The arrival of mounds of brown sargassum on the coast's normally pristine white sand beaches comes just as tourism is recovering to pre-pandemic levels, although employment recovery in the country's top tourist destination has been slower.
With more algae spotted floating in the sea, experts fear that this summer of 2022 could be as bad or worse than the catastrophic year of 2018 when the largest amount of sargassum to date was reported.
"We can say that the current situation is alarming," said Mexican Navy Secretary José Ojeda, who has been tasked with trying to collect the sargassum at sea, before it reaches the beaches.
The navy currently has 11 sargassum collection boats operating. But the marina's figures show that the portion they have been able to collect before it hits the beach has been decreasing. In 2020, the marina collected 4% of the sargassum at sea, while 96% was raked up on the beaches. But that figure dropped to 3% in 2021 and about 1% so far in 2022.
Allowing the algae to wash up on beaches creates not only a problem for tourists but the environment, said Rosa Rodríguez Martínez, a biologist in the coastal town of Puerto Morelos who studies reefs and coastal ecosystems for the National Autonomous University of Mexico.
So much seaweed is washing up on the beaches that hotels and local authorities are using excavators and backhoes because the normal equipment of rakes, shovels, and wheelbarrows is no longer sufficient.
"Collecting the sargassum with heavy machinery also lifts a large amount of sand, which contributes to beach erosion," said Rodríguez Martínez. "There is so much sargassum that you can no longer use small machinery, you have to use heavy machinery, and when the excavators come in, they take more sand with them."
Rodríguez Martínez is concerned that 2022 could be worse than the previous peak year. "In the last few days there have been amounts that have not even been seen in 2018," he said.
Not all beaches have been affected equally; many in Cancun and Isla Mujeres are usually free of significant amounts of sargassum, but much of the Riviera Maya has been badly affected.
Carlos Joaquín, governor of the coastal state of Quintana Roo, said the number of tourists arriving by air so far this year (some 3.54 million) is 1.27% above 2019 levels, before the pandemic. However, Joaquin said only about 83% of the 98,000 jobs lost during the pandemic have been recovered.
Sergio León, the former head of the state's business federation, said the algae invasion "has affected us, it has affected our image nationally and internationally. Obviously, not only visually, but in terms of environmental damage."
"The Mexican navy is making an effort, but it needs more, it's not enough," said León. "The ideal would be to collect the algae before they reach our beaches."
Rodríguez Martínez said that, given the limited number of Navy ships and funds, the best solution might be to hang floating barriers offshore and collect the sargassum in waters closer to shore.
But he points to another problem: what to do with the thousands of tons of stinking seaweed collected each year, mainly by private hotel owners. Some simply dump the piles collected on the beach into disused limestone quarries, where salt and minerals collected in the ocean can leach into the groundwater. Others simply dump them in forests or mangroves, which is equally damaging.
Although some have attempted to use the sargassum to create bricks or fertilizer, the lack of official policies and long-term plans make it difficult to obtain large investments for such schemes. Early reports in the 2010s suggested that the masses of algae came from an area in the Atlantic off the north coast of Brazil, near the mouth of the Amazon River. Increased nutrient flows from deforestation or fertilizer runoff could be fueling the algal bloom.