Environmental factors impacting phytoplankton response to the cold water mass in the Yellow Sea

This study investigates the impact of the Yellow Sea Cold Water Mass (YSCWM) on phytoplankton functional groups and its ecological significance, utilizing a Multilayer Perceptron (MLP) model to reveal the complex interactions between environmental factors and phytoplankton communities. Based on functional traits such as cell size, temperature adaptability, nutritional mode, and photosynthetic efficiency , the phytoplankton in the Yellow Sea was categorized into functional groups. Groups 1 and 3(G1&G3), dominated by small to medium-sized species, exhibit adaptations to low-light mixed nutrition and eurythermal autotrophy , respectively, while Group 2(G2) thrives in high-light autotrophic conditions, and Group 4(G4), characterized by small-sized boreal species, displays both autotrophic and heterotrophic traits, highlighting their ecological adaptability in dynamic marine environments. The results indicate that the formation of the cold water mass facilitates the ecological adaptation of functional groups with strong tolerance to low temperatures, particularly psychrophilic groups. The seasonal dynamics of the cold water mass not only reshape the composition of phytoplankton communities but also influence their productivity and biomass distribution by modulating water temperature and nutrient concentrations. To further quantify the driving role of environmental factors, the MLP model was employed to analyze the influence of temperature, salinity , nutrients, and light on the distribution of functional groups. The findings highlight that temperature variation is the primary factor driving the dynamic response of phytoplankton functional groups to the cold water mass, with the coupling effect of temperature and nutrient concentrations significantly affecting community stability and diversity. By applying the MLP model, this study develops a new framework to analyze the relationships between phytoplankton groups and environmental factors. It further investigates the ecological impacts of the Yellow Sea Cold Water Mass, highlighting its role in shaping phytoplankton community dynamics and marine ecosystem stability.