Correct Answer - Option 3 : biomagnification
Concept -
Biomagnification:
- The term "biomagnification" refers to the rise or increase of non-biodegradable pollutants in the food chain in increasing amounts at each higher trophic level caused by an intoxicating atmosphere.
- Substances that are non-biodegradable, long-lived, mobile, soluble in fats, and bioactive undergo the process of biomagnification by entering the food chain.
- Examples of these pollutants are -
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Heavy metals such as mercury and arsenic.
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Pesticides such as polychlorinated biphenyls and DDT (dichloro-diphenyl-trichloroethane).
- These substances are absorbed by organisms through the food they eat.
How do they enter the food chain?
Take an example of a crop field -
- In a crop field, DDT, an insecticide, is used.
- This DDT is non-biodegradable and starts to seep within the soil and reaches the water table underground and mixes in the surrounding water bodies like lakes or rivers or ponds. (acting as a pollutant)
- The aquatic organism, like phytoplankton, in the lakes and ponds, take in the DDT mixed in water to make their food.
- Thus, from here, the very first organism of the food chain, intakes the DDT, incorporating it in the food chain.
- Zooplanktons then intake these phytoplanktons as their food, and alongside the DDT.
- As the next organism in the food chain comes, the intake of DDT continues from one to the next till the highest trophic level.
- At each trophic level, the concentration of DDT increases.
- The concentration at the highest trophic level is the maximum and causes severe health effects
Why these non-biodegradable organisms magnify?
- DDT and other non-biodegradable substances are contained in animal fat which takes several years to degrade.
- As the fat is eaten by predators, the levels of DDT biomagnify.
- It may also apply to the number of toxins in individual animals since a top predator can "accumulate" more toxins when it eats several polluted food sources. (this is why it is called biomagnification)
- The concentration of a pollutant increases from one link in the food chain to another (for example, infected fish can contaminate the next customer and continue up a tropic food web as each stage absorbs an increasing amount of pollutant).
Explanation -
- Biomagnification is called the rise or increase of non-biodegradable pollutants in the food chain in increasing amounts at each higher trophic level caused by an intoxicating atmosphere.
So, the correct option is - Biomagnification.