[Biology Class Notes] on Biomagnification Pdf

Every living organism on this planet requires chemicals to function correctly. However, the Biomagnification definition suggests that when the accretion of some non-essential chemicals increases within living organisms, it can become harmful to them. Biomagnification is a kind of condition in which the chemical concentration extends the concentration of its food in an organism when the major exposure path occurs from the diet of an organism. The food web biomagnification is defined as the trophic enrichment of contaminants within food webs and results in the preceding increase in chemical concentrations with increasing animal trophic status.

 

What is Biomagnification?

Biomagnification means gathering various unimportant and, at times, harmful substances by organisms at different levels of a food chain. It occurs when industrial, agricultural, and human wastes are dumped into the oceans via rivers, sewers, streams, etc. Most of this waste is toxic and dangerous and deposited on the sea bed. The bottom feeders of a food chain consume these and gradually, it is carried to the top of that particular food chain.

 

Furthermore, the concentration of toxic materials increases with every step up on a food chain. Ultimately, it affects humans as they sit on top of most of the food chains. Human beings consume fishes that are higher on the food chain. Therefore, they are likely to carry a substantial amount of these toxic elements.

 

The containment information about biomagnification states that heavy metals such as mercury and arsenic are also involved. Additionally, pesticides like polychlorinated biphenyls (PCBs) compounds and DDT are entering the human body via the food that they consume.

 

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A Real-Life Example of Biomagnification

A real-life example of biomagnification is –

• When a marsh is sprayed to control mosquitoes, it releases a trace amount of DDT. When mixed with water, it accumulates in the cell of various aquatic organisms.

• Once feeders up the food chain, such as clams and fishes, eat these organisms, they consume that DDT. Moreover, the concentration of DDT is ten times greater compared to the previous stage.

• This concentration of DDT moves up the food chain from one tropic level to another. For instance, if a seagull consumes one such fish, it will accumulate more DDT. According to studies, there was a 1000 times increase in the concentration of DDT in phytoplankton as compared to the concentration in water, 13 times higher in zooplankton as compared to phytoplankton, around 40 times higher in different fishes as compared to zooplankton and 25 times higher in fish-eating birds compared to fishes. DDT affects the calcium metabolism of birds and results in the thinning of eggshells.

• During the 1940s and 1950s, DDT was extensively used to decrease the mosquito population and this led to a rapid decline in the bird population.

• Another prominent biological magnification example is the presence of mercury in various predatory fishes. Fishes like swordfish, shark, tuna, orange roughy, king mackerel, etc., contain a higher level of toxic mercury than smaller fishes.

 

This level is so high that health experts ask pregnant women to avoid consuming these fish. It can damage the nervous system of the baby.

 

Causes of Biomagnification

1. Products Used in Agriculture: Chemical used in the agriculture sector is highly toxic and plays a pivotal part in biomagnification. Examples of such chemicals are various pesticides, herbicides, fungicides, and different inorganic fertilizers. Ultimately these chemicals penetrate the soil and then are carried to rivers and oceans via surface runoff. As a result, they enhance the biomagnification definition of causing harm to an entire food chain.

 

2. Industrial Activities: Toxic by-products released by various industries are a significant cause of biomagnification. Additionally, the gas emission by them pollutes the air and harms the ecosystem even further.

 

3. Organic Contaminants: Organic substances like manures and biosolids contain essential nutrients such as carbon, nitrogen, and phosphorus. Plants primarily use these. However, the industrial use of these substances causes biomagnification.

 

4. Mining: Mining produces by-products like copper, cobalt, zinc, lead and several other toxic chemicals. These substances are then deposited in soil and water resources and subsequently contaminate them.

 

Effects of Biomagnification

• A significant effect of biological magnification is noted on human health. For instance, in recent years, a large number of individuals who have consumed seafood regularly have been diagnosed with cancer. The reason behind such a phenomenon is the presence of mercury.

• Other noted biomagnification effects are reproduction and development of all animals, destruction of coral reefs, and most significant disruption in the natural food chain and the ecosystem.