Discuss the causes of depletion of mangroves and explain their importance in maintaining coastal ecology. (UPSC IAS Mains 2019 General Studies Paper – 1)
Mangroves are salt-tolerant vegetation that grows in intertidal regions of rivers and estuaries. They are referred to as ‘tidal forests’ and belong to the category of ‘tropical wetland rainforest ecosystem’. Mangrove forests occupy around 2,00,000 square kilometres across the globe in tropical regions of 30 countries. India has a total mangrove cover of 4,482 sq km. However, more than 35% of the world’s mangroves are already depleted.
Causes of Depletion
- Clearing: Large tracts of mangrove forests have been cleared to make room for agricultural land, human settlements, industrial areas, shrimp aquaculture etc. As a result, mangroves get depleted to the tune of 2-8 percent annually.
- Overharvesting: They are also overexploited for firewood, construction wood and pulp production, charcoal production, and animal fodder.
- Damming of rivers: Dams built over the river courses reduce the amount of water and sediments reaching mangrove forests, altering their salinity level.
- Destruction of coral reefs: Coral reefs provide the first barrier against currents and strong waves. When they are destroyed, even stronger-than-normal waves reaching the coast can wash away the fine sediment in which the mangroves grow.
- Pollution: Mangroves also face severe threats due to fertilizers, pesticides, discharge of domestic sewage and industrial effluents carried down by the river systems.
- Climate change: Unusually low rainfall and very high sea surface and air temperatures caused severe threats to the survival of mangrove forests.
Importance of mangroves in maintaining coastal ecology
- Mangroves are among the most productive terrestrial ecosystems and are a natural, renewable resource. For instance, Sundarbans in the Gangetic delta supports around 30 plant species of mangroves.
- Mangroves provide ecological niches for a wide variety of organisms. They serve as breeding, feeding and nursery grounds for fisheries and provide timber and wood for fuel.
- Mangrove forests act as water filters and purifiers as well. When water from rivers and floodplains flow into the ocean, mangroves filter a lot of sediments, hence protecting the coastal ecology including coral reefs.
- Mangroves act as shock absorbers. They reduce high tides and waves and protect shorelines from erosion and also minimise disasters due to cyclones and tsunami.
Given their importance, strict enforcement of the coastal regulation measures, scientific management practices and participation of the local community in conservation and management are essential for the conservation and sustainable management of the precious mangrove forests.
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