Life after death in the pelagic: Non‐predatory zooplankton mortality and the “ghost carbon pump”

The biological carbon pump is traditionally framed as a trophically mediated process in which zooplankton mortality is attributed mainly to predation, routing carbon through fecal pellets and higher trophic levels before export. Increasing evidence, however, shows that nonpredatory mortality—caused by different environmental stressors—accounts for a substantial fraction of zooplankton losses. These deaths produce intact carcasses that sink as discrete particles, forming an often overlooked pathway of particulate organic carbon export. Here, I synthesize current evidence to formalize the “ghost carbon pump”: the direct transfer of zooplankton biomass to depth via nonpredatory mortality. Carcasses represent a distinct export pathway whose rapid sinking and intense microbial processing redistribute remineralization vertically and may contribute to mismatches between measured particulate organic carbon flux and mesopelagic respiratory demand. As warming, stratification, and deoxygenation intensify, this pathway warrants explicit evaluation in carbon budget assessments.