1. Introduction . Marine ecosystems are complex entities [ 1 ] in which phytoplankton are the foundation and provide about half of the global primary production [ 2 ]. As the base of the food chain, phytoplankton plays an important role in the marine ecosystem [ 3 , 4 ]. The high concentration of phytoplankton forms phytoplankton layers [ 5 , 6 , 7 ], which affect the biogeochemical process of the upper ocean. Therefore, the study of phytoplankton is of great significance to th...