Harnessing microalgae for sustainable aquaculture and mariculture: Marine pollution mitigation and circular economy strategies.

The global growth of aquaculture and mariculture has led to severe environmental challenges, including nutrient overloading, chemical contamination, habitat degradation, and microplastic pollution. This review critically examines the sources and impacts of aquaculture-derived pollution while proposing microalgae-based bioremediation as an innovative and sustainable solution. Microalgae support nutrient cycling, carbon capture, and pollutant removal, making them a versatile tool for reducing aquaculture's ecological footprint. The review further evaluates the integration of microalgae into aquaculture systems for wastewater treatment, feed enhancement, and integrated multi-trophic aquaculture (IMTA), offering a circular economy model that promotes sustainability. It also reviews relevant policies, including FAO guidelines, regional environmental frameworks, and eco-certification schemes, to underscore governance practices enabling responsible aquaculture. Technological innovations such as recirculating aquaculture systems (RAS), biofiltration, and AI-assisted environmental monitoring are discussed for their role in improving system efficiency and minimizing waste. Key challenges such as economic viability, scalability, and regulatory compliance are effectively addressed to identify pathways for large-scale implementation. By integrating scientific advancements, policy insights, industry practices, and real-world applications, this review offers a roadmap for transitioning to a low-impact, climate-resilient aquaculture industry, while aligning with United Nations Sustainable Development Goals (SDGs): SDG 6 (Clean Water), SDG 12 (Responsible Consumption), and SDG 14 (Life Below Water). Future perspectives highlight the need for interdisciplinary research and stronger policy support to scale up microalgae innovations for sustainable and environmentally responsible aquaculture development.