Toxic Metals Found in Mexican Caribbean Sargassum

Puerto Morelos, Mexico — A study led by Rosa Elisa Rodríguez Martínez, a researcher at the Academic Unit of Reef Systems of the Institute of Marine Sciences and Limnology, has identified alarming levels of toxic metals in sargassum washing ashore in the Mexican Caribbean. The findings, based on 63 samples collected between 2018 and 2019, confirm the presence of arsenic, copper, manganese, and molybdenum, among other elements, which in high concentrations pose risks to human health and local ecosystems.

Toxic Elements Exceed Safety Limits

The research, conducted in collaboration with the National Autonomous University of Mexico (UNAM), El Colegio de la Frontera Sur, the Salvador Zubirán National Institute of Medical Sciences and Nutrition, and Florida International University’s Department of Biological Sciences, detected multiple hazardous substances. These include aluminum, calcium, chlorine, iron, potassium, magnesium, phosphorus, lead, rubidium, sulfur, silicon, strontium, thorium, uranium, vanadium, and zinc.

"While some of these elements are essential nutrients, others can become toxic at high concentrations," Rodríguez Martínez stated in an interview with UNAM Global. "Arsenic is the most concerning, as it was found in all collected samples, with most exceeding established limits for human and animal consumption."

Ecological and Health Risks

The study highlights the growing threat posed by decomposing sargassum, which releases organic matter and bacteria into coastal waters. This process turns the water brown, reduces oxygen levels, and increases concentrations of sulfide, nitrate, and ammonium—conditions that have led to the death of seagrass, fish, crustaceans, mollusks, and coral since 2015.

"From 2018 onward, we’ve observed increased mortality in marine fauna," Rodríguez Martínez noted. "While a direct link to sargassum hasn’t been proven, the deteriorating water quality undoubtedly contributes to these deaths."

Urgent Calls for Action

Researchers emphasize the need for proper sargassum removal before decomposition begins, as stranded algae can contaminate beaches, coral reefs, mangroves, and even groundwater. The study also recommends rigorous testing before using sargassum in food or pharmaceutical industries due to its toxic metal content.

"Mexico has the research capacity and resources to address this problem effectively," Rodríguez Martínez concluded. "More studies like this are critical to developing solutions for the massive sargassum influx affecting the region."

The findings underscore the urgency of coordinated efforts to mitigate the ecological and public health risks associated with sargassum in the Mexican Caribbean.