Florida mangroves

The distribution of the mangrove community in Florida is shown in red. Cedar Keys and Ponce de Leon Inlet are the northern limits of the mangrove community.

The Florida mangroves comprise an ecosystem of the coasts of the Florida peninsula, including the Florida Keys. The Florida mangrove community includes three mangrove species, Red Mangrove (Rhizophora mangle), Black Mangrove (Avicennia germinans) and White Mangrove (Laguncularia racemosa), and one species that is variously classified as a mangrove or a mangrove associate, Buttonwood (Conocarpus erectus). These plants have differing adaptions to conditions along coasts, and are generally found in partially overlapping bands or zones. The Red Mangrove grows closest to open water. It has multiple prop roots, which may help to stabilize the soil around its roots. Next comes the Black Mangrove. It does not have prop roots, but does have pneumatophores, which grow up from the roots to above the water level. The White Mangrove grows closest to shore. It may have prop roots and/or pneumatophores, depending on conditions where it is growing. The Buttonwood grows in shallow, brackish water or on dry land.

Mangroves can survive along most of the length of the Florida peninsula because the winter climate is moderated by the warm waters of the Gulf of Mexico on the west coast and the Gulf Stream on the east coast. The Florida Mangrove community is found as far north as Cedar Key on the Gulf coast of Florida, and as far north as the Ponce de Leon Inlet on the Atlantic coast of Florida. Black Mangroves can regrow from roots after being killed back by a freeze, and are found by themselves a little further north, to Jacksonville on the east coast and along the Florida Panhandle on the Gulf coast . As Florida is sub-tropical in climate, it is not ideal for mangroves, and the trees tend to be shorter and the leaves smaller in Florida than in tropical regions.

Locations

As of 1981, mangrove communities covered an estimated 430,000 to 540,000 acres (1,700 to 2,200 km²) in Florida. Ninety percent of the Florida mangroves are in southern Florida, in Collier, Lee, Miami-Dade and Monroe Counties. Approximately 280,000 acres (1,100 km²) of mangrove forests are in the hands of the Federal, State and local governments, and of private, non-profit organizations. Most of those acres are in Everglades National Park. Mangroves cover a wide band all along the southern end of the Florida peninsula facing on Florida Bay, from Key Largo across to close to Flamingo, then inland behind the beaches and marl prairies of Cape Sable and all around Whitewater Bay. From Whitewater Bay a broad band of mangroves extends up the Gulf coast to Marco Island, including the Ten Thousand Islands.

Mangroves also extend throughout the Florida Keys, although coverage has been reduced due to development. Florida Bay is dotted with small islands, which are often no more than mud flats or shoals more or less covered by mangroves. Biscayne Bay also has extensive mangroves, but the northern part of the Bay has been largely cleared of mangroves to make way for urban development. Mangrove coverage is limited elsewhere, with the largest areas in the Indian River Lagoon on the east coast, and the Caloosahatchee River, Pine Island Sound and Charlotte Harbor estuaries and Tampa Bay on the west coast.

Human activity has impacted the mangrove ecosystem in Florida. While the coverage of mangroves in Florida at the end of the 20th century is estimated to have decreased only 5% from a century earlier, some localities have seen severe reductions. The Lake Worth Lagoon lost 87% of its mangroves in the second half of the 20th century, leaving a remnant of just 276 acres (1.12 km²). Tampa Bay, home to the busy Port of Tampa, lost over 44% of its wetlands, including mangroves and salt marshes, during the 20th century. Three-quarters of the wetlands along the Indian River Lagoon, including mangroves, were impounded for mosquito control during the 20th century. As of 2001, natural water flow was being restored to some of the wetlands.

Habitat and shelter

The Florida mangrove system is an important habitat for many species. It provides nursery grounds for young fish, crustaceans and molluscs. Many fish feed in the mangrove forests, including snook (Centropomus undecimalis), Gray or Mangrove snapper (Lutjanus griseus), Schoolmaster snapper (Lutjanus apodus), tarpon, jack, sheepshead, red drum, Hardhead Silverside (Atherinomorus stipes), juvenile Blue Angelfish (Holocanthus bermudensis), juvenile Porkfish (Anisotremus virginicus), Lined Seahorse (Hippocampus erectus), Great Barracuda (Sphryaena barracuda), Scrawled Cowfish (Lactophrys quadricornis) and Permit (Trachinotus falcatus), as well as shrimp and clams. An estimated 75% of the game fish and 90% of the commercial fish species in south Florida depend on the mangrove system.

The branches of mangroves serve as roosts and rookeries for coastal and wading birds, such as the brown pelican (Oelicanus occidentalis), roseate spoonbill (Ajajia ajaia), Frigatebird (Fregata magnificans), Double-crested cormorant (Phalacrocorax carbo), Brown Noddy (Anous stolidus), Great White Heron and Wurdemann's Heron, color phases of the Great Blue Heron (Adrea herodias), Osprey (Pandion haliaetus), Snowy Egret (Egretta thula), Green Heron (Butorides striatus), Reddish Egret (Dichromanassa rufescens) and Greater Yellowlegs (Tringa melanoleuca). Other animals that shelter in the mangroves are the American Coot (Fulica americana), American Crocodile, Bald Eagle, Peregrine Falcon, Eastern Diamondback Rattlesnake (Crotalus adamanteus), Mangrove Snake (Nerodia clarkii compressicauda) and the Atlantic Saltmarsh Snake (Nerodia clarkii taeniata ).

Above the water mangroves also shelter and support snails, crabs, spiders, bromeliads of the genus Tillandsia, including Spanish moss, and Reindeer lichen. Below the water's surface, often encrusted on the mangrove roots, are sponges, anemones, corals, oysters, tunicates, mussels, starfish, crabs, Florida Spiny Lobster (Panulirus argus) and seagrasses.