A giant blob of seaweed called the “Great Atlantic Sargassum Belt” (Scientific American) is headed for Florida, the Gulf of Mexico, and the Caribbean. This belt of seaweed is composed of Sargassum, a type of brown macroalgae found in the ocean. Sargassum can be beneficial to marine life—it is a “floating habitat” for fish, mammals, marine birds, etc.—and blooms are typical (CNN).
However, since 2011, unusual amounts of Sargassum have been piling up. Last year, a record-breaking 22 million metric tons of the seaweed were floating in the Atlantic Ocean. Blooms are growing in size almost every year, and scientists are expecting another intense bloom this year. Just in February, there were six million metric tons of Sargassum in the Atlantic. This number is expected to be even higher this March (Scientific American).
What causes Sargassum to bloom? Well, nutrients like nitrogen and phosphorus, which are found in agricultural runoff from rivers like the Mississippi, Amazon, and Congo, can feed the algae. Saharan dust clouds—they contain nitrogen, phosphorus, and iron—and changes in the sea currents, may also contribute to blooms. Warming temperatures foster Sargassum growth as well (FIU News; The New York Times).
The Great Atlantic Sargassum Belt may seem innocent, but it does pose a threat to marine life and humans. If Sargassum accumulates and decays on shores, it can suck oxygen out of the water, harming the marine life there (The New York Times). Additionally, rotten Sargassum emits hydrogen sulfide gas. Hydrogen sulfide not only smells like rotten eggs, but it also can cause headaches, irritation to the eyes/nose/throat, and respiratory problems (The Scientific American).
Sargassum buildup, which might reach up to five or six feet tall on Caribbean coasts, has serious implications for the tourism industry. Many tourists have an aversion to Sargassum, and cleanup can be difficult and expensive. Millions of dollars have been and will be spent on fishing nets, dump trucks, and heavy equipment (like tractors). And, unfortunately, many of the tools used for cleanup are intensive and can disrupt marine life (CNN). Hopefully, innovators will be able to create eco-friendly technology to clean up beaches covered in Sargassum, or, even better, we will find ways to mitigate Sargassum blooms.