Mangrove Forest

Mangrove Forest
Red Mangrove

 

 Florida has approximately 1042.5 square miles (2,700 square kilometers) of mangrove forest, a subtropical coastal ecosystem. The Ten Thousand Islands area, including Ten Thousand Islands National Wildlife Refuge, is comprised of about 232 square miles (600 square kilometers) of mangrove forest, making Southwest Florida home to one of the world’s largest mangrove systems. 


Mangrove Species
Three species of mangrove are dominant in Florida’s systems.     

Red Mangrove, Rhizophora mangle:
The red mangrove is easily distinguished by its prop root system. Multiple prop roots grow downward from the branches and are suspended up to 3 feet (1 meter) or more over the soil and water, giving the tree extra support and soil stabilization in the harsh coastal environment. The prop roots also help combat hypoxia, or oxygen deficiency, by allowing for direct intake of oxygen through the root structure. Red mangroves are also easily distinguishable through their viviparous seeds, 6 inch (15cm) cigar-shaped propagules. These propagules germinate while attached to the tree. The seedling then falls to the water to take root at the parent base or to be carried by water for development in other appropriate habitat. Highly adapted to survive in salty and wet conditions, this mangrove grows closest to open water.

Black Mangrove, Avecennia germinans:
The black mangrove does not have prop roots like the red mangrove. Rather, this tree has pencil-shaped root projections called pneumatophores. These structures project from the soil at the tree’s base to absorb oxygen for the rest of the root system that is underground and under water. The black mangrove is less tolerant of highly saline conditions than other mangrove species such as the red mangrove. It is commonly found growing just above the high tide and at higher elevations where its roots are better exposed to air.

White Mangrove, Laguncularia racemosa:
The white mangrove typically has no visible roots, although peg roots may develop when the tree is flooded for significant amounts of time or grows in oxygen-depleted sediments. With roots that lack strong adaptations to tolerate salt and water, this mangrove species is found further inland and on higher ground than red and black mangroves. The white mangrove is also the least cold-tolerant of Florida’s three mangrove species. Its range does not extend north of Levy or Volusia Counties.


Life among the Mangroves 

Florida’s mangrove systems are important habitat for many species. It is estimated that 75% of game fish and 90% of commercial fish species in South Florida depend on the mangrove system.

Mangrove systems provide sheltered and nutrient rich nursery grounds for young fish, crustaceans, and mollusks. Clams, shrimp, and many fish feed in the mangrove forests and live among the complex root systems. Common fish species found feeding and reproducing within the mangroves of Ten Thousand Islands NWR include:
• Snook (Centropomus undecimalis) 
• Gray or Mangrove Snapper (Lutjanus griseus)
• Tarpon (Megalops sp.) 
• Sheepshead (Archosargus probatocephalus)
• Red Drum (Sciaenops ocellatus) 
• Goliath Grouper (Epinephelus itajara) 
• Hardhead Silverside (Atherinomorus stipes)
• Great Barracuda (Sphryaena barracuda)
• Scrawled Cowfish (Lactophrys quadricornis)
• Permit (Trachinotus falcatus)


Roosts and rookeries for coastal and wading birds are also made available by the intricate branches of mangroves. Birds commonly found utilizing the mangrove habitat of Ten Thousand Islands NWR include:
• Brown Pelican (Oelicanus occidentalis)
• Roseate Spoonbill (Ajajia ajaia)
• Magnificent Frigatebird (Fregata magnificans)
• Double-crested cormorant (Phalacrocorax carbo)
• Osprey (Pandion haliaetus)
• Snowy Egret (Egretta thula)
• Reddish Egret (Dichromanassa rufescens)

Sources 

 Florida Museum of Natural History (FLMNH). 2014. Mangroves. Retrieved from: https://www.flmnh.ufl.edu/fish/southflorida/mangrove/introduction.html

Odum, W. E., C. C. McIvor, and T. J. Smith. 1982. The ecology of the mangroves of South Florida: a community profile. U.S. Fish and Wildlife Service, OBS Publication FWS/OBS-81/24, Washington, D.C. 144pp
Rey, J.R. and C.R. Rutledge. 2013. University of Florida, IFAS Extension, EDIS. Mangroves. Retrieved from: http://edis.ifas.ufl.edu/in195

Stevens, P.W., Fox, S.L., and C.L. Montague. 2006. The Interplay between Mangroves and Saltmarshes at the Transition between Temperate and Subtropical Climate in Florida. Wetlands Ecology and Management. 14(5), pg 435-444.

Facts About Mangrove Forest

Mangrove forests only grow in tropical and subtropical climates because they cannot survive freezing temperatures

Due to development and habitat degradation, 1/5 of the world’s mangrove systems are estimated to have been lost from 1980 to 2010

Mangrove systems stabilize the coastline by reducing erosion and causing sediment to settle as tidal waters are slowed