The Effects of Hydrogen Peroxide on Bacterial Community Structures during Selective Suppression of Planktothrix...

Cyanobacteria blooms are a widespread challenge, causing significant negative impacts on freshwater ecosystems. Utilizing chemicals that leave no harmful residues and selectively target cyanobacteria offers a promising, environmentally friendly strategy to control these blooms. This study investigates the effects of hydrogen peroxide (H₂O₂) application on controlling cyanobacteria proliferation and evaluates its impact on prokaryotic communities. The findings revealed that applying H₂O₂ at 2 mg L^-1 selectively suppressed Planktothrix agardhii blooms with no notable adverse effects on non-targeted phytoplankton. H₂O₂ degraded significantly within the first 4 h of the experiment, and no traces were detected after 24 h. Following treatment, chlorophyll-a levels decreased significantly, by ~55% within 1 h and ~ 90% within 2 h, compared to the initial measurements. The bacterial community composition also changed notably after H₂O₂ addition. Rheinheimera dominated the prokaryotic community on day 3, representing 40.3%, but diminished to about 1% by the end of the experiment. In contrast, H₂O₂ application triggered Noviherbaspirillum species, their abundance gradually increased over time. The results highlight the potential of the H₂O₂ application to control P. agardhii blooms effectively, though further research at larger scales, such as mesocosm experiments or whole-ecosystem trials, are needed to fully understand its usage in bloom mitigation.