Tulum seaweed update: sargassum strikes again in 2021

16/04/2021

Tourists visiting the beaches of Tulum, a dream destination in the Mexican Caribbean, are encountering an invader that threatens to affect the already battered local tourism: hundreds of tons of sargassum, a brown alga seaweed that when decomposing on the beaches releases a foul odor that scares visitors away but also affects coral reefs and marine fauna and flora living on the coast.

Tulum seaweed update. The beaches of Cozumel, Tulum, Xcalak and Mahahual are affected by these algae that drive away tourists and affect the marine flora and fauna.
Tulum seaweed update. The beaches of Cozumel, Tulum, Xcalak and Mahahual are affected by these algae that drive away tourists and affect the marine flora and fauna.

"The magnitude of the sargassum is such that it is not possible to contain it," says Esteban Amaro, director of the Sargassum Monitoring Network, a Cancun organization that prepares a daily report on the progress of the invasive algae.

Sargasso begins to affect the Mexican Caribbean from April, with the arrival of spring and warmer temperatures and extends until September. So far, in addition to Tulum, it has affected the tourist beaches of Playa del Carmen, Cozumel, Xcalak, and Mahahual.

"We have an important arrival. In one single one, millions of cubic meters can arrive, which translates into thousands of tons. It is very complicated to handle," Amaro admitted to EL PAÍS in a telephone interview.

For local businessmen, the arrival of the algae is a nightmare that keeps them awake at night year after year, but this 2021 makes them even more nervous due to the drop in visitors that the Caribbean region has experienced as a result of the covid-19 pandemic, which hit Mexican tourism hard.

It is the owners of coastal businesses, such as restaurants and hotels, who must invest to clean the coasts, a strenuous job with few results, given that the seaweed reaches the beaches in enormous quantities. It has a negative effect not only on tourism. When it decomposes, it releases toxic organic substances that affect coral reefs and marine fauna and flora that live along the coastline.

"Hundreds of tons arrive every day. It is humanly impossible to collect them. There is no human or technical capacity to do it in a single day," says Amaro.

Sargassum has always been present in the Caribbean, but since 2011 it has arrived massively to the paradisiacal Mexican coasts. Amaro explains that this phenomenon, studied by scientists, has occurred due to the warming of ocean waters, one of the consequences of climate change. It alters marine currents, winds, and sea temperature, which favors the growth of sargassum.

In addition, the chemicals dumped into the rivers by agriculture, industry, and mining end up flowing into the sea, which become nutrients that the sargassum takes advantage of to reproduce. The largest arrival of the invasive algae occurred in 2015, but marine biologists and those who work monitoring the Caribbean coasts fear that this year will surpass that record.

"Right now in the Lesser Antilles, there is an incredible amount of sargassum that cannot be managed. The tendency is always that it arrives in the spring, and it increases until April and in May there is an important peak. In the summer it increases even more in quantity and frequency," says Amaro.

The authorities of Quintana Roo have already requested the support of the Navy to deal with the phenomenon and boats have been deployed to place anti-sargassum barriers in the places most visited by tourists, but the amount of algae that reaches the coasts is such that it is almost impossible to contain the invader. 

Ecological and economic disaster

Scientific evidence points out that the sargassum comes dragged by winds and currents from a new sea of ​​said seaweed, the old one is located in front of the United States, detected in 2011 in the equatorial zone of the Atlantic, between South America and Africa. There, the mouths of large rivers laden with nutrients, the remnants of human activity, desertification, and global warming, encourage its proliferation.

"It has more nutrients than the original sargasso sea, on top of that there are the problems of deforestation in Africa and South America," explains Brigitta Van Tussenbroek, a researcher at the National Autonomous University of Mexico (UNAM).

"Everything is anthropogenic, it's not something natural", she adds about the phenomenon, which has also affected other points of the Caribbean such as Barbados, Guadalupe, and Bonaire. The Dutch scientist, with 30 years of work in the area, warns that the sargassum is accelerating changes in the ecosystem between 10 and 100 times, so urgent measures "forceful" involving the national government.

"There is hope but we do not have much time, it's a question of years, not decades," she warns. Once on the beach, the sargassum should be removed as soon as possible. Otherwise, it is broken down by bacteria that consume the oxygen in the water, killing animals that live in it, while its dark trail blocks sunlight, eliminating life from the seafloor.

In addition, it ends with the turquoise tone of the Caribbean, a phenomenon that could be irreversible because it is unknown if this ecosystem can recycle waste, explains Marta García, a Spanish scientist at the Institute of Marine Sciences of the UNAM in Puerto Morelos.