Additional Coverage:
Massive Seaweed Blooms Threaten Caribbean and Gulf Coastlines, Impacting Tourism and Marine Life
PUERTO MORELOS, Mexico – Coastal communities across the Caribbean and Gulf of Mexico are grappling with an unprecedented surge of sargassum seaweed, which is carpeting beaches, damaging ecosystems, and unsettling local economies reliant on tourism.
According to a recent report from the University of South Florida’s Optical Oceanography Lab, approximately 27 million metric tons of sargassum were recorded in these waters in July alone. The invasive algae forms dense mats along shorelines, emitting a strong, unpleasant odor as it decomposes.
This year marks a troubling shift: scientists have observed sargassum proliferating directly within the Caribbean and Gulf regions, rather than being carried there by ocean currents as in previous years. Brian Barnes, a marine scientist at the University of South Florida, noted, “None of this is normal. Every year is a little bit of a new story.”
The Great Atlantic Sargassum Belt, which has been expanding since 2011, has steadily increased seaweed deposits along coastlines. Factors such as agricultural runoff, rising sea temperatures, and changes in weather patterns are believed to contribute to the algae’s growth. Last year’s record-breaking 40 million metric tons appears to have fueled this year’s early and abundant bloom, with Barnes explaining that the “2025 bloom was so big it never really left,” enabling a new local surge.
Environmental and Economic Impact
In June, sargassum levels in the Caribbean reached all-time highs, while the Gulf of Mexico saw nearly 5 million metric tons, almost twice last year’s record. Experts anticipate that 2026 will rank as the second largest sargassum bloom on record.
Mexico has committed $115 million to combat the growing problem. On peak days, up to 9,000 tons of seaweed wash ashore along the nation’s Caribbean coast, yet current cleanup efforts can manage only about 1,200 tons daily.
The consequences are visible in tourist hotspots like Playa del Carmen, where businesses face downturns as visitors stay away from beaches overwhelmed by foul-smelling seaweed. Alan Vázquez, a local waiter, recently closed his restaurant early due to a lack of customers, lamenting the impact on the vibrant community and fearing further job losses.
Puerto Rico is also battling record sargassum accumulation, particularly in areas like La Parguera, with the territory’s natural resources secretary calling the current concentration unprecedented. Last year’s massive influx prompted a state of emergency declaration, surpassing previous records.
Environmental sociologist Emmanuel Maldonado González warned that what was once considered an occasional event is now an escalating hazard with long-term implications.
Ecological Concerns and Health Risks
While sargassum mats in open waters can provide habitat for marine species such as turtles and seabirds, their presence near shorelines is damaging. The seaweed depletes oxygen levels in the water, harms mangroves, and blocks sunlight essential for coral reefs and seagrass beds. When washed ashore, it obstructs hatchling turtles from reaching the ocean, and heavy machinery used for removal risks destroying fragile nests.
In the U.S. Virgin Islands, residents face thick layers of seaweed extending up to 25 feet into the water, making access difficult. The decomposition of sargassum emits toxic gases like ammonia and hydrogen sulfide, which can cause nausea, headaches, and respiratory issues, raising public health concerns.
In response, communities such as those on the French Caribbean island of Martinique have taken measures including opening shelters for residents affected by the noxious fumes. Local crews there have collected over 11,500 tons of sargassum this year, utilizing barriers and manual collection, then processing the seaweed for compost and bioenergy.
Rising Trends and Future Outlook
Research using artificial intelligence by the University of South Florida and the U.S. National Oceanic and Atmospheric Administration found that macroalgae blooms have increased by more than 13% annually in tropical Atlantic and Western Pacific regions from 2003 to 2022, covering nearly 17 million square miles at peak.
As the frequency and scale of these blooms grow, coastal communities face mounting environmental and economic challenges, underscoring the urgent need for coordinated response and sustainable management strategies.