Massive seaweed blob washing up on Florida beaches is shrinking

  • Amid peak blooming season, researchers see a downward trend in sargassum
  • Sargassum quantity decreased by 15% from April to May 2023, research shows
  • Expert: Seaweed usually increases April to May; “a surprise” it decreased

FORT LAUDERDALE, Fla. (NewsNation) — A massive blob of seaweed that stretched along Florida beaches earlier this year has started to shrink, according to researchers at the University of South Florida.

The 5,000-mile-long mass of seaweed, part of what’s called the Great Atlantic Sargassum Belt, stretches from the Atlantic Ocean and into the Caribbean. It started washing up Florida shores in April.

Throughout the Caribbean and up and down Florida’s shores, residents and coastal communities have been preparing for a record-setting amount of sargassum to come ashore.

Experts said the floating seaweed belt is a natural phenomenon in the ocean, but when it washes up on beaches it rots, creating a toxic, smelly mess that can cause breathing problems for those with respiratory issues.

Yet, scientists at the University of South Florida’s College of Marine Science released a report that shows the quantity of sargassum has decreased by 15% from April to May 2023. It marks the first time it has shrunk during this time of year since 2011 when the studies of the seaweed first began.

“In the past two years, from April to May, the amount of sargassum always increased, but not this year,” said Chuanmin Hu, a USF professor of optical oceanography. “The total amount of sargassum in the Atlantic Ocean actually decreased from April to May. That is truly a surprise to me.”

Researchers use satellite imagery to determine changes. The report shows the sargassum quantity was halved from March to April, then halved again from April to May, but scientists aren’t sure why.

“In total, it decreased by 15%, but that is not uniform everywhere,” Hu said. “In some parts of the ocean, it decreased by more than half. In other places, it decreased a little bit or increased a little bit.”

To some people, 15% may not seem like a lot, but experts said anything that reduces 11 million tons, even by a little bit, is worth noting. Even with the decrease, coastal areas are still preparing for large quantities of the sargassum to make landfall in the coming months, but this new finding makes many hopeful there will be less to clean up when it comes ashore.

Peak seaweed blooming season is in June and July

Florida health officials are warning people about a wave of seaweed smelling like rotten eggs, and while the seaweed itself doesn’t pose a threat, tiny sea creatures that live in it can cause skin rashes or blisters.

Science News

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