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#Explained: What is bio-magnification?

Bio Magnification

Bio-magnification, or biological magnification, or bio-amplification, is when the concentration toxic substances or pollutants increases in the body of an organism with each stage in the food chain.

With the consumption toxic substances at every stage in the food chain, the concentration of pollutants increase drastically for the eventual consumer.

In simpler terms, the process of that increase is referred as bio-magnification.

Bio-magnification in Pond ecosystem | Source: Wikicommons

Food Chain

Food chain is a representation of who eats whom. It starts with blind fixing sunlight which is consumed by herbivorous animals then they are eaten by carnivores then bigger carnivores. The primary purpose of the food chain is two transfer energy from one organism to another. However, not only energy is transferred in this process but also toxic chemicals.

Example of Aquatic Food Chain | Source: Wikicommons

When an organism eats food it only gets a section of energy that the food has, as most of the energy is lost through metabolism or through heat. With energy you also receive the pollutants. The more you eat, the more the pollutant will accumulate in your body.

Most of the agriculture production takes place with the help of chemical inorganic substances which gets added into organic organisms metabolism as nutrient to increase its production. However every organism has a limit up to which it can utilise energy or inorganic substances. Anything extra just stays in the body and causes problems.

Examples for bio-magnification

In the aquatic environment, concentrations will be greater in shellfish than in the plankton on which they feed, and even greater in animals at the top of the food chain such as large predatory fish or mammals.

Also Read: 33 Aquatic species worldwide at high risk

On land, biomagnification occurs through the accumulation of pollutants from soil to plant, leaves to worms or insects and finally to birds and mammals. Pollutants can also be found in the eggs of contaminated birds.

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Humans can also accumulate these pollutants from food. On average, in humans, the concentration of the pollutants in fatty tissues is over a hundred times greater than in the food they eat.

Causes of Bio-magnification

Agriculture products:

Agriculture sector more commonly uses three types of pesticides: herbicides, insecticides and fungicides. And, when products from such agricultural fields is consumed with organisms, leads to the accumulation of toxic substances inside the body. When the soil containing these chemicals is released in the rivers, it contaminants the aquatic lives.

Mercury and lead are major chemical which are used, and then become part of aquatic ecosystem.

Organic contaminants:

Manures and bio solids are industrially processed and contain contaminants that are harmful to humans and plants.

Industrial activities:

The toxic substances are released into the lake, soil, ocean and river by the factors and industries. Also the gas released in the environment acts as pollutants which enters the food chain.

Mining activities:

In the ocean deep sea mining is done to extract metals like aluminium, zinc, gold. During this process large amounts of sulphide is generated and gets deposited in soil and water resources destroying the marine life.

Effects of Biomagnification

  • Biomagnification makes humans more prone to kidney problems, cancer, birth defects, liver failure, heart diseases and respiratory problems.
  • Toxic chemicals such as selenium and mercury harm aquatic creatures’ reproductive organs.
  • Cyanide is used in fishing and gold leaching. The main cause of coral reef destruction is cyanide. Many marine creatures use coral reefs for food as well as for living. So, the destruction of coral reefs harms the lives of many aquatic animals.
  • The food chain gets disturbed due to the toxins and chemicals released into the water bodies. The small organisms absorb the toxins and are eaten up by larger organisms. As a result, the toxins are collected in the higher level of organisms.
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Metals are not degradable because they are elements. Organisms, particularly those subject to naturally high levels of exposure to metals, have mechanisms to sequester and excrete metals. Problems arise when organisms are exposed to higher concentrations than usual, which they cannot excrete rapidly enough to prevent damage. These metals act as poison and finally lead to death.

Ways to avoid Bio-magnification

  • Use of chemicals in agriculture should be minimised and organic farming should be adopted.
  • Waste from factories should be treated before releasing it to the environment. Use of plastic should be avoided.
  • Waste should be treated properly and recycling should be done.


Solution to reduce biomagnification are very simple and yet aren’t followed. Every country needs strict laws to make people follow them. These solutions are something that has been taught to us in class 6. If people forgot these basic topics, then there is no need for advanced education.

It is clearly known that human activities are not just harming other species but also itself. So many chemicals are used in everyday life. To grow crops we are using chemicals, and even to store food chemicals are used. Even to wash food and remove chemicals from them, chemicals are used. This is just a series of ironies.

Humans are polluting air, water and land like we can replace them. We don’t think twice before harming nature. We might soon face nature’s fury which may endanger our civilization.

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