Within Tulum lies the largest caves system in the planet, Sac Actún , a paleontological treasure where fauna fossils dating from 10,000 BC have been found, as well as human remains older than the Mayan civilization .
At ground level, the President of Mexico, Andrés Manuel López Obrador , plans to build the Mayan Train route and one of the train stations, which would pose a threat to these sites of high biological and cultural value.
For several decades, specialists have taken it upon themselves to document the region’s multiple caves systems. To this date, a total of 358 have been registered, representing around 1,400 kilometers of aquatic labyrinths that constitute the largest freshwater reserve in Mexico , though it is estimated that there are still many caverns left to discover. For the construction of the Mayan Train, it will be necessary to know the exact location of these water bodies to prevent damages or collapses.
“These aquifers constitute one of the largest freshwater reserves in the planet and are deeply important for the ecosystem since many tree roots feed from these water bodies. Furthermore, it is vital for the sustainability of the entire jungle, as well as the present and future of the entire peninsula,” commented Francisco Remolina, former director of the Yum Balam Flora and Fauna Protection Area, and member of the Experts Group for the Preservation of Wild Felines in Mexico .
Arturo Bayona, head of the Great Mayan Aquifer Project ’s environmental studies, stated that, should the track be installed on surfaces with a thin karst layer, there will be a risk of breakage. “Soil studies are fundamental for the project, since they will allow to determine whether the layer of rock will be strong enough to hold the weight of the train and endure the vibration that it will cause in its path.”
Tran body vibration is one of the main concerns among experts. “Some of the cave systems are very unstable. We have no way of knowing if there might be a two-ton rock beneath the track or a rock that can be easily moved. We also need to consider that the train will generate vibration for years to come, which may speed the natural collapse process,” stated Emiliano Monroy Ríos, a hydrogeologist from the Northwestern University Technological Institute .
“Our first recommendation is that, if the government is planning to build something there, we need to make sure that the soil conditions are adequate and the construction project should avoid drilling deep into the ground. An ideal layout should take karst areas into account, as well as underground areas, all of which would imply a formal study to determine the level of porosity, structure, and support that the train must have,” said Guillermo de Anda, an underwater archaeologist and leader of the Great Mayan Aquifer Project (GAM) .
The Mayan Train will use an existing rail line that goes through the states of Campeche and Yucatán , in addition to an entirely new 542-kilometer track to cross Quintana Roo . Specialists have stressed that a geophysical probe is needed throughout the route to assess soil conditions, including the already-existing track.
“When those tracks were built, we had no idea that the peninsula’s underground structures even existed, nor did we know of its geological composition. How can we be sure that the rail line does not pass over a cavity that is 200 meters wide or has several underwater caves? ”
“It is estimated that it would take at least one year to elaborate all the necessary studies throughout the 1,520 kilometers of railway with minimum reach ,” stated Monroy.
The hydrogeologist reminded that it had taken three years for scientists to confirm the presence of an underwater cave underneath the Chichén Itzá pyramid , with a reach of 70 x 70 meters.
As for the water itself, during the exploration of underwater and dry caves, specialists have found animals that had not been reported to exist in Quintana Roo before, such as pit vipers –some of the most venomous serpents in Latin America-, banded centipedes, and the natural show of the “Hanging snakes cave,” which is unique in the world.
“It is a very diverse and delicate region. I have no doubt that we will find new aquatic species hiding in the depths of the Yucatán peninsula, within very specific microsystems, as is the case with the remipedia. These ecosystems are fragile and any chemical change might alter them deeply, though they are already being altered by waste water pollution coming from big cities,” stated Bayona.
The biologist Arturo Bayona considers that one of the main issues with the Mayan Train project will be the construction of train stations –one of which has been projected for Tulum- due to the “amount of waste water that thousands of users will generate.” He stressed that several touristic sites did not have an adequate sewage system or waste water treatment systems.
Emiliano Monroy explained that caves systems have a natural function as regulators of the hydrological equilibrium in the region . In Sac Actún and Ox Bel , water filtered from the jungle is redirected towards the ocean.
“This freshwater discharge at the shore is essential for the existence of mangroves, which maintain a very important equilibrium in the region, serving as nutrient regulators as well as protection from hurricanes. Coral reefs directly depend on the survival of mangroves ,” stated Monroy.
Jaguars in danger
After the Amazon, the world’s most important jaguar population is found in the Yucatán peninsula . According to Remolina, member of the Experts Group for the Preservation of Wild Felines in Mexico, the train route will go through regions where a big part of the jaguar population –an endangered species- is found.
To build the Mayan Train, commented Francisco Remolina, would imply placing a physical barrier within the jaguar’s natural habitat. These animals are in need of a broad territory for themselves, an area where they can hunt, reproduce, and nurture their cubs. In the case of the jaguar, this space is of between 30 and 50 square kilometers .
“If we were to build a ‘wall’ that stops the jaguar from crossing to the other side, we would make it more difficult for the animal to find a mate and reproduce with individuals that show slight genetic differences, thus impeding their access to a wider genetic pool,” he stated, adding that the enclosure of the jaguar population in smaller spaces would damage their reproductive process, jeopardizing their survival.
“If the project is for the greater good of society, we will not oppose. But we need to be very careful so that the train is built properly, supported by scientific evidence,” concluded Guillermo de Anda, head of the Great Mayan Aquifer Project.
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