The massive mass of kelp washing across the Atlantic Ocean toward Florida may contain deadly flesh-eating bacteria.

The 5,000-mile-wide kelp clump is made up of sargassum kelp, which has massively bloomed to form the “Great Atlantic Sargassum Belt.”

A Florida Atlantic University study published in the journal water research discovered that sargassum and accompanying floating plastic can become inundated with Vibrio species of bacteria, creating a “perfect pathogen storm.”

The researchers found that the stranded sargassum seaweed harbors high levels of bacteria, and that the bacteria can easily adhere to the surface of marine plastic debris, which accumulates in large volumes within the seaweed mass.

florida sargassum
A bather walks through sargassum seaweed that washed ashore on May 18, 2023, in Key West, Florida. A huge mass of sargassum seaweed formed in the Atlantic Ocean heading towards the coast of Florida and the coast of the Gulf of Mexico.
Photo by Joe Raedle/Getty Images

Vibrio bacteria, particularly the vibrio vulnificus species, it can lead to brutal infections and even necrotizing fasciitis, leading to the bacterium being nicknamed “flesh-eaters.” Vibrio can infect by eating contaminated shellfish or through an open wound in someone’s flesh, usually from seawater, according to the Centers for Disease Control and Prevention. Infected wounds can become necrotic, with the flesh itself dying and rotting away.

About 1 in 5 people with the infection die, the CDC says, usually quickly after becoming infected. Fortunately, necrotizing fasciitis is rare: only about 0.4 people in 100,000 are infected each year in the United States.

    vibrio vulnificus
File image of the bacterium Vibrio vulnificus. The bacteria can lead to life-threatening infections such as necrotizing fasciitis, also known as the “flesh-eating” virus.

“I don’t think at this point anyone has really considered these microbes and their ability to cause infections,” Tracy Mincer, lead author of the study. water research article and assistant professor of biology at FAU’s Harbor Branch Institute of Oceanography and the Harriet L. Wilkes Honors College, in a statement.

“We really want to make the public aware of these associated risks. In particular, caution should be exercised regarding the harvesting and processing of sargassum biomass until the risks are further explored.”

The kelp mass has only been growing: Researchers at the University of South Florida Laboratory of Optical Oceanography found that, in March and April, the kelp mass was estimated to contain about 13 million tons of sargassum, a record amount for that time of year.

Vibrio bacteria may actually fuel the growth of algal blooms, according to the water research paper.

“Another interesting thing that we discovered is a set of genes called ‘zot’ genes, which cause leaky gut syndrome,” Mincer said. “For example, if a fish eats a piece of plastic and becomes infected with this Vibrio, which then causes leaky gut and diarrhea, it will release waste nutrients like nitrogen and phosphate that could stimulate the growth of sargassum and other surrounding organisms.”

mexican sargassum
Sargassum seaweed accumulates along the shoreline on a beach in Cancun, Mexico, on May 23, 2023. The amount of sargassum was so bad at one point that members of the Navy flooded the beaches with pitchforks to break up the spots.
Photo by DANIEL SLIM/AFP via Getty Images

The algae began to appear on the beaches of Florida and Mexico in recent months, as well as Caribbean islands such as Guadalupe. The huge volumes of seaweed have required a great deal of effort to remove in the past.

“The beaches are narrow and not very wide, so it just covers them up,” Stephen Leatherman, a professor of coastal sciences at Florida International University, previously said. news week. “It was so bad in Cancun a couple of years ago that 2,000 people in the Navy had to go out with pitchforks and other means, just trying to clear the beach so they could see the sand.”

This can expose beach cleaners to Vibrio bacteria, with the risk of infection through open wounds.

Other impacts from seaweed include respiratory problems from the hydrogen sulfide released by decaying algae.

“Anyone with compromised lung function should avoid areas with sargassum blooms: when the seaweed decomposes, it releases hydrogen sulfide. [the smell of rotten eggs] and can be a respiratory irritant,” Kait Parker, an atmospheric scientist at the Weather Company, previously said. news week.

Hydrogen sulfide is a toxic gas that can cause respiratory problems and eye irritation, as well as acute sargassum toxicity in high doses, causing seizures, dizziness, headaches, weakness, and nausea.

“Also, sargassum should not be eaten as it contains heavy metals such as arsenic and cadmium. As for cleaning, it’s best left to professionals. While the flowers are not harmful to the touch, microorganisms that living on them can cause skin irritation,” Parker said.

Do you have an animal or nature story to share with news week? Do you have any questions about sargassum? Let us know via

Leave a Reply

Your email address will not be published. Required fields are marked *