2026 Sargassum bloom on track to be the largest, smelliest season yet
He’s back and bigger than ever, but that’s not a good thing. Thanks to warming global temperatures and changing ocean conditions, marine biologists are already expecting this year’s seasonal changes Sargassum blooms will reach record proportions as they drift across the Atlantic Ocean. Island-sized biomasses don’t just grow. They are also forming earlier than ever.
Sargassum is a genus of brown leafy algae characterized by its gas-filled sacs called pneumatocysts. These allow algae to float and grow on the surface of the water, where they provide shelter and food for several marine organisms such as fish, crabs and eels. However, thanks to its chemical composition, Sargassum loses much of its usefulness once washed ashore. As it begins to decompose, biomass releases large amounts of hydrogen sulfide, infamous for its “rotten egg” smell. Exposure to large amounts of stinky plants often causes throat, nose, and eye irritation, but the problems are much more serious for other nearby creatures. Too much Sargassum on a beach can prevent sea turtles from nesting and make it difficult for those that hatch to return to the ocean. Particularly dense piles of the substances also block sunlight and prevent native plants from germinating.
Sargassum is named for its original habitat in the Sargasso Sea off the east coast of the United States, but the algae is on the move. Warmer ocean temperatures, combined with nutrients from agricultural waste runoff, have supercharged the algae, allowing it to grow at an exponential rate. In 2011, marine biologists first identified what is now known as the Greater Atlantic Sargassum Belt, which stretches from the West African coast to the Gulf of Mexico. With the exception of 2013, flowering has not only returned to the United States, but it has also become more pronounced each year. The Belt set a new biomass record of 37.5 million tonnes in 2025, and experts estimate it will be even greater this season.
Researchers estimate more than 9.3 million tonnes Sargassum is already on its way to Florida and the Caribbean. This is much earlier than in previous years, largely thanks to the particularly strong easterly trade winds. Once we arrive at the beaches, cleanup crews will begin removing rotting plants as quickly as possible. However, this comes at a high cost. Miami-Dade County, Florida, previously estimated the dismantling would cost about $35 million. Sargassum of its beaches each year.
If there is any good news, it is that organizations, researchers and even swimmers are not interested in the issue. Sargassum unprepared season. Several groups track algal blooms, including the University of South Florida’s Optical Oceanography Laboratory, as well as the National Oceanic and Atmospheric Agency’s weekly report. Sargassum forecast.
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