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Giant Seaweed Mass Visible From Space Threatens Florida Beaches

The sargassum bloom is around 5,000 miles wide – double the width of the U.S. – and is believed to be the largest in history.

SOUTHWEST FLORIDA — A giant seaweed mass – so large it can be seen from outer space – is making its way toward southwest Florida. The sargassum bloom is around 5,000 miles wide, double the width of the U.S., and is believed to be the largest in history.

“What we’re seeing in the satellite imagery does not bode well for a clean beach year,” Brian LaPointe, a research professor at Florida Atlantic University’s Harbor Branch Oceanographic Institute, told NBC News.

Brian Lapointe, Ph.D., co-author and a research professor at FAU’s Harbor Branch, emerges from a seaweed bloom.


Last year, Hurricane Ian pummeled the southwest coast of Florida, putting a damper on the end of the summer season. But this year, as the temperatures get hotter and more people head to the beach, a warning is being issued.

This past week, the southwest coast experienced a flare-up of toxic red tide algae, causing residents to complain of burning eyes and breathing problems. Conditions are expected to worsen throughout the summer.

Sargassum Seaweed Blooms in Florida. USF College of Marine Science - University of South Florida.

The bloom, which can provide a habitat for marine life, also has the potential to cause numerous problems. As it travels toward the coastline, it can deprive offshore coral of sunlight. In addition, when the seaweed decomposes, releasing hydrogen sulfide, air and water quality is affected.

The seaweed can block intake valves at power plants and desalination facilities and stop boats from navigating marinas safely. Fish often get caught up in the tangled mess and die, washing up on beaches.


The bloom is starting to make its way towards Key West this week. Forecasters expect large clumps of seaweed mats to begin washing ashore in southwest Florida in May.

The toxic fumes from the red tide are worse when excess sargassum (seaweed) and decaying fish add more nitrogen to the water. The Florida Wildlife Commission is warning people to stay away from areas overwhelmed with algae due to possible rashes, skin irritation, and burning eyes and lungs. Anyone with asthma or lung disease should avoid areas of the beach experiencing blooms.

Currently, there are three main strategies for managing seaweed. State parks leave it on the beach to naturally decay. Most large cities remove it with bulldozers and dispose of it into landfills. But some researchers are exploring ways to convert the nutrient-rich sargassum into “ecoal,” a type of charcoal used for cooking fuel.