Factors controlling the seasonal distribution of pelagic Sargassum
Factors controlling the seasonal distribution of pelagic Sargassum
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DOI：
10.3354/meps12646
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发表时间：
2018-07-12
影响因子：
2.5
通讯作者：
Gower, Jim F. R.
中科院分区：
文献类型：
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作者：
Brooks, Maureen T.;Coles, Victoria J.;Gower, Jim F. R.
远洋马尾藻（S. flutans和S. natans）是北大西洋热带和亚热带的特有种，为多样化和经济上重要的生态系统提供了栖息地。在这里，我们调查是什么控制的马尾藻季节性分布，使用耦合建模方法，集成输出的数据同化1/12度HYCOM模拟，1/4度耦合HYCOM-海洋地球化学模型，和个人为基础的拉格朗日马尾藻生长模型。被动平流，浮游颗粒没有马尾藻生理聚集在北大西洋中部亚热带环流在每年的时间尺度，并没有显示与卫星观测的马尾藻分布一致。然而，在较短的时间尺度上，平流本身可以解释高达60%的下一个月观察到的分布在一年中的某些时期。热带大西洋和马尾藻海之间的连通性在很大程度上是单向的，马尾藻海是马尾藻的“死胡同”。通过将生长、死亡率和简单的繁殖公式添加到马尾藻颗粒的被动平流中，可以生成与所有季节的观测结果相匹配的分布，准确率为65%至75%。阐明海洋环流和马尾藻生理学似乎是成功再现生物量季节分布的关键。我们提出了一个概念模型的马尾藻季节性周期，结合新的信息，在热带大西洋的人口。此外，我们认为，墨西哥湾和热带大西洋西部地区的马尾藻种群可能会不成比例地影响全流域的生物量。
Pelagic Sargassum (S. fluitans and S. natans) is endemic to the tropical and subtropical North Atlantic, where it provides habitat for a diverse and economically important ecosystem. Here, we investigate what controls the Sargassum seasonal distribution using a coupled modelling approach that integrates output from a data-assimilating 1/12 degrees HYCOM simulation, a 1/4 degrees coupled HYCOM-biogeochemical model, and individual-based Lagrangian Sargassum growth models. Passively advected, buoyant particles with no Sargassum physiology aggregate in the central North Atlantic Subtropical Gyre at annual time scales and do not show distributions consistent with satellite observations of Sargassum. However, at shorter time scales, advection alone can explain up to 60% of the following month observed distribution during some periods of the year. Connectivity between the tropical Atlantic and Sargasso Sea is largely one-way, with the Sargasso Sea acting as a 'dead end' for Sargassum. Adding growth, mortality and a simple formulation of reproduction through fragmentation to the passive advection of Sargassum particles generates distributions that match observations with 65 to 75% accuracy across all seasons. Incorporating both ocean circulation and Sargassum physiology appears to be key in successfully reproducing the seasonal distribution of biomass. We propose a conceptual model of the Sargassum seasonal cycle that incorporates new information about a population in the tropical Atlantic. Additionally, we suggest that the Gulf of Mexico and Western Tropical Atlantic are regions whose Sargassum populations may disproportionately influence the basin-wide biomass.