Toxicity effects of harmful algal blooms in aquatic ecosystems: A review of modern remediation approaches and prospects

Harmful algal blooms (HABs) pose significant ecological, economic, and public health risks, primarily through the production of potent toxins by algae species such as cyanobacteria, dinoflagellates, and diatoms. The increasing frequency and severity of HABs have raised concerns globally, particularly as anthropogenic activities, climate change, and nutrient enrichment in aquatic environments exacerbate their occurrence. This review explores the various drivers of HAB formation, including nutrient pollution from agricultural runoff, urbanization, and industrial discharges, alongside the impacts of climate change on water temperature, stratification, and nutrient dynamics. It highlights the biological characteristics of the major HAB-forming species, such as Microcystis, Karenia brevis, and Pseudo-nitzschia, which contribute to their persistence and toxicity in both freshwater and marine systems. Additionally, the review critically examines current remediation strategies, encompassing physical, chemical, and biological approaches, as well as emerging methods like the use of biofilms and nanoparticles. Although significant progress has been made in understanding HABs and mitigating their effects, challenges remain, particularly in scaling and implementing these methods effectively across diverse ecosystems. The review concludes by identifying key research gaps and future perspectives in the field, emphasizing the need for integrated management strategies, improved monitoring systems, and innovative technologies to address the growing threat of HABs. Sustainable, eco-friendly solutions that balance efficacy and environmental impact are crucial for long-term HAB management.