Maarg Manthan · Topic 13.17

Biological Pollution: Sources and Effects

Environment & Ecology › Air, Marine, Noise and Other Pollution · Topic 13.17

Biological pollution is the harmful introduction or spread of living organisms, their parts or products into environments where they do not naturally occur or where they upset natural balance. The main forms are invasive alien species, pathogens and disease agents, allergens such as pollen and moulds, and in some definitions genetically modified or engineered organisms released without control. Sources include trade and transport (ballast water, ship hulls, timber and plants), deliberate introduction for gardens, farming, forestry, fisheries and the pet trade, accidental escape from aquaculture, and spread through travel, climate change and changes in land use. In India, serious invaders include water hyacinth (Eichhornia crassipes), Lantana camara, Parthenium hysterophorus, Prosopis juliflora, Mikania micrantha and Chromolaena odorata among plants, and African catfish, tilapia and the golden apple snail among animals. Effects include loss of native species, changed food chains and soils, damage to crops, fisheries and health, spread of disease and high economic costs. Control rests on prevention, quarantine, early detection, removal and public awareness.

5 min read · UPSC Prelims · Environment & Ecology · Air, Marine, Noise and Other Pollution

At a Glance

Main form Invasive alien species
Water invader Water hyacinth
Forest invader Lantana
Farmland weed Parthenium
Control Prevention, quarantine
Exam link UPSC Prelims, Environment & Ecology: Air, Marine, Noise and Other Pollution

Where Does It Fit?

This topic follows noise pollution and moves to a form of pollution caused by living organisms. It connects to earlier material on invasive species and biodiversity loss, and leads to radioactive and thermal pollution. Previous topic: Noise Pollution: Causes, Levels and Health Effects. Next topic: Radioactive Pollution: Sources and Effects.

What Are the Sources and Examples of Biological Pollution?

Source or pathway	Examples
Trade and transport	Ballast water of ships, hull fouling, timber, plants and soil moved across regions
Deliberate introduction	Ornamental plants, fodder crops, forestry species, aquaculture and pet species later escaped or naturalised
Accidental escape	Fish from farms, seeds in grain imports
Agriculture	Weeds arriving with imported wheat, as with Parthenium
Travel	Pathogens spreading with people and animals
Climate change	Warmer conditions let pests and vectors spread to new areas
Allergens	Pollen, moulds and spores that cause allergies and asthma

What Are Important Invaders in India and Their Effects?

Water hyacinth: from South America; forms dense mats on lakes and rivers, blocks light and oxygen; once called the Terror of Bengal
Lantana camara: ornamental shrub from tropical America that has overrun forests and reduces grass for wildlife
Parthenium (Congress grass): weed that arrived with imported grain, causes allergies and crop loss
Prosopis juliflora: introduced to green dry land, spreads and lowers groundwater and native grassland
Mikania micrantha: mile-a-minute vine smothering trees in the north-east and Kerala
African catfish and tilapia: fish that outcompete and eat native fish
Golden apple snail: rice pest in wetlands
Effects: native species decline, ecosystem change, economic cost, health problems and loss of livelihoods

What Else Should You Remember?

Alien species: species outside its natural range
Invasive alien species: alien species that establish, spread and cause harm
Biological pollution: a wider term covering pests, pathogens and allergens as well
Ballast water: moves organisms between ports across the world
Fouling: organisms attached to ship hulls travel and may invade ports
Island vulnerability: islands such as Andaman and Nicobar are very sensitive to invaders
Chital in Andaman: introduced deer have damaged forest undergrowth
Mongoose and rats on islands: prey on native birds and reptiles
Eupatorium (Chromolaena): a weed spreading across forests and fallows
Sphagneticola and Ipomoea: other weeds that choke water bodies
Gambusia: mosquito fish introduced to control malaria that harms native fish
Carp species: common carp and grass carp introduced for aquaculture
Nile tilapia: introduced for farming and now widespread in reservoirs
Pathogens: diseases like avian influenza, African swine fever and chytrid fungus in amphibians
Genetic pollution: escape of genes from engineered or farmed organisms into wild relatives
Plant Quarantine Order, 2003: regulates import of plants and plant products into India
Biological Diversity Act, 2002: has a provision on invasive alien species
National Biodiversity Authority: has been tasked with guidance on invasive species
Economic cost: weed control and crop loss amount to large sums every year
Biological control: use of natural enemies, as with the Zygogramma beetle on Parthenium and weevils on water hyacinth
Mechanical control: hand removal and harvesters
Community role: local people clear weeds and use them for crafts and compost
Convention on Biological Diversity: Article 8(h) asks countries to prevent introduction of alien species
Link to previous: see Noise Pollution: Causes, Levels and Health Effects
Link to next: see Radioactive Pollution: Sources and Effects
Link to invasive species: see Endemic Species, Keystone Species, Indicator Species, Invasive Species
Caution: lists of invasive species change as new studies appear, so check the latest national lists
Exam hint: learn invasive species with origin, habitat and harm
Infectious diseases: pathogens that jump to new regions, such as through trade in animals, are a part of biological pollution in a broad sense
Aquaculture escapes: fish such as tilapia and African catfish escaped from farms and now compete with native fish
Citizen reporting: apps and community monitoring help to spot new invaders early

Why Does It Matter for the Exam?

Water invader: Water hyacinth
Law: Plant Quarantine Order 2003
Control: Prevention, biological control
Current affairs link: National invasive species lists
Common errors: calling all alien species invasive

As an analytical point, biological pollution is hard to undo, because living invaders reproduce. Prevention at borders and ports, quick action when a new invader first appears and public awareness are far cheaper than long-term control.

Why Is This Topic Important?

Source Trade, release
Harm Native loss
Fix Prevent early

What Came Next?

The next topic covers radioactive pollution: sources and effects. Next topic: Radioactive Pollution: Sources and Effects.

Key People and Terms

Alien species Non-native species
Invasive species Harmful alien species
Ballast water Ship stability water
Quarantine Border check for pests
Genetic pollution Gene flow from alien stock
Biocontrol Natural enemy control

Exam Corner

Points to Remember

Water hyacinth: mats on water.
Lantana: forest invader.
Parthenium: Congress grass.
Law: Plant Quarantine Order, 2003.
Best fix: prevention.

Do Not Confuse With

Alien and invasive species Non-native versus harmful non-native
Biological pollution and biological control Harmful introduction versus planned natural enemy use
Invasive and endemic species Spreading harm versus native to one region

Memory Hook

Hyacinth chokes water, Lantana owns forest, Parthenium wins the field.

Mains Angle

Questions ask for examples and control. These points help.

Sources Trade, release
Cases India
Control Prevention

A Question You May Face

An original practice question, not a past paper question.

“What is biological pollution? Discuss its sources and effects with Indian examples, and suggest control measures.”

How to Answer

Define Invaders.
Sources Trade.
Cases India.
Way Prevent.

GS Relevance

Prelims: invasive species, sources, examples. GS Paper 3: biological invasions and control.

Frequently Asked Questions

What is biological pollution?

Biological pollution is the introduction or spread of living organisms, such as invasive alien species, disease-causing microbes and allergens, into environments where they cause harm. It includes the arrival of weeds and animals from other regions through trade, travel and release, and it can damage native species, ecosystems, agriculture, fisheries and human health.

What are invasive alien species?

Invasive alien species are species that have been introduced outside their natural range by human actions, and that establish, spread and cause harm to native species, ecosystems, the economy or health. Examples in India are water hyacinth, Lantana camara, Parthenium, Prosopis juliflora, African catfish and the golden apple snail.

Why is water hyacinth a problem?

Water hyacinth, a floating plant from South America, grows very fast in nutrient-rich water and forms dense mats that block sunlight and oxygen, kill fish and aquatic life, obstruct boats, irrigation channels and fishing and breed mosquitoes. It spread widely in India's lakes, rivers and ponds and is hard and costly to remove.

How do invasive species arrive in a new region?

They arrive through trade and transport, such as ship ballast water and hulls, imported timber, grain and plants; through deliberate introduction for gardens, forestry, fodder, fisheries and the pet trade followed by escape; and through travel and the spread of pests helped by climate change and disturbed land.

How can biological pollution be controlled?

Control starts with prevention: quarantine and inspection of imports, ballast water treatment and careful rules on species introduction. Other measures include early detection and rapid response, mechanical removal, natural enemies for biological control, restoration of native vegetation, community involvement and awareness, and monitoring through national invasive species lists.

PYQ Practice — Statement Analysis

1 Water hyacinth is an invasive aquatic plant.

True

It forms dense mats.

2 All alien species are invasive.

False

Only those that spread and harm.

3 Ballast water can carry alien organisms.