Synergistic ammonium and carbon removal in aquaculture effluent using red seaweed Agardhiella subulata.

The environmental challenges posed by nutrient-rich aquaculture wastewater emphasize the need for sustainable bioremediation strategies that integrate carbon capture and utilization (CCU) with effective nutrient removal. The bioextractive potential of Agardhiella subulata (AS) was investigated under fish wastewater (FW) and ammonium-supplemented fish wastewater (AFW) conditions. Over 14 days, AS cultivated in AFW exhibited a 67% higher growth rate, reaching a carbon capture efficiency of 10.42 g C/ton of water/day (a 168% increase), and achieving an ammonium removal rate of 2.39 mg/L/day. Metabolomic analysis indicated that nitrogen enrichment activated nitrogen assimilation and protein biosynthesis pathways, enhancing AS's capacity to thrive in high-nitrogen environments. These findings underscore AS's dual functionality in nitrogen cycling and carbon sequestration, reinforcing its role as a sustainable solution for aquaculture wastewater management. AS's potential for bioactive compound production also highlights its value in circular economy frameworks, positioning it as a promising candidate for next-generation aquaculture systems.