A giant seaweed blob so large it can be seen from space is threatening to transform beaches along Florida’s Gulf coast into a brown morass, scientists say.
The 5,000-mile-wide sargassum bloom –believed to be the largest in history at twice the width of the continental US – is drifting ominously toward the Sunshine State, NBC News reported.
“It’s incredible,” Brian LaPointe, a research professor at Florida Atlantic University’s Harbor Branch Oceanographic Institute, told the news outlet.
“What we’re seeing in the satellite imagery does not bode well for a clean beach year,” he added.
The thick algae mats are mostly harmless as they drift between Africa’s western coast and the Gulf of Mexico – and even provide a habitat for certain marine life and absorb carbon dioxide.
However, they can wreak havoc closer to shore, where they block light from reaching coral and negatively impact air and water quality as the seaweed rots.
LaPointe said massive piles typically wash ashore in South Florida in May, but the algae are already inundating beaches in Key West.
Brian Barnes, an assistant research professor at the University of South Florida’s College of Marine Science, told NBC News that the sargassum can cause major problems even in coastal waters.
“[I]t can block intake valves for things like power plants or desalination plants. Marinas can get completely inundated and boats can’t navigate through,” he said.
“It can really threaten critical infrastructure,” Barnes added.
More than a decade ago, scientists noticed that the unsightly blooms were beginning to grow at alarming rates. They have since documented their proliferation in the tropical Atlantic.
“Before 2011, it was there but we couldn’t observe it with satellites because it wasn’t dense enough,” Barnes told NBC News. “Since then, it has just exploded and we now see these huge aggregations.”
In 2019, a study in the journal Science estimated that more than 20 million metric tons covered the Atlantic in what has been dubbed the “Great Atlantic Sargassum Belt.”
Researchers have found that human activities and climate change are filling rivers that flow into the Atlantic with nitrogen and other nutrients.
“You have the Congo, the Amazon, the Orinoco, the Mississippi — the largest rivers on the planet, which have been affected by things like deforestation, increasing fertilizer use and burning biomass,” LaPointe told the outlet.
“All of that is increasing the nitrogen concentrations in these rivers and so we’re now seeing these blooms as kind of a manifestation of the changing nutrient cycles on our planet,” he said.
Last summer, the United Nations’ Caribbean Environment Program said possible factors causing high levels of sargassum included a rise in water temperatures from climate change, and nitrogen-laden fertilizer and sewage that nourish the algae.
The Biden administration declared a federal emergency in 2022 after the US Virgin Islands warned of unusually high amounts of sargassum clogging machinery at a desalination plant near St. Croix that was struggling to produce water and meet demand amid a drought.
Experts first noted large amounts of sargassum in the Caribbean Sea in 2011, and the problem has occurred practically every year since.
With Post wires