Here’s what you’ll learn when you read this story:Although most dissolved inorganic carbon fixation occurs at the ocean’s surface, some of that fixation budget originates from the deep ocean. In a new study, scientists suggest that microbial heterotrophs are aiding ammonia-oxidizing autotrophs in fixing inorganic carbon in the deep ocean. This helps us better understand both the deep ocean food web and our ocean’s carbon-storing abilities. However, scientists are still pondering the various mechanisms that the deep ocean uses to fix that carbon. Most inorganic carbon fixing takes place at sea level, thanks to surface-dwelling phytoplankton who—like other land-based autotrophs (i.e.