Is river pollution to blame for the explosion of sargassum growth?

An attempt to contain sargasso in Mexico has some success. Photo: Courtesy
An attempt to contain sargasso in Mexico has some success. Photo: Courtesy

Reaserchers point to pollution from rivers in South America and the United States as the likely cause of rapid sargassum growth.

The sargasso sea was first observed by Christopher Columbus in 1492. However, since that time, that relatively small patch of seaweed has been transformed into a floating island of biomass spanning over 5,600 miles.

The latest theories identify the principal culprit to be the discharge of nutrients and pollutants from mighty rivers such as the Amazon in Brazil, the Mississippi in the United States and the Orinoco in Venezuela. 

The Amazon river alone discharges an average of 209,000 cubic meters of water into the ocean every second. While a precise correlation linking river pollutants with the explosive growth of sargassum has yet to be established, scientists say that evidence for the theory continues to mount. 

“The ocean’s chemistry must have changed in order for the blooms to get so out of hand,” said Chuanmin Hu, a researcher at the University of South Florida College of Marine Science.

Earlier: Lopez Obrador plays down sargassum problem, calling it a ‘minor issue’

River contamination aside, most scientists agree that climate change is at least partly to blame for the problem.

The floating, brown seaweed has been spotted on several beaches including Tulum and Playa del Carmen.

Tourism authorities in Quintana Roo said they expect only a moderate uptick in sargassum but have already begun to prepare cleanup crews. 

Over the past weekend, some beaches in Cancun and Playa del Carmen presented low to moderate amounts of sargassum. However, most beaches remained mostly free from the unsightly and stinky seaweed.

Over the last weekend, beaches in Cancún were mostly clean of sargassum. Photo: Carlos Rosado van der Gracht

Carlos Rosado van der Gracht

Born in Mérida, Carlos Rosado van der Gracht is a Mexican/Canadian blogger, photographer and adventure expedition leader. He holds degrees in multimedia, philosophy and translation from universities in Mexico, Canada and Norway.