November 9, 2008

“˜Sea Monster’ On Verge Of Extinction In Mexico City

Beneath the gondolas in the remains of a great Aztec lake lives a monster-like creature called the axolotl, which looks something like a Muppet with a slimy tail, feather-like gills and mouth that curls into an strange smile.

Also known as the "water monster" and the "Mexican walking fish," the axolotl (pronounced ACK-suh-LAH-tuhl) was a crucial part of Aztec legend and diet.  Despite Mexico City's sprawling development, the foot-long salamander survived until now in the polluted canals of Lake Xochimilco, now a Venice-style destination for tourists poled along by Mexican gondoliers in festively painted  boats.

However, scientists are now racing to save the creature from extinction as it struggles against the draining of its lake habitat and deteriorating water quality.  And adding insult to injury, nonnative fish introduced to the canals are now eating its lunch "” and its offspring.

The long-standing International Union for Conservation of Nature now includes the axolotl on its annual Red List of threatened species, and experts say the creature could be wiped out in just five years.  

Some are considering repopulating Xochimilco with axolotls bred in captivity, while others are calling for a series of axolotl sanctuaries in canals cleared of invasive species.

"If the axolotl disappears, it would not only be a great loss to biodiversity but to Mexican culture, and would reflect the degeneration of a once-great lake system," Luis Zambrano, a biologist at the Autonomous University of Mexico (UNAM), told the Associated Press.

While the total number of axolotls in the wild is not known, the population has dropped from 1,500 per square mile in 1998 to just 25 per square mile this year, according to a survey by Zambrano's scientists using casting nets.

The figures represent a steep fall from grace for the creature with feathery gills and a visage resembling that of the 1970s Smiley Face that inspired poet Ogden Nash to coin the phrase: "I've never met an axolotl, but Harvard has one in a bottle."

Millions of axolotl once lived in the vast lakes of Xochimilco and Chalco on which Mexico City was built.  Using four stubby legs to pull themselves along the bottom or their stocky tails to swim like alligators, they sought plentiful aquatic insects, small fish and crustaceans for food.

According to legend, Xolotl "” the dog-headed Aztec god of death, lightning and monstrosities "” changed into an axolotl to flee into Lake Xochimilco upon hearing he was about to be killed by other gods.

The axolotl's decline began when Spanish conquerors began draining the lakes, which continued over time to quench the thirst of one of the world's largest and fastest-growing cities. Lake Chalco was completely drained during the 1970s to prevent flooding.  And in the 1980s, Mexico City began pumping wastewater into the few remaining canals and lagoons of Xochimilco.

Two decades ago, African tilapia were introduced into Xochimilco in an imprudent effort to create fisheries.  The tilapia then joined with Asian carp to dominate Xochimilco's ecosystem, eating the axolotl's eggs while competing with it for food.

Researchers say the axolotl is also threatened by agrochemical runoff from farms and treated wastewater from a nearby Mexico City sewage plant.

Roberto Altamira, a 32-year-old local fisherman, remembers the axolotl as a part of the local diet when he was a boy.

"I used to love axolotl tamales," he told the AP as he rubbed his stomach and laughed.   

However, people no longer eat axolotls, he says, primarily because fishermen almost never find them.

"The last one I caught was about six months ago," says Altamira, a long-time gondolier in Xochimilco's narrow waterways.

Meanwhile, the axolotl population is mushrooming in laboratories, where researchers study its remarkable traits, such as its ability to completely re-grow lost limbs.  Axolotls have played critical roles in research on embryology, regeneration, evolution and fertilization.

The axolotls have the rare trait of retaining their larval features throughout their entire adult life, something called neoteny.  And although the creatures live all of their lives in water, they can breathe both under water with gills or by taking breaths of air from the surface.

On a 9-foot-wide "lentejilla" covered canal, with air that smells of sewage and sulfur, Zambrano's researchers test water quality and look for axolotls.  A team member finds the trademark water ripple of an axolotl, and the crew hurls its net.  But just two tilapia in a sopping-wet mass of lentejilla are captured.

Scientists are not yet in agreement on how to save the axolotl.  A pilot sanctuary is expected to open in the coming months in the waters around Island of the Dolls.

Zambrano proposes up to 15 axolotl sanctuaries in Xochimilco's canals, where scientists would install a barrier and clear the area of nonnative species.

Ben Johnson, the Toronto Zoo's curator of amphibians and reptiles, said that without carp, the water would clear and plants the axolotl depends upon to breed could flourish again..

"If you take the insults away, the lake has an amazing latent potential to heal itself," he told the Associated Press.

Veterinarian Erika Servin, who runs the Mexico City government's axolotl program at Chapultepec Zoo, is looking into potentially introducing axolotls from the lab into the canals.  However, further study is needed to ensure the process doesn't cause diseases and genetic inbreeding issues.

Xochimilco residents may be yet another obstacle.
Scores of people make their living pulling tilapia from canals or growing flowers and vegetables on nearby land. Removing the fish or closing down nearby farms would likely face significant opposition.

But one thing is certain, time is running out as the debates continues.

Considering its role in research alone, "we owe it to the axolotl to help it survive," said Johnson.


Image Courtesy Of Google


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