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Tracking brown macroalgae in the Atlantic Ocean

A large amount of sargassum is floating eastward in the Atlantic Ocean and is expected to create beach hazards as is runs into coastlines.
Red flags fly over a Florida beach, indicating it is closed to the public.
Posted at 12:36 PM, Mar 27, 2023

People along coastlines are preparing for what's supposed to be a major sargassum year. 

Sargassum is brown macroalgae floating on the surface of the Atlantic Ocean. 

The University of South Florida said the 6.1 million tons of sargassum observed in February was the second-largest amount ever recorded for the month. 

It's expected to accumulate and move eastward, creating beach hazards as it runs into coastlines.

While some sargassum has already reached Key West, experts say most of it will arrive in the summer months.

Although it could hamper beach activities for vacationers, sargassum is an essential ecological feature. The University of South Florida notes that it provides food, shade and shelter to fish, shrimp and crab. 

Brownish looking seaweed variety called sargassum in shores of Florida.

5,000-mile-long sargassum seaweed bloom headed toward Florida's coast

It could disrupt beach fun and ecosystems in Florida, Mexico and the Caribbean this summer.

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"It is also a marine resource for other uses such as biomass for food, fuel, and as a possible source of pharmaceutical materials," the university states. 

However, there is a downside to large amounts of sargassum when it decomposes on beaches. Not only does it smell like rotten eggs, but it can also lead to dead marine life and an abundance of insects. 

“If you have got all this toxic hydrogen sulfide and anoxic water, you basically have a dead zone," Brian LaPointe, a professor at Florida Atlantic University, told Scripps News Tampa. "You have no oxygen in the water, which can lead to fish kills."

Sargassum cleanup is a costly proposition. Miami-Dade County reported in 2019 that it would need $45 million to clean up seaweed from its beaches. 

A health alert sign warns visitors to Sand Key Park of the presence of Red Tide.

Burning eyes, dead fish; red tide flares up on Florida coast

The Florida Fish and Wildlife Conservation Commission warns people to not swim in or around red tide waters.

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