Why in news?
Researchers reported on 18 August 2025 that coral reefs in the Gulf of Mannar off the Tamil Nadu coast are recovering after two decades of scientific restoration. The success highlights how sustained efforts can revive degraded marine ecosystems.
Background
Coral reefs are marine ecosystems built by tiny animals that secrete calcium carbonate. Often called the “rainforests of the sea”, they support roughly a quarter of all marine species, protect coastlines from erosion and provide livelihoods through fishing and tourism. The Gulf of Mannar contains a chain of 21 islands with rich coral diversity. In the late 20th century the reefs were badly damaged by coral mining, overfishing, pollution and coastal development. Climate change added further stress through rising sea temperatures and ocean acidification, causing mass bleaching events in 2010 and 2016.
Restoration efforts
- Leadership: The rehabilitation programme has been led by the Suganthi Devadason Marine Research Institute and the Tamil Nadu Forest Department since 2002.
- Methods: Scientists transplanted coral fragments onto artificial structures such as concrete frames, clay pots and specially designed reef modules (triangular and perforated trapezoidal blocks). Fast‑growing species like Acropora were used to kick‑start recovery.
- Scale: Over 50 thousand coral fragments have been transplanted onto more than 5 thousand substrates, restoring roughly 40 thousand square metres of reef.
Outcomes
- High survival: Survival rates range from 55 % to nearly 80 %, with some species showing even higher success.
- Rising biodiversity: The number of young corals settling on the artificial reefs increased dramatically, and fish density rose from about 14 per 250 m² in 2006 to 310 per 250 m² in 2020.
Challenges ahead
- Climate stress: Repeated bleaching from warming seas threatens restored reefs.
- Cost and labour: Coral transplantation and monitoring require trained divers, equipment and long‑term funding.
- Genetic balance: Heavy reliance on fast‑growing species can reduce genetic diversity and make reefs more disease‑prone.
- Ongoing pressures: Plastic pollution, unregulated tourism and coastal projects continue to damage reefs.
Way forward
- Expand restoration: Replicate successful methods in other Indian reef systems such as the Andaman, Lakshadweep and Lakpat reefs.
- Community stewardship: Train local fishing communities to serve as reef guardians, ensuring sustainable fishing and ongoing monitoring.
- Use technology: Deploy drones, remote sensing and artificial intelligence to map reefs, detect bleaching events and monitor health in real time.
- Develop resilient corals: Explore assisted evolution to breed heat‑resistant coral strains and diversify species used in restoration.
- International cooperation: Strengthen partnerships under Sustainable Development Goal 14 and the Paris Agreement to secure funding and share expertise.
Conclusion
The Gulf of Mannar’s coral revival shows that science, policy support and community engagement can bring marine ecosystems back from the brink. Sustained action is essential to protect these underwater treasures and the livelihoods they support.