Assessing the Influence of a New Entrance to a Fishing Harbor on Coastal Phytoplankton Dynamics Using Principal Component Analysis and Structural Equation Modeling

Principal Component Analysis (PCA) was used to analyze the physico-chemical variables in Anping Fishing Harbor and its adjacent area, and Structural Equation Modeling (SEM) was used to investigate the influence of the variables on phytoplankton dynamics. The PCA result revealed five important latent variables affecting the area: phosphate and silicate nutrients, river input, heavy metal pollution, dissolved oxygen (DO), and nitrates. SEM results further revealed that river input significantly affected phytoplankton in the area, followed by nitrate concentration. The effect of heavy metals, phosphate, and silicate on phytoplankton was not significant. DO was positively affected by phytoplankton and negatively affected by freshwater river input in the area. In a complex system with anthropogenic and natural impacts, PCA helps to reveal the sources of influence on phytoplankton dynamics in the area, whereas SEM provides a simple ecological model revealing the direct and indirect, as well as the relative importance of each influence.