Golden algae (Prymnesium parvum) blooms present significant challenges to aquatic ecosystems and aquaculture operations, producing toxins that impair respiratory functions in gill-breathing organisms and leading to considerable economic and ecological losses. Current management strategies often rely on algaecides, chemical treatments, dilution, or adjustments to water chemistry, but these methods may be impractical in certain systems. Humic acid, an organic compound derived from natural decomposition, provides a carbon source for beneficial bacteria and has been used commercially in recirculating aquaculture systems and agriculture for diverse purposes.
This study explored the potential of humic acid as an alternative approach to managing golden algae blooms by assessing its ability to reduce nutrient concentrations and control algal proliferation. A controlled experiment was conducted using various dosages of humic acid (prophylactic, low, and high) applied to outdoor systems mimicking pond environments, with and without soil presence. Key water quality metrics, including total phosphorus and nitrogen, were monitored before and after treatment. Results showed significant phosphorus binding within six hours across all treatments and the most notable nitrogen reductions observed in soil-present conditions. By week 5, prophylactic treatments significantly reduced golden algae cell counts, while low and high doses achieved similar results by week 6, keeping cell concentrations below bloom thresholds (<10,000 cells/mL).
These findings highlight the efficacy of humic acid, particularly as a prophylactic treatment, in preventing and mitigating golden algae blooms while reducing nutrient availability. This research supports the use of humic acid as a cost-effective, environmentally sustainable management tool for golden algae and potentially other harmful algal blooms, with promising applications in aquaculture and natural aquatic systems.