NA­TURE’S NOTE­BOOK

Crit­i­cal habi­tat for South­west Florida ecol­ogy and econ­omy

Times of the Islands - - Departments - BY WIL­LIAM R. C OX Wil­liam R. Cox has been a pro­fes­sional na­ture pho­tog­ra­pher and ecol­o­gist for more than 35 years. Visit him on­line at williamr­cox­pho­tog­ra­phy.com.

Man­groves

Man­grove habi­tats in Florida range from St. Johns County on the east coast and Levy County on the west south­ward into the Caribbean. There are four species of man­groves in south Florida: red man­grove, white man­grove, black man­grove and but­ton­wood.

The most dom­i­nant species is red man­grove, rec­og­nized by its ar­range­ment of stilt- like prop roots and its habit of pro­duc­ing large, fleshy seeds that ger­mi­nate while still on the par­ent plant. Red man­grove is dom­i­nant in low marsh ar­eas along the ocean­front, tidal creeks, canals and low basins. Black man­grove is more dom­i­nant in high marsh ar­eas. As­so­ci­ated with the black man­grove for­est are the white man­grove and but­ton­wood species, which are re­stricted to ar­eas of less sig­nif­i­cant tidal ac­tion.

Man­grove forests are trop­i­cal and sub­trop­i­cal and are killed back by freez­ing tem­per­a­tures along the Cen­tral Florida coasts. How­ever, black man­groves are more tol­er­ant of freez­ing tem­per­a­tures and thus are the species that pioneer coastal ar­eas north of the sub­trop­i­cal zone. They can be distin­guished by their emer­gent, pen­cil- like root ex­ten­sions, known as pneu­matophores. Man­grove is­lands ex­pand dur­ing hur­ri­cane- free in­ter­vals. Man­grove species are mostly as­so­ci­ated with sa­line wa­ter and soils, but they can also tol­er­ate fresh­wa­ter en­vi­ron­ments.

Man­grove forests, at no cost to man, pro­vide pro­tec­tion from storms, shore­line sta­bil­ity, aes­thet­i­cally pleas­ing ex­pe­ri­ences, and habi­tat for valu­able birds, mam­mals, am­phib­ians, rep­tiles, fishes and in­ver­te­brates. They are an im­por­tant at­trac­tant for tourism on Sani­bel Is­land, di­rectly or in­di­rectly draw­ing pho­tog­ra­phers, bird­ers, fish­er­men, boaters, hik­ers and oth­ers who en­joy these unique trop­i­cal habi­tats and their as­so­ci­ated wildlife. They also pro­tect sev­eral en­dan­gered species of wildlife and par­tially sup­port ex­ten­sive coastal food webs.

The im­por­tance of man­grove habi­tats to fish and wildlife was well doc­u­mented by Wil­liam E. Odum et. al. in 1982 in The

Ecol­ogy of the Man­groves of South Florida: A Com­mu­nity Pro­file ( reprinted i n 1985). More than 217 species of salt­wa­ter and fresh­wa­ter fish species spend part of their life cy­cle in man­grove habi­tats. This in­cludes both commercial and sport fish such as red­fish, snook, mul­let, men­haden, spotted sea trout, gray and other snap­per, sheepshead, jacks, la­dy­fish and jew­fish. Many other fish species play sig­nif­i­cant roles in the food web for many species of birds, mam­mals and fish.

Im­por­tant in­ver­te­brates that are de­pen­dent on man­groves i nclude pink shrimp, spiny l ob­ster, oys­ters and blue crabs. Many other in­ver­te­brates are also im­por­tant in the eco­log­i­cal food web as­so­ci­ated with man­grove forests, par­tic­u­larly in­sects, which pro­vide food for many species of birds. Over 200 species of in­sects have been iden­ti­fied in man­grove habi­tats.

Bird uti­liza­tion of man­grove com­mu­nity types is sig­nif­i­cant, with sev­eral bird groups us­ing man­groves for food, shel­ter and nest­ing. This in­cludes wad­ing birds, prob­ing shore­birds, float­ing and div­ing wa­ter birds, aeri­ally search­ing birds, birds of prey and ar­bo­real birds.

In sum­mary, man­grove habi­tats are very valu­able to fish, wildlife and man. Man­grove forests help pro­tect the shore­line from ero­sion caused by storms and heavy waves. They con­trib­ute to a healthy econ­omy for Sani­bel Is­land and south Florida by main­tain­ing a di­verse ecosys­tem for fish and wildlife that en­cour­ages many types of tourism. The best man­age­ment for this ecosys­tem is preser­va­tion by im­prov­ing wa­ter qual­ity runoff and pre­vent­ing de­struc­tion of man­grove habi­tats.

Red and white man­groves help pro­tect

this shore­line on Sani­bel Is­land.

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