- An alien species refers to one that has been introduced outside its native range.
- According to experts, alien species become “invasive” when they are unintentionally or intentionally transported beyond their usual habitats, where they outcompete local species and disrupt the ecological balance.
- Phenotypic plasticity, or the ability to adapt physiologically to new conditions, is a common trait among invasive species.
- These species often exhibit characteristics such as rapid reproduction and growth, high dispersal ability, adaptability to various food sources and environmental conditions, and a capacity for quick reproduction.
- Invasive alien species, being foreign to the ecosystem, can cause significant harm to the economy, environment, and even human health.
- Their impact extends to crucial sectors like agriculture, forestry, fisheries, and natural systems, which are vital for the livelihoods of people in developing countries.
- Invasive alien species exacerbate poverty and pose threats to overall development by damaging these essential elements.
- The detrimental effects are further intensified by climate change, pollution, habitat loss, and human-induced disturbances.
INTRODUCTION OF INVASIVE ALIEN SPECIES
Invasive alien species pose a significant threat to ecosystems by outcompeting native species and disrupting ecological balance. Here are some examples of common invasive alien species and the means by which they are introduced:
African Apple Snail (Achatina Fulica):
- Origin: Originally discovered in the Andaman and Nicobar Islands.
- Spread: Now widespread across India.
- Impact: Endangers the habitat of indigenous species.
Papaya Mealy Bug (Paracoccus marginatus):
- Origin: Native to Mexico and Central America.
- Impact: Damaged papaya crops in Assam, West Bengal, and Tamil Nadu.
Cotton Mealy Bug (Phenacoccus Solenopsis):
- Origin: Native to North America.
- Impact: Significantly negatively affected Deccan cotton production.
Amazon Sailfin Catfish (Pterygoplichthys pardalis):
- Impact: Decimated fish populations in Kolkata’s wetlands.
Human-Related Factors Contributing to the Introduction of Invasive Species:
Wildlife Trade:
- Overview: Exotic plants and animals are traded globally, contributing significantly to the introduction of invasive species.
- Impact: The illegal wildlife trade, estimated to generate 10 to 20 billion euros annually by the Worldwide Fund for Nature (WWF), poses a substantial threat to ecosystems.
Tourism:
- Overview: Traveling to different nations, whether intentional or inadvertent, plays a role in the spread of invasive alien species.
- Impact: Tourists may unintentionally transport invasive species, affecting local ecosystems and biodiversity.
Hunting and Fishing:
- Overview: Historical hunting and fishing activities have introduced various species to new environments.
- Examples: Barbary sheep and catfish were introduced to significant parts of Europe through hunting and fishing practices.
Transport and International Trade:
- Overview: Invasive species often travel undetected in ship hulls, cargo holds, and aircraft during transportation and international trade.
- Impact: Global movement of goods facilitates the unintentional spread of invasive species to different regions.
Abandoned Pets:
- Overview: Escaped or abandoned exotic pets can establish populations in non-native ecosystems.
- Examples: Raccoons, monk parakeets, and red-eared slider turtles are instances of abandoned pets that have become invasive species.
Crops and Fur Industry:
- The horticulture and clothing industries serve as entry points for invasive species.
- Examples: The American mink in Europe and the upright prickly pear in Africa and Oceania have been introduced through these industries.
INVASIVE SPECIES AND CLIMATE CHANGE
Invasive Alien Species (IAS) constitute a significant factor in the loss of biodiversity, species extinction, and pose a global threat to food security. The intricate relationship between IAS and climate change manifests in various ways:
- Spread and Establishment:
- Climate change facilitates the proliferation and establishment of numerous alien species, presenting new opportunities for them to become invasive.
- Resilience and Vulnerability:
- Natural habitats, agricultural systems, and urban areas may experience reduced resilience to climate change due to IAS, while climate change, in turn, compromises habitats’ resistance to biological invasions.
- Inclusion in Policies:
- IAS must be integral to climate change policies, encompassing preventive biosecurity measures against their spread and swift responses for monitoring and eradicating potential invasive species.
- Extreme Climatic Events:
- IAS can be transported to new areas and encounter reduced habitat resistance during extreme climatic events like hurricanes, floods, and droughts linked to climate change.
- New Avenues for Introduction:
- The melting ice caps, resulting from climate change, create novel routes like Arctic shipping, significantly decreasing travel time between Asia and Europe and elevating the chances of alien species surviving the journey.
- Shifts in Distribution:
- With climate warming, numerous IAS exhibit the capability to swiftly expand to higher latitudes and altitudes, surpassing the adaptability of native species.
- Success of New Invaders:
- Climate change may enable the success of alien species introduced by humans, which had previously failed to establish themselves, leading to the emergence of new invaders.
- Habitat Suitability Changes:
- The changing climate will render specific habitats, like temperate forests and freshwater systems, more suitable for the thriving of alien species.
Harmful Effects of Invasive Alien Species:
Ecological Impact:
- Direct Alteration of Ecosystems:
- Description: By competing with indigenous species for resources, IAS directly reshape the community structure and species composition of native ecosystems.
- Consequence: This competition can lead to shifts in species dominance and overall ecosystem dynamics.
- Indirect Ecological Effects:
- Description: IAS can have significant indirect effects on nutrient cycling, ecosystem function, and ecological relationships among native species.
- Consequence: Interactions such as shared natural enemies, intermediaries, or shared resources can result in cascading effects that are challenging to detect and predict.
- Complex Consequences:
- Description: Combined effects of multiple invasive species in an ecosystem can lead to large and complex consequences.
- Consequence: The interplay of various invasive species can create intricate ecological challenges, making it difficult to mitigate and manage the overall impact.
- Biotic Invasion and Biodiversity Loss:
- Description: Biotic invasion, ranked among the top five causes of global biodiversity loss, is increasing due to tourism and globalization.
- Consequence: Through competitive exclusion, niche displacement, or hybridization, invasive species may drive local native species to extinction, leading to potential homogenization of global wildlife and plant species.
Environmental Impact:
- Direct Impact on Human Health:
- Description: IAS can directly impact human health by introducing infectious diseases, often imported by travelers or vectored by exotic bird, rodent, and insect species.
- Consequence: Diseases transmitted by invasive species can have widespread health implications for both humans and wildlife.
- Indirect Health Effects:
- Description: Invasive species contribute to indirect health effects as pesticides and herbicides used in their control infiltrate water and soil.
- Consequence: These chemical substances can have lasting effects on public health, with the potential to contaminate soil and water resources.
- Vector-Mediated Diseases:
- Description: Introduced species like birds, rodents, and insects act as carriers and reservoirs for human diseases.
- Consequence: Vectors such as mosquitoes and fleas have historically spread diseases like typhus, yellow fever, malaria, and bubonic plague.
- Spread of Invasive Diseases:
- Description: Invasive diseases, exemplified by the spread of the West Nile virus, have detrimental effects on humans, birds, animals, and reptiles.
- Consequence: Such outbreaks highlight the interconnectedness between invasive species and the transmission of diseases.
Economic Impact:
- Global Cost of Management:
- Description: Worldwide, an annual cost of 1.4 trillion dollars is incurred to manage and eradicate invasive species.
- Consequence: The economic burden associated with invasive species management underscores the need for effective prevention and control measures.
- Local Economic Impacts:
- Description: Some invaders may negatively impact local economies.
- Consequence: Early detection and swift action are crucial to minimizing costs associated with invasive species management.
- Cost-Benefit Considerations:
- Description: There is a cost-benefit consideration in managing invasive species, where the expense of searching for and controlling a tiny invasive population may outweigh the initial cost.
- Consequence: Focusing efforts on invasive populations causing harm is sometimes deemed more cost-effective than extensive searches for smaller populations.
Invasive Species in India:
India stands as a global biodiversity hotspot, contributing significantly to the world’s documented species. Despite covering only 2.4% of the world’s land area, India accounts for 8% of the world’s biodiversity, as estimated by the World Conservation Monitoring Centre (WCMC), with 1,604,000 documented species globally.
- Floral Diversity:
- India boasts a rich floral diversity, with 33% or 4,900 out of 15,000 flowering plant species considered endemic to the country’s current political boundaries.
- Agri-Biodiversity Hub:
- India plays a crucial role in agri-biodiversity, contributing 167 species to global agriculture and hosting 320 species of wild crop relatives within its native habitat.
- Invasive Alien Plants:
- The focus of current investigations in India is on 173 species of invasive alien plants. Among them, species like Alternanthera philoxeroides, Cassia uniflora, Chromolaena odorata, Eichhornia crassipes, Lantana camara, Parthenium hysterophorus, and Prosopis juliflora are identified as particularly harmful.
Invasive Alien Species Law in India:
India has taken legislative steps to address the issue of invasive alien species, marking the first attempt to combat them through legislation. In 2021, an amendment to the Wildlife Protection Act of 1972 introduced provisions specifically addressing invasive alien species.
The Wildlife Protection Act of 1972 underwent an update in 2021, introducing the term “Alien Invasive Species” to address invasive alien species.
- Government Authority:
- The amended law grants the Central Government the authority, under Section 62A(i), to control or prohibit the import, trade, possession, or spread of invasive alien species that pose a threat to India’s wildlife or habitats.
- Definition of Invasive Alien Species:
- The Bill defines “invasive alien species” as any animal or plant species not indigenous to India. Its introduction or expansion is deemed to endanger or negatively impact wildlife or the environment.
This legislative step reflects India’s commitment to tackling the challenges posed by invasive alien species, recognizing the potential threats they pose to the country’s unique biodiversity and ecosystems.
FAQs – Invasive Alien Species:
1. What is an alien species, and when does it become invasive?
An alien species is one introduced outside its native range. It becomes invasive when transported beyond its usual habitats, outcompeting local species and disrupting the ecological balance.
2. What traits make a species invasive?
Invasive species often exhibit rapid reproduction, high dispersal ability, adaptability to various conditions, and quick growth, traits attributed to phenotypic plasticity.
3. How do invasive alien species impact the economy, environment, and human health?
Being foreign to ecosystems, invasive species can cause significant harm to agriculture, forestry, fisheries, and natural systems, exacerbating poverty and posing threats to development. They can also introduce diseases impacting human health.
4. What are some common invasive alien species in India?
Examples include Alternanthera philoxeroides, Cassia uniflora, Chromolaena odorata, Eichhornia crassipes, Lantana camara, Parthenium hysterophorus, and Prosopis juliflora.
5. How are invasive alien species introduced to new areas?
Introduction methods include wildlife trade, tourism, hunting, fishing, transport and international trade, abandoned pets, and industries like crops and fur.
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