Sex and the single reptile: reproductive problems in Florida alligators may be an early warning for people

E: The Environmental Magazine, Jan-Feb, 1996 by Fred Wright, Jr.

The focus of this alarm is Florida's third-largest freshwater lake, Lake Apopka, covering 30,000 acres near Orlando and once an internationally recognized mecca for bass fishermen. Now only splintered remnants of once-numerous fishing camps remain because of the lake's shrinking bass and bluegill populations.

Scientists decided to examine bass as well as alligators because both are at the top of the food chain and both are long-lived, giving them a chance to accumulate contaminants in their bodies over time - like humans. "Theoretically, we have data that suggest this could be a fundamental problem elsewhere in Florida and the U.S. It's definitely a canary in a coal mine," suggests Louis Guillette, a UF zoology professor.

Lake Apopka has suffered from what may be called "battered lake syndrome" for decades. Because of relentless development, its alligator, turtle and bass populations have been on the decline at least since the 1980s. UF scientists, who recently received funding for a five-year study of the lake and its environs, have documented a near-90 percent drop in Apopka alligators over 20 years.

A chemical spill in 1980 and ongoing agricultural pesticide contamination are the primary reasons for the lake's problems, according to researchers. They found that fewer male alligators are being born, and those that are "don't appear normal," explains Tim Gross, a reproduction endocrinologist at UF. "When their gonads are sectioned, they're abnormal. Their hormone production is abnormal as well." Both females and males are showing abnormally high levels of estrogen. Low levels of testosterone are showing up in male alligators and bass.

The lake's biggest battering took place in 1980, when the now-defunct Tower Chemical Company spilled large amounts of the pesticide Dicofol into a stream that drains into the lake. The chemical company's buildings have since been designated a Superfund cleanup site by the U.S. Environmental Protection Agency (EPA). The ingredients in Dicofol, including DDT and its derivative, DDE, are called "endocrine disrupters," which can cause hormonal imbalances that result in reproductive problems.

"We're eating the fish and we're exposed to these same environments where these contaminants are occurring," Gross says. "It may not be too far in the future that we see fallout from it. For humans, it doesn't mean gross deformities, but people less and less able to have offspring."

The scientists make several forays a year to Lake Apopka to harvest alligator and turtle eggs, which are taken back to Gainesville, where they are incubated and hatched. Surviving hatchlings - those not "sacrificed" for dissection - are returned.

Gross, who says he personally wouldn't eat the fish in Lake Apopka, is consulting in studies of pesticide and herbicide effects on fish at other sites around the country. He says that appearances can be deceiving. "In the environment," he says, "animals may look like they're doing fine, but they won't be as reproductively capable as their parents. But we may not see the actual effects for 10 to 20 years."

Co-researcher Franklin Percival agrees. "What's happening is not a short-term, immediate thing. It's long-term and quite insidious." Percival's specialty is the alligator, yet there is much data still missing about the state's population. Percival candidly admits that the numbers are only guesses. The best estimate is that there are a million 'gators in Florida, but the number is only a guess. It's even difficult to pin down Lake Apopka's 'gator population. Percival estimates the lake's 'gators numbered around 2,000 before the chemical spill, but the population crashed to 400 to 500 and is now up to 700 to 800.

What isn't guesswork is that the lake's 'gators are in trouble. There clearly are fewer alligators under six feet living there. Percival argues that what's happening at Lake Apopka may be a marker for much more widespread environmental problems. "We don't know any implications for human health," Percival says, "but I'd be concerned. The contaminants are out there globally."

Even though alligator population numbers seem to be on the rise in Lake Apopka, how sexually healthy will these young 'gators be when they mature? "There can still be a problem with these hatchlings not being able to reproduce," Percival says.

Without question, young 'gators born in Lake Apopka have a tough swim ahead of them. According to Allan Woodward, alligator research biologist with the Florida Game and Fresh Water Fish Commission, "The survival rate of alligator eggs in Lake Apopka is 15 to 20 percent, while in other Florida lakes it's 50 to 60 percent."

The scientists are cautious, but they know that what they're seeing may not be an isolated phenomenon. Roxanne Conrow, an environmental specialist with the St. Johns River Water Management District, says, "This isn't the only site in Florida that has a problem. This could be the tip of the iceberg."

CONTACT: University of Florida Interdisciplinary Center for Biotechnology and Research, Beecs Reproductive Analysis Core, 12085 Research Drive, Alachua, FL 32615/(904) 462-0864.