A. What is an Invasive Alien Species?

An invasive alien species is a non-native organism introduced outside its natural range that establishes and spreads, causing or threatening ecological, economic or social harm.

• Alien species: An organism occurring outside its natural range due to human introduction.
• Invasive species: An introduced organism that spreads and causes, or is likely to cause, harm.

Important: Not all alien species are invasive.

Examples include water hyacinth in many freshwater ecosystems and invasive cordgrass in certain coastal wetlands.

B. What is Cordgrass?

Scientific context: Cordgrass commonly refers to plants in the genus Spartina.

Cordgrass is a group of grasses adapted to coastal and salt-marsh environments. Some species have been introduced for erosion control, sediment stabilisation and land reclamation.

However, certain introduced cordgrass species can spread aggressively across tidal mudflats, creating dense stands that alter the structure and functioning of coastal ecosystems.

C. What Are Tidal Mudflats?

Tidal mudflats are low-lying coastal areas consisting mainly of fine sediment that are exposed at low tide and covered by water at high tide.

Ecological importance:

1. Provide feeding grounds for migratory shorebirds.
2. Support worms, molluscs, crustaceans and other invertebrates.
3. Contribute to nutrient cycling and coastal food webs.
4. Store carbon under suitable environmental conditions.
5. Support fisheries and other ecosystem services.
6. Dense invasive vegetation can transform open mudflats and change the availability of feeding and breeding habitats.

D. What Is Ecological Restoration?

Ecological restoration is the process of assisting the recovery of a degraded, damaged or destroyed ecosystem.

In the case of invaded wetlands, restoration may involve:

1. Removing or controlling invasive vegetation.
2. Re-establishing native plant communities.
3. Restoring natural tidal flows and sediment processes.
4. Monitoring biodiversity and ecosystem recovery.
5. Preventing reinvasion through long-term management.

Simply removing an invasive species may not be sufficient if the original habitat conditions are not restored.

E. Why Can Invasive Species Be Difficult to Eradicate?

1. Rapid growth and extensive reproduction.
2. Seeds or plant fragments spreading through water, wind or human activity.
3. Regrowth from surviving underground plant parts.
4. Large areas of infestation and difficult terrain.
5. High costs of repeated treatment and ecological monitoring.
6. Risk of harming native species through poorly planned control measures.
7. Management therefore often combines prevention, early detection, targeted removal and long-term monitoring.

F. What Is the Precautionary Principle?

The precautionary principle states that a lack of complete scientific certainty should not be used as a reason to postpone proportionate measures to prevent the risk of serious or irreversible environmental damage.

Application: Before introducing a non-native plant for grazing, erosion control or land reclamation, authorities should assess its invasive potential, examine alternatives and establish monitoring mechanisms.

G. International Framework: Convention on Biological Diversity

The Convention on Biological Diversity (CBD) provides an international framework for biodiversity conservation, sustainable use and fair and equitable sharing of benefits arising from genetic resources.

Its Article 8(h) calls on parties, as far as possible and as appropriate, to prevent the introduction of, control or eradicate alien species that threaten ecosystems, habitats or species.

The Kunming–Montreal Global Biodiversity Framework also includes Target 6, which focuses on reducing the introduction and establishment of invasive alien species and minimising their impacts.

6. Relevance for UPSC

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• GS Paper III: Biodiversity, environmental conservation, ecosystem restoration and invasive alien species.
• GS Paper I: Coastal landforms, wetlands, tides and coastal ecology.
• GS Paper II: International environmental conventions and biodiversity governance.
• Essay: Development versus conservation; unintended consequences of human intervention in nature.

Key takeaway: The cordgrass episode demonstrates that an intervention intended to improve land productivity can cause long-term ecological damage. Prevention, early detection and ecosystem-based management are often more effective than decades of eradication work.