Sargassum

This past summer, beaches in Florida and the Caribbean have been piled high with foul-smelling sargassum seaweed, often in record amounts. It is the visible sign of a vast marine ecosystem that emerged in 2011 and now spreads across a 5,500-mile-long belt from Mexico to West Africa and Florida to Brazil.

Significant blooms of the brown seaweed Sargassum in the tropical Atlantic have been taking place since 2011, impacting tourism in the Caribbean. A more general observation is that between 2003 and 2022, macroalgal mats and microalgal scum have expanded around the globe. A recent study looked at the rise of macroalgae blooms across the globe over the past two decades.

Each summer, vast quantities of Sargassum seaweed spread across the tropical Atlantic and foul the coasts of the Caribbean Islands, the Gulf of Mexico, and northern South America. The Sargassum is not only bad for tourism, it also disrupts ecosystems by providing massive amounts of food for many marine species, upsetting the balance of those systems.