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Giant floating bloom of Sargassum seaweed will likely be largest ever recorded

A mass of Sargassum seaweed floating toward the West Coast of Florida in the Gulf of Mexico will likely be the largest ever recorded, the University of South Florida said Friday. 

The Sargassum bloom is expected to increase in size, with the quantity likely peaking in June or July. Major beaching events are "inevitable" along the east coast of Florida, the ocean side of the Florida Keys and around the Caribbean, researchers at the college said. While the exact timing is difficult to predict, major impacts are expected throughout the next few months.

Beaching on Florida will come down to wind, wave and tidal conditions, according to the National Oceanic and Atmospheric Administration (NOAA.)

"Given the complexity of its motion, growth, and decay, it is not possible to forecast the timing of beaching," NOAA said. "However, given the size and number of the current Sargassum patches, there is a strong chance that Sargassum carried by the Florida Current may reach the Florida coast despite wind and wave conditions."

Large Algae Bloom In Atlantic Ocean Makes Way To Florida Beaches
A tractor plows seaweed that washed ashore into the beach sand on March 16, 2023, in Fort Lauderdale, Florida.  / Getty Images

Large accumulations of the seaweed have been a recurrent problem in the Caribbean, in the Gulf of Mexico and in the tropical Atlantic since 2011, according to the NOAA. 

Once the seaweed washes up, it can cause some serious — and stinky — problems. As Sargassum decomposes, it starts to smell like rotten eggs. The hydrogen sulfide released by rotting Sargassum can lead to eye, nose and throat irritation, according to Florida health officials. It could be worse for those with asthma.

People who visit beaches after Sargassum has washed up should avoid touching or swimming near the seaweed, health officials said. Organisms living in the seaweed, such as jellyfish larvae, can irritate the skin.

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