Besieged by seaweed, the Caribbean is scrambling to use it

PUERTO MORELOS, Mexico September 29 (Reuters) – As the sun rises in the Mexican state of Quintana Roo, home to the white sands of Cancun and Tulum, Rear Admiral Alejandro Lopez Zenteno readies his sailors for another day of dragging rafts of brown algae towards the shore and out of sight of tourists sipping cocktails.

Zenteno is leading the operation for the Mexican Navy, which coordinates with state and local governments to protect a trade of visitors to the region that was valued at more than $ 15 billion a year before the coronavirus pandemic struck, according to the Quintana Roo tourism secretariat.

When washed up on shore, the plant – known as sargassum – turns black and emits a sewer odor so powerful it’s known to make travelers sick. It attracts insects and turns the area’s famous turquoise waters for snorkeling to a sickly brown.

And it keeps coming. Since 2011, algae here and in the Caribbean has exploded for reasons scientists suspect to be linked to climate change but do not yet fully understand.

In Quintana Roo alone, the Mexican navy has since March removed more than 37,000 tonnes of Sargassum – more than the weight of three Eiffel Towers – from the surrounding beaches and waters.

“We don’t expect this to end anytime soon,” Zenteno said aboard an algae clean-up vessel known as “sargacero,” one of 12 deployed by the Navy.

Meanwhile, entrepreneurs in the region are looking for ways to monetize the sludge. They are experimenting with algae products including animal feed, fuel, building materials, and even signature cocktails.

“Sargassum is considered a nuisance,” said Srinivasa Popuri, a Barbados environmental specialist at the University of the West Indies. He sees the Caribbean as “blessed” with a resource that grows naturally and does not require any land or other inputs to thrive.

Popuri is working on extracting substances from algae that could have applications for the pharmaceutical, medical and food industries.

Whether such efforts prove viable remains to be seen. Marketing algae can be difficult given the cost of collecting it.

Yet creativity flourishes with algae.


One of the most significant potential uses is in the demand for alginates, a biomaterial extracted from brown algae, which is a common ingredient in food thickeners, wound care and waterproofing agents for its gel-like properties.

The global market in 2020 was worth nearly $ 610 million, a figure expected to reach $ 755 million by 2027, according to consulting firm Global Market Insights.

Omar Vazquez, meanwhile, builds houses.

Vazquez, owner of a nursery in the seaside town of Puerto Morelos near Cancun, had been using Sargassum as a fertilizer for several years. In 2018, he came up with the idea of ​​making it into a building material. He said the resulting Sargassum “bricks”, baked in the sun, allow him to build a house 60% cheaper than if he used traditional cement blocks.

Now nicknamed “Señor Sargazo” by his neighbors, Vazquez said he built and donated 10 of these houses to local families in need. He hopes to turn his now patented “Sargablock” hardware into a for-profit franchise.

“Everyone complained that Sargassum stank, Sargassum is a problem. What I did was find a solution, ”said Vazquez, 45, showing Reuters around“ Casa Angelita, ”the first house he built with seaweed and named it. in honor of his mother.

The Ritz-Carlton in Cancun has found a tastier use of Sargassum. For a while, he served a cocktail made with tequila, vinegar, sugar, rosemary and a syrup made from sanitized seaweed.

Some companies are nervous about depending on a resource whose supply is variable: there is no way to know how much could grow in a year.

Others fear that large-scale harvesting for commercial initiatives could lead to indiscriminate picking up of sea turtles and other endangered creatures.

Still other efforts await scientific safety testing. In Jamaica, entrepreneur Daveian Morrison is building a processing plant to expand his experiments, including turning algae into charcoal that people can burn instead of firewood. He said his high-protein plant-based animal feed recipe has proven successful on a local goat farm, but requires more testing to ensure the algae does not contain levels dangerous arsenic or other harmful substances.

In Barbados, a research team from the University of the West Indies distills sargassum along with waste from a rum distillery to produce methane, which can be turned into compressed natural gas to power transport across the island.

“There’s this beautiful coincidence that the ocean is producing all of this biomass,” said Legena Henry, a professor of renewable energy at the university. She said she would convert her own car to run on fuel soon, hoping for a wider rollout next June.


Sargassum is mostly found in the Sargasso Sea in the North Atlantic, where algae has been documented for hundreds of years. How he traveled south to the tropical Atlantic is unclear.

Some scientists have speculated that the intense 2010 hurricane season transported part of it to the west-central Atlantic, sowing the seeds of a new belt of sargassum which now stretches nearly 9,000 kilometers. .

This algae explosion “might just reflect the system moving to a tipping point,” said biologist Joseph Montoya of Georgia Tech University. “We do not know.”

It is also not known why the flowers of Caribbean sargassum reached such monstrous masses. Scientists say climate change, water pollution, Amazon deforestation and dust from the Sahara Desert are all likely factors.

New research published in May in the journal Nature Communications points to another suspect: Large rivers – including the Amazon in particular – pump more human wastewater and agricultural runoff into the ocean, where nutrients likely fertilize them. Sargassum.

The University of South Florida has been tracking Sargassum since 2011 and recorded a significant rise in 2015. In May, a record 18 million metric tonnes was detected by satellite in the tropical Atlantic and Caribbean. According to Chuanmin Hu, an oceanographer at the University of South Florida, this represents an increase of almost 6% from the previous May record set in 2018 and more than 800% from levels seen a decade ago.

Mexico’s coastline is particularly vulnerable, thanks to a swirling ocean current in the western Caribbean Sea that draws Sargassum to the country’s beaches. A July 21 map from the Quintana Roo Sargassum Monitoring Network, a non-governmental organization, showed that 28 of the state’s 80 beaches were experiencing “excessive” amounts of Sargassum, the most serious grade.

Reporting by Cassandra Garrison in Puerto Morelos, Jake Spring in Brasilia and Sarah Marsh in Havana; edited by Katy Daigle and Marla Dickerson

Our Standards: Thomson Reuters Trust Principles.

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