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American Alligator
credit: Jan Kronsell/CCSA

Prime Suspect

Central Florida's Lake Griffin is home to somewhere between 4,000 and 6,000 American Alligators — huge reptiles, the largest on the continent. In a typical year, a handful of these creatures dies. But the past few years have been anything but typical for Lake Griffin's alligators. More than 200 of them have perished since 1998 alone, and no one seems to know why. A study conducted in Brazil, though, has provided researchers with a possible cause.

The culprit, it seems, may be an algae in the lake's waters. Called cylindrospermopsis, it's a blue-green microscopic algae that floats in the lake and produces toxic substances known to affect the liver and kidneys of animals. Yet initial examinations of the alligators that died in Lake Griffin revealed no signs of damage to their internal organs. In other words, the tests ruled out cylindrospermopsis as the reason for the alligator deaths.

Then, last fall, a group of Brazilian, Chilean, and Japanese scientists published a study in the journal Toxicon that linked cylindrospermopsis to severe neurological disorders in animals. The study prompted further tests by veterinarians at the University of Florida on the Lake Griffin alligators, and these more thorough tests revealed that the alligators did, in fact, suffer from neural impairments, not the least of which were lesions in their brains.

The test results, coupled with the fact that the cylindrospermopsis blooms have been especially abundant in Lake Griffin for the past several years, seem to point to a direct correlation between the algae and the increase in alligator deaths. Still, some researchers have their doubts. Habitat degradation, chemical contamination, and poor nutrition — one or all of these factors could also be responsible. And even if algae is confirmed as the sole cause of the deaths, there are no easy solutions for resolving the problem. It concerns the ecology of Lake Griffin as a whole, all 9,000 acres of it.

 

 

 

 

 

2007 eNature.com