Why is it in the News?

In a bid to manage the teeming population of chital (spotted deer) in Ross Island (officially known as the Netaji Subhash Chandra Bose Island), the Andaman and Nicobar Islands administration recently sought help from the Wildlife Institute of India.

What are Invasive Alien Species (IAS)?

• According to the Convention on Biological Diversity (CBD), Invasive alien species are plants, animals, pathogens, and other organisms that are non-native to an ecosystem, and which may cause economic or environmental harm or adversely affect human health.
• In particular, they impact adversely upon biodiversity, including the decline or elimination of native species - through competition, predation, or transmission of pathogens - and the disruption of local ecosystems and ecosystem functions.
• Invasive alien species, introduced and/or spread outside their natural habitats, have affected native biodiversity in almost every ecosystem type on Earth and are one of the greatest threats to biodiversity.
• Since the 17th century, invasive alien species have contributed to nearly 40% of all animal extinctions for which the cause is known (CBD, 2006).
• The problem continues to grow at great socio-economic, health, and ecological costs around the world.
• Invasive alien species exacerbate poverty and threaten development through their impact on agriculture, forestry, fisheries, and natural systems, which are an important basis of people’s livelihoods in developing countries.
• This damage is aggravated by climate change, pollution, habitat loss, and human-induced disturbance.

What are Some Examples of Invasive Wildlife in India?

• The list of invasive wildlife in India is dominated by certain species of fish such as the African catfish, Nile tilapia, red-bellied piranha, and alligator gar, and turtle species such as the red-eared slider.
  • The red-eared slider, for instance, is a favorite among India’s exotic pet owners, and many have been abandoned in local water bodies.
  • This turtle, native to North America, notoriously edges out local freshwater species, owing to its fast rates of reproduction, and the following competition for food.
• With regards to species of fish, many were introduced in India to feed the demand for those maintaining aquariums.
  • For instance, the African catfish was brought over from Bangladesh specifically for aquaculture purposes. “
  • The occurrence of C gariepinus (the species’ scientific name) has been reported from several inland systems of India including the mighty rivers like Ganga, Yamuna, Sutlej, Godavari, Periyar River, and the lakes like Vembanad Lake.

How do IAS Impact Native Flora and Fauna?

• The invasive species act as disruptors in the food chain and disturb the balance of the ecosystem.
• In habitats where there is no competition, invasive species can dominate the entire ecosystem
  • For instance, “in Keoladeo Park, Bharatpur in Rajasthan, which is a UNESCO World Heritage site, the African catfish have been known to prey on waterfowls and migratory birds as well.
• Studies have shown that the proliferation of chital in the Andamans has affected the regeneration of native vegetation, as the deer are known to consume seeds and seedlings.