Comparative assessment of phytoremediation using Eichhornia crassipes, Pistia stratiotes, and Ipomoea aquatica floating beds for phytoplankton community restoration and microcystin-LR removal in eutrophic pond water.

Ecological floating beds (EFBs) represent a sustainable, nature-based solution for remediating eutrophic waters, with plant species selection being a critical determinant of treatment performance. This study assessed the remediation potential of three floating macrophytes Eichhornia crassipes, Pistia stratiotes, and Ipomoea aquatica under cyanobacterial bloom stress. Results demonstrated that all three species significantly reduced concentrations of dissolved nitrogen and phosphorus, with I. aquatica exhibiting the highest removal efficiencies (93.7% for both nitrogen and phosphorus). Notably, I. aquatica elicited a pronounced ecological shift in phytoplankton community structure, effectively suppressing cyanobacterial dominance while promoting the proliferation of green algae, including Scenedesmus, Dictyosphaerium, and Pediastrum. Meanwhile, the macrophytes accumulated microcystin-LR (MC-LR), predominantly in leaves, whereas MCs-degrading bacteria, such as Sphingomonas, Novosphingobium, and Pseudomonas, were detected in root-associated compartments. The notable enrichment of the Serratia further corroborated its putative role in algal toxin degradation within I. aquatica. Furthermore, all species exhibited physiological tolerance to bloom-induced oxidative stress, as evidenced by up-regulated antioxidant enzyme activities. Collectively, these findings support the integration of I. aquatica into EFB systems as an effective ecological management tool for restoring phytoplankton community structure and mitigating toxin risks in waters impacted by harmful algal blooms.