A rare desert spring ecosystem considered one of Mexico’s 13 natural wonders is threatened
Feb. 23, 2009
Sprawling across a cactus-studded valley in México's Chihuahuan Desert is a place like no other on the planet. It's called Cuatrociénegas, and it is a crunchy expanse of land isolated in a basin ringed by mountains like salt on the rim of a margarita glass. The seemingly dry, desert area, however, is best known for its life-giving waters—pools, wetlands and rivers filled to the brim with an amazing assortment of unique species.
"This is an incredibly diverse area for this part of the world, with more endemic species per area than the Galápagos Islands," says Dean Hendrickson, curator of ichthyology at the Texas Natural Science Center.
But Cuatrociénegas is not immune to change, and its rare ecosystems are under increasing pressure from climate change, invasive species and agriculture. Hendrickson, who has been visiting the area since 1979, now finds himself working with others to forge a sustainable future for the region.
"My vision is to get a big interdisciplinary, international project going and try to find solutions that we can propose to the local community," he says.
He has established a permanent research station in town, and he hopes this will encourage more researchers from other fields to begin projects there.
"There are very complex issues here that go way beyond simple biology and conservation and get into sociology and economics," he says.
One of México's 13 natural wonders
In Cuatrociénegas, the water links everything and everyone. At times, it seems invisible, and the basin looks like a vast uninterrupted plain of yuccas, cacti and grasses. But hidden among the desert flora are more than 200 azure pools, or pozas. Water also seeps up to fill sinkholes, snakes across the valley in rivers and canals, and spreads out into marshes spiked with cane. It comes down in deluges during lightning-laden storms over the mountains and quickly disappears. And in some places, huge caches of water sit just six feet below the surface of the soil.
Residents of towns in the basin are fond of calling it "líquido vital," and indeed these various bodies of water not only nourish the community, but also have allowed for the evolution of a unique flora and fauna.
"Cuatrociénegas has been a relatively stable wetland for at least 30,000 years and it probably goes back much further," says Hendrickson. "It was a closed isolated aquatic system without a surface outlet, so you have all these critters that evolved in isolation. Nearly all the fauna is endemic to some extent."
Hendrickson first became interested in Cuatrociénegas through his research on one of area's endemic fish, Minckley's cichlid, which comes in two unique interbreeding morphs. One of the morphs has big jaws and teeth used to crush snails and the other has much more delicate jaws and teeth for slurping up algae and the like.
He says the pozas and wetlands are like islands of water in a sea of desert, and this has resulted in the evolution of more than 70 unique species in the valley. Eighty percent of the fish species are endemic. The world's only aquatic box turtle calls the valley home, and stromatolites—rare relics of ancient Earth created by algae and bacteria—grow like coral reefs in many of the pozas.
Because of this rareness, the area was incorporated into México's national preserve system in 1994 as the Área de Protección de Flora y Fauna Cuatrociénegas. It is considered one of country's 13 natural wonders.
"But it is also extremely threatened," says Hendrickson.
Sixteen of the valley's species, including the box turtle, are in danger of extinction. Thirty-nine are threatened. And the springs, streams and marshes have been changing and drying quickly.
Water, water everywhere
Marshes and lakes that once covered acres and acres are now as dry as the bones of dead horses bleaching in the desert sun. One of the most obvious of these is a place that is still called, ironically, the Garabatal River.
The Garabatal went dry, says Hendrickson, after water was diverted from its source, a popular local swimming hole called Poza la Becerra, by the Becerra canal, which was constructed in 1968. The canal shuttles water across the valley and is used to irrigate fields of melons and alfalfa on the southeast side of the town of Cuatrociénegas. The canal may have also contributed to the drying of a large shallow lake next to the Garabatal called Laguna Grande.
On a trip last August, Hendrickson noticed another major change. The wetlands that support one of the larger and most dense populations of the endangered aquatic box turtle, Terrapene coahuila, were far drier than he'd ever seen.
"Obviously, this is a super dynamic system in terms of water, and it naturally fluctuates," said Hendrickson, while standing on the cracked mud of a recently dried pool, "but I've never seen it this dry before."
The turtles spend almost 90 percent of their daily lives in the shallow wetlands of the basin, munching on submerged vegetation and just about anything else they can find.
Jennifer Howeth, who recently graduated with a Ph.D. in ecology, evolution and behavior, began a comprehensive study of the avocado green reptiles about six years ago. She engaged in rigorous mark and recapture studies to document the turtles' population size, growth rates, reproduction and mortality. She also collected their DNA to get a sense for how genes moved through the population.
From the data she and others have gathered, she estimates that the turtle population hovers somewhere between 2,000 and 2,500. That's not very many turtles, in a global sense, which is one of the reasons they are listed as one of the 25 most endangered turtles on the planet. They are in peril, says Howeth, because the shallow, muddy wetlands where they live are drying up fast. They are further threatened by collectors who sell them to the pet trade.
However, the density of the box turtle is one of the highest in the world, and Howeth says they have a very strong impact on the ecosystem in Cuatrociénegas.
"If the species were to go extinct, you would see a major shift in the balance of the ecosystem," she says.
Protecting such a species, explains Howeth, can go a long way.
"If you have a conservation plan targeted to preserve the box turtle, you will save many of the other species," she says. "The shallow wetland habitats that the turtles live in are more susceptible to drying and fragmentation. So if you conserve those wetland habitats, then you're going to conserve all the endemic species associated with them."
A community and its water
People have been drawn to the Cuatrociénegas basin and its waters for millennia. Artifacts point to humans using the springs for more than 10,000 years. Canals have been built in the valley since the 1880s, and the water was used to irrigate courtyard gardens, public plazas, vineyards, fruit and nut groves, and alfalfa and melon crops. The canals ran flourmills and filled swimming pools where people picnicked beneath oases of lush trees.
Lourdes "Lulu" Ferriño's Italian great-great grandfather settled there and established a winery. When the family land was being divided up in the 1990s, she chose to keep the old mill and has spent the past decade renovating it into a bed and breakfast.
"I chose the mill because I like the sound of the water," she says.
But that water is no more. A stream that originated as springs in the neighboring Ocampo Valley once filled a one-meter wide pipe, supplying the village's drinking and irrigation water and powering the mill. Now, groves of dead pecan trees, dried vineyards and a dusty scar snaking across Ferriño's yard are all that remain of the stream. The village has been forced to drill its own water wells in search of ever deepening water.
The Ferriño winery is still in operation, but now imports its grapes.
Many people living in the town of Cuatrociénegas have quietly blamed increased agriculture in the Ocampo Valley for drying their water supply, and new research supports their view.
In the 1970s, wells started dipping into the Ocampo aquifer, and the scale of agriculture increased even further in the 1990s. Big companies, such as Mexican dairy giant LaLa and retailer Soriana, have been sticking straws deep into the aquifer.
Hydrogeologist Brad Wolaver, who recently graduated with a Ph.D. from the Jackson School of Geosciences, discovered that the aquifer is recharged by rain falling on the surrounding mountaintops, but the wells are drawing down the aquifer faster than the rain can replenish it, which is about one meter per year.
"All the springs dried up because of the high capacity wells put in there for alfalfa, corn and potato agriculture," he says.
At some point in the recent past, he says the water level decreased enough that the aquifer stopped flowing over and filling the town's reservoir. Wolaver estimates that the water in Ocampo itself will become unusable through decreases in pressure and declines in quality.
"You've maybe got about 20 years of usable water left," he says.
Increased water use in the neighboring valley has clearly affected the town, but what about all the springs in the Cuatrociénegas basin itself? Scientists previously thought the springs in the basin were also recharged by rain falling on its surrounding mountains. But Wolaver found that the springs in the Cuatrociénegas pozas discharge much more water than can be coming from mountain rainfall alone.
"That means that recharge that's going to springs in the valley is coming from outside the basin," he says.
In other words, the aquifer is huge, and Wolaver says, "If there are agricultural operations in neighboring valleys, like Ocampo, the pumping will have some impact on spring discharge down in the Cuatrociénegas valley itself."
Progress and protection in the valley
It should be easy enough to say then, that large-scale agriculture should be halted and that fields should be abandoned in and around the basin. But the situation is much more complex. Residents need to make a living, and they need to grow food.
The community was in an uproar this past summer when CONANP (México's National Commission of Protected Areas and manager of the Cuatrociénegas reserve) and PROFEPA (the national environmental law enforcement agency) shut down La Becerra for swimming. Hoteliers were upset that the closure would affect tourism. Residents and visitors wanted to be able to swim in one of the few places still open to them. The reserve director began receiving death threats and there were several sit-ins in his office.
Ernesto Enkerlin, national director of CONANP, says the closure of La Becerra is one of many growing pains that the town and reserve will likely weather together. Before the reserve was established, almost all of the pozas were used for bathing, either by people or livestock.
"They were open access and were being heavily degraded that way," he says.
Enkerlin and his organization would like to see tourism evolve from people wanting to take a dip in pozas, to something "more sophisticated" and nature-based, where more tourists will come to appreciate the biodiversity and uniqueness of the place.
"But that's part of a process," he says, "and we're going to be working on that."
Plans are in the works to create a conservation cultural center, which Enkerlin says will only create a few jobs, but will, it is hoped, bring more ecotourists to the area. This will in turn create related service jobs. CONANP is also starting a program to provide incentives for farmers and ranchers who own water rights to install new irrigation systems that will reduce their costs, increase the land's productivity and save water.
"We're going to be keeping water in the system so that the pozas maintain their levels," he says.
CONANP has several other major programs in store for the valley, and Enkerlin is optimistic.
"I'm very certain that there are some good times coming for Cuatrociénegas," he says.
Laura Villareal Guevara, a city council member specializing in ecology and sanitation, shares a similar sentiment.
"For the state government of Coahuila, Cuatrociénegas is really the cherry on top of the cake, the reason tourists would come to the state," she says. "I am confident that this place will not disappear if the federal government really makes sure that the water in Cuatrociénegas is well managed and well used."
Research can lead to sustainability
Still, Hendrickson feels there is a lot of work ahead, and that more research needs to be done to help people make the tough decisions. Wolaver's work clears up a big part of a murky picture, but there is very little data showing how much the place has dried. Hendrickson is beginning a project to compare old aerial photos of the basin from 1968 with new geo-referenced photos taken in 2006.
"That may be the first time we can say with some rigor what percentage of the former wetlands of the valley have dried in the past 30 to 40 years," he says. He estimates it could be 50 to 70 percent drier.
It's that kind of data that will be useful when people need to make conservation decisions.
"Every interest group is going to have to compromise somewhat to really arrive at a sustainable solution," he says. "I hope we can get serious soon about how to involve more disciplines and really make this place sustainable."
The good news, from Hendrickson's perspective, is that people are talking about the issues and most everyone is concerned for the future of the town and reserve.
"Families have lived here for many generations and everybody wants to see it as beautiful as it used to be," he says.