Biomagnification Definition Biology

May 23, 2023, 16:45 IST

All ecosystems have food chains as a part of them. In a food chain, producers and consumers establish trophic levels through which energy is transferred through the act of eating and being eaten. Here, food and biomolecules are used, stored, and transformed by metabolism in a regular process. Furthermore, breakdown or degradation is a crucial component of any food chain. This proves that almost all naturally occurring materials are degradable. But what happens when a non-degradable substance enters the food chain? Read further to know more about the concept of biomagnification in detail.

Biomagnification - Meaning

Biomagnification is defined as any increase in the concentration of a toxin, such as a pesticide, in the tissues of resistant species at successively higher trophic levels in a food chain.

When non-degradable chemicals enter the food chain, they can’t be easily broken down, digested, or ejected. After they enter the food chain they are transported up the trophic levels with an increase in their concentration. This increase or amplification at subsequent trophic levels is termed biomagnification or bioamplification. This phenomenon can disrupt the whole food chain and can also be lethal at times.

Causes and Example

There are several harmful toxins in our environment that can lead to biomagnification. Here, let’s look at some of them in detail.

• Pesticides and Pollutants

Numerous pesticides, including DDT, dieldrin, and aldrin have extended environmental half-lives. They are often not biodegradable and are fat-soluble. Thus they are deposited in the fatty tissues of both animals and humans after entering the food chain. Eventually, their concentration increases as they reach higher trophic levels.

Other contaminants include radioactive compounds like strontium-90 and heavy metals like lead, copper, and mercury. They have also been often linked to this phenomenon of biological magnification.

• Mining Activities

Other similar toxic contaminants are the compounds released from mining activities. This includes mineral deposits and materials like zinc, cobalt, copper, cobalt, and lead. When released into the aquatic environment and nearby farmland, they are often absorbed by aquatic and farm animals and crops. This eventually increases their toxicity to dangerous levels.

• Air Pollution

In addition to contributing to air pollution, exhaust gasses from vehicles and industries are causes of biomagnification as well. These air pollutants can dissolve in rain and result in acid rain. Thereafter, soil and water bodies take up the chemicals in this acid rain. Thus the toxins are gradually ingested into the food chain.

• Example - Biomagnification of DDT

A classic example of biomagnification would be the ill effects of DDT. This also led to the banning of this pesticide in most countries.

Usually, a little amount of DDT pesticide is sprayed to get rid of mosquitoes. This pesticide eventually builds up in the cells of certain aquatic creatures when combined with water. Furthermore, the concentration of DDT rises with each trophic level in an aquatic habitat. It is barely noticeable in water but is biomagnified to a high concentration as in fish-eating birds.

Effects of Biomagnification

The increasing concentration of toxins is often lethal to animals at the higher end of the food chain. Some of the ill effects of this biomagnification are discussed below:

• Very high DDT concentrations disrupt avian calcium metabolism. This causes thinning ofeggshells and causes them to break early. This can ultimately lead to a reduction in bird numbers.
• If the pesticides are in solution, DDT and other organochlorine pesticides are absorbed through the skin, the intestinal tract, and the lungs' alveoli. Thus they can cause serious illness in most mammals. In some, a high DDT concentration results in liver enlargement, liver necrosis, brain injury, and also cancer.
• Apart from disrupting the metabolism of mammals, they also affect coral reefs. Coral reefs are being destroyed mostly as a result of the use of cyanide in fishing and gold leaching. They can destroy many small aquatic animals which further leads to the destruction of coral reefs. Thus biomagnification has the ability to disrupt any food chain.

How To Control Biomagnification?

Biomagnification is mainly brought on by agrochemicals. The use of agrochemicals has a number of negative effects on soil, humans, and other living things. Thus reverting to non-chemical farming methods such as using biofertilizers, and biopesticides are the only solution.

Apart from that, we should control the use of toxic lead paints, PVCs, and heavy metals. Nearly all industrially produced goods (including petroleum) contain certain heavy metals, such as lead, arsenic, and mercury, whose use can be controlled to lessen their biological magnifying effects.

Biomagnification: FAQs

Q1. Define biomagnification

Ans. The term biomagnification refers to the accumulation and amplification of certain toxic substances in the bodies of organisms at successive trophic levels of a food chain.

Q2. What is bioaccumulation?

Ans. Bioaccumulation denotes the gradual accumulation of substances such as pesticides and toxins in organisms. This occurs when a substance is absorbed by an organism at a faster rate that is often higher than the rate at which it is ejected.

Q3. What is the difference between bioaccumulation and biomagnification?

Ans. Bioaccumulation is the first step in which a toxin enters the food chain and builds up in an organism. This often happens within a trophic level. Whereas biomagnification is a mechanism by which toxins are transferred from one trophic level to another.

Q4. What are the causes of biomagnification?

Ans. The use of toxic insecticides, agricultural pesticides, fertilizers, and heavy metals can lead to biomagnification. Apart from that, industrial waste, mining activities, water pollution, and air pollution can also cause this phenomenon.

Q5. What are the effects of biomagnification?

Ans. As a result of biomagnification, humans are more likely to develop heart disease, cancer, kidney, liver, and birth defects. It also disrupts the eggshell formation in avian creatures. Furthermore, they also lead to the destruction of coral reefs.