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Invasive Alien Species
Trade tariffs close borders but may open doors to invasive alien species
Context: New trade agreements and connections between previously unlinked countries can increase the risk of invasive alien species spreading across continents. These species may travel with goods, plants, or animals, disrupting local ecosystems.
What are Invasive Alien Species (IAS)?
- Invasive alien species are organisms—plants, animals, pathogens, or other life forms—that are introduced outside their natural habitats, where they cause harm to biodiversity, ecosystems, the economy, or human health. They are recognised as one of the greatest threats to global biodiversity.
- According to the Convention on Biological Diversity (CBD), since the 17th century, invasive alien species have been responsible for nearly 40% of all documented animal extinctions.
The Root Causes
- Global trade, including ballast water and plant shipments, continues to spread non-native species.
- Weak quarantine and inspection, especially in developing countries, let IAS slip in.
- Habitat fragmentation, deforestation, and infrastructure like roads degrade ecosystems and make them more vulnerable.
- Climate change is expanding the geographic suitability for invaders; for example, warmer temperatures in Jharkhand accelerate Lantana’s spread.
Globalisation and the Invasion Pathways
- The rise in global trade, travel, tourism, and transport has created numerous pathways for the introduction and spread of invasive species.
- Species introductions may be intentional (such as for ornamental purposes or biological control) or accidental (through contaminated goods or ballast water from ships). For instance:
- Zebra mussels (Dreissena polymorpha), native to the Caspian and Black Seas, now disrupt fisheries, damage infrastructure, and outcompete native molluscs in North America.
- Water hyacinth (Eichhornia crassipes), from the Amazon basin, has spread to over 50 countries across five continents. It clogs waterways, kills aquatic life, affects local livelihoods, and creates breeding grounds for disease vectors.
- The ship rat (Rattus rattus), native to the Indian subcontinent, has caused extinctions of island birds and is now widespread worldwide.
- Pathogens like avian influenza A (H5N1) exemplify how invasive species can severely affect both human and animal populations across temperate and tropical regions.
The Case of the Giant African Snail
- Around 1847, the giant African snail (Lissachatina fulica) arrived in colonial Calcutta, likely hidden in plant crates or trade goods from East Africa.
- Initially admired for its size and shell, the snail became India’s most persistent invasive alien species.
- Benefiting from India’s warm, humid climate and lack of natural predators, the snail rapidly spread from Bengal to the Western Ghats, devastating crops and ornamental plants.
It displaced native snails, altered soil ecosystems, and became a carrier of rat lungworm, posing health risks to humans and wildlife.
The Economic and Ecological Cost
- A 2022 study estimated that India lost $127.3 billion (₹830 crore) to invasive alien species over the past 60 years—the second-highest national loss globally, behind only the United States. Yet, this figure is based on just 10 species, out of over 2,000 alien species known in the country.
- Globally, annual environmental losses from invasive species in countries like the U.S., U.K., Australia, South Africa, India, and Brazil are estimated to exceed US$100 billion.
- The economic toll is even higher for aquatic and semi-aquatic invaders, which damage water infrastructure, public health systems, and fisheries. One of the most costly culprits is the yellow fever mosquito, which threatens public health and incurs high control costs.
Policy and Governance Issues
- Regulatory Gaps: India lacks a national policy for invasive alien species management. A committee formed in 2021 under the Indian Council of Forestry Research and Education (ICFRE) to draft a policy has yet to release any document.
- Legal Definition Gaps: Under the 2022 Wildlife Protection Act, invasive alien species are defined based on political boundaries, not ecological relevance. This excludes species like Pogostemon, though invasive in non-native regions.
- Conservationists argue for ecological region-based definitions, aligned with the UN Convention on Biological Diversity (CBD).
- Removal efforts—using CAMPA, Project Tiger, and state funding—are costly and often lack scientific rigor. Lack of sustained post-removal monitoring makes eradication efforts “largely ineffective” . Karnataka’s Bandipur reserve targets 10 ha/year of removal but faces manpower and regrowth issues.
