<b>The biological performance of a pond recirculating aquaculture system for farming the giant freshwater prawn (</b><b><i>Macrobrachium rosenbergii</i></b><b>)</b>

Recirculating aquaculture systems are an important means of achieving sustainable development within the aquaculture industry. In this study, we established a pond recirculating aquaculture system (PRAS) for freshwater prawn (<i>Macrobrachium rosenbergii</i>) farming and evaluated its biological performance. In this system, conventional water quality indicators, antibiotics, heavy metals, and microbial community composition were monitored for four months. The results showed that the specific growth rate of the giant river prawn was 5.28% day^-1. The aquaculture effluent undergoes one cycle in the biological purification pond, reducing the levels of total nitrogen (TN, 13%), total phosphorus (TP, 50%), ammonia nitrogen (NH₄⁺-N, 34%), nitrite nitrogen (NO₂⁻-N, 30%), dissolved inorganic phosphorus (DIP, 57%), chromium (Cr, 34%), cadmium (Cd, 11%), iron (Fe, 25%), and manganese (Mn, 35%). In addition, the recirculating water system maintains antibiotic levels at a low level of enrofloxacin (ENR, 273.36~293.89 ng/L), other categories of antibiotics (0.54~171.58 ng/L). Biological treatment concomitantly increased the relative abundance of nutrient- and heavy-metal-removing bacteria (e.g., <i>Pseudomonas</i>) in the water. Critically, correlation analysis shows that NH₄⁺-N, NO₂⁻-N, DIP, and Cr emerged as key drivers of microbial community structure. In summary, PRAS is an biologically optimised production model that is worthy of broader implementation.循环水产养殖系统是实现水产养殖业可持续发展的重要途径。本研究构建了一套用于养殖罗氏沼虾（<i>Macrobrachium rosenbergii</i>）的池塘循环水产养殖系统（pond recirculating aquaculture system, PRAS），并对其生物学性能进行了评估。本系统对常规水质指标、抗生素、重金属及微生物群落组成开展了为期四个月的监测。结果显示，罗氏沼虾的比生长速率为5.28%/天。养殖尾水经生物净化塘一轮循环处理后，总氮（TN，去除率13%）、总磷（TP，去除率50%）、氨氮（NH₄⁺-N，去除率34%）、亚硝态氮（NO₂⁻-N，去除率30%）、溶解态无机磷（DIP，去除率57%）、铬（Cr，去除率34%）、镉（Cd，去除率11%）、铁（Fe，去除率25%）及锰（Mn，去除率35%）的含量均得到降低。此外，该循环水系统可将抗生素浓度维持在较低水平：恩诺沙星（enrofloxacin, ENR）浓度为273.36~293.89 ng/L，其余类别抗生素浓度为0.54~171.58 ng/L。生物处理同步提升了水体中营养盐及重金属去除菌（如假单胞菌属<i>Pseudomonas</i>）的相对丰度。尤为关键的是，相关性分析结果表明，氨氮（NH₄⁺-N）、亚硝态氮（NO₂⁻-N）、溶解态无机磷（DIP）及铬（Cr）是塑造微生物群落结构的关键驱动因子。综上，PRAS是一种经生物学优化的水产养殖生产模式，具备广泛推广应用的价值。