Effects of the submerged macrophyte Ceratophyllum demersum L. on restoration of a eutrophic waterbody and its optimal coverage

In the paper, submerged macrophyte Ceratophyllum demersum L. was selected, and four simulation systems at 0, 20%, 33% and 50% restoration coverage (COV) were used to evaluate the purification effects of submerged macrophytes on restoration of a nutrient-polluted waterbody. The results showed that the water quality was improved significantly in the presence of C. demersum L. Specifically, turbidity and concentrations of TP, NH4+-N, Chl.a were reduced by more than 60%. PCA and Pearson's correlation analysis indicated a significant negative correlation between their reductions and COV of the C. demersum L. (P < 0.05). ANOVAs and PCCA showed no significant differences among groups with different COV of C. demersum L. Based on comprehensive consideration, 20% is probably the optimal restoration coverage area for C. demersum L. in eutrophic shallow lakes.