Record-breaking sargassum invasion in Atlantic, Caribbean threatens to foul beach resorts

A record-breaking 37.5 million metric tons of seaweed was detected during May, with biologists warning that some Caribbean resorts may be blanketed by the naturally-occurring phenomenon during the coming weeks. According to a new report from the University of South Florida’s Optical Oceanography Lab, the observed amount of seaweed was the largest detected amount in the Atlantic basin since monitoring began in 2011.“As predicted last month, while the spatial distribution patterns of Sargassum remained stable, Sargassum amount in each region increased in May considerably,” researchers stated.“In every (area) but the Gulf of Mexico region, Sargassum amount exceeded its historical record.

In particular, total Sargassum amount from all regions combined further increased from 31 (million) tons in April to 37.5 (million) tons in May, making a new record.”Small amounts have already been detected on some beaches along the Gulf Coast and Florida, with experts and beachgoers alike wondering if or when the more substantial blooms will invade beaches across the southern US.During typical years, the Florida Keys may see widespread reports during the late spring, with more significant impacts across the Florida peninsula during the summer and fall.Photos and videos from eastern Puerto Rico show several waterways and beaches covered by the seaweed, with likely months to go before their inundation is over.“Although 2025 is a record year in terms of Sargassum amount, whether a beach or small region receives record-high Sargassum inundation depends not only on the offshore Sargassum amount, but also on local factors that are difficult to predict, including winds and ocean currents,” USF staff stated.The exact causes of the growing blooms are not fully understood, but researchers point to climate change, fertilizer runoff and deforestation in South America as possible significant contributors.Health experts say that while the seaweed may look and smell unpleasant, i...