A record-breaking blob of smelly seaweed is arriving in Key West — and tourists aren’t happy about it

By Leyla Santiago, Zoe Sottile and Sara Weisfeldt, CNN

Ginny Matts and her boyfriend were excited to celebrate her 60th birthday in Key West. But their vacation was spoiled by an unexpected guest: a record-breaking amount of smelly seaweed known as sargassum that is coating the iconic Florida island’s popular beaches.

What Matts and her boyfriend, Jason Hytreck, encountered was the Great Atlantic Sargassum Seaweed Belt, a floating mass of brown seaweed that spans more than 5,000 miles and forms yearly from the shores of Africa to the Gulf of Mexico.

The mass this year set a new record with scientists finding more seaweed from the blob present in the Caribbean Sea than any other April on record, according to a report from the University of South Florida. Scientists measured 3 million tons of seaweed, which emits a gas that can smell like rotten eggs, in the Caribbean, the report shows.

The blob of smelly seaweed is hitting beach shores just as Florida’s tourist season hits its stride — a major economic driver in the state.

Matts and Hytreck drove hours from Bradenton, Florida, to celebrate Matts’ big birthday. They told CNN on Sunday they were shocked by the amount of seaweed on the beach.

“It’s like 75 yards of seaweed out before you even hit clear water,” said Hytreck. “I grew up in Florida and I mean, this is not what we expected to see when we came in here — this much seaweed.”

Matts said that she felt uncomfortable swimming in the water because of the strong smell.

“It’s a big disappointment as far as that goes really,” she said. “When I’m on vacation, I want to be in the water.”

The stinky mass has set a new monthly record, scientists say

Scientists have tracked the huge blooms of sargassum seaweed that form across the Atlantic Ocean since 2011 — and this year’s mass is setting new records with its size, they say.

The amount of Sargassum seaweed continues to increase over previous months in most regions, according to the latest outlook from the University of South Florida (USF) Optical Oceanography Lab.

In the Caribbean Sea, the seaweed totals set a new monthly record, the outlook shows.

“As expected, Sargassum quantity in most regions has increased continuously from previous months, with the Caribbean Sea setting a new record for the same month of all previous years,” Chuanmin Hu, the Director of the Optical Oceanography Lab at USF, told CNN.

He said that the “only exception is the eastern Atlantic,” which is likely due to clouds obscuring the sargassum in the satellite images.

The amount of sargassum is expected to continue to increase, according to the outlook, meaning the blob is going to worsen as tourist season picks up in Florida and other tropical areas.

“The total Sargassum quantity is expected to increase over the next few months, with impacts of beaching events in the CS (Caribbean Sea) and GoM (Gulf of Mexico) worsening accordingly,” states the report.

The Great Atlantic Sargassum Belt has appeared in the Caribbean Sea “every summer since 2011” except for 2013, according to the USF Optical Oceanography Lab.

What is sargassum?

Sargassum is a catch-all term for over 300 species of brown algae. The algae is actually beneficial when it’s adrift at sea, as it provides food and protection for fish, mammals, marine birds, crabs and other organisms.

But when the seaweed hits the beaches, it accumulates in obstructive, rotten-smelling mounds. In addition to being irritating for beachgoers, the sargassum mounds can also damage ocean life and be dangerous to humans. When there’s too much of the seaweed, it deprives oxygen from the water, creating dead zones. And the gas emitted from the rotting algae is toxic and can cause respiratory problems.

The fluctuations in the mass of sargassum are believed “to be a result of climate variability and other natural and unnatural processes,” USF’s Optical Oceanography Lab says on its website

Cleaning up sargassum on beaches can be both expensive and difficult, according to the Sargassum Information Hub. For instance, front-end loader dump trucks are often used to remove sargassum that’s accumulated more than a foot. But the heavy equipment can crush sea turtle eggs, damaging already fragile populations.

Leaving the sargassum in place creates its own problems: The algae contains arsenic, which can leach into groundwater.

Scientists are still working to understand why the seaweed is growing so much and how it can be managed.

In the meantime, the clumps of algae will likely continue to be an inconvenience for travelers visiting Key West.

Donna Schaffer, a Key West visitor from Illinois, told CNN the seaweed is a “nuisance.”

“We came here to walk on the beach and we had to walk through seaweed to get to the beach, so it’s not that much fun,” she said.

At the same time, she said she understands it’s out of our control.

“Well, it’s nature,” she went on. “It’s going to do what it’s going to do, you can’t stop it.”

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