Blue carbon ecosystems are coastal and marine ecosystems that capture and store large amounts of carbon in their biomass and sediments. The main blue carbon ecosystems are mangroves, seagrass meadows and salt marshes.
They are important because they combine climate mitigation, coastal protection, biodiversity conservation and livelihood support. Unlike many terrestrial forests, blue carbon ecosystems store a major share of carbon in waterlogged soils and sediments, where decomposition is slow and carbon can remain locked for centuries.
Major Types
The three major blue carbon ecosystems are mangroves, seagrasses and salt marshes.
Mangroves are salt-tolerant forests found in tropical and subtropical coastal zones. In India, important mangrove areas include the Sundarbans, Bhitarkanika, Mahanadi delta, Godavari-Krishna delta, Pichavaram, Gulf of Kachchh and Andaman-Nicobar Islands.
Seagrass meadows are flowering plants found in shallow coastal waters. They are important in areas such as the Gulf of Mannar, Palk Bay, Lakshadweep and Andaman-Nicobar waters.
Salt marshes are coastal wetlands found in intertidal zones. They are more common in temperate regions but also occur in some Indian coastal landscapes, especially in mudflat and estuarine areas.
Climate and Ecological Importance
Blue carbon ecosystems are among the most efficient natural carbon sinks. They capture carbon through plant growth and store it in sediments below the surface.
Their importance is not limited to carbon. They also protect coasts from erosion, storm surges and cyclones. Mangroves, for example, reduce wave energy and act as natural buffers during extreme weather events.
They also support marine biodiversity. Mangroves and seagrasses act as nursery grounds for fish, prawns, crabs and molluscs. This makes them directly linked with coastal fisheries and local livelihoods.
Their major functions include:
- long-term carbon storage
- coastal protection from storms and erosion
- nursery habitat for fish and shellfish
- support to coastal livelihoods
- water filtration and sediment trapping
- protection of deltaic and estuarine ecosystems
This makes blue carbon ecosystems important for both climate policy and disaster-risk reduction.
India’s Relevance
India has a long coastline and several important mangrove, estuarine and seagrass ecosystems. Therefore, blue carbon is directly relevant to India’s climate and coastal management strategy.
The India State of Forest Report 2023 recorded India’s mangrove cover at 4,991.68 sq km, showing a small decrease compared to the previous assessment. The Sundarbans remain India’s largest mangrove area, followed by Gujarat and Andaman & Nicobar Islands among major mangrove regions.
India’s blue carbon potential is important for:
- Nationally Determined Contributions under climate policy
- coastal resilience under cyclone-prone conditions
- fisheries-based livelihoods
- wetland and mangrove conservation
- climate finance and carbon markets
- disaster-risk reduction in coastal states
Blue carbon is also linked with schemes and programmes such as MISHTI, which focuses on mangrove plantation along the coastline and salt pan lands.
Specific Threats and Concerns
The main threat to blue carbon ecosystems is land-use change in coastal areas.
Mangroves are often affected by aquaculture expansion, port development, coastal infrastructure, pollution, river-flow changes and encroachment. Once mangrove soils are disturbed, stored carbon can be released back into the atmosphere.
Seagrass ecosystems face pressure from dredging, trawling, coastal pollution, sedimentation and declining water clarity. Since seagrasses need sunlight for photosynthesis, turbid and polluted waters can seriously damage them.
Salt marshes are vulnerable to reclamation, coastal construction and sea-level rise.
The biggest concern is that degradation of blue carbon ecosystems creates a double loss: carbon storage capacity is reduced, and previously stored carbon may be released.
Conclusion
Blue carbon ecosystems are coastal carbon sinks such as mangroves, seagrasses and salt marshes.
They are important because they store carbon, protect coasts, support fisheries and strengthen climate resilience.
For India, blue carbon ecosystems are especially significant because of the country’s long coastline, cyclone-prone deltas, mangrove-rich regions and coastal livelihood dependence. Their protection should be seen not only as biodiversity conservation, but also as climate action and coastal security.
