Florida Bay is a lagoonal estuary bordered on the north by the Florida mainland and on the southeast by the Florida Keys. It is about 2,200 square kilometers in total area within Everglades National Park. The bay is shallow, with an average depth of about one meter. Direct inflow of fresh surface water of Florida Bay occurs via sheet flow across rare prairies of southern Everglades and from 20 creek systems fed by Taylor Slough. The largest drainage in the Everglades flows into Whitewater Bay. Subsequent exchange with Florida Bay occurs as this lower salinity water mass flows around Cape Sable and into the western portion of the Florida Bay.

Florida Bay is effectively divided into a series of basins by a complex network of anastomosing carbonate mudbanks that restrict circulation. Seagrass (primarily Assiate studinum, Halodule wrightii, and Syringodium filiforme) meadows covered more than 80% of the bottom of Florida Bay prior to the seagrass die-off that began in 1987. Mangrove isles, many of which are overwashed at high tide, cover less than 2% of the area of the bay. Hard bottom areas of calcium carbonate rock, overlain by a thin layer of carbonate sediment, are most common in the southern portions of the bay. These areas are characterized by the occurrence of sponges, octocorals, and macroalgal patches.

In addition to its recreational and aesthetic benefits, Florida Bay holds a great economic benefit in its role as an estuary. In fact, the nursery value of estuaries is often advanced as one of the key arguments for their preservation and restoration worldwide. Estuaries function as nursery grounds for a variety of species of juvenile fishes and invertebrates. There, adult forms develop, grow, and spawn, later to be harvested off shore. Florida Bay serves as a nursery ground for at least 22 species of commercially and recreationally harvested species.

[Hydrology][Next:Shark River Slough]