Sargassum Crisis: Mexico’s Beaches Turn Toxic

Quintana Roo, Mexico — The Mexican Caribbean is facing one of the worst sargassum episodes in its history. Scientific projections indicate that during the summer of 2025, the amount of sargassum reaching the coasts of Quintana Roo, Yucatán, and other tourist areas will increase by 40% compared to previous years.

Leticia Durand Smith, a researcher at the Regional Multidisciplinary Research Center of the National Autonomous University of Mexico (UNAM), warns that this phenomenon will reach unprecedented levels, surpassing even the records of 2018 and 2023, when millions of tons of these macroalgae invaded beaches and reefs.

The Growing Threat of the Atlantic Sargassum Belt

The Great Atlantic Sargassum Belt, a floating mass stretching from West Africa to the Gulf of Mexico, continues to expand due to factors such as increased ocean nutrients from agricultural fertilizers and wastewater, as well as global warming.

In 2024, Quintana Roo alone collected 37,000 tons of sargassum in shallow waters. This year, the magnitude could be even greater, affecting not only tourism but also public health and marine ecosystems.

Ecological Collapse: A Developing Environmental Disaster

Sargassum is not merely a nuisance for beachgoers; its accumulation and decomposition are triggering an ecological collapse in the Mexican Caribbean. Studies led by Rosa Elisa Rodríguez Martínez, a UNAM researcher in Puerto Morelos, reveal that these algae contain high concentrations of heavy metals such as arsenic, lead, copper, and manganese, which slowly poison the sea.

The decomposition of sargassum consumes vast amounts of oxygen, creating dead zones where marine life cannot survive. The so-called “brown tide” blocks sunlight, preventing photosynthesis in corals and seagrasses, which are essential for maintaining ecosystem balance. Thousands of fish and crustaceans have washed up dead on shores due to oxygen depletion and water toxicity.

Since 2015, a 27% loss of coral reefs has been recorded in some areas, exacerbated by “White Syndrome,” a disease that spreads faster in polluted waters. Sea turtles are also affected, struggling to nest on beaches covered in sargassum. Additionally, there has been an alarming increase in fibropapillomatosis, a disease causing tumors on their skin.

Shorebirds are losing their feeding habitats as sargassum smothers the small organisms they depend on.

Aquifer Contamination and Toxic Beaches

When sargassum decomposes on the sand, it releases gases such as hydrogen sulfide and ammonia, which are not only foul-smelling but also toxic. If not properly removed, leachates penetrate the karst soil of the Yucatán Peninsula, contaminating the underground aquifer—the region’s primary source of freshwater.

The gases emitted by decomposing sargassum cause eye, throat, and skin irritation. Cleanup workers and tourists have reported nausea, headaches, and skin rashes.

Economically, sargassum directly impacts tourism, the region’s main industry, resulting in multimillion-dollar losses when beaches are overrun by algae.

Efforts to Combat Sargassum

UNAM researchers have developed Sargapanel, a construction material made from dried sargassum mixed with gypsum and resins. This fire-resistant material serves as an eco-friendly alternative that reduces deforestation (by replacing wood) and prevents sargassum from decomposing on beaches.

Some hotels and local governments are investing in specialized vessels to collect sargassum before it reaches the shore, avoiding decomposition.

UNAM has urged the creation of a legal framework to regulate sargassum disposal and promote its utilization. Additionally, Mexico, as one of the most affected countries, must lead scientific studies to understand and combat the phenomenon.

Corruption in Sargassum Cleanup

An investigative report titled From Fox to AMLO: Ghost Companies Took Over 11.4 Billion Pesos exposed an institutionalized system of corruption, where shell companies drained public funds with the complicity of officials.

The investigation revealed that during Enrique Peña Nieto’s administration (2012–2018), the National Fund for Tourism Development (Fonatur) allocated millions of pesos to ghost companies for supposed sargassum cleanup and beach maintenance in destinations like Cancún, Playa Espíritu (Sinaloa), and Huatulco. However, there is no evidence these services were ever performed.

Fonatur Infraestructura (Fonatur’s construction branch) awarded 151 contracts worth $29.7 million pesos to companies later declared nonexistent by Mexico’s tax authority (SAT).

In response to transparency requests, Fonatur claimed the services were provided but offered no further proof beyond documents signed by two former officials.

The alleged work should have resulted in sargassum-free beaches, maintenance of spaces in integrated tourism projects in Bahía de Banderas, Huatulco, and San José del Cabo, and beautification of Cancún’s Kukulcán Boulevard, the backbone of the hotel zone.