Patterns and driving mechanism of global marine phytoplankton blooms

Marine phytoplankton blooms have negatively affected environmental and human health, and economic welfare by producing toxins, creating hypoxia, harming fisheries, and disrupting food webs. By integrating and analyzing data from multiple databases, we found that the area of phytoplankton blooms in the Northern Hemisphere exceeds that in the Southern Hemisphere and the seasonal pattern differed between hemispheres. In the Northern Hemisphere, a bimodal pattern driven by interactive effects of human activities and natural factors has led to bloom outbreaks, dominated by a diatoms and dinoflagellates. In contrast, in the Southern Hemisphere, where human activity is comparatively low, phytoplankton blooms are primarily driven by natural factors and dominated by dinoflagellates. Through statistical analysis of geoscientific models, we determined the explanatory power of single-factor effects and the coupled effects of every two factors, which quantitatively reveals the driving mechanism of global marine phytoplankton blooms. Our findings provide a global perspective for a deeper understanding of the formation and driving processes of algal blooms in the context of global climate change and intensified human activities, which can provide guidance for global marine algal bloom prediction, early warning and management.