A Blanket Of Seaweed Smothers Coastlines From The Caribbean To Mexico

PUERTO MORELOS, Mexico — Swaths of seaweed are blanketing nan beaches and coastlines of nan Caribbean and Gulf of Mexico, suffocating shorelines and snuffing retired marine life while spooking visitors successful areas that dangle heavy connected tourism.

Some 27 cardinal metric tons of self-sustaining sargassum person been recorded successful nan Atlantic, Caribbean and Gulf of Mexico successful July, according to a study released Friday by nan University of South Florida’s Optical Oceanography Lab.

The prickly seaweed covers miles of coastline, releasing a foul smell arsenic it rots onshore.

This twelvemonth marks nan first clip that scientists person observed sargassum increasing successful ample quantities successful areas including nan Caribbean and nan Gulf of Mexico, alternatively of being swept into those areas by water currents.

The algae usually reproduces asexually arsenic it travels from Western Africa, said Brian Barnes, a marine intelligence and investigation adjunct professor astatine nan University of South Florida. “None of this is normal,” he said. “Every twelvemonth is simply a small spot of a caller story.”

The Great Atlantic Sargassum Belt has been increasing since 2011, dumping an expanding magnitude of seaweed on coastlines successful nan Caribbean and nan Gulf of Mexico. Experts person said that cultivation runoff, warming waters and changes successful wind, existent and rainfall could beryllium factors.

The sargassum that began reproducing successful nan region earlier than accustomed this twelvemonth stems from a grounds 40 cardinal metric tons reported past year.

“The 2025 bloom was truthful large it ne'er really left,” Barnes said. “It was capable to commencement a caller bloom locally.”

Seaweed threatens tourism

Sargassum levels successful nan Caribbean reached grounds levels successful June, while nan magnitude coming successful nan Gulf deed 5 cardinal metric tons successful June, astir double past year’s record, according to nan University of South Florida.

Scientists expect 2026 to beryllium nan second-largest magnitude of sargassum recorded successful nan Atlantic, Caribbean and Gulf of Mexico, noting that June unsocial saw 34 cardinal metric tons, which was only 10% little than nan year-earlier period.

Mexico said Thursday it plans to put $115 cardinal to tackle nan blooming algae, which poses an biology and economical threat. The authorities estimates that up to 9,000 tons scope its Caribbean coastline connected nan worst days. Given existent resources, Mexico says it tin stitchery only 1,200 tons of sargassum a day.

On a caller evening, Alan Vázquez closed nan edifice wherever he useful arsenic a waiter successful nan celebrated tourer municipality of Playa del Carmen because location were nary customers. He had resisted closing for respective hours, hoping he would person a extremity and salvage nan day, but immense quantities of decomposing sargassum are turning nan famed turquoise waters black, driving distant tourists.

“It’s sad that specified a beautiful and lively spot ... has ended up for illustration this,” Vázquez said.

He fears suffering nan aforesaid destiny arsenic 4 of his colleagues who were laid disconnected 2 months agone because of a driblet successful tourism that has devastated hotels and businesses successful nan authorities of Quintana Roo, 1 of Mexico’s tourism gems, wherever income fell 30% successful nan first half of nan year, according to estimates from section businesses.

In Puerto Rico, sargassum blankets nan waters astir celebrated tourer areas, including La Parguera.

“I don’t callback ever having that overmuch attraction successful truthful galore places astatine once,” said Waldemar Quiles, nan U.S. territory’s earthy resources secretary.

Much of nan grounds sargassum reported past twelvemonth ended up on Puerto Rico’s coastline, prompting nan politician to state a authorities of emergency.

It surpassed nan erstwhile grounds of immoderate 22 cardinal metric tons group successful 2022.

“It’s not a one-off arena anymore,” said Emmanuel Maldonado González, an biology sociologist astatine East Carolina University. “It’s becoming a increasing hazard.”

Experts pass proliferation will worsen

Patches of sargassum successful unfastened waters supply a patient breeding crushed for wildlife, including turtles, food and seabirds, and tin beryllium “a spot of an oasis of life successful nan mediate of nan ocean,” Barnes said.

But erstwhile it’s person to shore, it reduces oxygen successful nan water, smothers mangrove roots and blocks sunlight from reaching coral and seagrass.

Once it washes ashore, it tin forestall recently hatched oversea turtles from reaching nan ocean, while nan dense machinery utilized to region it from beaches risks destroying vulnerable turtle nests, scientists say.

“The coastlines are not built for this,” Barnes said.

In nan U.S. Virgin Islands, group are stepping arsenic acold arsenic 25 feet connected mats of seaweed earlier moreover reaching nan water, according to Amy Dempsey, an biology consultant.

“This is by acold nan worst I’ve seen it successful nan past 5 years,” she said. “We are getting slammed successful nan Virgin Islands.”

The smell of rotten eggs permeates communities wherever ample piles of decaying sargassum emit ammonia and hydrogen sulfide.

“The effects of these gases connected group tin beryllium severe,” warns nan U.S. Environmental Protection Agency, noting it tin origin nausea, headaches and lung irritation.

Used successful composting and bioenergy production

Officials connected nan French Caribbean land of Martinique precocious opened a shelter to temporarily location those affected by nan toxic gases aft residents protested.

So acold this year, crews successful Martinique person collected much than 11,500 tons of sargassum — including 638 tons successful 4 days unsocial this period — according to authorities data. Sea barriers drawback immoderate of nan seaweed, while crews connected statement cod nan remainder by hand, storing and processing it for composting and bioenergy production.

Researchers astatine nan University of South Florida and nan U.S. National Oceanic and Atmospheric Administration utilized artificial intelligence and recovered that from 2003 to 2022, macroalgae blooms accrued by much than 13% a twelvemonth successful nan tropical Atlantic and occidental Pacific.

Overall, nan blooms reached 16.9 cardinal quadrate miles, according to a study published earlier this year.

Sánchez and Coto constitute for nan Associated Press. AP newsman María Verza successful Mexico City contributed to this report.