藻类死亡的关键参与者，从而将生物量从较高营养级转移到 DOM 池中，这一过程被称为“病毒分流”。为了解码环境中病毒分流的代谢足迹，我们诱导了Emiliania huxleyi的大量繁殖，并使用非靶向外代谢组学跟踪其演替过程。我们表明，绽放演替会引起外代谢景观的动态变化。我们发现了一组由病毒感染诱导并在开花消亡期间释放的含氯碘代谢物。在受病毒感染的海洋E. huxleyi中进一步检测到这些代谢物绽放。因此，我们认为氯和碘的卤化作用是病毒诱导的E. huxleyi DOM 的一个明显标志，为病毒分流的代谢后果提供了见解。