Abstract:

In the past decades, the increasing amount of macroalgal blooms has been reported worldwide. These include the green tides near the East China Sea (dominant species is Ulva prolifera) and the golden tides in the Caribbean Sea and the Atlantic Ocean (dominant species is pelagic Sargassum), both are causing negative impacts on the coastal ecosystem, local environment, and economy. Satellite observations provide a synoptic view of the surface ocean. However, to monitor floating algae dynamics from space, one major obstacle is to reduce the impacts of various confusing signals that hinder algae detection. Using their spectral and spatial signatures, machine learning algorithms were designed to detect the macroalgal blooms and achieved high accuracy on various ocean color sensors. The workflow was successfully applied to 20-year satellite records. This work led to the discovery of the great Atlantic Sargassum belt, which is now known as the largest macroalgal bloom in the world. Simulations using historical satellite-derived maps are able to reproduce the seasonal bloom patterns, revealing that the formation of the Sargassum belt is mostly driven by the physical transport of surface currents and winds. Evidence was found to suggest the linkage between the bloom intensity and the Amazon riverine nutrients, arousing concerns on the human impacts on the marine ecosystem.

Biography:

Dr. Mengqiu Wang is a Professor currently working at Wuhan University. Her research focus on using remote sensing data to look into the surface ocean dynamics (especially floating vegetation) and their linkage to climatic variations and human interventions. She has published over 20 papers, including one published on Science Magazine, and one coauthored paper published on Nature Communications. Her work has been highlighted twice by International Ocean-Colour Coordinating Group through press release, and has been reported by public media including BBC news, CNN, National Public Radio (NPR), the Washington Post, etc. In 2020, Discovery Magazine selected her study on the great Atlantic Sargassum belt as the top 50 stories on the Science that matters No.47.

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