India’s Kariyachalli Island has lost more than 80% of its land area and could disappear by 2036. Researchers and residents are fighting erosion and climate change with artificial reefs, coral and seagrass.
Image: R. Satish Babu/AFP
The sun beats down on the island of Kariyachalli as workers bend over wooden frames, securing bright green seagrass shoots. Later, they will anchor the structures to the seafloor. What is happening here off India’s southern coast is a race against time. Seagrass, coral and artificial reefs are intended to help a slowly eroding island survive.
Image: R. Satish Babu/AFP
Kariyachalli is part of a chain of 21 islands off the coast of Tamil Nadu. More than 80% of its land area has been lost — of the 20.85 hectares it had in 1969, only 3.14 hectares remain. According to government estimates, the island could disappear completely by 2036 if no action is taken.
Image: R. Satish Babu/AFP
Erosion and rising sea levels also threaten the mainland’s coastlines. Through artificial reefs, coral transplants and seagrass beds, efforts are underway on Kariyachalli to restore the island’s natural protective barriers and make the coastline more resilient to erosion.
Image: Pavel Nalini Natarajan/AFP
Divers install wooden frames covered with seagrass on the seafloor. A 2004 tsunami showed just how important islands and reefs are. More than 8,000 people died in Tamil Nadu at that time. Researchers believe that coral reefs, seagrass beds and small islands mitigated the force of the waves. “They absorb the impact,” explains marine scientist K. Diraviya Raj.
Image: R. Satish Babu/AFP
The Gulf of Mannar is one of Asia’s most biodiverse marine regions. Corals, endangered dugongs and hundreds of fish species call this area home. But this natural shield has been weakened: coral degradation, overfishing, pollution and warmer seawater have taken their toll. Around Kariyachalli, the reef area shrank from about 500 hectares in 2005 to just 197 hectares in 2021.
Image: R. Satish Babu/AFP
Nature-inspired technology is now helping restore Kariyachalli. About 8,500 artificial reef modules will be placed offshore. These multi-ton structures reduce wave energy and create surfaces for coral growth. Experts are also planting corals and seagrass on the ocean floor to strengthen habitats and protect the island from erosion in the coming years.
Image: R. Satish Babu/AFP
But while volunteers plant new corals, the ocean continues to warm. A severe coral bleaching event in 2024 killed numerous colonies and highlighted just how vulnerable the ecosystem remains. For Raj, the marine scientist, giving up is not an option. The corals must be preserved so that they can adapt to changing climate conditions over the long term and form “the reef of the future.”
Image: R. Satish Babu/AFP
The project is about more than just nature conservation for Devkani. The 47-year-old takes a 25-minute boat ride to the island every day to prepare seagrass frames. In the past, her family had to take out high-interest loans during lean months. “But this year, thanks to the work at sea, we didn’t have to,” she says. Protecting the island thus generates additional income.
Image: R. Satish Babu/AFP
This project is tied to her future, says seagrass worker Martina. “Growing seagrass increases the reproduction of fish and saves the ecosystem,” says the 29-year-old. This benefits people who make their living from the sea. As workers anchor frames in the water, more than just an island’s fate is at stake off Kariyachalli: it’s about habitats, coastal protection and the future.
Image: R. Satish Babu/AFP9 images1 | 99 imageshttps://p.dw.com/p/5Nadj
