One of the bottlenecks for commercial implementation of integrated multi-trophic aquaculture (IMTA) is the difficulty in quantifying its environmental performance. We reviewed a large body of literature to determine the variability in nutrient dynamics within different IMTA systems (open sea-cages, land-based flow-through and recirculating aquaculture systems), with the aim to provide a generic framework to quantify nutrient retention efficiencies in integrated aquaculture systems. Based on the eco-physiological requirements of the cultured species, as well as the response of “extractive” species to waste from “fed” species, the maximum retention efficiency was defined for a conceptual four-species marine IMTA system (fish–seaweed–bivalve–deposit feeder). This demonstrated that 79%–94% of nitrogen, phosphorus and carbon supplied with fish feed could theoretically be retained. In practice, however, various biological and environmental factors may limit retention efficiencies and thereby influence the bioremediation of IMTA systems. These biological (waste production, stoichiometry in nutrient requirements) and environmental (temporal and spatial connectivity) factors were therefore evaluated against the theoretical reference frame and showed that efficiencies of 45%–75% for closed systems and 40%–50% for open systems are more realistic. This study is thereby the first to provide quantitative estimates for nutrient retention across IMTA systems, demonstrating that a substantial fraction of nutrients released from fish culture units can be retained by extractive species and subsequently harvested. Furthermore, by adapting this framework to the design and the condition prevailing for a specific IMTA system, it becomes a generic tool to analyse the system's bioremediation potential and explore options for further improvement.

中文翻译：

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综合多营养水产养殖中的养分保留效率

综合多营养水产养殖（IMTA）商业实施的瓶颈之一是难以量化其环境绩效。我们回顾了大量文献，以确定不同 IMTA 系统（开放式海笼、陆基流通和再循环水产养殖系统）内养分动态的可变性，旨在提供一个通用框架来量化养分保留效率综合水产养殖系统。基于养殖物种的生态生理要求，以及“提取”物种对“喂养”物种废物的响应，定义了概念性四物种海洋 IMTA 系统（鱼-海藻-双壳类动物饲养者）。这表明 79%–94% 的氮，理论上可以保留鱼饲料提供的磷和碳。然而，在实践中，各种生物和环境因素可能会限制保留效率，从而影响 IMTA 系统的生物修复。因此，根据理论参考框架对这些生物（废物产生、营养需求的化学计量）和环境（时间和空间连通性）因素进行了评估，结果表明封闭系统的效率为 45%–75%，开放系统的效率为 40%–50%更现实。因此，这项研究首次对 IMTA 系统中的养分保留提供定量估计，表明从鱼类养殖单元释放的大部分养分可以被采掘物种保留并随后收获。此外，