QUES . Discuss the causes of depletion of mangroves and explain their importance in maintaining coastal ecology. UPSC 2019 G S MAINS PAPER 1
HINTS:
Also refer https://fotisedu.com/ecological-significance-of-mangroves/
Straddling land and sea and teeming with life, mangrove forests are key to healthy coastal ecosystems – but only recently have people begun to realize their importance.Ironically, during this same period, mangroves have disappeared with alarming speed.
Extent of depletion of mangroves
By some estimates, less than 50 percent of the world’s mangrove forests were intact at the end of the 20th century, and half of those that remain are in poor condition.
Mangrove forests are among the most threatened habitats in the world, and mangrove loss is rampant across the globe.
Thailand has lost 84 percent of its mangroves, the highest rate of mangrove loss of any nation, while the Ivory Coast, Guinea-Bissau, Tanzania, Mexico, Panama, Malaysia, Myanmar, Pakistan, and the Philippines have each lost more than 60 percent of their mangrove forests.
Most mangroves grow on public land, only about 1 percent of which receives any sort of protection.
Even where some legal designation or protection is in place, preserving mangroves is difficult because of development in the form of: shrimp farming, tourism, agriculture, coastal development, charcoal and lumber industries.
Causes of depletion of mangroves
Forest clearing and pollution originating from aquaculture and agriculture are the single biggest factor, accounting for around 47% of global mangrove forest loss. Climate change and associated sea-level rise, droughts and coastal acidity constitute the second biggest factor behind the mangrove decline. Urbanisation and coastal development are the third major social-ecological driver.
Shrimp Farming: By far the greatest threat to the world’s mangrove forests is the rapidly expanding shrimp aquaculture industry. Hundreds of thousands of acres of lush wetlands have been cleared to make room for artificial ponds that are densely stocked with shrimp. Shrimp farmers dig channels to supply the ponds with enormous quantities of freshwater and seawater. These water diversions alter the natural flow of water that maintains the health of surrounding mangroves as well as ecosystems farther inland and offshore. Diverting water can harm mangroves by preventing their seeds from being dispersed via seawater, and it can kill the trees by cutting off freshwater supplies.
Tourism: Irresponsible tourism can destroy the very resources people are coming to see. As tourists hike, drive, or paddle into once-remote areas, they bring with them garbage, sewage, noise, fumes, lights, and other disturbances that can damage mangroves and the surrounding ecosystems. Walking off paths, lighting fires, feeding wildlife, anchoring on reefs, and collecting shells and plants are also destructive.
Agriculture: Many thousands of acres of mangrove forest have been destroyed to make way for rice paddies, rubber trees, palm oil plantations, and other forms of agriculture. Farmers often use fertilizers and chemicals, and runoff containing these pollutants makes its way into water supplies. Despite their resilience, mangroves can tolerate only a limited amount of industrial and agricultural pollution without dying. In addition, waterways are often diverted for irrigation or paved over for roadways, which alter the natural flow of water. Because mangrove forests are adapted to tidal fluctuations, they can be destroyed by such changes to their habitats.
Coastal Development: Coastal development takes many forms, from ports and docks to hotels, golf courses, marinas, and convention halls. Everyone loves being near the sea, but as streams and wetlands are filled by roads and concrete, they can no longer process natural chemicals. Worse still, pollutants that accompany development can damage individual trees or whole tracts of mangroves. With buildings come people, traffic, garbage, and noise, each of which takes its toll on the plants and animals that inhabit rich coastal ecosystems.
Charcoal and Lumber Industries: Chopping down mangroves for charcoal and timber is an important cottage industry for many coastal communities. Mangrove wood is used for building material, fencing, and fuel. It also yields valuable, high-quality charcoal. In places where fishing has declined below subsistence levels, many people have turned to charcoal production for their livelihood, which furthers the cycle of habitat loss and fishery decline.
Reduction in river water levels: The mangroves are more prevalent in areas where the rivers meet the sea. The system requires a fine balance between salt and sweet water to survive. Reduction of river water due to dams has caused destruction of mangroves.
Sea level rise and coastal erosion: Due to global warming, the sea levels are continuously rising. The rising sea levels have flooded large areas of mangrove forests. This has resulted in their depletion. This has been supplemented by continuous erosion by sea towards the land.
Mangroves’ role in preserving coastal ecology
• Foundation of the intricate marine food chain.
• Creating breeding habitats for water creatures and birds.
• The mangroves show edge effect, which means that they have large species diversity in comparison to marine or terrestrial ecosystem.
• Removing and absorbing toxins from runoff from the uplands.
• Sediment stabilisation at the bottom.
• Improvements in water quality. 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.
• Preventing erosion along the shore.
• They supply timber, fire wood, medicinal plants and edible plants to local people.
• For coastal communities, mangroves serve as the first line of defence. They create natural barriers that safeguard coastal towns from storm surge, flooding, and cyclones as well as stabilise shorelines by reducing erosion. They also provide numerous employment opportunities to local communities and augment their livelihoods.
Recent major reports on climate change and global biodiversity have highlighted unique threatened ecosystems like mangroves. Globally coordinated conservation policies and raising awareness remain vital for slowing mangrove decline.
External link: https://www.downtoearth.org.in/blog/wildlife-biodiversity/scientific-management-of-mangroves-is-need-of-the-hour-64007
