Vaan Island artificial reef restoration yields Rs 61.67 crore socio-ecological benefits

Key facts

• Vaan Island in the Gulf of Mannar shrank 92% from about 20 hectares in 1969 to 1.53 hectares by 2015 due to coral mining, sea-level rise and reef degradation.
• Scientists deployed 10,600 artificial reef modules around Vaan Island starting in 2015 under the Tamil Nadu Coastal Restoration Mission.
• Post-restoration, the island area expanded to over 2.3 hectares and now supports an average of 81 coral colonies per module.
• Reef-associated fish density rose eight-fold from 106 to 875 individuals per hectare, and 26 native plant species were preserved.
• The project generated socio-ecological benefits worth Rs 61.67 crore against an inflation-adjusted cost of Rs 26.37 crore, yielding a benefit-cost ratio of 2.34.
• Mainland coastal protection contributed Rs 28.57 crore (46% of total value), sediment trapping and nutrient cycling Rs 13 crore, and fisheries gains Rs 13.43 crore.
• Tamil Nadu has begun a Rs 50 crore restoration project for Kariyachalli Island, with artificial reef deployment to finish within a month.