Sargassum seaweed pathogen washes up en masse on beaches Early Birds

Sargassum seaweed pathogen washes up en masse on beaches Early Birds


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Volunteers remove seaweed that has been washed away

© Arno Verhoeven / Mangrove Maniacs Bonaire

A huge pile of seaweed, full of plastic and bacteria, could have unhealthy effects on the coasts of Florida and the Caribbean. This is what Linda Amaral-Zettler published an article about recently with her colleagues from the United States. Some media have reported that these bacteria may include a “flesh-eating” species known as Vibrio vulnificus, but this is not the case.

The brown algae, called Sargassum, is native to the Sargasso Sea in the North Atlantic Ocean. This algae bloom has become a growing problem for beachgoers around the world in recent years, with algae infestations en masse.

Unwelcome guest

Sargassum leftovers on the beach are smelly and heavy and, according to the new research, full of bacteria from the genus Vibrio. said Linda Amaral Zettler, a marine biologist at the Royal Netherlands Institute for Marine Research (NIOZ) and final author of the research book.

The team identified a number of previously undescribed Vibrio species in water, plastic and algae samples that carried key genes shared by their pathogenic peers. “This means that these bacteria may also possess the ‘machinery’ needed to infect humans and cause disease,” Amaral-Zettler said.


About a dozen bacteria in the genus Vibrio cause vibrio, a disease that can occur when humans swallow bacteria or when microbes infect an open wound. If ingested, the bacteria can cause severe diarrhea, abdominal cramps, fever, and vomiting. As for wound infections, one strain of Vibrio can sometimes cause what are called flesh-eating infections, scientifically known as necrotizing fasciitis, in which the skin around an infected wound quickly dies.

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Dangers of sargassum and plastic on the beach

“I don’t think anyone has thought about these microbes and their ability to cause infection at this point,” said Tracy Mencer, senior author at Florida Atlantic University. “We want to raise public awareness of these risks. We need to be especially careful about harvesting and processing Sargassum biomass until the risks are investigated more thoroughly.”

What does that mean for beachgoers? “I don’t think people should run around screaming Sargassum,” Amaral-Zettler says. “But they should be responsible and aware that there are risks in exposing yourself to these types of substances.” It is important to note that Sargassum seaweed clumps also have a high content of plastic, which Vibrio bacteria can quickly attach to and multiply within minutes, the study found. In addition, there are also known risks associated with washing sargassum ashore, such as eye and throat irritation due to toxic substances released from the decomposing seaweed.

Risks to marine life

Marine algal vibrio can have consequences for the environment. For example, just like humans, fish can get diarrhea after eating Vibrio bacteria. This extra stool provides additional nutrients in the water. This can lead to more sargassum.

Algae infestations can suffocate coral reefs. In addition, large amounts of algae lead to low oxygen in the water as the algae die and begin to rot. This creates a “dead zone” where no other marine organisms can survive.

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