The National Aeronautics and Space Administration (NASA) recently undertook a study highlighting the loss of mangrove cover on Katchal Island, part of India’s Nicobar archipelago. This report also detailed global mangrove losses over the past two decades. Mangroves are a crucial part of coastal ecosystems due to their resilience in extreme conditions and notable contributions to biodiversity.
Understanding Mangroves
Mangroves are tropical plants known for their adaptability to loose, wet soils, saltwater, and periodic submersion by tides. They thrive in harsh environments with high salt and low oxygen concentrations. To facilitate respiration, mangroves develop special roots, known as pneumatophores, as oxygen in their soil is often limited or non-existent.
These tree-like plants possess a distinct survival technique. Their seeds germinate while attached to the parent tree, growing into a propagule—a vegetative structure capable of giving rise to a new plant.
Mangroves play a pivotal role in the ecosystem by trapping and cycling organic materials, chemical elements, and nutrients in coastal areas. They serve as a primary food chain resource for marine organisms and offer habitat and nursery grounds for diverse marine species. Additionally, by reducing wind and wave action in shallow shoreline areas, mangroves act as natural storm buffers.
Mangrove Cover: Global and Indian Perspectives
Globally, mangroves cover approximately 150,000 sq kms, with Asia boasting the largest number. South Asia accounts for 6.8% of the world’s mangrove cover. Interestingly, India contributes 45.8% of the total mangrove cover in South Asia, equivalent to 4992 sq. kms, which is 0.15% of the country’s total geographical area. The Sundarbans in West Bengal, a UNESCO World Heritage Site and home to the Royal Bengal tiger, Gangetic dolphins and Estuarine crocodiles, is the world’s largest mangrove forest region.
India’s second-largest mangrove forest is found in Bhitarkanika, Odisha, formed by the delta of the Brahmani and Baitarani rivers. This is one of India’s most significant Ramsar wetlands. The Godavari-Krishna mangroves span from Odisha to Tamil Nadu on India’s eastern coastline.
Findings from NASA’s Study
NASA’s study revealed the extent of tidal wetland loss between 1992 and 2019 on Katchal Island, with mangroves experiencing the highest ratio of loss among examined tidal wetlands, which also included tidal flats and marshes. A net decrease of 3,700 sq kms was observed from 1999 to 2019. However, there were also gains of 2,100 sq kms, indicating the dynamism of these ecosystems.
The reasons for the loss include natural causes such as earthquakes and tsunamis, other factors like sea-level rise, shoreline erosion, storms, altered sediment flow, and subsidence, and human-induced activities. About 27% of losses and gains were directly attributed to human activity, including development, water diversion projects, and land conversion for agriculture or aquaculture.
There appears to be little likelihood of the previous mangrove cover being fully restored, although there has been an increase in their numbers in other areas due to their propagation through propagules.
Future Conservation Strategies
The emphasis moving forward should be on linking conservation efforts with broader socio-environmental perspectives, involving active community engagement, enhancing environmental security, and minimizing the risk from natural disasters. Holistic adoption of such anticipatory adaptation measures could provide the key to successful and effective ecosystem management.
