Massive blob of sargassum seaweed reaching Florida beaches

The unsightly mass of seaweed will bring pungent odors to tourist hotspots, taking a bite out of the local ecosystem and economy.

To the disappointment of Floridians and vacationers alike, a record-breaking giant blob of smelly and annoying sargassum seaweed has reached the shores of the Sunshine State after traveling for weeks over the open sea.

Piles of sargassum — an accumulation of large brown algae that floats in mass quantities — can stretch for miles across the ocean and are a beneficial habitat for marine species such as fish, sea turtles, crabs and shrimp.

But the massive chunks are an annoyance for beachgoers when the stinky mass reaches the shore, as the overabundant lumps of seaweed emit the foul, pungent scent of hydrogen sulfide as they decompose. The unbearable smell, comparable to rotten eggs, has even been known to cause respiratory issues for those with breathing problems.

And with the amount of sargassum set to increase during the peak bloom months of June and July, officials in Florida are getting nervous about its potential impacts on residents and vacationers -- and on the local economy. 

“Our beach could literally be clean at 8 a.m. and three to four hours later a giant mat of sargassum the size of a mall will come in like the blob, like a Stephen King movie,” Boynton Beach Ocean Rescue Chief Tom Mahady told the Palm Beach Post. “It’s not pleasant for swimmers.”

Video obtained by NPR the first week of May shows the massive sargassum bloom impacting beachgoers along the Florida Keys in Marathon, with the typically blue ocean covered several feet deep with the algae’s brownish hue.

"Onshore, the seaweed can be a nuisance, cutting off access to beaches, hampering use of coastal waters, disrupting coastal ecosystems, and making a huge, stinking mess as it decomposes," the National Oceanic and Atmospheric Administration's climate website states. The organization is working on a weekly risk assessment for beaches at risk of a sargassum incursion.

In April, sargassum levels in the Caribbean Sea broke records, with the massive algae belt growing to an estimated 13 million tons in size, according to the University of South Florida Optical Oceanography lab. The Caribbean Sea sargassum belt was observed at 3 million tons in size. Sargassum has also been reported on beaches in southern regions of Hispaniola, Jamaica and Puerto Rico. 

The South Florida optical oceanography lab reported in 2019 that sargassum growth is tied to higher nutrient levels in runoff from the Amazon River, as well as upwelling in the eastern Atlantic Ocean, when the water rises up from beneath the surface to replace water that was pushed away by winds blowing across the ocean surface. Upwelling in the Atlantic brings cooler water and nutrients to the surface, where sargassum grows.

Brian LaPointe, a research professor and algae expert at Florida Atlantic University, told the Palm Beach Post that sargassum overgrowth is also due to the seaweed building on itself, starting each new crop with ample seed material.

“It really becomes a problem when it piles up … it literally fills man-made canals, coming right up in front of people's homes and surrounding docks,” LaPointe said.

The massive quantities can also clog boat propellers, impacting another popular summer activity for Florida residents and tourists.

In 2019, a buildup of sargassum at Bill Baggs Cape Florida State Park near Miami got it knocked off a ranking of America’s best beaches. A 2020 report by Monroe County officials stated that large sargassum growth could lead to a $20 million loss for the Key West tourism industry, leading to a loss of around 300 jobs.

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Palm Beach has also fallen victim to the bothersome seaweed in recent years, with town council member Bobbie Lindsay commenting that the beach was “unusable” for much of last summer due to the rotten smell and the sargassum “scratching your thighs” as residents and tourists walked the beach.

To combat the growth this time, Palm Beach officials plan to either bury the sargassum on the island's north end -- or remove it entirely if there is too much to bury. Another suggestion, made by LaPointe, was to keep the seaweed in “floating barriers” off the coast, something areas of the Keys have begun to use, along with Mexico’s Tulum National Park.

Others are attempting out-of-the-box ideas to combat the growth, including the U.K. group, Seaweed Generation, and its AlgaRay autonomous robot, which could drag sargassum patches into the ocean and sink the algae 1,000 meters below the surface. The AlgaRay technology is still in its pilot phase but could be ready to operate as soon as 2024.

“It’s a bit like a seaweed Roomba,” Seaweed Generation CEO Paddy Estridge told NPR. “It goes through the water very, very slowly and, a bit like Pac-Man, scoops up the seaweed.”

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