Q. Discuss the various important functions of Mangroves. Also enumerate the various threats that they are facing
A. Mangroves are incredibly productive coastal ecosystems found in the tropics and subtropics. ‘The current assessment shows that mangrove cover in the country is 4921 sq km. which is 0.15 per cent of the country’s total geographical area (32,87,469 sq km. Source: Census of India, 2011).
They are known for their different looking roots that poke up into the air from shallow water. Among the meshed webs of roots are fish nurseries, enabling humans to make a living from the marine life in and around the mangroves. The mangrove tree species, including the Sundari, which has historically helped the local economy in the construction of boats and bridges.
Purification of water
Mangroves filter and trap sediment from run-off and river water before it reaches adjacent ecosystems. It also helps to reduce the turbidity of the water and allowing essential light to reach ecosystems.
Protects from coastal erosion
Mangroves also contribute towards retarding coastal erosion and are a better alternative than building expensive embankments. Mangroves help in building and consolidating silt.
Barrier to disasters
Mangroves also play another important role for humans, protecting communities from major storms. Climate change is more than rising temperatures, and the increased frequency and intensity of cyclones, hurricanes and typhoons is apparent. Mangrove roots can break up the force of a storm surge, soaking up some of its energy and protecting people living on coasts from cyclone damage. Mangrove roots and branches form a barricade against the intrusion of saline water and also act as wind breakers. This is especially important considering that coastal zones are extremely low-lying areas. Losses per cyclone for communities with 6m of mangroves per metre of coastline were double that of communities protected by 25m per m of mangroves.
Protection of low lying areas
Storm surges and flooding from cyclones, which deposit salts, are greater without mangrove protection. Even a small rise in sea level can be disastrous if mangroves are not present to buffer the impact of the sea when the sea rises during storm conditions. In Bangladesh, for example, rice agriculture is increasingly impossible as fields are flooded with seawater. Mangrove protection from cyclones also reduces longer term deterioration of low-lying inland areas with rising sea levels.
Role in Climate Change
Mangrove forests cover just 0.5% of the world’s coasts but account for an estimated 10-15% of coastal carbon capture.
• Mangrove ecosystems in the country are currently under threat from developmental activities across coastal regions like port construction, tourism, industrialisation and ensuing effluent pollution and other activities like agriculture, aquaculture, wood harvesting, etc.
• It was recently reported that around 54,000 mangroves spread over 13.36 hectares will be cleared for the Mumbai-Ahmedabad High speed train corridor.
• Other studies have shown that over the last 30 years, around 40% of mangroves in the west coast of India have been converted into farmlands and housing colonies while 35,000 hectares of mangroves have been lost to shrimp farming.
• Lack of education and awareness regarding the importance of mangroves, and ignorance of rules and regulations regarding conservation of mangroves.
• Conflicting objectives at different levels of government and in different locations need joining up.
• Difficulties of protection because of the scattered geographic distribution of mangroves.
According to a 2017 report by the Forest Survey of India (FSI), the country’s mangrove cover has increased by 181 sq km between 2013 and 2017. But this statistic ought to be read with caution because there are two major disclaimers.
The count most definitely included nascent mangrove plantations and this is problematic because many fully-grown mangroves are razed and plantation drives are undertaken to ‘compensate for the loss’. These plants will take a very long time to grow up and perform their ecological and carbon sequestration functions. Also, most mangroves plantations are monocultures, a practice which can never compensate for the functions of a multi-species natural forest.
The second disclaimer is the fact that about 40% of India’s mangrove cover is open and sparse, according to the FSI report.
• The long-term solution to coastal and marine ecosystem degradation requires a holistic and integrated approach.
• People’s involvement in mangrove management on public lands, Plantation of mangroves for creating green belts and post-planting monitoring.
• Programmes to raise people’s awareness of the importance of mangroves, e.g. through films, exhibitions, newspapers, study tours in the mangrove forests, establishment of mangrove parks and celebration of Mangrove Conservation Day.
• Enforcement of environmental protection laws.
• Bridging gaps between existing policies and implementation and promoting best practices in collaborative coastal forest protection.
Governments need to be able to act using general principles that can be translated to the great majority of locations for which there are not the resources for local studies. Robustly evidenced global models such as this make that possible. The clock is ticking as mangroves are rapidly lost worldwide. Mangroves are just one aspect of coastal ecosystems and economies – effective management will mean integration with seagrass systems, coral reefs and so on.