Mangroves
Mangroves border more than half of Florida's peninsular shoreline and are one of the great natural resources of our state.
Benefits of the Mangrove Tree
Mangroves provide many benefits to man and the marine environment. - Mangrove wetlands provide breeding, nursery and feeding areas for a great variety of life, including endangered and threatened species.
- Mangroves also filter upland run off.
- Mangroves buffer wave action during intense tropical storms (including hurricanes).
- Mangroves hold soil during periods of heavy precipitation stabilizing shoreline sediments.
Key Contribution
While many people are aware of these mangrove benefits, few of us know about one of the most important contributions these trees make to marine ecology. That contribution is in the form of the leaf litter that falls from mangroves and is subsequently broken down by microorganisms to begin the first link in the food chain for a large segment of the tropical aquatic community, including most of our important commercial and sport fish species.
The Entire Ecosystem is Threatened
Mangroves are a type of tree that has adapted to growing in or near salty water along sheltered coastlines. However, these coastlines are also prime locations for homes, hotels and condominiums. It is estimated that more than 23,500 acres of mangroves have been lost through dredging and filling in Florida, primarily to develop waterfront property. Additional unknown acres of mangroves have been altered by trimming activities to obtain a better view of the water. Because of previous losses and alterations of mangroves, combined with limited public ownership, Florida's state and local governments have found it necessary to adopt regulations concerning the alteration of this fast-dwindling natural resource. Violation of these regulations may result in fines of up to $10,000 per day per offense, or even criminal prosecution and imprisonment.
Mangrove Identification
There are three species of mangroves in Florida: Red, Black, and White Mangroves. They are easily identified by distinctive root structures, reproductive structures (propagules) and leaf shapes. The cutting of each of these mangroves species is regulated in Florida.
Red Mangrove trees exhibit arching prop or aerial roots which extend downward from the trunk and lower branches. Since most of these roots extend into shallow waters, they are very effective at
- dissipating wave energy
- providing shelter for small marine organisms
- increasing surface area for sponges, algaes, mollusks, tunicates, and egg attachment among other things
The red mangrove also has an unusual long, pencil-shaped reproductive structure, called a propagule. Unlike a seed or fruit of most trees the propagule germinates while on the tree and is immediately ready to put out roots as soon as it drops and lodges in the soil.
These propagules develop during the summer months and are commonly seen drifting in the water or stranded along the shoreline in late summer and early fall.
The top surface of the red mangroves lanceolate-shaped leaves is a shiny, dark olive-green, but the underside is a light green, usually with small dark spots.
Black Mangrove
Avicennia germinans
Identified by the presence of numerous finger-like projections (pneumatophores) which extend upwards above the sediment from the root system. The top surface of the lance-shaped leaves is a dull, dark green, but the underside is a distinctively lighter, silver-green color without dark spots. The leaves are often coated with salt crystals, especially during dry periods. The propagules of this species resemble pointed lima beans.
Lacks prop roots and pneumatophores, but can be identified by the leaf shape.
The leaves are more oval than those of the other two species and often have a
small notch at the tip. The two small bumps, one on either side of the stem just
below the leaf blade are also an identifying characteristic. The leaves are a
uniform pale green on both surfaces. This species has a relatively small, oblong
propagule that is wrinkled.
