There might be a 5,000-mile wide belt of it clogging up the Atlantic Ocean and threatening to wash up on beaches in Florida and Mexico, but seaweed, at least in other coastal regions, could help shore up economic growth. While hoteliers, beach-goers and fishing crews in the Americas fret about the encroaching Great Atlantic Sargassum Belt, estimated to be the world’s biggest seaweed bloom, coastal regions in Africa and Asia could capitalise on a wave of demand for “nutrient-rich seaweed products,” according to researchers in the US. Harvested as a food crop for thousands of years in countries as far-flung as Japan, Indonesia and Ireland, seaweed has also been deployed as a fertiliser and more recently has been in demand as an ingredient in cosmetics.