Patterns and drivers of microeukaryotic distribution along the North Equatorial Current from the Central Pacific Ocean to the South China Sea

Microeukaryotes have been recognized as highly abundant and diverse both in form and function, however, data on their diversity and distribution along marine currents remain scarce. Herein, the distribution of microeukaryotes in surface seawaters was analyzed along a 9000 km stretch of the North Equatorial Current (NEC) and its bifurcation using high throughput DNA sequencing. Significant distance-decay patterns were detected, and the microeukaryote communities were further divided into Central Pacific Ocean (CPO), Western Pacific Ocean (WPO), and South China Sea (SCS) groups. Statistical analyses suggested that the microeukaryotic assembly in the WPO is maintained by the CPO community transported via the NEC. Environmental selection contributed more to community variations than spatial processes did. Temperature and salinity were the two most important environmental factors to shape the examined communities. Altogether, characterizing the microeukaryotic diversity and distribution along the NEC provided an insight into the drivers of their distribution in open oceans.