LAKE APOPKA
When Guillette began studying Florida's alligators in 1985, he had no idea how explosive his work would become. He had a simple goal: to survey the health of the alligators. Alligator ranchers wanted to know how many eggs they could collect and raise for hides without harming the population. Guillette and his colleagues had identified lush Lake Apopka, Florida's fourth largest lake, as a likely source. They soon discovered, however, that Apopka's alligator eggs were in short supply. The alligator population was 90% smaller than it had been a decade earlier, and the eggs there were three times as likely to die before hatching as eggs from other lakes. Why were female alligators having problems making good eggs?
To find out what was wrong, Guillette decided to raise some of these eggs in the lab. In 1992, his research team collected eggs not only from this troubled lake but also from Lake Woodruff where the alligator population was thriving. The healthy eggs from Woodruff would be a "control" group, used for comparison. That comparison proved informative. When baby alligators from each lake finally hatched, the most obvious difference was in their viability: many of the Lake Apopka hatchlings died within the first 10 days. But even more significant differences emerged when Guillette began to measure hormone of the old alligators.
Guillette found that Apopka's alligators had atypical hormone levels. Males had the low testosterone levels of a female: over three times lower than in normal males from Lake Woodruff. Apopka's females, for their part, had twice the normal amount of estrogen. It appeared that the entire population had been "feminized" during embryonic development. When Guillette looked closer, he found abnormalities in the reproductive organs of these alligators as well. Under a microscope, he could see that the males had poorly developed testicles that started to produce sperm unusually early in life. The females, too, had unusual structures in their ovaries. Normally the ovaries contain many units called follicles, each housing a single egg. In Lake Apopka females the follicles housed up to three or four eggs, and those eggs had many nuclei instead of just one. None of the Lake Woodruff alligators had these defects. Convinced he must have done something wrong to get these results, Guillette repeated his research the next year. The results were the same. It was then that Guillette began to look at phallus size in these animals.
So the
most striking finding was the alligators' small penis size: they were 25%
smaller than in normal males. Furthermore, as I`ve already told you, these
males had testosterone levels as low as a typical female's - a serious threat
to their fertility. By contrast, the alligators of Lake Woodruff developed
normally. For them, more testosterone meant larger phallus size. Lake Woodruff
is located in a national wildlife refuge on the St. Johns River, about
The hypotesis turned out to be true. These chemicals did cause depressed testosterone, smaller penis size, and anatomical defects in male alligators that would have otherwise hatched normally. In females, the chemicals caused elevated estrogen levels.
Recently, Guillette made another disturbing discovery. He found shorter penises and abnormal hormone levels in alligators from other lakes, including Lakes Okeechobee and Griffin. These are average lakes in the state of Florida, not ones adjacent to a chemical company site like Lake Apopka. The finding has scientists concerned. Alligators with undersized testicles and penises may seem like a problem only for other alligators, but scientists at the University of Florida argue that what happens to 'gators today may well happen to humans tomorrow.