ABSTRACT: Aquaculture farm cages have the ability to interact with local circulation due to the drag caused by the cages. We examined how the drag influences the residence time of particles within fish farms in the southwest Isles region of New Brunswick, Canada, in the Bay of Fundy using a high-resolution hydrodynamic model. To accomplish this, we parameterized the cage drag in the model and modeled flow structures at multiple spatial scales, ranging from several meters within the cages, to tens of kilometers in the adjacent open ocean. We used models with and without cage drag to demonstrate how residence time was influenced by the imposition of the cage infrastructure. Our examination indicated that the drag produced by cages is able to significantly change the residence time of particles. The magnitude of the change is strongly sensitive to the timing of tides, tidal speeds and specific locations of farms. Our results suggest that the flushing properties of the wastes from aquaculture activities—for example, feed and subsequently fecal material—are strongly related to flow properties and their interactions with cages. These results emphasize that the design of fish farms should explicitly account for the influence of physical infrastructure (i.e. cages) on depositional processes in order to try and minimize environmental effects.

中文翻译：

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模拟网箱阻力对芬迪湾养鱼场内颗粒停留时间的影响

摘要：水产养殖场网箱由于网箱产生的阻力而具有与局部循环相互作用的能力。我们使用高分辨率水动力模型研究了阻力如何影响加拿大新不伦瑞克省西南部岛屿地区芬迪湾的养鱼场内颗粒的停留时间。为了实现这一点，我们在模型中参数化了网箱阻力，并在多个空间尺度上对流动结构进行了建模，从网箱内的几米到邻近开阔海域的几十公里。我们使用有和没有笼子阻力的模型来展示停留时间如何受到笼子基础设施的影响。我们的研究表明，笼子产生的阻力能够显着改变颗粒的停留时间。变化的幅度对潮汐的时间、潮速和农场的具体位置非常敏感。我们的研究结果表明，水产养殖活动产生的废物（例如饲料和随后的粪便）的冲刷特性与流动特性及其与网箱的相互作用密切相关。这些结果强调养鱼场的设计应明确考虑物理基础设施（即网箱）对沉积过程的影响，以尽量减少环境影响。