If tidal conditions are optimal, mangroves can flourish far inland, along the upper reaches of coastal estuaries. Evolutionary adjustments to varying coastal marine environments have produced some astounding biological characteristics within mangrove plant communities. Certain species of mangroves exclude salt from their systems, others actually excrete the salt they take in via their leaves, roots, or branches. In salt excluding mangrove species , the mangrove root system is so effective in filtering out salt that a thirsty traveler could drink fresh water from a cut root, though the tree itself stands in saline soil. The mangroves as a resource Most people have thought of mangroves as noxious impenetrable swamps full of diseases, and they used to be destroyed as a public health measure, but now we know better.
Mangroves are very productive coastal resources that are useful in many ways.
Mangrove trees grow well in their special conditions, and, like the tropical forest, they produce a lot of leaves and other organic matter, detritus . Instead of accumulating in the soil, the leaves fall in the water, where they rot and provide food for microbes and planktons. The areas near mangroves are thus often very important for the fisheries. Mangroves are an important source of food and materials for many coastal people. Crabs, clams, oysters, fish and other food are often collected there.