Record sargassum seaweed bloom smothers Caribbean and Gulf of Mexico shores

A blanket of sargassum seaweed has enveloped Caribbean and Gulf of Mexico coastlines, creating an ecological and economic crisis that has left communities grappling with its toxic effects and financial fallout. The invasive algae, which thrives in warm waters and nutrient-rich runoff, has blanketed miles of beaches, suffocating marine life and deterring tourists in regions reliant on coastal economies.

Scientists report that 27 million metric tons of sargassum were recorded in the Atlantic, Caribbean, and Gulf of Mexico in July 2026, according to the University of South Florida’s Optical Oceanography Lab. This year marks the first time the seaweed has grown in large quantities locally in the Caribbean and Gulf, rather than being carried from West Africa by ocean currents. Brian Barnes, a marine scientist at the University of South Florida, described the phenomenon as “none of this is normal,” emphasizing that the pattern defies historical trends.

The crisis intensified after a record 40 million metric tons of sargassum washed ashore in 2025, which scientists say created a self-sustaining bloom in the region. By June 2026, the Caribbean saw its highest sargassum levels on record, while the Gulf of Mexico recorded 5 million metric tons—nearly double the previous year’s peak, according to the University of South Florida. June alone accounted for 34 million metric tons of the algae, just 10% less than the same period in 2025. Scientists expect 2026 to be the second-largest amount of sargassum recorded in the Atlantic, Caribbean, and Gulf of Mexico, following the 2025 record.

The environmental toll is severe. As the seaweed decays on shore, it releases ammonia and hydrogen sulfide, causing a noxious odor and posing health risks such as nausea, headaches, and respiratory irritation. In Martinique, officials opened a shelter to house residents affected by the toxic fumes, while in the U.S. Virgin Islands, people walk up to 25 feet on mats of sargassum before reaching the water. The algae also disrupts marine ecosystems by depleting oxygen, smothering mangroves, and blocking sunlight from coral and seagrass. Sea turtles face additional threats, as sargassum on beaches can trap hatchlings and destroy nests through removal efforts.

Economically, the crisis has devastated tourism-dependent regions. In Mexico’s Quintana Roo, sales at hotels and businesses fell 30% in the first half of 2026, with restaurants like the one in Playa del Carmen shuttering due to the lack of customers. Alan Vázquez, a waiter in the area, described the scene as “sad” and warned of a growing risk of job losses. Puerto Rico’s governor declared a state of emergency after last year’s sargassum surge, which exceeded 22 million metric tons—the previous record set in 2022.

Mexico has allocated $115 million to combat the bloom, though the government acknowledges it can only collect 1,200 tons of seaweed daily, far below the 9,000-ton peak on the worst days. Another source mentions a £85 million investment, reflecting discrepancies in reported figures. Meanwhile, Martinique has processed over 11,500 tons of sargassum this year, using barriers and manual collection to manage the influx. Researchers at the University of South Florida and the National Oceanic and Atmospheric Administration found that macroalgae blooms in the tropical Atlantic and Western Pacific have increased by more than 13% annually since 2003, covering 16.9 million square miles.

Experts point to a combination of factors driving the crisis, including agricultural runoff, warming ocean temperatures, and shifting wind and current patterns. Emmanuel Maldonado González, an environmental sociologist at East Carolina University, called the recurring blooms “a growing hazard,” noting that the phenomenon is no longer an isolated event. “It’s not a one-off,” he said, highlighting the need for long-term solutions to address the root causes.

As the seaweed continues to wash ashore, the region faces a dual challenge: mitigating its immediate impacts while confronting the broader environmental shifts fueling its spread. For now, communities remain caught between the relentless advance of the algae and the uncertain future it portends.