While the true Everglades is a freshwater habitat, its waters drain into and nourish the prolific estuarine and marine portions of Everglades National Park, the boundaries of which extend far out into Florida Bay and the Gulf of Mexico. Marine and estuarine fishes in these waters command abundant interest from aquarists, connoisseurs, and fishermen, but they are also an important food supply for many fish-eating birds.
The important ecological functions of the area are its support of fish-eating birds and its habitat as a nursery for a great many marine fishes, all based on the high productivity that arises from freshwater inputs from the Everglades as well as the neighboring Big Cypress Swamp ecosystems. Wading birds utilize the mud flats of Florida Bay, the shallows of the mangrove swamps, and other coastal habitats, and ospreys fish in the more open waters. All of these species prey heavily on the young of larger game fishes and on the high diversity of nongame species.