Atlantic sargassum mass growing early, setting records, eyeing Florida

Last year’s 5,500-mile-long swath of yellow-brown seaweed stretching over the Atlantic Ocean from West Africa to the Gulf of Mexico was called the Great Sargassum Belt. Perhaps what’s growing out there this year should be christened “colossal.”

Researchers at the University of South Florida’s satellite-based Sargassum Watch System said last year’s sargassum bloom was so big it posed challenges on a hemispheric scale for marine ecosystems and coastal towns in terms of tourism, fishing, and marine life.

The size of this upcoming summer’s fledgling bloom is already setting records.

“Sargassum abundance in the interior central Atlantic increased, but it increased so substantially that the abundance reached a new record from all previous December months,” the USF sargassum experts published online. “This indicates that 2024 will be another major Sargassum year.”

The weight of last year's sargassum belt was estimated to be 13 million tons at its peak. Going into this month, researchers predicted its weight was already approaching 5 million tons, which is up from one million tons in November.

The USF College of Marine Science will receive about half of a $3.2-million grant from the NOAA Monitoring and Event Response for Harmful Algal Blooms program, which is a five-year collaboration that aims to better forecast sargassum blooms and to discover how to prevent them from plaguing coastal communities.

Parts of the Sunshine State’s coastline, particularly along the eastern shores of the Florida Keys, were among the beaches that had to contend with environmental, economic, and social challenges due to feet-deep accumulations of sargassum last year.