Sargassum Crisis: Mexico’s Beaches Turn Toxic

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

Leticia Durand Smith, a researcher at the Regional Center for Multidisciplinary Research at the National Autonomous University of Mexico (UNAM), warns that this phenomenon will reach unprecedented levels, surpassing even the records set in 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 alone, 37,000 tons of sargassum were collected in shallow waters off Quintana Roo. This year, the magnitude could be even greater, affecting not only tourism but also public health and marine ecosystems.

Ecological Collapse: A Looming 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 are slowly poisoning the sea.

As sargassum decomposes, it consumes large amounts of oxygen, creating dead zones where marine life cannot survive. The so-called “brown tide” also 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 shorelines 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.

Contaminated Aquifers 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, the leachate seeps into the Yucatán Peninsula’s karst soil, 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

Researchers at UNAM have developed Sargapanel, a construction material made from dried sargassum mixed with gypsum and resins. This fire-resistant and heat-tolerant material offers 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, preventing decomposition.

UNAM has emphasized the need for 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 better understand and combat the phenomenon.

Corruption in Sargassum Cleanup Efforts

An investigative report titled From Fox to AMLO: Phantom Companies Took Over 11.4 Billion Pesos exposed an institutionalized system of corruption in which 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 nonexistent companies for supposed sargassum cleanup and beach maintenance in destinations such as Cancún, Playa Espíritu (Sinaloa), and Huatulco. However, there is no evidence these services were ever performed.

Fonatur Infraestructura (Fonatur’s construction division) 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.