Mangroves are a unique group of plants that line many tropical shores and, when present within coral reef ecosystems, contribute to the overall productivity and biological diversity of these systems. In coral reef ecosystems, they occupy the shoreward margins of back reef zones.
These unique plants provide both food and shelter for a variety of associated plant and animal life. The unusual and complex prop root system forms a nursery ground for young fishes, and a substrate to which all manner of algae, sponges, and other invertebrate animals may attach. Falling leaves and nesting birds add nutrients to the water below, thereby enhancing opportunities for the growth of other nearby marine life.
One of the rare terrestrial plants able to tolerate direct immersion in sea water, these plants also play a key role in creating land from the sea by trapping and consolidating sediments that would otherwise be swept away and dissipated by the sea. This reduces the chance of seagrasses and corals being damaged by excessive sedimentation.
The sediment mounds accumulated by seagrasses may eventually form sufficient substrate for colonization by mangroves. Thus, these hardy pioneers are instrumental in the building of new shorelines, and in some cases, islands.
This unique and valuable group of plants has been decimated over the last century, cut for fuel and building materials or removed as part of coastal development projects in many parts of the world. In recognition of their unique ecological value and increasing rarity, they are now increasingly protected by law in most places.
Readers seeking more information on mangroves are referred to our “Additional Resources” section, which contains lists of recommended readings specific to the topic of coral reef plants.