Hydrogen peroxide as a mitigation against Microcystis sp. bloom

Area of Science:

• Aquatic Ecology
• Environmental Science
• Toxicology

Background:

• Harmful algal blooms, particularly Microcystis sp., are prevalent in earthen ponds.
• Microcystis overgrowth disrupts water quality (DO, pH) and produces toxins harmful to aquatic life.
• Cyanobacterial toxins pose risks to aquatic animals in aquaculture settings.

Purpose of the Study:

• To evaluate the efficacy of hydrogen peroxide (H2O2) as a treatment for Microcystis sp. in laboratory and field pond conditions.
• To assess the specificity of H2O2 treatment on Microcystis sp. and its impact on other algal communities.
• To determine the safety of H2O2 treatment for aquaculture species, specifically Tilapia and Giant tiger prawn.

Main Methods:

• Laboratory experiments involving controlled application of H2O2 to Microcystis cultures.
• Field trials in three earthen ponds with measured H2O2 application (7 mg/L).
• Monitoring of Microcystis cell counts, overall algal community composition, and gill status of aquatic organisms post-treatment.

Main Results:

• A 64.7% reduction in Microcystis sp. was observed in laboratory settings.
• An average reduction of 43% in Microcystis sp. cell counts occurred within one hour in pond trials.
• H2O2 treatment specifically targeted Microcystis sp., leaving other algae species unaffected and promoting a shift towards beneficial algae.
• No adverse effects on the gill status of Tilapia and Giant tiger prawn were noted.

Conclusions:

• Hydrogen peroxide (7 mg/L) is an effective and specific treatment for reducing Microcystis sp. blooms in pond environments.
• The treatment promotes a favorable shift in the algal community structure.
• H2O2 application appears to be a safe mitigation strategy for cyanobacteria in pond aquaculture, with no observed negative impacts on key fish and crustacean species.