英语听力：自然百科 墨西哥“水怪” 濒临灭绝

　　Beneath the tourist gondolas on Lake Xochimilco in Mexico lives a creature that resembles a monster. Known as the “water monster” or “Mexican walking fish”, the axolotl is type of salamander.

　　The Ambystoma Mexicano, this species, is the axolotl of Xochimilco. It's in severe danger ofextinction. Basically, the causes of extinction are water contamination, destruction of habitat, the introduction of exotic fish including tilapia and carp, and people hunting them to eat or to keep as pets.

　　Historically, abundant populations of axolotls lived in the once-giant lakes of Xochimilco and Chaco, near Tenochtitlan, which is modern-day Mexico City. Today the number of axolotls in the wild is not known. But the population has reportedly dropped from about 1500 per square mile in 1998 to a mere 25 per square mile this year.

　　The animal is listed as critically endangered by the International Union for Conservation of Nature. Some are pushing for a series of sanctuaries in canals, cleared of invasive species. Others are considering repopulating the lake with axolotls bred in captivity. More research is needed to make sure the process doesn’t link to disease and genetic problems from inbreeding.

　　But conservation has faced daunting challenges. The axolotl’s natural habitat has all but vanished, and what remains is severed polluted. Out species of fish have been introduced which threaten to out-compete the salamander. But as the clock ticks, time is running out for this ancient Mexican monster.