A giant seaweed belt 5,000 miles wide has its sights set on Florida, where it could wreak havoc as it washes ashore.
Sargassum is a golden-hued seaweed – a large macroalgae – that’s continuously whisked atop the ocean’s currents. Unlike other types of seaweed, such as the kelp that’s anchored to the shallow ocean floor, sargassum is adapted to live on the open sea and lives solely in floating patches.
The Great Atlantic Sargassum Belt in the Atlantic Ocean is the largest macroalgae bloom in the world. As of 2023, the belt is estimated to weigh about 5.5 million metric tonnes and extends 5,000 miles (8,000 kilometers), stretching from West Africa to the Gulf of Mexico.
The matted brown seaweed stretches for miles across the ocean and provides breeding ground, food, and habitat for fish, sea turtles, and marine birds, according to the National Oceanic and Atmospheric Administration (NOAA).
Sargassum has been around for close to 30 million years, first being reported by Christopher Columbus in the 15th century. It was not until 2011 that a massive bloom was reported, and scientists began serious studies of the macroalgae.
The sargassum nearing U.S. beaches later this year will have spent time off the western coast of Africa, then the high seas of the Atlantic Ocean, and finally in the Caribbean Sea, where much of the sargassum resides this time of year.
Once it washes ashore, sargassum is a nuisance, reports CTV News Canada — a thick, brown algae that carpets beaches, releasing a pungent smell as it decays and ensnares humans and animals who step into it.
And cleaning the mess of decaying seaweed off the beaches is a round-the-clock operation for hotels and resorts.
Human health is at risk
When sargassum decomposes, it releases ammonia and hydrogen sulfide, which accounts for the rotten-egg stench. Brief exposure isn’t enough to make people sick, but prolonged exposure, especially to those with respiratory problems, can be dangerous, scientists say.
It can irritate people’s eyes, nose, and throat, and trigger breathing issues for people with asthma, The Hill reports. Some sargassum has already started washing up in Florida, the health department said Friday, but the worst is unfortunately still to come.
Brian Lapointe, a researcher at Florida Atlantic University’s Harbor Branch Oceanographic Institute, told CNN he believes the activity will peak in July.
“This is an entirely new oceanographic phenomenon that is creating such a problem — really a catastrophic problem — for tourism in the Caribbean region, where it piles up on beaches up to 5 or 6 feet deep,” Lapointe said.
