The recurring influx of sargassum—a brown, floating seaweed—has become a persistent challenge for coastal communities across the Caribbean, the Gulf of Mexico, and South Florida. Since 2011, these blooms have grown in frequency and scale, forming what is now known as the Great Atlantic Sargassum Belt. In 2025, the biomass within this belt was estimated to exceed 37,500 million tons, with forecasts indicating that 2026 could set new records.

While earlier theories attributed the growth to factors like nutrient runoff from the Amazon and Congo river basins, Saharan dust, or shifting ocean temperatures, researchers have identified a new, self-sustaining mechanism. According to the study, the seaweed has created a “sargassumsphere”—a floating ecosystem where fish, shrimp, and other organisms reside. These creatures concentrate nutrients through their waste and the decomposition of older seaweed, effectively fueling the expansion of future blooms.

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To validate this theory, researchers developed a mathematical model using nitrogen and isotopic data from the U.S. Virgin Islands. The model successfully replicated historical bloom patterns from 2011 to 2022 and accurately predicted the size and evolution of blooms in 2023 and 2024.

As these blooms appear likely to persist, experts are shifting focus toward long-term management and resource utilization. Potential applications for the harvested biomass include renewable biofuel production, agricultural soil amendments, and sustainable construction materials. For instance, researchers in Barbados have explored combining sargassum with rum industry wastewater to create biofuel, while initiatives in Mexico and Brazil are testing the seaweed as a component in bricks and building panels.

Source: The Conversation