CROCLIST: FW: [venomlist] Follow Up on Gharial Deaths: National Geographic

[Steve Grenard]

      Rare Reptiles' Mass Die-Off Due to Poison-Induced Gout
      Paroma Basu in New Delhi, India
      for National Geographic News

      March 12, 2008

      Invasive fish carrying industrial chemicals likely triggered the
recent die-off of 110 critically endangered reptiles known as gharials in a
central Indian river sanctuary, scientists announced last week.

      Since December officials have found the crocodile-like animals washed
ashore dead along the banks of the largely pristine Chambal River, one of
the few unpolluted rivers in India.

      But the bulk of reptile fatalities occurred along a 22-mile
(35-kilometer) stretch near the Chambal's confluence with the Yamuna,
considered to be of the dirtiest rivers in the world.

      Researchers therefore think an unidentified substance might be seeping
into the Chambal and affecting the gharials' food supply.

      Autopsies of the animals revealed evidence that they perished from
gout, a painful metabolic disease, after ingesting polluted fish.

      "Gharials that are already infected with the toxin will continue to
die," said Ravi Singh, secretary general and CEO of the India branch of WWF.

      The international conservation group is coordinating efforts by the
government, other animal-welfare groups, veterinarians, and state
departments to conduct an investigation and contain the crisis.

      "If this mass die-off has truly stemmed from ongoing pressures on the
habitat, people should know that there's no short-term fix."

      Kidney Lesions

      Conservation groups say that no more than 1,400 gharials are left in
the wild, living in pockets of India and Nepal.

      More than 300 of these individuals live in the National Chambal
Sanctuary along the Chambal River, which contains the largest of the world's
three breeding populations.

      When the reptiles began to wash up dead in December, post-mortem
examinations revealed chemical-laced lesions on the animals' kidneys.

      These lesions probably caused the onset of debilitating gout, said
Paolo Martelli, one of four veterinarians with the World Conservation Union
sent in to examine the dead reptiles.

      Gout is painful inflammation caused by a buildup of microscopic
crystals of uric acid in the joints. Kidneys normally remove most uric acid
from the blood.

      The doctors also found surprising amounts of fat in the animals'
tissues, Martelli added, which could be explained by the growing abundance
of a cichlid fish from Africa known as tilapia in Indian rivers.

      The species was introduced in the region a few years ago to boost
Indian aquaculture. It has since grown so plentiful that gharials now feed
on it almost exclusively.

      As tilapia move from polluted rivers into the Chambal, they ingest and
store chemicals in their tissues. Gharials eating the abundant fish
therefore accumulate even larger amounts of potentially harmful substances
in their body fat.

      "When cold temperatures came, the uric acid precipitated [separated
into a fine suspension of solid particles] and began causing problems," said
Martelli, who is based in Hong Kong.

      "So winter coupled with excess food could have made the gharials more
susceptible to the toxin," he said.

      "As the temperatures warm up, the animals will improve. But next
winter may again be a delicate time for the gharials."

      Two Indian laboratories are still trying to determine exactly what
kind of chemical is to blame.

      Experts think that the agent is either an industrial chemical being
released into the Yamuna by a new facility or one that was used by an older
plant that shut down and illegally dumped all its waste in the river.



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