Ecology of Sunder Van and Chilka lake – A highly diversified Indian Ecosystem
The Sundarbans (Sunder Van) and Chilika Lake represent two of India’s most vital and ecologically diverse coastal ecosystems. While both are located on the eastern coast and influenced by the Bay of Bengal, they offer distinct ecological services—one acting as a massive carbon-absorbing forest barrier and the other as a massive avian and aquatic nursery.
The Sundarbans: The Amphibious Mangrove Realm
The Sundarbans, a UNESCO World Heritage site, is the largest contiguous mangrove forest in the world. It is a transition zone between the saline Bay of Bengal and the freshwater of the Ganges-Brahmaputra delta.
Key Ecological Features:
- Adaptive Flora: The forest is dominated by the Sundari tree (Heritiera fomes). Plants here have evolved specialized features like pneumatophores (aerial roots that breathe in oxygen-depleted mud) and viviparous germination (seeds germinating while still attached to the parent tree).
- Apex Predator: It is the only mangrove forest in the world inhabited by the Royal Bengal Tiger. These tigers have adapted to a semi-aquatic lifestyle, becoming excellent swimmers who hunt fish, crabs, and water monitor lizards.
- Biodiversity Hotspot: Home to the Ganges and Irrawaddy River Dolphins, saltwater crocodiles, and the rare Batagur baska (Northern River Terrapin).
- Environmental Guardian: The mangroves act as a natural “bio shield,” absorbing the energy of cyclonic storms and preventing coastal erosion.
Chilika Lake: The Brackish Water Jewel
Located in Odisha, Chilika is Asia’s largest brackish water lagoon. It is an assemblage of marine, brackish, and freshwater ecosystems, divided into four distinct ecological sectors based on salinity.
Key Ecological Features:
- Avian Paradise: It is the largest wintering ground for migratory birds in the Indian subcontinent. Over a million birds from as far as Siberia and the Caspian Sea flock to the Nalabana Bird Sanctuary (a marshy island within the lake).
- Iconic Fauna: Chilika is the only known habitat in India for the endangered Irrawaddy Dolphin. It also supports the unique Barakudia limbless skink, an endemic species.
- Hydrological Balance: The lake’s salinity fluctuates seasonally. During monsoons, freshwater from 52 rivers lowers salinity, while in summer, the seawater influx through a narrow mouth increases it.
- Livelihood Hub: The lake supports over 200,000 fisherfolk, producing significant yields of prawns, crabs, and fish like the Khainga (Mullet) and Ilis (Hilsa).
Comparison at a Glance
| Feature | Sundarbans (Sunder Van) | Chilika Lake |
| Ecosystem Type | Mangrove Forest / Delta | Brackish Water Lagoon / Estuary |
| Primary Vegetation | Halophytes (Sundari, Garan, Keora) | Seagrass, Algae, and Marshy Grasses |
| Flagship Species | Royal Bengal Tiger | Irrawaddy Dolphin |
| Key Function | Carbon sequestration & Storm buffer | Migratory bird habitat & Fish nursery |
Shared Challenges & Conservation
Despite their resilience, both ecosystems face critical threats:
- Siltation: In Chilika, the choking of the lake mouth by silt reduces seawater exchange; in Sundarbans, reduced freshwater flow due to upstream dams increases salinity.
- Climate Change: Rising sea levels threaten to submerge low-lying islands in the Sundarbans, while extreme cyclones damage the fragile habitats of both regions.
- Anthropogenic Pressure: Illegal prawn farming, overfishing, and pollution from nearby industrial zones disrupt the food chain.
Insight: While the Sundarbans protects the land from the sea, Chilika acts as a bridge for species migrating between the sea and freshwater. Their health is a direct barometer for the ecological stability of the Bay of Bengal coastline.