The Great Concentration of Sargassum Seaweed in the Caribbean Affects Coastal Areas

Paris – 20.06.2026: The massive influx of Sargassum seaweed at extremely high densities continues in the Caribbean, putting great pressure on the environment and local residents. This brown seaweed, which has become increasingly common in the Atlantic since the early 21st century, has reached record levels in recent months and is increasingly negatively affecting coastal areas.

Satellite data from May 2026 show the highest-ever Sargassum biomass densities, particularly concentrated in the Caribbean Sea and the Gulf of Mexico. The Sargassum season usually runs from May to August, with peak months expected in the summer months of June and July. Experts forecast it will continue to increase in the coming weeks.

The French Caribbean region is the hardest hit. On the island of La Désirade in Guadeloupe, accumulated seaweed is so dense that it significantly reduces air quality and causes health problems for residents. At the Diamant beaches in Martinique, Sargassum also covers the area thickly, making it almost unusable as a recreational spot.

The main drivers behind the strong Sargassum outbreaks are a combination of factors. The seaweed primarily grows off the western coast of Africa and is carried to the Caribbean by ocean currents. In addition, increased nutrients, particularly from the Amazon basin, have created favorable conditions for rapid growth and large biomass increases.

The decomposition of Sargassum biomass on beaches releases hydrogen sulfide gas, a toxic gas that can seriously affect health, especially for people with respiratory problems. The environment is also severely damaged when dense seaweed layers threaten coastal ecosystems and negatively impact the local economy, especially tourism – the main source of income for the islands.

To mitigate the consequences of large amounts of drifting seaweed, affected areas have implemented various measures. These include using machinery to collect seaweed on beaches, setting up floating barriers to reduce the amount of seaweed reaching the shore, as well as initiatives to sustainably exploit the seaweed such as making organic fertilizer or an energy source.

Despite response measures, the situation remains tense. Scientists and local authorities emphasize the urgency of international cooperation to build effective long-term strategies to control Sargassum influxes. Only joint efforts can protect the environment and improve the quality of life for affected residents.

The current situation highlights the complexity of environmental changes caused by human activities together with climatic factors. The Sargassum issue requires sustainable solutions coordinated at a global level to minimize negative impacts on the Caribbean in the long term.