Mangroves occupy a large, roughly triangular area at the southwestern tip of southern Florida, where a maze of islands along the coast is intersected by mangrove-lined channels. Here, where the salt water of the Gulf of Mexico and Florida Bay meets fresh water that has traveled from Lake Okeechobee in central Florida, is the largest area of mangrove swamps in North America. The dominant species along the edges of the sea and the numerous channels is the red mangrove—water within the channels is normally stained brown from tannin contained in the leaves of this species. In addition to their role in stabilizing shorelines with their large prop roots, red mangroves are crucial to the Everglades ecosystem, acting as a nursery for many species of fish, as well as shrimp, mussels, sponges, crabs, and other invertebrates. The other principal mangrove species in the Everglades are the black mangrove and white mangrove. Both of these grow closer to the shore than red mangroves, so they are in contact with seawater only at high tide. The Everglades swamps provide a feeding and nesting site for several mammals, including swamp rats, and numerous bird species, such as herons, egrets, gallinules, anhingas, and brown pelicans. While much of the region has an abundant alligator population, the swamps are the sole remaining stronghold in the US for the rare and endangered American crocodile. Also occasionally spotted in the channels between the mangroves are West Indian manatees (sea cows). The Florida mangroves are sometimes damaged by the hurricanes that hit the region, Hurricane Andrew in 1992 being an example. Hurricanes damage mangroves in two ways: strong winds may defoliate them, and storm surges harm them by depositing large quantities of silt on their roots. Fortunately, mangrove forests are resilient ecosystems, and they usually regenerate fully from hurricane damage within a few years.
Since 1983, the Mayan cichlid, an exotic fish species from Central America, has been spreading rapidly through the mangrove swamps and other wetland areas of the Everglades. No one yet knows what effect it may have on the region’s ecosystem. There are worries that it may displace native fish species; alternatively, it could be occupying a new “niche” that no other fish species has filled.