Causes and solutions for the Great Atlantic Sargassum Belt

大大西洋马尾藻带的成因及解决方案

• 批准号: 2443098
• 金额: --
• 依托单位: University of Leeds
• 依托单位国家: 英国
• 项目类别: Studentship
• 财政年份: 2020
• 资助国家: 英国
• 起止时间: 2020 至 无数据
• 项目状态: 未结题
• 来源: https://gtr.ukri.org/projects?ref=studentship-2443098
• 关键词: Causes; solutions; Great; Atlantic; Sargassum

BackgroundSince 2011 the appearance of large amounts of seaweed (various species of Sargassum) on the beaches of the Caribbean Sea has become an annual problem e.g. in Barbados and Trinidad and Tobago. Small amounts of Sargassum reaching shores has beneficial effects - fertilising plants that strengthen shorelines, providing food for local species, etc., but the recent massive landings damage local ecology and economies and is challenging to clear up.On shore, as well as blocking beaches and discouraging swimmers, the Sargassum releases sulphurous odours as it decomposes. Removal is time-consuming, expensive and can damage the beaches. Incoming rafts smother sea grasses and coral reefs, while local fishermen struggle to get into the water, with the huge rafts of seaweed blocking their engines and fishing gear. There is also the risk to the sea turtle population, which comes ashore to nest. Nesting sites can be blocked by the Sargassum or damaged by removal work - and the turtles may become entangled and die.The new source of Sargassum appears to be in the tropical central Atlantic (the Great Atlantic Sargassum Belt, GASB e.g. Wang et al., 2019). Some possible causes have been suggested, such as the increase in discharge of nutrients from the Amazon, due to deforestation and increased use of agricultural fertiliser, as well as changes in sea surface temperature (SST) due to global warming and the biochemical composition of the seawater. The Sargassum has been observed in satellite images (e.g. MODIS) to extend from Brazil to West Africa (Wang et al., 2019), and it is then transported NW by the Guiana Current along the Lesser Antilles Island arc and into the Caribbean Sea.The ProjectThis project is an exciting opportunity to get involved in interdisciplinary research in marine science, exploring the connections between physics, biogeochemistry and ecology, to address a real problem in managing our oceans. It will equip you with important skills in remote sensing and modelling, as well as management of Big Data, with opportunities to learn about AI and machine learning.Here we propose to examine the transport of Sargassum by a regional numerical model of the 3D baroclinic hydrodynamic circulation (using a regional NEMO model embedded in the global NEMO model: Wilson et al., 2019), modulated by the Stokes' drift caused by wind waves (from the WAVEWATCH III model, hereafter referred to as WW3, see Bricheno and Wolf, 2018). The model can capture the 3D circulation (driven by tides, winds, freshwater discharge from rivers and heat fluxes), as well as surface temperature and salinity, allowing us to explore the variability of the source conditions and transport and dispersion within the Atlantic Ocean and the Caribbean Sea. This may also provide a useful predictive tool for occurrence of the nuisance seaweed and help understand the mechanisms and impacts of options that may be applied to its management.Tools and MethodsThe methods to be used include:Examination of satellite data from MODIS (to examine extent and variability of Sargassum distribution in space and time)Examination of other satellite datasets e.g. satellite altimetry data from Sentinel-1 and Sentinel-2 for sea level and waves, SST (from AVHRR) and salinity (from SMOS), to validate the 3D baroclinic hydrodynamic-wave coupled modelRunning the coupled NEMO-WW3 model of Caribbean Sea, with boundary forcing from global NEMO and WW3 models, model diagnostics, validation and scenario testingThe PARCELS (or other) particle-tracking methodology will be applied to track to dispersion of the Sargassum through the model.

背景自2011年以来，加勒比海海滩上出现大量海藻（各种马尾藻属）已成为每年的问题，例如在巴巴多斯和特立尼达和托巴哥。到达海岸的少量马尾藻具有有益的影响-为植物施肥，加强海岸线，为当地物种提供食物等，但最近大量的海藻登陆破坏了当地的生态和经济，清理工作也面临挑战。2在海岸上，海藻分解时释放出硫磺味，不仅阻塞了海滩，阻碍了游泳者。清除是耗时，昂贵的，并可能破坏海滩。来袭的木筏淹没了海草和珊瑚礁，而当地渔民则挣扎着下水，巨大的海藻木筏挡住了他们的引擎和渔具。海龟上岸筑巢也有风险。海龟的筑巢地点可能会被马尾藻堵塞，或因清除工作而受到破坏，海龟可能会被缠绕并死亡。马尾藻的新来源似乎是在热带中大西洋（大大西洋马尾藻带，GASB，例如Wang等人，2019年）。有人提出了一些可能的原因，例如由于森林砍伐和农业化肥使用的增加，亚马逊河的营养物质排放量增加，以及由于全球变暖和海水的生物化学成分造成的海面温度变化。在卫星图像（例如，中分辨率成像光谱仪）中观察到马尾藻从巴西延伸到西非（Wang等人，2019年），然后由圭亚那海流沿沿着小安的列斯群岛岛弧向西北方向输送，进入加勒比海。该项目该项目是一个令人兴奋的机会，可以参与海洋科学的跨学科研究，探索物理学，生物地球化学和生态学之间的联系，以解决管理我们海洋的真实的问题。它将为您提供遥感和建模以及大数据管理方面的重要技能，并有机会学习人工智能和机器学习。在这里，我们建议通过3D斜压流体动力学环流的区域数值模型（使用嵌入全球NEMO模型的区域NEMO模型：Wilson等人，2019），由风浪引起的斯托克斯漂移调制（来自WAVEWATCH III模型，以下称为WW 3，参见Bricheno和Wolf，2018）。该模型可以捕获3D环流（由潮汐，风，河流淡水排放和热通量驱动）以及表面温度和盐度，使我们能够探索大西洋和加勒比海内源条件和运输和分散的变化。这也可以提供一个有用的预测工具，以预测滋扰性海藻的出现，并帮助了解可能适用于其管理的各种方案的机制和影响。工具和方法将使用的方法包括：中分辨率成像光谱仪卫星数据的检查（审查马尾藻属在空间和时间上的分布范围和可变性）审查其他卫星数据集，例如Sentinel-1和Sentinel-2的卫星测高数据，以了解海平面和波浪、SST（来自AVHRR）和盐度（来自SMOS），对三维斜压水动力-波浪耦合模式进行了验证。利用全球NEMO和WW 3模式的边界强迫，模式诊断，验证和情景测试PARCELS（或其他）粒子跟踪方法将被应用于跟踪通过模式的马尾藻的扩散。