Giant Seaweed Blob With 'Rotten Eggs' Smell Could Cover Florida's Beaches

A huge 5,000-mile-wide blob of seaweed with a rotten eggs smell is floating in the Atlantic and bound to stink up Florida's beaches, a geoscientist and coastal ecologist says, and is a "huge problem."

The seaweed, which is known as sargassum, is not just a nuisance to clear up.

"People hate the smell. It's like rotten eggs," Stephen Leatherman, who is also known as "Dr. Beach," told Newsweek. "You know how rotten eggs smell. Because it's not just the seaweed itself but there are bits and pieces, there's little crabs in there, small fish get caught up. It's a natural ecosystem in its own way. But all that stuff gets beached, and it rots and stinks."

Leatherman said this is a major problem for Florida because it deters visitors and is expensive to clear. The giant mass of sargassum is likely to hit Florida's beaches just as tourism season begins.

Sargassum seaweed is seen on the shores of Le Gosier on the French overseas islands of Guadeloupe on November 13, 2022. LOIC VENANCE/Getty

"The beaches are narrow and not very wide, so it just covers them up," Leatherman continued. "It was so bad in Cancún a couple of years ago that 2,000 people in the Navy had to go out there with pitchforks and other means, just trying to clean it off the beach so they could see the sand," Leatherman said.

The smell is not the only problem the seaweed brings.

When sargassum washes ashore, it begins to decompose. When this process begins, it leads to a release of hydrogen sulfide and ammonia gas emissions. This can actually cause problems for people with a sensitive respiratory system and conditions like asthma. It can also cause wider environmental problems.

It is unlikely to cause severe danger to humans, but it could be a sign of worse things to come as it continues to worsen.

Sargassum is not new—experts have been tracking the blobs for over a decade. In fact, it is natural for them to occur in the ocean. But certain factors have exacerbated it in recent years, causing it to grow larger.

"This is really gotten way beyond what we've seen in the past," Leatherman said. "It's all been happening in the last decade or so. And I think there are a number of reasons for it. One is what's happening in the Amazon."

He continued: "The Amazon is being deforested to make more agricultural land and to improve agriculture in Brazil. But when you do that, you have to add fertilizer, and a lot of fertilizer. Unfortunately, it enters the Amazon River, which is one of the largest rivers in the world, and pushes its waters way out in the ocean. And out there it hits the Sargassum belt, and then it multiplies by the billions over days or over time. And so I think that's one of the big problems, that we're getting so much more of it in the Caribbean, in South Florida and the South Atlantic."

African dust is also a factor. The Saharan dust clouds that extend for miles across the ocean can also contribute to the buildup of sargassum.

The dust contains nitrogen and phosphorus, and these all help to fertilize the seaweed bloom.

"The other thing is, of course, the Earth is warming up, and it really feeds on warmer waters. So that can be a factor," Leatherman said.

He went on: "For South Florida, it is a huge problem because it's very expensive. It deters visitors from coming. They don't like it. They don't like being in the water or swimming with it. It's always been in the water a small amount and it's always been dealt with, but now huge amounts of it show every mile or more. Now it's even worse in the Caribbean, like some of the smaller islands like Barbados, which depends almost totally on tourism. And the beaches are covered and who's going to visit those beaches?

"I was in the British Virgin Islands a few years ago, and I measured 5 feet or so on the top of the sand. Five feet. And the beach wasn't very wide and was completely covered," he said.

The "only good thing" about sargassum is that it is not as dangerous as red tide, Leatherman said. Red tide is a harmful algae bloom that produces toxins. It can be extremely harmful to wildlife. Red tide has recently been detected in Florida, and many fish have died as a result.

Sargassum is not the same. Although it can smell and affect respiratory problems, it is not toxic like red tide.

"This doesn't really kill many fish. A few, but it can actually kill turtles if the mass is so extensive that turtles have to go up for air every 20 minutes or so. They go under it, these huge masses that can go for a mile or so in the worst areas. Then some turtles have actually drowned underneath them. But that's fairly rare," Leatherman said.

The bottom line is that there has always been sargassum seaweed on beaches.
In fact, Christopher Columbus thought the huge floating mats were land before he arrived in the Bahamas. But the problem is getting worse.

"It's natural. But now nature's starting to get out of control," Leatherman said,

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