Signs say stinky, scratchy seaweed summer simmers
Record levels of seaweed in the Atlantic may pile up on Florida and the Gulf Coast this summer.
GALVESTON, TEXAS - APRIL 25: People walk on East Beach alongside seaweed, also known as sargassum, in Galveston, Sunday, April 27, 2025. (Jill Karnicki/Houston Chronicle via Getty Images)
Tracking seaweed might sound like a boring job, but the scientists at the University of South Florida Optical Oceanography Lab take it very seriously.
At the end of last week, they sounded the alarm: Sargassum seaweed is forming earlier and in more abundance than ever this season in the Atlantic -- 40% worse than the record year of 2022.
Seaweed covers the Atlantic shore in Frigate Bay, St. Kitts and Nevis, Wednesday, Aug. 3, 2022. (AP Photo/Ricardo Mazalan)
What is Sargassum?
Sargassum is a kind of seaweed, which is a type of algae. Sargassum never touches the seafloor until it dies, tends to float in islandlike chunks and serves as breeding grounds for fish, turtles, birds and other animals.
Where is the seaweed now, and where will it go?
Composite floating algae density for the week of April 30 to May 6, 2025. (USF)
The largest concentration of the 30 million metric tons of seaweed is currently in the the eastern Caribbean Sea and western Atlantic and is 200 percent higher than historical records in April. Some of that seaweed will make it to Florida and the Gulf Coast later in the summer, but the devil is in the details. Ultimately, currents and wind patterns will dictate which beaches are inundated with the brown stuff.
Although seaweed has shown up recently near Miami and Galveston, Texas, those are more typical localized events and don't show up on the USF tracker, which gives a regional look at where the largest concentrations of seaweed are via satellite.
Seaweed inundates a beach in Martinique in 2025. (USF/Jean Philippe Marechal)
Is seaweed dangerous?
The hydrogen sulfide gas it releases when it rots is not only stinky but can irritate your eyes, nose and throat, the Miami Herald says. The seaweed can also contain jellyfish or sea lice that can irritate your skin.
Because it discourages beach tourism, in 2022, Miami-Dade County spent $3.9 million to haul the seaweed to a landfill before tourists arrived each morning. This year, officials launched a competition to find new ways to recycle the piles of sargassum—and they may have no shortage of raw material to work with.
A young boy plays walks across seaweed that has accumulated on the beach, Tuesday, June 24, 2014, in Port Aransas, Texas. The Sargassum is piled and removed as it continues to wash onto the beach. (AP Photo/Eric Gay)
