"You see metres high of sargassum piled up on shore but you're also seeing it in the ocean," says Iris Monnereau, a Barbados-based fisheries expert with the UN's Food and Agriculture Organisation ...

The seaweed has inundated beaches, causing an environmental nuisance. As of June 2018, the Great Atlantic Sargassum Belt, as scientists call it, extended 8,850km (5,500 miles) and was made up of ...