Dr. Hashem Abbas Madkour
Researcher at the National Institute of Oceanography and Fisheries, Red Sea Branch (Egypt)
Coastgoers in the tropics and subtropics encounter concentrations of mangroves that are densely and remarkably widespread in tidal and runoff zones along the edges of beaches or within coastal areas near beaches, and their leaves, branches, intertwined roots and shallow waters usually attract a large number of birds, fish, crustaceans and other creatures, thus becoming a rich habitat and an integrated community that includes a large number of marine organisms, not just mangroves This exciting plant is a group of coastal bicotyledonous and monocotyledonous trees and shrubs that can grow amid waterlogged sediments, anaerobic soils (low in oxygen) and salt water.
The term MAngrove itself, although it expresses its direct meaning of that plant, is usually intended to describe the living environment in which it grows with a number of plants and animals in the surrounding soil and sediments, and not only the Mangrove plant. The term is derived from two words, the first is a Portuguese word, Mangue, which means tree, and the English word, Grove, which means tree plant. Some scholars have suggested limiting the word Mangrove to refer only to salt-tolerant plants that make up mangroves, and Mangal to refer to salt marshes and forests in which mangroves usually grow and live with other flora and fauna.
The nature of the plant and its functional
characteristics Qurum is generally a salt-tolerant plant, but its tolerance to this salinity varies from species to species. For example, the red species known as Rhizophora has a relatively low tolerance to high salinity of only 50,000 ppm, so its degree of development and growth is generally considered sluggish compared to other species of Mangrove. In contrast, the gray or black variety known as Avicennia can grow at a high salinity of up to 65,000 ppm.
Mangroves belong to the type of angiosperms and are distinguished from other plants that their seeds begin to germinate while they are on the branches of the tree, and remain attached to the mother tree until maturity, and once they reach this stage, they begin to fall automatically into the water, to immerse their small roots in the soil, and then start growing again to appear as a new tree or a small plant. If they fall during the period of high water during the tidal period, the seeds remain afloat on the water until the water recedes and the seed meets solid ground in which it can take root. Most mangrove trees are bisexual and pollinated by bees, small insects, butterflies, bats and birds.
The plant is physiologically adapted to the harsh environment in which it grows and lives through more than one unique characteristic. First of all, respiration is carried out by adventitious roots that grow from the lower parts of the plant and head upward against gravity to appear above the water as growing vertical stems. By the appearance of these roots above the surface of the water, the plant can obtain the oxygen necessary for its vital processes. The salt glands on the surface of the leaves help the plant adapt to high salinity and act as pumps that push excess salts out of the plant's body, although some other mangrove species adapt differently to live and grow in salt water.
There is more than one environmental and geographical factor that controls the growth and spread of Mangrove in an area, the most important of which is the availability of a certain geographical nature, such as the presence of narrow bays and protected coastal areas that enjoy calm water and allow water flow, which helps to speed up the deposition of silt, the formation of loose clay soil, the reception of ground sediments rich in nutrients and organic matter, and the need for an appropriate tidal level so that seawater does not rise permanently and completely submerge the roots of the plant, hindering it from breathing and obtaining the oxygen necessary for its survival.
Classification of mangrove populations
There is more than one way and basis for classifying mangrove populations, such as the color of seeds and fruits as mentioned above, but depending on the nature of the geographical location, the drainage system and the water medium in which these communities grow, mangrove forests can also be divided into 4 main types, as follows:
Mangrove river forests They grow and develop along estuaries in the interior affected by salty seawater intrusion. They are characterized by high water flow and fast flow of sediment and nutrients, with low salinity tolerance by 10 to 20 parts per thousand compared to other species.
Fringe Mangrove Forests are found and spread in the form of a narrow belt on the edge of the coasts and along protected beaches facing the sea, which are usually characterized by gradient terrain and extensive and extended flood areas due to high tides, so they are able to withstand higher levels of salinity.
Basin Mangrove Forests include mangrove populations that grow in ponds and low-lying areas that usually derive their water and sediments through seawater flooding or high tide. As such, it has a rather slow flow of water, extends over vast areas as wide as the basin, and is considered moderate in terms of its tolerance to salinity.
Dwarf Mangrove Forests include stunted and limited growth mangrove populations near salt lakes and high saline coastal bays. The stunting of this species is due to the environmental conditions and factors to which it is subject, which are usually nutrient deficiencies, poor water flow and high salinity, which is the main cause of plant stunting.
As for the sediments that make up the soil of mangrove forests, they mostly consist of fine and soft sediments with organic content, but there may also be a mixture of carbonaceous and other materials, which resulted and were deposited from more than one source and sedimentary process, such as transport through valleys, air deposition, and the products of the erosion process of coral reefs and rocks. Beach, as well as wave movement that leads to the sorting and redistribution of sediments.
The size of the grains and the nature of the texture that makes up these sediments also varies depending on the location of the mangrove forest and its proximity to the coast and coastal waters. Mangrove forest sediments near the shore vary greatly in grain size and mineral composition as a result of the strong mixing process between the carbonate components coming from the sea side by waves and coastal currents. On the one hand, and the continental components coming inland via air deposition or transport by valleys on the other hand.
As for the mangrove deposits found in tidal flats, they are characterized by the predominance of coarse limestone sand, while the mangrove deposits found in the inland areas are characterized by the dominance of continental materials, and the mangrove deposits found in the forests and low-lying coastal areas are characterized by the dominance of mud and clay sediments.
environmental role Mangrove forests perform a number of vital functions, and provide several benefits to human communities living near the coasts and the ecosystem of coastal areas in general, as the beginning of the aerial roots of the plant spread abundantly around mangroves, and sometimes extending deep into the soil for about two meters, stabilize sediment and coastal soil, which contributes to protecting beaches from erosion and erosion. These roots also work with intertwined tree trunks to trap sediments, silt and other materials coming from the land and prevent them from moving to the sea, which in turn contributes to the protection of other coastal habitats, especially coral reefs and sea grasses from damage because they always need clear water and free of any turbidity.
In addition, mangrove forests support the food chain, have high organic content, provide shelter and protection for a wide range of marine animals and migratory and endemic birds, contributing to enhancing biodiversity and enriching commercially important fish and crustacean populations. It is estimated that each square mile of mangrove forests and swamps can produce about 124 tonnes of fish per year.
Mangrove forests also play a vital role in the fight against climate change, as they are highly capable of absorbing excess carbon from the atmosphere and then burying and storing it in soil and subsediment, reducing the impact of global warming causing climate change. This carbon is known as blue carbon because it is absorbed by natural habitats that grow in marine (blue) waters.
Mangrove is not limited to its environmental role, as it provides other valuable benefits and services to some coastal human communities, local populations and fishermen. Mangroves are a good pasture for herds of camels and goats that feed on the leaves and fruits of the plant rich in organic protein, when other plants are not available, especially during the summer season and drought. Tree branches and timber are also used as firewood and fuel, which may explain why mangrove populations closer to human populations are retreated and destroyed compared to those isolated or found on remote islands and coasts. Non-wood parts of mangroves, especially bark and leaves, are also used to extract and produce important chemical extracts such as tannins, gums and dyes.
In addition, the mangrove forests and marshes have charming and picturesque views, so they are considered an attraction for tourists, as they can be used to stimulate ecotourism.
It is incumbent upon humanity to protect this generous habitat from the increasing negative factors to which it is exposed, especially coastal development processes that lead to the removal and deduction of large areas of it, thus losing valuable contributions and benefits. We should also work to enrich and develop Mangrove in new locations, because growing one tree from this habitat means giving habitat, shelter and life to more than one species.