Miami’s Escalating Sargassum Invasion

Sargassum, a floating brown algae native to the Sargasso Sea, has formed a “Great Atlantic Sargassum Belt” that stretches from West Africa to the Gulf of Mexico. Since 2011 the bloom has doubled roughly every five years, driven by nutrient runoff from major rivers (Amazon, Congo, Mississippi), warmer ocean temperatures, and altered circulation patterns. Researchers link the trend to climate-related increases in extreme rain events that flush additional nitrogen and phosphorus into the ocean.

The Guardian

In July alone, Miami-Dade County removed about 9,000 tons of seaweed from its 17 miles (27 km) of beaches—the highest single-month total on record. The county’s annual budget for sargassum removal is $3 million, financed by tourist development taxes. Approximately 700 sea-turtle nests have been recorded this nesting season, prompting crews to pause equipment during nesting hours. Satellite data this summer showed 33.5 million tons of sargassum in the belt, the second-largest amount observed, trailing the 38 million tons measured in 2025.

The Guardian

County chief of conservation Chris Bumpus oversees the beach-cleaning operation, noting that heavy equipment is permitted only outside the 30-minute-pre-sunset to sunrise window to protect nesting turtles. He emphasizes that the current surge “is a game-changer” for South Florida and that mitigation measures alone will not resolve the underlying nutrient influx. Research professor Brian LaPointe points to the need for more study of land-based sources and suggests that, as sargassum degrades on shore, it loses much of its marine life, potentially easing open-water removal restrictions in the future.

The Guardian

• “Back in July, the beach looked clean for about an hour,” — Chris Bumpus

The Guardian

• “I think this year has been kind of a gamechanger in that we’ve seen major inundations here in south Florida, more than we’ve ever really seen in past years, and comparable to what’s been happening in the Caribbean, Mexico and the Dominican Republic,” — Brian LaPointe, a research professor at Florida Atlantic University Harbor Branch

The Guardian

• “What we’re seeing is that as this excessive amount of sargassum comes ashore it’s affecting coral reefs and seagrass beds and creating dead zones, which strips the oxygen out of the water,” — Brian LaPointe, a research professor at Florida Atlantic University Harbor Branch

The Guardian