Shelly-Ann Cox, chief fisheries officer for the Barbados government, has been working on sargassum mitigation for more than a decade. The first places to really feel the impact of sargassum were the Windward Islands in the Caribbean. Vast rafts arrive without warning, often in calm sunny weather at the height of tourist season, smothering miles of coastline in golden seaweed, which piles up, sometimes metres high, turning brown and fetid as it rots. In June 2022, Hu estimated the size of the Great Atlantic Sargassum Belt to be 24.2m tonnes – about four times the weight of the Great Pyramid of Giza.Ī sargassum landing event is a spectacular phenomenon. Chuanmin Hu and his team from the University of South Florida’s (USF) optical oceanography laboratory had been monitoring it using satellite imagery since 2011 and had seen it explode in size. Unwilling to believe his eyes, he talked to other oceanographers, who confirmed that there was a huge sargassum bloom in the South Atlantic. Oceanographer Ajit Subramaniam on a research expedition. “One moment we were in the blue sea, then bam! It was all around the ship for tens, hundreds of metres.” “Here was something I’d never seen before,” he says. Oceanographer Ajit Subramaniam, who has run scientific research expeditions in the South Atlantic for 25 years, first noticed it in 2018. What is alarming, is the rate at which it is growing. Under the surface it teems with life, like an upside-down reef.

But even early witnesses recognised its value: it provides a safe harbour and breeding ground for fish, turtles and other marine life. Distinguished by bubble-like formations in its stems that keep it floating on the surface, pelagic sargassum has sloshed about in the Atlantic since well before Christopher Columbus sailed across the wide Sargasso Sea: in 1492, he wrote that he feared his boat would be trapped in it.

It is beautiful, layered like golden mats on the surface of the open ocean. Sargassum floating on the waters of Guadeloupe in the Caribbean.

Google earth view