Intensive marine aquaculture generates complex pollutants, including nutrients and, threatening marine ecosystems. Biological treatments are effective but vulnerable to disruptions, especially during typhoons, which alter water quality and microbial communities. This study examined a mariculture tailwater (MTW) treatment system in Hainan over a year, focusing on seasonal performance in nutrient and ARGs removal, microbial community dynamics, impacts of environmental changes on functional microorganisms, and interactions of hosts of antibiotic resistance genes. The system effectively removed NH