MIAMI — The American alligator, symbol of the untamed Everglades, is facing a new challenge. In a development that has puzzled scientists, practically no baby alligators hatched last season in a central Florida lake that has one of the greatest concentration of alligators in the state.
Unable to find out why hundreds of alligator eggs in Lake Griffin didn't hatch - and worried that fertility woes could affect other species - scientists have launched an unprecedented research effort to get to the bottom of the alligators' trouble.
"What is of concern is that we don't know what caused it," says biologist Tim O'Meara of the Florida Game and Fresh Water Fish Commission. "Is it a one-time natural occurrence or is it the degradation of our lakes that is causing this?"
The red flag was raised this fall when alligator farmers told the state that a dismal 4.4 percent of the 1,033 eggs they collected were hatching - compared with 50 percent normally. (The farmers gather eggs from Lake Griffin and grow the reptiles until they reach marketable sizes.)
Since then, 20 out of 3,800 alligators living in the lake have died. There's also been unexplained deaths of turtles and snakes. "Whatever is now affecting the reproduction of alligators is also affecting fish," says Perran Ross, a Florida Museum of Natural History crocodile specialist who will lead the state-research consortium.
A precipitous drop in the alligators' egg viability isn't new. Following a massive pesticides spill into Lake Apopka in the mid-1980s, the alligator population crashed from 4,000 to 400 and their hatching rate plunged from roughly 54 percent to less than 4 percent.
But there is no known toxic spill at Lake Griffin, and only hints of any other problems. And while this one bad hatching season doesn't seem to have affected the alligator population, the issue of why eggs aren't hatching must be addressed.
"It seems possible there is a long-term ... accumulation of problems that are all connected and are causing the alligator population to collapse," says Dennis David, the Florida Game and Fresh Water Fish Commission's alligator expert.
Some scientists point out that the water in Lake Griffin has turned murky, raising concerns about toxic blooms like blue-green algae that created problems for coots in Arkansas and livestock in Africa and Australia. Changes in aquatic vegetation, mainly caused by the phosphorus-rich runoff from muck farms, could also mean that "alligators may be getting different food to eat," says Mr. David. "Eggs are made up of fat: If you eat the wrong kind of food, you produce lousy ... egg yolks."
Whatever the reason, few dispute that pesticide and fertilizer use on agricultural lands adjacent to Lake Griffin, coupled with urban development, herbicides, and water-management procedures have spelled trouble for alligators. In contrast to Lake Griffin, Florida's most pristine lakes have hatching rates as high as 80 percent.
"It may be an indication of what happens to lakes when they are completely surrounded by people, towns, agriculture, suburbs, all of which have things that run off into the lake," says Dr. Ross. "It is conceivable we're looking at a phenomenon that will be widespread in Florida lakes. The question is, what can we do about it?"