Importance of Mangroves in our enviroment
Mangroves are commonly found in the intertidal zone of tropical and subtropical sheltered coastlines. They are not affected by forest fires, but about 50% (50,000 km²) of their total areal extent, particularly in Asia, Australia, Madagascar and the Caribbean, are potentially exposed to tropical cyclones, typhoons and hurricanes. In the mangroves of India and Bangladesh, especially at the mouth of the Ganges, the threat from strong winds, surges driven by storm waves and floods, is one of the most deadly in the world. Paradoxically this mangrove area, known as “The Sunderbans,” bears the largest natural mangroves of the world in a single block (about 6,050 km², i.e., 2,000 km² in India and 4,050 km² in Bangladesh). Emphasis in this paper is on the impacts of windstorms in the mangroves of the Bay of Bengal, deducted from field observations and satellite image analysis, including forest destructions and forest alterations like defoliation. The final result of our analysis is that mangrove species are able, in this part of the world, to heal cyclonic wounds and maintain their total areal extent constant in the absence of human interference.
Mangrove Threats and Solutions
Mangrove forests are one of the world’s most threatened tropical ecosystems
More than 35% of the world’s mangroves are already gone. The figure is as high as 50% in countries such as India, the Philippines, and Vietnam, while in the Americas they are being cleared at a rate faster than tropical rainforests.
Removal of mangroves or disturbance may cause:
Increased risk of Acid Sulphate Soils
Disturbing acid sulphate soils, which are associated with low oxygen soils characteristic of mangrove forests, results in a threat to the health of humans, fauna, and flora in contact with the dangerously acidic waters.
Accelerated rates of coastal and riverine bank erosion can result in bank collapse, loss of coastal foreshore, and can result from clearing of disturbance of mangroves. Retaining mangroves as erosion buffers makes it unnecessary to build erosion-prevention devices such as the expensive sea walls that are already common along stretches of the Redlands coast.
Loss of habitat
Destruction and/or degradation of mangroves results in a loss of vital habitat for:
birds – migratory birds and other terrestrial and marine birds use these wetlands to roost, breed and feed (mangrove flower nectar and fish, crabs etc)
fish – all parts of mangroves are protected under the Fisheries Act 1994, as they provide young fish spawn with a vital source of food (e.g.. decaying leaves) and protection from prey and the battering of the tide
seagrasses and dependent fauna – large amounts of organic matter (e.g.decaying leaves) produced by mangroves are swept out to enrich the seagrass beds – without mangroves, seagrasses are not able to sustain the dugongs, turtles and fish that feed and live in them
other fauna – crabs and molluscs, and other marine fauna, depend on the mangroves to provide shelter, food and habitat
Increased coastal flooding
Without mangroves and salt marshes to soak up the tidal and freshwater inputs, there is potential for heavy flooding during high tides. Removal of mangroves places the inhabitants of foreshore developments at risk.
Degraded water quality
Removal or degradation of mangroves results in higher erosion, which will increase the turbidity (amount of particles and sediment in the water) of coastal and riverine waters. The nutrient levels, including nutrients associated with development (e.g. chemicals from industrial and farming activities), will increase if mangroves are not there to act as filters and trap these nutrients for recycling in the mangrove ecosystem.
Higher nutrient levels may result in ‘eutrophication’ evidence by algal blooms, which cover the water surface blocking the sunlight and oxygen from reaching other marine and freshwater organisms. Higher turbidity and sediment in nearshore and riverine environments can also result in the smothering of bottom-dwelling organisms.
Mr Puran doshi Secretary – Mumbai Congress. Ex – Corporator has taken a stand to protect Mangroves in Colaba. Mangroves have disappeared at an alarming speed. The shortage of open land for construction and the high value of real estate means the city’s remaining mangrove forests are facing an uncertain future. At such rapid destruction Mr Puran doshi, stood & raised his voice against destruction of Mangroves