The beauty of Lake Bacalar, according to Claudio Del Valle, goes beyond the seven brilliant shades of blue, which range from the vivid turquoise to the deep cobalt, of the Mexican lagoon.
In fact, says the local tour guide, it goes up to 100 m deep — in the limestone bottom of the lake, which is home to the oldest life on the planet.
Del Valle explains that the most important thing when visiting the long, narrow lake near the border with Belize is to leave no traces.
He spent years taking groups on pre-dawn stand-up paddle tours as the sun cast its first rays over the lagoon.
“Thanks to the stand-up paddle, I had the opportunity to explore most of the lagoon… it was so unique, so majestic, so beautiful,” he says.
“The clarity of the water gives this unique coloration from blue to green; it was delightful to enjoy.”
But the “Lake of the Seven Colors” is under grave threat, says Del Valle, which could not only permanently change its color but also lead to the destruction of an ancient population of stromatolites, a living fossil that predates humans, dinosaurs and even even the plants.
Del Valle moved to Bacalar in 2017 after the 7.1 magnitude earthquake in Puebla left him with post-traumatic stress disorder.
Following the advice of a psychologist friend, he left his home in San Cristóbal de las Casas, 700 km southwest of Bacalar, in search of a more peaceful environment.
And he was amazed at what he found.
“It was heaven,” he said, seeing the lagoon at Bacalar for the first time.
“Each sunrise and sunset was unbelievable, each one was unique. But now I see what’s happening…and it breaks my heart, it’s not right.”
Lake Bacalar has been heading for an ecological disaster for the past decade, according to Luisa Falcón, a microbial ecologist at the National Autonomous University of Mexico in Mérida.
In November 2015, Mexico’s federal environmental protection agency issued a pollution alert for the lake.
The problem peaked in June 2020, when Lake Bacalar’s hue turned opaque brown. And he still hasn’t fully recovered.
But if nothing is done, the damage can go far beyond the aesthetic hue of the water, warns Falcón.
Bacalar is home to the world’s largest freshwater microbialite reef — rock-like structures formed by thousands of microbes that precipitate carbonate minerals.
“Bacalar microbialites have an age ranging from decades to over 9,000 years,” she says.
But it is the living fossil counterpart of the microbialite, the stromatolites, which dates back to “approximately 3.5 billion years”, making the Bacalar population the oldest evidence of life on Earth.
Stromatolites resemble a cauliflower—large beige “padded” structures that grow on the limestone bottom of the pond.
They look like rocks, but they are actually alive.
The sediment is deposited millimeter by millimeter, with the help of photosynthetic organisms called cyanobacteria, until the structures transform into an underwater rock mound that can be seen on the surface of shallow water.
Cauliflower-like stromatolites still exist in only a few places in the world—and the population of Bacalar reveals a story that has stopped in time, like the temperature or geochemical composition of water millions of years ago.
That’s because they actually preserve the physicochemical conditions of the water in its incredibly slow sedimentation process.
Essentially, stromatolites also help to recycle elements. The microbes that make up a stromatolite take carbon from the CO2 in the air and deposit it on the carbonate at the bottom of the lake to store it.
Like trees, their counterparts out of the water, stromatolites actively improve our environment.
But the problem facing stromatolites is twofold, says Falcón.
The lake is fed by a 450 km underground river that is part of the world’s largest cave and water tunnel system along the Yucatan Peninsula.
In fact, this is good for stromatolites — the carbonate rock in the tunnels is thought to make them grow larger than normal, proliferating on the surface of the pond.
But karst environments, in which groundwater flows through fractures and cave systems interconnected to water bodies, also make stromatolites more vulnerable to upstream changes.
And deforestation of the rainforest upstream from the lagoon has increased “exponentially” over the past decade due to unsustainable agricultural practices, explains Falcón.
This has led to an increase in sediment, pesticides and fertilizers reaching the water during the rainy season.
High levels of nitrogen and ammonia are being registered in the lagoon, especially near the city.
The composition of water is changing — and algae and molluscs are multiplying at an accelerated rate.
So far, no research has shown that microbialite communities can recover from environmental damage in the short term.
The local tourism industry played an important role in the degradation of Bacalar.
“Bacalar as a tourist destination has received more and more attention, but without the necessary urban planning, including sufficient sewage treatment and sanitation facilities,” says Falcón.
A study in which Falcón is co-author looked at large amounts of Firmicutes bacteria, found in the human intestine, in the lagoon.
In addition, Del Valle says the frantic tourism industry on the lake — including boats, kayaks, jet skis, anchors, fins and even people standing at the edge of the lake — is damaging the surface of the stromatolites.
When their surface is perforated, they die, just like coral reefs.
“There are many hostels, hotels, Airbnbs, many don’t care about the stromatolites and mangroves that allow the lagoon’s natural resources to regenerate,” he says.
In a way, says Del Valle, as a former tour guide, he was part of the problem.
Bacalar, south of the famous tourist spots of Quintana Roo, Cancún, Tulum and Playa del Carmen, has been attracting around 100,000 tourists a season in recent years. And local operators were profiting.
“We were doing advertising and publicity to make that place more famous and popular, knowing that there is no infrastructure, planning, projects to protect the lagoon,” he says.
Local researcher and biologist Silvana Ibarra, member of the Citizen and Scientific Council for the Restoration and Preservation of the Bacalar Aquifer and Lagoon System, agrees.
“The increase in tourists in Bacalar was 600% in three years, and the hosts are not prepared: they do not accept the capacity that the ecosystem can support”, she says.
But the decline in tourist activity over the past 12 months has given the lake’s 42 km length a chance to recover.
“These problems started a decade ago and got worse two years ago, but the improvement during the pandemic was demonstrated because we saw animals like the otter again”, explains Ibarra.
This slowdown in tourist activity also brought the colors of the lake back to life.
With more sustainable tourism, Lake Bacalar can continue its recovery and restore its reputation as the “Lake of the Seven Colors”.
And there are several simple ways for tourists to do this, according to Ibarra. She advises never touching, stepping or sitting on the pond’s stromatolites.
And it says that visitors should enter the pond barefoot, and never wearing sunscreen or makeup, as both can whiten the stromatolites.
In general, she recommends: “Stay in eco-friendly hotels and very, very importantly: reduce waste.”
“Come in knowing it’s a fragile natural sanctuary that must be handled with care,” she adds.
“It is important to protect the lagoon and especially adapt to the territory, because otherwise its natural beauty and services will be lost.”
Meanwhile, before travel returns to pre-pandemic levels, Del Valle says it’s up to local tour operators to save the crystal-clear lagoon — the largest on the Yucatan Peninsula.
Del Valle approached several operators surrounding the lagoon to help make their tourism services more sustainable.
“The locals own all the boats in the lagoon, in their hundreds. I talked to many of them several times to persuade them,” he says.
“I offered them, for free, training for stand-up paddle tours, for sailing trips, things that don’t affect the lagoon.”
“I hope that, when the time is right, there will be a change in society and with that, the most important thing, which is nature, will start to recover”, he says.
Recalling his first impressions of the then-glorious Lake Bacalar, at a time when he was struggling with his own trauma, Del Valle pauses.
“He really started to make me feel good [de novo]”, evaluates.
In some ways, he adds, the now-threatened pond was a catalyst for his own healing.
“It was the first time in my adult life that I had this feeling of belonging to a ‘thing’.”
He now hopes that, with a little help, Mexico’s “Lake of the Seven Colors” will also recover.
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