By Sarah Morland
MEXICO CITY, July 31 (Reuters) - Hundreds of Mexican hotel workers, tractor operators and specialized Navy personnel are heading out to the beach each day at dawn to clean record masses of rotting sargassum seaweed off pristine Caribbean coastlines around popular tourist resorts.
The seasonal phenomenon has caused hotels across the Caribbean to cut rates and invest millions of dollars in clearing up piles of the foul-smelling algae from their beaches, while governments and businesses
look for solutions.
HOW IT STARTED
Sargassum - a brown seaweed that forms floating mats on the ocean surface - was historically confined to the so-called Sargasso Sea in the North Atlantic, but unusually strong winds around 2010 blew sargassum into nutrient-rich tropical waters off West Africa, where it found ideal growing conditions.
The displaced seaweed turned into a self-sustaining belt that rides on ocean currents to northern Brazil and through the Caribbean, bringing masses of algae onto Caribbean island nations, the popular Riviera Maya and into the Gulf of Mexico.
In the tropical Atlantic, sargassum feeds on nutrients running in from major rivers such as the Amazon, Orinoco and Congo rivers, as well as upswells from the deep ocean, Saharan dust and warming sea temperatures.
WHERE IT'S GOING
The University of South Florida's Optical Oceanography Lab expects 2026 to be at least the second-largest year for sargassum abundance, with more seaweed likely to heap up around the Caribbean and southeastern Florida in coming months.
Brian Barnes, research assistant professor at the university's College of Marine Science, who works in the lab, told Reuters the novelty of the phenomenon and its seasonality makes predicting its future course challenging.
"Before 2010 there's nothing, and since then we've gone to up to 1 million metric tons over the entire area in 2011 to 40 million last year," he said, suggesting the seaweed could be doubling in mass every five years.
RECORD NUMBERS IN MEXICO
In Mexico, authorities are looking to protect key tourist destinations along its picturesque Riviera Maya - including Cancun, Tulum and Playa del Carmen - by buying more boats to pick up sargassum and floating bigger barriers off the coast.
Mexico, which collects the overwhelming majority of its sargassum after it lands on its beaches, has picked up some 96,151 metric tons this year, up from 92,783 tons last year, according to government data.
"Experience has taught us the best way to face sargassum is to intercept it in the sea before it hits our coasts," Mara Lezama, the governor of southern Quintana Roo state, told a press conference on Thursday.
Federal Mexican officials are expecting a new open-sea sargassum vessel to arrive within a month, and are looking to source more ships from Japan and supply smaller Mexican-made vessels to the Dominican Republic.
CARBON CREDITS
Some companies have sought to obtain carbon credits for sending out boats to make bales of sargassum - which releases methane as it decomposes - and then sinking these to the sea floor, but this practice has raised concerns about potential abuses, impacts on deep-sea ecosystems and over-harvesting offshore clusters.
"It's a balance because offshore sargassum is a natural habitat and there's tons of turtles and fish that live among it," Barnes said. "So if you try and sweep the Caribbean clean, you're going to have a lot of collateral damage."
Barnes said many companies had contacted him for advice on carbon credit projects, but he was not convinced they would yield positive results.
WHEN LIFE GIVES YOU SARGASSUM
The overabundance of sargassum has inspired a number of entrepreneurs to try to turn the seaweed into new energy sources or lucrative commercial products, overcoming challenges such as safely removing toxic metals absorbed into the algae.
Environment Minister Alicia Barcena said that of close to 200 projects in Mexico at least 11 had the potential for scaling up industrially and 39 were already making products, ranging from fuel, fertilizers, laminates and bioplastics to craft sandals.
Felix Navarrete, an executive at sargassum refiner Carbonwave, said his company was already selling fertilizer abroad and, after receiving a regulatory nod from Mexico's sanitary watchdog, was now looking to sell to domestic farmers.
Carbonwave is also looking to supply materials to the cosmetic and textile sectors. The state government of Quintana Roo, meanwhile, plans to expand a biofuel plant in Cancun.
WHAT'S NEXT
While Caribbean government and industry leaders have warned of the scale of the crisis, they also urge tourists to keep visiting their beaches and make the most of their vacations by staying up to date and opting for less-affected areas.
Mexico is set to host a joint European Union-Caribbean conference on sargassum in early October in Cancun, where representatives will discuss how to expand sargassum collection while protecting beaches and coral reefs.
(Reporting by Sarah Morland; Editing by Tom Hogue)
