Aug 22, 2022 - News

Sargassum seaweed interrupts fun in the sun in Miami

Sargassum seaweed is pictured along the beach in Miami Beach.

Sargassum seaweed in Miami Beach in July. Photo: Martin Vassolo/Axios

Miami's beaches have looked a little browner this summer as increased amounts of sargassum seaweed have washed up on Florida's shores.

Driving the news: Miami-Dade County reports that local beaches have seen their highest levels of seaweed since 2019, when the county first started tracking monthly data.

  • In July, crews removed about 7,400 cubic yards of seaweed — most of it from South Beach. That's double the amount collected last July.

What's happening: A record amount of seaweed — 24.2 million tons — formed in the Atlantic Ocean in June, according to the University of South Florida Optical Oceanography Lab.

Why it matters: The brown floating seaweed provides critical habitat for marine life in the open ocean between the Gulf of Mexico and West Africa, but it has overwhelmed coastal regions over the last decade, Florida International University coastal science professor Stephen Leatherman wrote in 2021.

  • The overgrowth of sargassum can trap sea turtle hatchlings or cause fish kills — and impact tourism by deterring swimmers, Leatherman told Axios.

Plus: When it decomposes, the seaweed releases a pungent smell.

Between the lines: Leatherman said that global warming and nutrient runoff from fertilizers and pollution are factors in the rise of sargassum levels.

The good news: Seaweed levels in Miami-Dade have decreased so far in August due to changes in wind direction, according to Tom Morgan, chief of operations for Miami-Dade County Parks, Recreation and Open Spaces.

Yes, but: Sargassum season runs from March to October, so Morgan said we'll have to wait and see if levels increase to July conditions again. Wind direction, currents and tide can impact monthly levels, he told Axios in an email.

  • "Depends on Mother Nature!"

How it works: The county maintains the 17 miles of beaches from South Beach to the Broward County line, and Crandon Park beach.

  • County contractors only have state permits to remove seaweed from parts of South Beach and near Haulover Cut, which is recycled into fertilizer.
  • Everywhere else, they use blade-mounted tractors to cut the seaweed and integrate it into the sand.

Be smart: You can get skin rashes or blisters from the tiny creatures that call the seaweed home, so try to avoid walking or wading through big clumps of it.


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