What is killing India's endangered gharials?

Can a mystery be solved in time to save the gharial from extinction? Two years ago, this critically endangered crocodile had just 200 adults left in the wild. Now that number is down to 100, after the animals began to mysteriously die last year.

Between November 2007 and March 2008, more than 100 dead gharials washed up on the banks of India's Chambal River. At the time, no one knew what was killing them. Initial theories blamed a "bacterial disease" which shut down the gharials' livers and lungs.

Now, after months of research, more clues have arisen. According to a report from BBC News, the gharials died of gout, brought on by kidney failure, which itself was brought on by exposure to toxic chemicals.

The Chambal River is apparently one of India's cleanest, but a neighboring river, the Yamuna, is "a toxic mess," according to the BBC. It is believed that the gharials are leaving their home river, eating fish in the Yamuna, and getting poisoned as a result.

This theory -- "educated speculation" on the part of biologists -- takes the gharials' eating habits and biochemistry into account. They feed only on fish, and they digest their food slowly, so they get a more concentrated amount of the toxic chemicals than other, warm-blooded predators in the area.

The problem was apparently exacerbated by winter, when cold weather made the gharials less able to metabolize their food. Again, this created a greater concentration of toxins in their systems.

So if this theory proves to be true, what comes next? Cleaning the Yamuna could take a decade of hard work, according to the BBC, and the gharials don't have that much time left. Another few years, and the gharial will be gone. For a species that numbered in the tens of thousands just 60 years ago, this is a tragedy that should weigh heavily upon us all.

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