The proliferation of Sargassum in the Tropical Atlantic has occurred almost every year since 2011, but a strong variability of biomass is observed among years. Essential knowledge about the drivers of Sargassum growth and decay is still lacking to explain this interannual variability. Benefiting from accurate basin scale Sargassum detections provided by remote sensing, and from physical and biogeochemical ocean simulations, we developed a Lagrangian drift-growth model to simulate Sargassum distribution over the period 2016–2020. The resulting trajectories and biomass time series of Sargassum aggregates were analyzed to highlight the main limiting factors of growth and decay. The nitrogen and phosphorous concentrations are found to be weakly restrictive compared to physical limiting factors, especially the temperature. In particular, the warm waters found off northern Brazil appear to be instrumental in triggering the end of seasonal growth of Sargassum. The timing of the seasonal warming of this region strongly impacts the quantities of Sargassum simulated each year. This suggests that this region should be monitored to anticipate the development of Sargassum and resulting strandings.

中文翻译：

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热带大西洋马尾藻生长和衰败的驱动因素：拉格朗日方法


自 2011 年以来，热带大西洋的马尾藻几乎每年都会增殖，但多年来观察到生物量的强烈变化。仍然缺乏关于马尾藻生长和衰变驱动因素的基本知识来解释这种年际变化。得益于遥感提供的准确流域尺度马尾藻检测，以及物理和生物地球化学海洋模拟，我们开发了一个拉格朗日漂流增长模型来模拟 2016-2020 年期间的马尾藻分布。分析了马尾藻聚集体的所得轨迹和生物量时间序列，以突出生长和衰变的主要限制因素。与物理限制因素（尤其是温度）相比，氮和磷浓度的限制性较弱。特别是，在巴西北部发现的温暖水域似乎有助于触发马尾藻季节性生长的结束。该地区季节性变暖的时间强烈影响每年模拟的马尾藻数量。这表明应该监测该地区以预测马尾藻的发展和由此产生的搁浅。