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Sargassum, the free-floating seaweed proliferating with climate change
10 April 2025
Swathes of Sargassum are rapidly spreading across the tropical Atlantic, with mats reaching depths of 7 meters and spanning hundreds of kilometres. In an article published by Fondriest.com, PML’s Dr. Yanna Alexia Fidai explains how this free-floating seaweed is proliferating due to climate change, shifts in ocean currents, and pollution.
Image above: Sargassum chokes a popular tourist beach in Barbados. (Credit: Yanna Fidai)
‘Until recently, Sargassum–a free-floating seaweed–was distributed throughout the Sargasso Sea, the north Caribbean Sea, and the Gulf of Mexico. But in the space of a decade, this seaweed has, as one scientist remarks, “Gone from a nonfactor to the source of a terrible crisis”.
Driven by climate change, anomalous North Atlantic Oscillation in 2009-2010 and a glut of anthropogenic pollutants, sargassum has proliferated.
Seasonally recurrent mats as deep as 7m now bloom in the “Great Atlantic Sargassum Belt” (GASB), which covers areas of the Atlantic from West Africa to the Caribbean Sea and Gulf of Mexico. Every year, millions of tons wash up along the shores of more than 30 countries.
Dr. Yanna Fidai is an Earth Observation and Remote Sensing Scientist at Plymouth Marine Laboratory in the UK. Inspired by the role environmental monitoring plays in understanding environmental change and improving management, much of her recent research has focused on sargassum.’