Pacific warming is accelerating ocean deoxygenation and threatening phytoplankton diversity. However, detecting warming-induced phytoplankton and oxygen trends and phytoplankton adaptive responses to warming remain largely unexplored, particularly over long-term observations. Herein, we establish a Bayesian-mechanistic model and incorporate a unique light-driven phytoplankton migration mechanism to assess the countervailing effects of Pacific warming on phytoplankton and oxygen dynamics and associated rigorous uncertainties. The present study indicated a considerable overestimation of phytoplankton light exposure under commonly applied light attenuation estimation by ignoring phytoplankton-light feedback. Subtropical phytoplankton presented weak migratory potential to ambient irradiance, while tropical taxa have engaged in dive migration strategy to mitigate photoinhibitory-induced declines in production. Moreover, physical mixing, rather than thermally-driven changes in oxygen solubility, predominantly drives Pacific deoxygenation. Such an analysis would permit the complete evaluation of the complex interplay between climate change and marine ecosystems.

marine phytoplankton,dissolved oxygen,vertical migration,pacific warming,Bayesian inference