In May, an unprecedented 37.5 million tons of seaweed was recorded, and biologists have raised concerns that natural events might affect several Caribbean resorts in the weeks to come.
A recent report from the University of South Florida Optical Oceanography Lab indicates this is the highest amount of seaweed detected in the Atlantic Basin since monitoring started in 2011. The researchers noted, “As anticipated last month, the spatial distribution of Sargassum has remained stable; however, the volume in each region has seen a significant increase.” They highlighted that in the Gulf of Mexico, levels exceeded historical records, growing from 31 million tons in April to a record-setting 37.5 million tons in May.
Some small amounts have already appeared on various beaches across the Gulf Coast and Florida, leading experts and beachgoers to speculate about the potential for larger blooms to affect U.S. shores.
Typically, the Florida Keys experience substantial seaweed blooms in late spring, with summer and fall bringing even more to the Florida Peninsula.
Images from eastern Puerto Rico depict numerous beaches and waterways choked with seaweed. While 2025 marks a banner year for Sargassum accumulation, the presence of record amounts on local beaches hinges on unpredictable factors like winds and ocean currents, according to USF staff.
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Though the reasons behind increasing blooms remain somewhat unclear, researchers suggest that climate change, fertilizer runoff, and deforestation could be key contributors.
Health experts mention that while the sight and smell of seaweed can be off-putting, it’s mostly harmless to humans. However, it poses significant challenges for the tourism sector, turning popular beaches into unappealing spots and forcing local governments to invest heavily in cleanup efforts.
To tackle the issue, Mexican authorities have initiated strategies to detect and contain seaweed around nearly forty busy beaches along the Yucatan Peninsula and Caribbean coast. Historically, the region typically sees seaweed cleaning land from April through October, but climate changes have exacerbated the situation in recent years.
The possibility of Florida facing similar issues again, like in 2023 when many beaches were overwhelmed with sticky seaweed, still hangs in the air.
Looking ahead, the report expresses hope that Sargassum will be managed throughout June, particularly in the Western Caribbean and Gulf Coast. While it may be a nuisance, brown algae plays a beneficial role for some marine life, providing food and shelter for small fish, crabs, shrimp, and other organisms.
