Zooplankton diel vertical migration enhances carbon export via distinct mechanisms in a warming North Pacific

Abstract

Zooplankton diel vertical migration (DVM) is a crucial marine organism behavior modulating particulate organic carbon (POC) export, yet its dynamic role under climate change remains uncertain. Using a coupled physical–biogeochemical model, we assessed how DVM affects carbon export under future scenarios at two contrasting North Pacific sites: Hawaii Ocean Time-series Station ALOHA (subtropical) and K2 (subarctic). Our simulations suggest that by the 2090s, migration depth remains stable at ALOHA but shoals to < 200 m at K2 as temperature cues override irradiance cues. Within the model framework, subsurface POC fluxes are enhanced under the assumed DVM representation, despite reduced migrator biomass. POC transfer efficiency in the twilight zone increases at both sites, driven by distinct mechanisms: enhanced large particle production at ALOHA, and reduced predator pressure and decreased remineralization by deoxygenation at K2. Our study incorporating zooplankton DVM into ecological modeling improves projections of the biological carbon pump in a warming climate.