A large mass of brown algae is drifting toward the US coast and Gulf of Mexico beaches. In all, about 6.1 million tons of the algae moved from the central Atlantic toward the Caribbean, marine scientists at the University of South Florida reported. That is the second largest amount of algae since records began in 2011. The first foothills of the cloud of algae have already washed up on beaches on Mexico’s Yucatán Peninsula, it said.
According to media reports, beaches on the island of Key West, on the southern tip of the USA, are already affected. The algae are affecting the important tourism industry in the region. When the seaweed rots after landing, it releases the rotten-egg-smelling gas hydrogen sulfide, the Florida Department of Health wrote on its website. The gas is not dangerous, but can irritate the eyes and respiratory tract. In addition, microorganisms living in the algae could lead to skin rashes, for example. Researchers also warn against consuming the algae or using them as fertilizer. They could contain large amounts of heavy metals such as arsenic or cadmium, it said.
The algae themselves are not new. Scientists wrote in a study from 2019 that Christopher Columbus had already described them in the 15th century. However, their spread has increased massively since 2011. The algae carpet extends from West Africa to the Gulf of Mexico, the scientists wrote. The exact reason for this is still unclear. However, the overgrowth could be related to the input of nitrogen and phosphorus into the oceans from large rivers such as the Amazon, Congo or Mississippi, said Brian Lapointe of Florida Atlantic University New York Times.