Much of Florida was once a tangled mangrove maze - now a protected species
The red mangrove (Rhizophora mangle) forests of coastal Florida are frequently overlooked, yet they are extremely important in a number of functions b
enefiting both the shoreline and sea environment. These short and sturdy trees reduce the water flow across the shoreline and augment sedimentation on land. They also represent a nursery ground for a variety of marine species, as well as a number of birds.
|Above: Mangrove communities play an essential role in protecting low-lying areas from erosion and provide a habitat for fish, crustaceans and birds.
Surpassed only by the reef environment, the red mangroves abound in biological activity. Unsuspected until sneaking up upon the tangled golden-red roots. Inside the meshwork of roots live an assortment of grunts, schoolmasters, gray snappers and occasionally a congregation of juvenile spiny lobster. Some fish species are well camouflaged amongst the roots and at first inspection it is difficult to discern their presence. There are usually scores of other marine plants and species of animals that inhabit the red mangroves, with many of them adapted to live at specific levels in the tidal zone. Snails, limpets, barnacles, oysters, tunicates, sponges, sabellid worms, shrimps, crabs, jellyfish are some of the invertebrates that live on or around the root system. Above the water line the foliage is a haven for mosquitoes. Their larvae, if not eaten by fish, will be born in the quiet water inside the mangroves. Birds will come to feast on the mosquitoes and some establish nests on the branches.
Succession in Mangroves
The red mangrove's ability to reclaim the land and live in a saltwater environment has made it a leader in the ecological sequence called succession. Succession is the different steps necessary for plants and animals to establish a climax community in a particular type of environment. The climax community is a balanced and stable ecosystem and is the final product in the sequence of events of succession. The mangrove's process of succession begins with the release of the seedling in the water. In general, land plants invest a lot of energy in producing massive amounts of seeds hoping a few will settle in the right environment and sprout. The mangrove, on the other hand, keep the seedling on the branches until the fruit is almost a foot long. The long and narrow fruit is so well adapted to survive in the saltwater that it can float for up to one year in this harsh environment. Once it settles it will penetrate the sand and root itself. Leaves will grow profusely and the production of prop roots which curve and extend into the water will begin. Leaves will steadily fall off and settle on the bottom. The leaves are decomposed by bacteria and marine fungi and over a period of time this changes the consistency of the muddy-sand to a richly packed sediment. Now that the soil is fertile, a nutritional cycle begins, attracting algae, filter feeders, marine grazers and predators. A complete marine food chain has now been established.
After years of accumulation of detrital material, the composition of the soil becomes anaerobic and the sediment build up is slightly too high for the mangrove to survive. This allows for the succession of the black mangrove (Avicennia nitida) which thrives in an area only periodically flooded by the tides. The black mangroves have developed specialized fingerlike air breathing rootlets called pneumatophores, to survive in this anoxic environment. As the black mangrove grows and more leaves fall on the moist muddy soil, the consistency of
the sediment changes again and succession continues. The next mangrove in line is the white mangrove (Laguncularia racemosa) which lives in a muddy saline ground. The white mangrove can be recognized by looking closely at the petiole or stem that supports the leaf where glands for removing excess salt exist. On slightly higher and dryer saline soil is the last in the mangrove family, the buttonwood (Conocarpus erecta). The buttonwood represents the end of the ecological succession of mangroves and can generally be identified by its jade and silver colored foliage.
|Above: migrating plovers take a break on a young mangrove colony. Without proper management of development, these ecosystems could easily be destroyed.
Conservation of Mangroves
Throughout coastal Florida you'll find endless tangles of mangrove forests that provide protection for a myriad of marine and land species. Its high density of decaying leaf matter provides a nutrientrich environment that is an essential base for the life cycle of many animals and plants. The firm grip the plants' roots take on the land helps prevent erosion caused by water currents, hence it augments the boundaries of the land.
The constant flow of water at the mouth of any mangrove creeks is essential for proper nutrient exchange and to maintain a flourishing mangrove community. Unfortunately many land developers do not see the benefits of mangroves and have already demolished far too many mangroves in Florida and elsewhere to build hotels, harbors and for residential development. A Florida law has been passed prohibiting interference with new mangrove systems.
The red mangrove has successfully adapted to a very harsh salty environment that has allowed it to survive for millennia without competition. Furthermore the chemical tannin, which gives mangroves their red colour is used by man as a tanning and dye agent. Potential enemies like marine borers and/or grazers find it unpalatable to eat the bark and leaves of this chemically-protected plant. However mangroves cannot tolerate changes in their environment from the introduction of pollutants. Pollution from towns, pesticides and insecticides and oil spills have a very adverse effect on the mangroves. Without proper management and care of this coastal vegetation, many life forms could cease to exist. It is therefore essential that people and governments take action to limit the destruction of mangroves.