Fig. 4: Structural equation modeling shown potential bottom-up cascading influences from nutrient stoichiometry to phytoplankton to zooplankton.

The red and green lines represent negative and positive relationships with “*”, “**” and “***” represent p < 0.1, p < 0.05, and p < 0.01. The gray lines represent the pathways considering in the model but with p > 0.1. The symbols “↑” and “↓” aside the stoichiometric ratios indicate a positive or negative relationship between the ratio and the first PCA component of the stoichiometry variable, respectively.