Record Seaweed Blooms Choke Caribbean and Gulf of Mexico Beaches

Beaches from Puerto Morelos in Mexico to islands across the eastern Caribbean have been blanketed in recent weeks by unusually large mats of sargassum, a brown seaweed that rots on contact with air and emits a sulfurous odor. Local officials say this year's bloom ranks among the largest ever recorded in the region.

A tourism and ecological problem

Hotels and municipal crews have deployed excavators, boats and manual labor teams to clear the algae before it decomposes on sand, but the volume arriving daily has outpaced cleanup efforts in several locations. Marine biologists say the decomposing seaweed depletes oxygen in shallow water, killing seagrass beds and threatening juvenile fish and sea turtle nesting sites.

• Sargassum volumes this year are among the highest since satellite tracking began over a decade ago
• Researchers link the blooms to nutrient runoff from rivers and warming sea surface temperatures
• Some resorts have installed offshore barriers to intercept the algae before it reaches shore
• Local fishing communities report declining catches near affected coastlines

Scientists tracking the Great Atlantic Sargassum Belt, a vast seaweed band stretching from West Africa to the Gulf of Mexico, say fertilizer runoff from major river systems combined with shifting ocean currents is fueling the growth. The belt has expanded substantially compared with a decade ago, according to researchers who monitor it using satellite imagery.

Economic stakes

Tourism boards in Mexico and several Caribbean nations have allocated emergency funds for cleanup, warning that visible seaweed piles and the smell of decomposition could deter visitors during peak summer travel. Governments are also exploring longer-term uses for the harvested algae, including as fertilizer and construction material, to offset removal costs.

Environmental groups are calling for coordinated regional monitoring and river-basin nutrient management, arguing that piecemeal beach cleanup does not address the root causes of the bloom.