Giant seaweed bloom’s beaching begins, expected to worsen

by Alix Martichoux - 05/01/23 10:36 AM ET

(NEXSTAR) – Bits of the Great Atlantic Sargassum Belt – a 5,000-mile-wide seaweed bloom – have started to wash up in Florida, but we’re likely months away from peak activity, researchers said Sunday.

While clouds over the Atlantic made it harder to monitor the seaweed bloom’s growth last month, satellite images showed currents and wind pushing the seaweed accumulation west, said the report from University of South Florida (USF) researchers.

“Record Sargassum abundance” – an estimated 3 million tons – was seen in the Caribbean Sea, the report said. The southern coasts of the islands Hispaniola, Jamaica, and Puerto Rico started to see “notable buildups” toward the end of April.

Some seaweed has also started to beach in Southeastern Florida, the university researchers said. Photos (below) show piles of the algae starting to accumulate on beaches in Fort Lauderdale, and videos posted by Fox Weather show it piling up in marinas and lagoons of the Florida Keys.

The real problems with sargassum – which can contribute to a healthy ocean ecosystem out on the water – start when the seaweed starts tumbling onto beaches. As it washes ashore and rots, the algae smell like rotten eggs. It can cause breathing issues for people with sensitivities and asthma.

A footprint near seaweed that washed ashore on March 16, 2023 in Fort Lauderdale, Florida. (Photo by Joe Raedle/Getty Images)
Beachgoers walk past seaweed that washed ashore on March 16, 2023 in Fort Lauderdale, Florida. Reports indicate that this summer, a huge mass of sargassum seaweed that has formed in the Atlantic Ocean is possibly headed for the Florida coastlines and shores throughout the Gulf of Mexico. The sargassum, a naturally occurring type of macroalgae, spans more than 5,000 miles. (Photo by Joe Raedle/Getty Images)
A tractor plows seaweed that washed ashore into the beach sand on March 16, 2023 in Fort Lauderdale, Florida. Reports indicate that this summer, a huge mass of sargassum seaweed that has formed in the Atlantic Ocean is possibly headed for the Florida coastlines and shores throughout the Gulf of Mexico. The sargassum, a naturally occurring type of macroalgae, spans more than 5,000 miles. (Photo by Joe Raedle/Getty Images)

“Sargassum is also known to often contain heavy metals that can be toxic to humans and animals,” the National Oceanic and Atmospheric Administration said.

Unfortunately, the worst of the beaching is yet to come.

“Looking ahead, the total Sargassum quantity is expected to increase over the next few months, with impacts of beaching events in the [Caribbean Sea] and [Gulf of Mexico] worsening accordingly,” the report said.

Researchers predict the “peak” of the 2023 season will come in June.

“Major beaching events are inevitable around the Caribbean, along the ocean side of Florida Keys and east coast of Florida, although the exact timings and locations are difficult to predict,” the USF researchers said last month.