Zooplankton Diel Vertical Migration in the Ocean: Global Patterns, Controls and Biogeochemical Impacts

Diel vertical migration (DVM) of zooplankton and micronekton is a major component of the oceanic biological pump, but is generally overlooked in global models of the Earth System. Here, we use a combination of observations and models to quantify the large-scale, population-level impact of DVM on the marine ecosystem and biogeochemistry. First, we present a global synthesis of DVM patterns in the ocean from acoustic data, and link it to regional physical and biogeochemical properties. Second, we implement explicit DVM in a size-structured one-dimensional NPZ model and evaluate it against observations from three major biomes in the Pacific Ocean. We include: realistic migration dynamics and trade-offs, vertical decoupling of feeding and respiration, and a representation of visual predation. We show that realistic migratory populations sustain active fluxes to the mesopelagic ocean between 20 and 40 % the particle export, and contribute up to half of the total respiration within the layers affected by migration. Third, we use a 3D ocean general circulation model coupled to a structurally efficient biogeochemistry representation to explore how DVM affects carbon, nutrient and oxygen cycles on a global scale.