"虾-藻-贝"串塘分区循环养殖系统氮磷收支研究OA

To address the challenges of niche conflict and restricted tailwater discharge in traditional polyculture ponds,this study constructed a"Shrimp-Microalgae-Shellfish"serial pond recirculating system based on the Integrated Multi-Trophic Aquaculture(IMTA)theory.Two experimental groups with low and high salinity(group L at 10‒15 and group H at 20‒25),were established to quantify the nitrogen(N)and phosphorus(P)budgets and analyze the regulatory effects of salinity.The results showed that:(1)Feed and sediment were the primary source and sink,respectively.Feed was the dominant input source of N and P(accounting for 87.79%/80.65%in group L,and 92.15%/86.50%in group H),while sediment deposition was the main output pathway(accounting for 49.44%/71.41%in group L and 54.47%/71.04%in group H).(2)Salinity exhibited a"trade-off"effect on cultured species.The high salinity environment optimized the osmotic energy expenditure of Litopenaeus vannamei,resulting in higher N and P utilization rates(31.47%and 10.07%),when compared to the low salinity environment.Conversely,the low salinity environment was more suitable for the physiological metabolism of Sinonovacula constricta,yielding better survival and nutrient utilization efficiency than the high salinity group.(3)Spatial partitioning enhanced purification,the system maintained favorable water quality parameters throughout the entire culture period without water exchange.The synergistic algae-clam unit achieved a total nitrogen(TN)removal rate of 49.04%‒55.47%and effectively reduced ammonia and nitrite,but its total phosphorus(TP)removal was relatively limited(31%‒32%).The study confirmed that the"Shrimp-Algae-Clam"serial system could achieve directional transformation and efficient utilization of nutrients through spatial partitioning.Given that a single constant salinity cannot simultaneously satisfy the optimal requirements of both shrimp and clams,it is recommended to implement dynamic salinity regulation based on the growth stages of the target species or to select euryhaline species to maximize the comprehensive benefits of the system.