Mar 23, 2023 - News

Tampa Bay researchers are tracking the big seaweed bloom near Florida

people walking along a beach covered in seaweed

Beachgoers walk past seaweed that washed ashore last week in Fort Lauderdale. Photo: Joe Raedle/Getty Images

University of South Florida researchers are studying a massive seaweed bloom that's starting to wreak havoc on Florida's beaches.

The really big picture: The Sargassum bloom is 5,000 miles wide, spanning twice the width of the continental U.S., and weighs an estimated 12 million tons — roughly half the record-setting total found across the Atlantic Ocean last year, Axios Miami's Martin Vassolo reports.

Threat level: It's already washing up along Florida beaches from Key West to Fort Lauderdale and is expected to hit Miami's beaches between May and June.

  • Florida International University coastal science professor Stephen Leatherman tells Axios it feels like a "flotilla of boats headed our way."
  • "It's coming, the invasion is coming," he said.

Yes, but: The bloom will spare Tampa Bay's beaches, which are already suffering from red tide.

Why it matters: Sargassum provides critical habitat for marine life in the open ocean, but it can also muck up beaches once it washes ashore.

  • When it hits the beach, Sargassum emits a gas that smells like rotten eggs, and the sea life that resides within can cause skin irritation.

Context: The large floating blooms have become an annual occurrence since about 2011, and USF researchers want to get to the bottom of why.

  • The phenomenon has been linked to nutrient runoff, the burning of fossil fuels and deforestation.

Zoom in: USF St. Petersburg's Optical Oceanography Laboratory, which says it is the leading source on Sargassum data, tracks and studies Sargassum blooms using satellites and fieldwork funded by NASA and the National Oceanographic and Atmospheric Administration (NOAA).

  • The lab is also working to improve tracking systems and make its biomass estimates more precise, as well as investigating biochemical properties of the bloom and its possible causes.

Going deeper: USF assistant research professor Brian Barnes cleared up a couple questions we had about the bloom.

  • Could our starving manatees eat it? No, manatees don't eat Sargassum. "They're very picky eaters," Barnes said.
  • Can we just take it apart before it washes ashore? Not exactly.

What he's saying: "The context here is that this is not a single 'blob,' but many smaller patches … sparsely distributed throughout the central Atlantic, Caribbean, and (to a lesser extent) Gulf of Mexico," Barnes explained.

  • Some offshore booms have been installed in the waters outside Florida to prevent Sargassum coming ashore. But the elongated floats commonly used to block other surface materials like oil and plastics can only remove a tiny fraction of the entire biomass included in the bloom.
  • "It would be physically impossible (and harmful to the offshore environment) to install a boom that would catch the entire bloom offshore."
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