WHAT ARE INVASIVE ALIEN SPECIES? The Convention on Biological Diversity (CBD) defines Invasive Alien Species (IAS) as “species whose introduction and/or spread outside their natural past or present distribution threatens biological diversity”. WHICH KIND OF SPECIES ARE INCLUDED? These include animals, plants, fungi, and even microorganisms, and can influence all kinds of ecosystems. CHARACTERISTICS OF INVASIVE ALIEN SPECIES The CBD, the United Nations’ global treaty on safeguarding biological diversity, sums up characteristics of IAS as follows: “arrive, survive and thrive.” This means that these species:
  • Need an introduction either through natural or human intervention (Arrive)
  • Survive on native food resources, (Survive)
  • Reproduce at a fast rate and edge out native species in the competition over resources. (Thrive)

INVASIVE ALIEN SPECIES UNDER WILDLIFE PROTECTION ACT

Invasive Alien Species are defined as “species of animal or plant which is not native to India, and whose introduction or spread may threaten or adversely impact wildlife or its habitat.” Crucially, this leaves out species within India which might be invasive to a particular region — like the chital in Andamans, which are protected in mainland India, but have become a menace in the island chain. Chitals in Andaman 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 WII.

WHEN WAS CHITAL INTRODUCED IN ANDAMAN?

Chital, Native to mainland India, were introduced to the tiny island (0.3 sq km small) by the british in the early 20th century. having no natural predators or competitors, and being good swimmers, chital swiftly spread across the Andamans. HOW HAVE THEY IMPACTED? 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.

HOW DO INVASIVE SPECIES DOMINATE FLORA & FAUNA?

  • K sivakumar, a professor in the Department of Ecology and Environmental Sciences, Pondicherry University, said that 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, the African catfish has been known to prey on water fowls and migratory birds.
    • The case of Chital in Andaman also falls in this category.
THE ECONOMIC IMPACT OF INVASIVE ALIEN SPECIES In September 2023, the UN-founded Intergovernmental Platform on Biodiversity and Ecosystem Services (IPBES) brought out an exhaustive report on invasive species. The report showed that around 37,000 established alien species were introduced worldwide, with roughly 200 new alien species introduced each year.
  • Along with causing dramatic changes to biodiversity and ecosystems, the global economic cost of ias was over $423 billion annually in 2019.
  • As per India’s National Biodiversity Action Plan of 2019, published by the National Biodiversity Authority, the cotton mealy bug (Phenacoccus solenopsis) is an invasive species native to north america, which has severely affected cotton crops in the Deccan, leading to yield losses.