Record levels of brown seaweed may wash ashore this summer, potentially harming human health
A record amount of sargassum, more commonly known as brown seaweed, may pile up on the shores of popular American beaches along the Gulf of Mexico this summer.
Last week's tropical rainstorm helped to wash up more sargassum, which lives in the ocean and helps provide an important habitat for many animals, like fish, crab, shrimp and turtle species. However, when the non-toxic plant washes ashore in large quantities, its decomposition process can be harmful to the health of humans and animals.
In what may be bad news for beachgoers and coastal residents, with high amounts of sargassum already floating through the Atlantic Ocean and Caribbean Sea, 2022 is looking like a summer in which the weed may be a prominent feature at the seashore.
"The seaweed itself is not toxic but can be harmful to other plants and animals as well as human beings once large amounts accumulate in coastal waters or on beaches," Dr. Chuanmin Hu, a professor of optical oceanography at the University of South Florida, explained to AccuWeather.
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A pile of sargassum accumulates in Miami Beach, Florida. |
According to reporting from Reuters, when sargassum decomposes, it releases hydrogen sulfide gas and ammonia. With prolonged exposure to decomposing sargassum and its harmful byproducts, beachgoers can develop symptoms such as heart palpitations, shortness of breath, dizziness, vertigo, headache and skin rashes.
During an eight-month period in 2018 when sargassum levels were high, the islands of Guadeloupe and Martinique saw more than 11,000 cases of acute sargassum toxicity. That year, the island nation of Barbados declared a national emergency due to high levels of sargassum.
With sargassum levels expected to be even higher than in 2018 in parts of the Caribbean Sea and the Gulf of Mexico, more cases of acute sargassum toxicity are likely this year, including in the United States. This year in Mexico, truckloads of brown seaweed have already been removed from beaches along the Gulf of Mexico, with the growth of sargassum starting earlier and more voraciously in 2022.
The growth and spread of the brown seaweed depends on a number of factors, including temperature, wind, sunlight, storms, and the loop currents in the Gulf of Mexico. One additional factor that Hu and his colleagues are investigating is climate change, but evidence is mixed on whether climate change would actually aid sargassum growth.
"There are experiments showing once temperatures are above a certain degree, sargassum growth actually slows down," Hu told AccuWeather National Reporter Bill Wadell.
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The proliferation of sargassum accelerated greatly starting in 2011, when its spread "reached a tipping point," according to Hu, causing larger-than-normal clumps of the weed to wash up onshore in the Caribbean, Brazil, and along the Gulf of Mexico. Since then, the threat poised by sargassum has only grown, with scientists still struggling to explain exactly why.
"In the past two months, April and May 2022, those two months already set a new record. Between March and April this year, sargassum total amount has simply doubled," Hu said. "[This] has never happened in history, but what is the reason in the vast ocean?"
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An aerial shot of Miami Beach, with a line of sargassum running down the middle of the sand. |
More than 18.8 million tons of sargassum was estimated to be floating about the tropical Atlantic, the Caribbean Sea, the Central West Atlantic and the Gulf of Mexico in May 2022, with the peak expected to occur later this June or July.
More information about sargassum, its spread, and the location of current and possible future sargassum blooms can be found online at the University of South Florida's Sargassum Watch System.
Additional reporting by Bill Wadell.
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