Abstract: In the process of culturing Caulerpa lentillifera, in order to explore the correlation between the pH and redox potential（Eh） of water body and the changes of fouling microalgae community, the acidimeter and redox potentiometer were installed in the culture pond, and 45 pieces of plastic hanging plates for microalgae adhesion test were placed at the seedling clamping plate for 90 days. Five plates were extracted every 10 days to analyze the microalgae population structure and record the pH and Eh in the same period. The results showed that 4 species belonging to 4 genera of Bacillariophyta and 4 species belonging to 4 genera of Cyanophyta were detected; the pH increased in the first 50 days, then stabilized in the last 40 days, and the Eh showed an upward trend in 90 days; in the early stage, the Diatom population was the dominant community when the pH and Eh were lower, and in the later stage, the Cyanobacteria population was the dominant community when the pH was higher. pH and Eh were significantly correlated with the population structure of fouling microalgae, positively correlated with Cyanobacteria population, and negatively correlated with Diatom population.

Key words: Caulerpa lentillifera, fouling microalgae, population structure, pH, redox potential（Eh）