Threats to the ecosystem


For most of its history, that massive rain-fed series of wetlands, lakes and rivers we call the Everglades flowed from just below Orlando and through Lake Okeechobee south to the tip of the Florida peninsula, as well as east and west towards the coasts. The Everglades covered almost 3 million acres.

“In the past hundred years, people have been digging canals and building dams in the Everglades so they could take water out of it, develop agriculture and build homes,” says Dr. Tom Van Lent, senior scientist at the Everglades Foundation. “We’ve built so many canals and drained so much water that the natural flow is interrupted.”

In fact, as the twentieth century dawned, early conservationists saw the dredging of the Everglades as the smart, progressive thing to do.

As a result, the Everglades is now less than half its original size. 1,800 miles of canals and dams break it up, with water control points and pump stations diverting the natural flow of water to coastal towns and cities. Water must be released to estuaries to prevent flooding and Florida finds itself in a situation where there is often too much water in the wet years, and not enough in the dry.

Sixty years ago, demographers predicted South Florida’s population would reach two million people by the 21st century. It’s already at seven million, and expected to double in the next 50 years.

All that growth has squeezed the Everglades as development reached inland from both coasts to accommodate the burgeoning population. And with the people came pollution, especially phosphorus from the fertilizers used in agricultural areas north and south of Lake Okeechobee.

Extremely low levels of nutrients, such as phosphorus, are part of the reason that the Everglades is a unique mosaic of sawgrass, tree islands, and open water. However, the nutrient pollution, such as that coming from agricultural runoff and other fertilizers, allows for the growth of species that upset the balance of the ecosystem such as cattails, harmful algal blooms and duckweed. The sulfur in this agricultural fertilizer, through a complex series of biological and chemical processes, leads to accumulations of toxic mercury in fish, birds, reptiles, and mammals, even in the endangered Florida panther.

Nutrient pollution and overdrainage are not the only threats the Everglades faces.  Exotic plants and animals can be thought of as a kind of biological pollution. Exotic animals, such as Burmese pythons, and exotic plants, such as Brazilian pepper and Australian pine, displace natives and threaten to disrupt ecosystem balance.