The city’s floating gardens are a prime party spot – but pollution has driven the axolotl population to the verge of extinction. Can a radical plan save them?

Like many residents of Mexico City, my experience of the floating gardens of Xochimilco has mostly been tinged with alcohol. After all, every weekend, this Unesco world heritage site turns into a bacchanal, with groups aboard the canals’ iconic boats celebrating everything from high school graduations to engagements and weddings.

But this is a weekday morning, and Carlos Sumano, who is steering my canoe through the floating gardens, or chinampas, says that sort of unfettered use has taken its toll on the ecosystem. During his six years working in Xochimilco, Sumano has come across everything from pushchairs to television sets in canals.

The loss of the axolotl is traumatic for Mexico City: the creature is vital both to its ecosystem and its imagination

Water pollution has also affected the region’s most unique creature: the axolotl.

When the Aztecs established themselves in the nearby city of Tenochtitlan, they found in Xochimilco what appeared to be the larva of a salamander. Fascinated, they called the animal “water monster” and incorporated it into their mythology as the mischievous and renegade brother of the god Quetzalcoatl.

Its divine character didn’t keep the Aztecs from eating it but, thanks in large part to the low-impact agriculture of Xochimilco, human and amphibian thrived.

Facebook Twitter Pinterest Farm pesticides and pollution from a nearby water-treatment plant make their way into Xochimilco’s canals. Photograph: Dario Lopez-Mills/Associated Press

However, with the arrival of the Spanish came the the start of many attempts to drain the Valley of Mexico’s system of lakes. Since then, the fates of the axolotl and Mexico City have been tragically tied.

From 1607 onwards, various canal construction and valley drainage attempts were undertaken and by 1950, Xochimilco was completely dry. Today, most of the water in Xochimilco’s 150km (93 miles) of canals comes from a water treatment plant located in nearby Cerro de la Estrella.

Pollution comes from the plant, but also from local residents, who use it as a sewer, and those who still farm the floating gardens using water-contaminating pesticides.

The wild axolotl is racing towards extinction. A 2003 study in Xochimilco by the Mexican Academy of Sciences found an average of 6,000 axolotls for each sq km; the latest survey, in 2015, has that number down to 36.

The loss of the axolotl is traumatic for Mexico City: the creature is vital not only to its ecosystem but also to its imagination. Murals and graffiti depicting the animal are ubiquitous: in fact, an axolotl recently won a contest for an emoji to represent the city.

The fascination extends beyond Mexico’s borders. Roger Bartra – a Mexican anthropologist who has drawn parallels between Mexicans and the axolotl – recently edited a collection of axolotl-inspired texts by Julio Cortázar, Aldous Huxley, Primo Levi, Giorgio Agamben and Octavio Paz.

What has enthralled authors and biologists around the world is the fact that, unlike its relatives, the axolotl does not metamorphise into a full-grown salamander; it lives in an eternal amphibian “childhood”, refusing to grow up.

Facebook Twitter Pinterest The axolotl recently won a contest for an emoji to represent Mexico city. Photograph: Paul Starosta/Getty Images

This aspect has confounded biologists. In 1804, the naturalist Alexander Humboldt was so excited by the species during his trip to Mexico City that he brought live specimens overseas and exhibited the creature at a scientific conference in Paris.

Since then, the animal has been bred profusely in home aquariums and laboratories around the world. Today the axolotl is studied for its ability to rebuild body parts and the recently revealed fact that it has the longest known DNA strand.

The interest is also gastronomic; according to the journal Nature, axolotls “are bred so widely in captivity that certain restaurants in Japan even serve them up deep-fried”.

A species is nothing without its natural habitat Luis Zambrano

“Yes, but a species is nothing without its natural habitat,” says Luis Zambrano, a systems biologist at Mexico’s National Autonomous University.

Zambrano leads a project called Refugio Chinampa seeking to bring the animal back to its natural habitat. According to him, tourism and water pollution are not the only causes for the axolotl’s demise. In the 1970s, as part of a nationwide poverty-relief project, the Mexican government introduced thousands of carp to Xochimilco.

“The idea,” Zambrano says, “was that these species were easier to breed and could, therefore, feed more mouths.” In the 1990s the same was done with tilapia. Hundreds were dumped into the canals.

Both species wreaked havoc, eating the axolotls’ eggs and displacing them from the position of top predator. According to Zambrano, tilapias currently make up 95% of the canals’ animal mass.

Refugio Chinampa focuses on building canals blocked off from Xochimilco’s main waterways, separating the axolotls from predators. Sumano is an agricultural planner who serves as the project’s community liaison.

Both nostalgic and hopeful about Xochimilco’s agricultural potential, Sumano says it once had the most productive crop-growing system in the world. He sighs as we pass through a floating garden that had been turned into a soccer field: “The owners consider it more profitable to rent their plots to soccer teams than to farm.”

Facebook Twitter Pinterest Partying on Xochimilco’s traditional Trajineras boats has taken its toll on the axolotls’ habitat. Photograph: Tomas Bravo/Reuters

Finally we arrive at local chinampero Felipe Barrero’s plot of land. Like many farmers involved in the project, Barrero – who can trace his family’s presence in Xochimilco two centuries back – has donated part of his plot to the axolotl cause. This means not only agreeing to the digging of a new canal, but also committing to not using pesticides.

“It has been hard to find chinamperos willing to collaborate,” Sumano says as we walk to the canal, “because they have the idea, promoted during the 60s, that pesticides and other chemicals are more efficient ways to grow vegetables.”

Barrero believes a change is coming from a younger generation of chinamperos seeking to apply the ecologically conscious agricultural practices of their forefathers, but that it will take time. At the canal, he excitedly jumps into his canoe and puts his hand inside the water to show me molluscs, worms and other creatures – proof of the quality of the habitat.

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The process of conditioning a canal for axolotls can take more than a year and involves careful building of a micro-ecosystem from the bottom up, from flora to fauna. Once the conditions are correct, a lab axolotl is released into this restored wilderness.

Thanks to the healthy ecosystem Barrero enthusiastically demonstrates to me, this has already happened in his canal: the axolotl population there is thriving.

All the same, heading home among the early-morning tourist boats starting to make their way through the canals, the only fish I see are tilapia.

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