Why In News?

Kariyachalli Island, one of the 21 islands in the Gulf of Mannar Marine National Park, is facing severe coastal erosion and the threat of submergence by 2036. 

What Is Kariyachalli Island?

  • Location: It is an uninhabited coral island in the Gulf of Mannar, off the southeastern coast of India, between Rameswaram and Thoothukudi in Tamil Nadu.

  • Protected Area: It forms part of the Gulf of Mannar Marine National Park, which contains a chain of 21 coral islands.

  • Marine Ecosystem: The island is surrounded by coral reefs and seagrass meadows that support marine biodiversity and protect the coastline from wave action.

  • Geomorphological Features: It possesses beaches, sand dunes, spits, sandy plains and strandlines.

  • Ecological Importance: Its surrounding marine habitats provide breeding and feeding grounds for fish and other marine organisms.

  • Livelihood Significance: Coral reefs and seagrass ecosystems support local fishing communities through fisheries productivity and coastal protection.

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  • Climate Significance: Coral reefs and seagrass meadows provide natural coastal protection and contribute to carbon sequestration.

Why Is Kariyachalli Island Shrinking?

  • Coastal Erosion: Persistent wave action removes sand and sediment from the island, reducing its landmass.

  • Sea-Level Rise: Rising sea levels increase the vulnerability of low-lying islands to coastal inundation and erosion.

  • Coral Reef Degradation: Damaged coral reefs lose their ability to dissipate wave energy, exposing the island to stronger wave action.

  • Coral Bleaching: Elevated sea temperatures cause corals to expel their symbiotic algae, reducing coral health and increasing reef vulnerability.

  • Seagrass Degradation: Loss of seagrass reduces sediment stabilisation and weakens the ecosystem's capacity to retain carbon.

  • Human-Induced Pressure: Historical coral mining and other coastal disturbances have weakened the natural protective system.

How Much Landmass Has Kariyachalli Island Lost?

  • Original Area (1969): Approximately 20.85 hectares.

  • Area in 2018: Approximately 5.97 hectares.

  • Area in 2025: Approximately 3.14 hectares at high tide, according to the latest reported assessment.

  • Overall Reduction: The island has lost more than 85% of its original landmass compared with 1969.

  • Submergence Projection: Earlier scientific assessments warned that the island could disappear by 2036 if the existing erosion trend continued. This is a projection, not a certain outcome.  

What Is the Tamil Nadu SHORE Project?

Tamil Nadu Sustainably Harnessing Ocean Resources (TN-SHORE) is an initiative focused on sustainable ocean-resource management and coastal resilience.

  • Financial Support: The programme receives support from the World Bank.

  • Implementing Institutions: The Tamil Nadu government, particularly its Environment, Climate Change and Forests Department, works with technical institutions including IIT Madras and the Suganthi Devadason Marine Research Institute (SDMRI).

  • Primary Objective: Protect vulnerable coastal ecosystems, restore degraded marine habitats and strengthen the climate resilience of coastal communities.

  • Kariyachalli Intervention: The island restoration programme combines artificial reef deployment, coral rehabilitation, seagrass restoration and blue-carbon assessment.  

Source: NEWINDIANEXPRESS

PRACTICE QUESTION

Q. With reference to Kariyachalli Island, consider the following statements:

  1. It is located in the Gulf of Mannar Marine National Park in Tamil Nadu.

  2. It is one of the 21 coral islands in the Gulf of Mannar.

  3. Its restoration is being undertaken under the TN-SHORE initiative.

  4. It is an inhabited island located in the Arabian Sea.

Which of the statements given above is/are correct?

(a) 1 and 2 only

(b) 1, 2 and 3 only

(c) 2, 3 and 4 only

(d) 1, 2, 3 and 4

Answer: (b) 1, 2 and 3 only

Explanation:

Statement 1 is correct: Kariyachalli Island is located off the coast of Thoothukudi in Tamil Nadu, within the Gulf of Mannar Marine National Park.

Statement 2 is correct: It is one of the 21 coral islands forming the island chain of the Gulf of Mannar Marine National Park.

Statement 3 is correct: Rapid coastal erosion and coral degradation have caused the island to shrink prompting a large-scale ecological restoration effort using artificial reef modules and seagrass planting under the World Bank-assisted TN-SHORE (Tamil Nadu Sustainably Harnessing Ocean Resources) project.

Statement 4 is incorrect: Kariyachalli is an uninhabited island located in the Gulf of Mannar (part of the Bay of Bengal / Laccadive Sea off India's southeastern coast), not in the Arabian Sea.