Mexican Caribbean entangled in seaweed invasion

Workers clear sargassum from the beach in Tulum in June. - Photo: Kayla Young

It’s a hot summer day in Tulum, Mexico. The sun shines down on the white powder sand and tourists fill beach chairs along the shore.

It’s an ideal day for a beach get-away.

The only problem is the view. Between the lounge chairs and the turquoise water, mounds of seaweed obscure the line of sight.

The guests that venture into the water find themselves tangled in the yellow-brown weed.

As quickly as workers can rake and wheel the plants away, more unsightly seaweed washes ashore.

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Like much of the Caribbean, Mexico’s Yucatan has been overwhelmed by sargassum blooms this season.

Based on data collected from major hotels, at least 220 million cubic metres of sargassum arrived at Mexico’s Caribbean coast in 2018, according to researcher Brigitta Van Tussenbroek with the Caribbean Seagrass Lab of the National Autonomous University of Mexico.

Cancun’s public beach is seen covered in sargassum right after sunrise, before workers begin the daily task of removing the seaweed with heavy machinery.

Sargassum data collection is relatively new, so it is difficult to compare recent data to previous years. Before 2015, the seaweed wasn’t a concern for Mexico. It arrived naturally, in manageable and environmentally friendly quantities.

Anecdotally, however, the frequency and quantity of arrivals are having a clear impact on Caribbean communities.

With the ‘sargassum season’ now stretching from March until November, the issue has become one of economic importance for the Quintana Roo state, home to Cancun, Playa del Carmen and Tulum.

Most of the residents here depend directly or indirectly on tourism, Van Tussenbroek explained.

She estimated the sargassum influx has contributed to a 20% drop in Quintana Roo tourism.

“A lot of hotels are really putting in a lot of effort and lot of money in to free the beach from sargassum. But, of course, in the long term, that’s not sustainable. We should avoid sargassum coming to shore at all,” she said.

Collection at sea

Back on the beach in Tulum, that’s what Grand Bahia Principe resort is attempting to achieve.

From 2018 to 2019, the luxury waterfront resort increased the number of workers dedicated to sargassum removal from around 60 to more than 100, according to Captain Edgar Capricho of Goimar, a sargassum-control company.

The remaining mounds of sargassum on the shore, however, indicate that dozens of workers armed with shovels, rakes, wheelbarrows and heavy machinery are not enough.

That’s where Capricho and his team come into play. They are part of a growing group of innovators in Mexico competing for sargassum-control contracts that can promise large hotels a return to their idyllic, postcard-perfect waters.

Goimar has been contracted to install net barriers designed to contain sargassum in the water. Rather than harvest the sargassum, as other companies have proposed, Goimar plans to reroute it deep at sea, so that the currents carry the seaweed away from the coast and allow it to continue its natural lifecycle.

While the task is labour intensive, requiring checking the nets every 15 minutes, it should involve far fewer workers than the current squadron of 100.

Twenty-two personnel will manage the nets 24 hours a day, Capricho said. Part of the job requires monitoring sea life and freeing any trapped turtles from the tangled masses.

“All of the living sargassum is contained in the upper area. The dying parts are contained in the … net [below],” Capricho said from the beach, where workers were beginning to unload the nets for installation.

“We have mesh nets which do the containing and we redirect it to the open ocean at 30 nautical miles to avoid the sargassum reaching us on the beach.”

Beach-side hotels in Mexico are exploring sargassum-control options, from manual removal to containment barriers at sea.

Environmental impact

Van Tussenbroek is hoping the Mexican government will embrace the concept of sea collection.

By the time sargassum washes onto the beach, she said the damage is already done.

The invasive weed isn’t just unsightly and stinky, but it can cause a number of environmental issues, from beach erosion to coral reef damage.

“The huge masses cause what we started to call ‘sargassum brown tide’ and they cause anoxia and lower pH and light inhibition. They kill basically all the benthos [marine organisms] which are there, and the benthos also fix the sand, so [that causes] more beach erosion,” she said.

“Also, all those nutrients, they’re being flooded into the reef system and even if you don’t see that actual brown tide … its effects are [seen] even further than the barrier reef, which for us, is about 2 kilometres from shore.”

As for turtle nests, she said, large sargassum masses on shore can cause eggs to rot and provoke temperature changes that affect the sex ratio of hatchlings. It will take more time, however, to understand the impact on the turtle population, she said.

Tourists visiting some of Mexico’s most popular beach destinations, including Tulum, have discovered shores overrun with seaweed, as resort managers scramble to respond. – Photos: Kayla Young

Coordinated response

One issue affecting Mexico, and much of the Caribbean, has been the lack of cohesion in sargassum response.

The complexity and newness of the problem has inhibited response efforts, Van Tussenbroek said, explaining that Mexico has struggled to unify municipal, state and federal agencies.

In mid-June, the Quintana Roo government declared a state of emergency over the sargassum invasion, in an effort to access greater funding. The declaration sparked controversy in Mexico, with President Andres Manuel Lopez Obrador describing the move as irresponsible.

The issue continues to strain Mexico politically, but Van Tussenbroek argues that it will be in the nation’s best interest to coordinate efforts and improve knowledge sharing.

“Of course, they don’t want to discourage tourists to come,” she said.

“But it is a mistake to minimise the problem and the tourists come here, see these huge masses of sargassum and [we] get bad publicity.”

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  1. The beaches are clean and are looking beautiful in the Riviera Maya right now. This article should have been published in June.
    If you want to see up to date pics join the Facebook Group: Sargasso Seaweed Updates Riviera Maya. The Mexican Navy, government, hotels , and local governments are doing things to combat the problem. Luckily, it’s been amazing for the last couple of months.