Mangroves love saltwater marshes and swamps. Some of the more spectacular mangrove specimens grow in coastal areas of Florida. Here and elsewhere, extensive lowland areas remain permanently flooded except in cases of very low tides that leave mangrove tree and shrub roots temporarily exposed. Unlike many other forms of plant life that would die there, mangrove trees and shrubbery over centuries of evolutionary adjustment have acquired the ability to survive constant immersion in briny water.
Mangrove roots evolved to extract nutrients from waterlogged silt and, with specially developed tubes or pores absorb oxygen and carbon dioxide from the atmosphere. Roots that rarely or never rise above the surface of the water produce tiny, hollow tubes that stick up into the air, while air enters those roots that regularly see the light of day through tiny pores in the bark. The root structure also has the capacity to exclude most of the salt that pervades coastal waters.
Mangroves benefit intertidal ecosystems several ways. The intertwining root complex helps prevent erosion of coastal lowlands by the wave action of ocean waters. In recent times, these tightly woven wooden seines have captured inundating sheens of oil and similar contaminates set adrift by offshore mishaps, preventing inland areas from becoming polluted.
The slowing of incoming tidal flows also causes nutritional sediment to become deposited in and around the roots. This provides a replenishable food source for tiny animals such as shrimps and nourishment for the mangroves as well. The mangrove roots in some areas provide anchorage for oysters, mussels, barnacles and other marine animals needing permanent moorage facilities. These life forms attract fish and other predatory creatures, thus establishing the first links in the food chain leading directly to human consumption requirements. A large variety of small fish thrive within the protection of mangrove roots, enjoying the quiet underwater haven. The leafy canopy of mangrove forests also provide food for numerous animals as well as shelter for those that inhabit the lofty branches.
The leaves form a critical link in the survival mechanisms of mangrove plants. The tiny pores in the leaves of mangroves dilate or contract, depending on the amount of salt-free water that enters the root system. This enables mangroves to survive in the absence of plentiful amounts of fresh water.
The importance of mangroves to coastal ecosystems seems obvious enough to warrant their protection from unfettered destruction. Nevertheless, farms, housing developments, golf courses and condominiums threaten their existence. It remains questionable if current conservation efforts can withstand civilization’s pressure on mangroves.
