Water Hyacinth

Context: Water hyacinths cover a vast portion of the Vembanad lake at Kumarakom in Kottayam district of Kerala. This invasive species is detrimental to fish and other aquatic species, and also affects the flow of water.

Water Hyacinth

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  • Water Hyacinth (Eichhornia crassipes) is a major freshwater weed found globally in lakes, rivers, and water bodies.
  • It is an invasive alien species, known for its rapid growth, regeneration, and ability to form dense colonies.
  • It obstructs sunlight, displaces native species, and is considered highly troublesome.

Historical Context and Introduction to Bengal

  • Introduction to India: Brought during British colonial rule from South America for ornamental purposes by George Morgan.
  • Ecological Impact: Disrupted native ecosystems, hindering agriculture, navigation, and fishing.
  • Economic Consequences: Contributed to agrarian decline, damaged infrastructure, and impeded river transport.

Early Efforts and Government Response

  • Initial Reaction: Recognized as a serious threat to agriculture and infrastructure.
  • Legislative Measures: Laws enacted such as the Bengal Waterways Act to combat its spread, but with limited success.

Utilization Efforts and Challenges

  • Research and Findings: Discovered high nutrient content (potash, nitrogen, phosphoric acid) suitable for fertilizers and animal feed.
  • Commercial Interest: Initial attempts to extract potash faced challenges due to variable quality.
  • Government Dilemma: Balancing eradication vs. utilization for economic benefit.

Scientific Exploration and Economic Prospects

  • Research Initiatives: Studied chemical composition and potential commercial uses.
  • Commercial Ventures: Interest from companies like Shaw and Wallace & Co. for potash extraction.
  • Government Response: Mixed reactions; Water Hyacinth Committee formed to deliberate.

Public Health and Environmental Impact

  • Public Health Concerns: Linked to malaria and cholera due to habitat for disease vectors.
  • Environmental Impact: Indirectly contributed to disease spread and ecological imbalance.

Eradication Efforts and Legislative Actions

  • Government Intervention: Passed Water-hyacinth Act (1936) for organized eradication drives.
  • Public Participation: Enthusiastic response from locals in clearing initiatives.
  • Success and Legacy: Control achieved by 1947; subsequent use in agriculture and handicrafts.

Current Status and Utilization

  • Present Situation: Water hyacinth remains in parts of India and Bangladesh but managed effectively.
  • Utilization: Used as organic fertilizer, fodder during floods, and in handicrafts.
  • Economic Impact: Shifted from nuisance to resource in some areas, contributing positively to local economies.

Invasive Alien Species (IAS) are non-native organisms introduced intentionally or accidentally outside of their natural habitats, whose introduction or spread

threatens biodiversity, ecosystems, economies, or human health. These species often outcompete native species, disrupt ecological balances, and pose significant challenges to management and conservation efforts.

Invasive Alien Species in India and Their Impact

India, with its diverse ecosystems and climates, is particularly vulnerable to the introduction and spread of invasive alien species. These species have been introduced through various pathways such as trade, agriculture, horticulture, and deliberate introductions for pest control or ornamental purposes. 

Some notable invasive alien species in India and their impacts include:

  • Water Hyacinth (Eichhornia crassipes)
    • Introduction: Brought during British colonial rule as an ornamental plant, now widely spread in water bodies across India.
    • Impact: Forms dense mats that block sunlight, reduce oxygen levels, and crowd out native aquatic plants. Disrupts water flow, affects irrigation, and impedes navigation. Economic losses due to reduced fisheries, agriculture, and tourism.
  • Lantana (Lantana camara)
    • Introduction: Introduced for ornamental purposes, now widespread in forests, grasslands, and degraded areas.
    • Impact: Forms impenetrable thickets, reducing biodiversity by outcompeting native vegetation. Alters soil composition and fire regimes, affecting ecosystem health and regeneration.
  • American Bullfrog (Lithobates catesbeianus)
    • Introduction: Introduced for aquaculture and as a biological control agent, escaped into natural habitats.
    • Impact: Predates on native amphibians and small mammals, disrupting local food chains. Competes with native species for resources and habitats.
  • Prosopis species (Prosopis juliflora and others)
    • Introduction: Introduced for afforestation, now invasive in arid and semi-arid regions.
    • Impact: Forms dense thickets, reducing grazing lands for livestock. Alters soil composition and groundwater levels, impacting local flora and fauna.
  • African Catfish (Clarias gariepinus)
    • Introduction: Introduced for aquaculture, escaped into natural water bodies.
    • Impact: Predates on native fish species, leading to declines in biodiversity and fisheries production. Alters aquatic ecosystems and reduces water quality.

Management and Control Strategies

The management of invasive alien species in India involves a multi-pronged approach including:

  • Prevention: Strengthening regulations on importation and cultivation of potential invasive species.
  • Early Detection and Rapid Response (EDRR): Monitoring and timely action to prevent establishment and spread.
  • Control Measures: Utilizing mechanical, chemical, and biological methods for eradication or population control.
  • Public Awareness: Educating stakeholders about the impacts of invasive species and promoting responsible practices.


Invasive alien species pose significant threats to India’s biodiversity, ecosystems, agriculture, and public health. Effective management and control strategies are essential to mitigate their impacts and safeguard native species and habitats. Collaborative efforts involving government agencies, researchers, NGOs, and the public are crucial in addressing this ongoing challenge.

Previous year question (2018)

Q. Why is a plant called Prosopis juliflora often mentioned in news?

(a) Its extract is widely used in cosmetics.

(b) It tends to reduce the biodiversity in the area in which it grows.

(c) Its extract is used in the synthesis of pesticides.

(d) None of the above

Ans: (b)

Practice question

Q. With reference to water hyacinth, consider the following statements:

1. It was introduced in India by Portuguese.

2. It crowds out native aquatic plants.

3. The British enacted legislation to eradicate this plant.

How many of the statements given above are correct?

(a) Only one

(b) Only two

(c) All three

(d) None of the above

Ans: (b)


Brought during British colonial rule from South America for ornamental purposes by George Morgan

Forms dense mats that block sunlight, reduce oxygen levels, and crowd out native aquatic plants

  • Government Intervention: Passed Water-hyacinth Act (1936) for organized eradication drives.
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