How invasive species threaten natural ecosystems

Description

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Context

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

Definition of IAS and issues with the definition

In India, the legal definition of IAS under the Wildlife Protection Act, 1972 (amended in 2022), is narrower.
They 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 that 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.

Impacts of invasive species in India

Impact native flora and fauna

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.

Examples-

In Keoladeo Park, Bharatpur in Rajasthan, which is a UNESCO World Heritage site, the African catfish has been known to prey on waterfowls and migratory birds as well.
The proliferation of chital in the Andamans has affected the regeneration of native vegetation, as the deer are known to consume seeds and seedlings.

Economic Impacts

As per Intergovernmental Platform on Biodiversity and Ecosystem Services (IPBES) brought out an exhaustive report on invasive species. Along with causing dramatic changes to biodiversity and ecosystems, the global economic cost of IAS was over $423 billion annually in 2019. These costs arise out of the damage IAS inflicts on an area’s natural ecosystem
For example, 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.

Other impacts

Predation and Herbivory: Many invasive species are predators or herbivores that lack natural predators or controls in their new environments. As a result, they can decimate populations of native species, leading to cascading effects throughout the food web. For example, invasive species like the cane toad in Australia or the brown tree snake in Guam have caused significant declines in native wildlife.
Habitat Degradation: Invasive species can cause habitat degradation through activities such as burrowing, grazing, or altering soil composition. This degradation can have far-reaching consequences for native plant and animal communities, as well as ecosystem services such as soil fertility and water quality.
Disease Transmission: Some invasive species can introduce new diseases to native populations, causing epidemics or population declines. For example, the chytrid fungus, introduced by the international amphibian trade, has led to massive declines in amphibian populations worldwide.
Human Health Risks: Invasive species can pose risks to human health through direct contact, disease transmission, or allergenic properties. For example, invasive plants like poison ivy or giant hogweed can cause skin irritation, while invasive mosquitoes can transmit diseases such as malaria, dengue fever, and Zika virus.
Cultural and Societal Impacts: Invasive species can also impact cultural practices and traditional knowledge systems. For indigenous communities, invasive species may disrupt customary practices such as hunting, fishing, or gathering, leading to loss of cultural identity and heritage. Additionally, invasive species can impact recreational activities such as hiking, birdwatching, or gardening, diminishing the quality of life for affected communities.

Initiatives taken at the National Level

Legal Framework: Various laws and regulations have been enhanced for the conservation of biological diversity to aid in the management of threats of invasive species. e.g. Biological Diversity Act of 2002, and the National Biodiversity Authority Act of 2002.
National Action Plan on Invasive Alien Species (NAPINVAS): The Ministry of Environment, Forest and Climate Change (MoEFCC) launched the National Action Plan on Invasive Alien Species (NAPINVAS) plan, which focuses on the prevention, early detection, control, and management of invasive species.
The National Invasive Species Information Center (NISIC) in India provides information and resources on invasive species in India.
The Himalayan Environmental Foundation has been working to control invasive species like Lantana camara in the Himalayas.

International Instruments and Programmes on Invasive Species:

Kunming-Montreal Global Biodiversity Framework (2022): Governments have committed to reducing the rate of introduction and establishment of invasive alien species by at least 50% by 2030.
Convention on Biological Diversity (CBD - 1992): Adopted at the 1992 Earth Summit in Rio de Janeiro, it recognizes invasive alien species as a major threat to the environment, second only to habitat destruction.
Convention on the Conservation of Migratory Species (CMS - 1979): This intergovernmental treaty aims to conserve migratory species and includes measures to control or eliminate invasive alien species already present.
Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES - 1975): Focuses on ensuring international trade does not threaten the survival of wild animals and plants; it also considers the impact of invasive species involved in trade.

Examples of Invasive Alien Species 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.

Some of the prominent examples of Invasive Alien Species in India are:

Lantana (Lantana Camara)

●Lantana is a highly invasive shrub that forms dense thickets, and outcompeting native vegetation. It is found in various parts of India, particularly in the Western Ghats.

Water Hyacinth (Eichhornia Crassipes)

●This aquatic plant proliferates, forming dense mats on water surfaces. It is common in water bodies across India.

Prosopis juliflora (Vilayati Keekar)

●This invasive plant has spread rapidly, leading to the degradation of native ecosystems. It is found in arid and semi-arid regions across India.

Needle Bush

●Its origin is from South America. It is distributed throughout India. It is found in thorny scrub and dry degraded forests and often creates close thickets.

Black Wattle

●Its origin is from South East Australia. It is distributed throughout India. It was introduced for afforestation in the Western Ghats region. It regenerates rapidly after fire and forms dense thickets.

Goat Weed

●Its origin is from America. It is distributed throughout India. It acts as an aggressive colonizer. Its troublesome weed in gardens, cultivated fields, and forests affects the native species.