Florida Bay is effectively divided into a series of basins by a complex network of anastomosing carbonate mudbanks that restrict circulation. 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.