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Question
The image given below represents the biomagnification of DDT in an aquatic food chain. Identify ‘A’ and ‘B’.
The image given below represents the biomagnification of DDT in an aquatic food chain. Identify ‘A’ and ‘B’.
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Solution
The correct option is A A - Large fish (DDT 2 ppm), B - Water (0.003 ppb)
The process by which a few toxic substances (like DDT) increase in concentration at successive trophic levels in the food chain is known as biomagnification.
Most of the insecticides are non-biodegradable and their residues have a long life. One common example is DDT (Dichlorodiphenyltrichloroethane). It was initially introduced in the 1940s as an insecticide (toxic substance used to kill insects) against mosquitoes.
Normally DDT is sprayed on water bodies to check the growth of mosquitoes. Once it is absorbed by the aquatic organisms, DDT cannot be metabolised, broken down or excreted out and will persist in the body of the organism. DDT normally accumulates in the fat containing tissues of the organisms, as it is highly soluble in fat.
Consider an aquatic food chain: zooplankton → small fish → large fish →fish-eating birds.
It has been observed that the concentration of the DDT progressively increases along the food chain from zooplankton to fish-eating birds through biomagnification.
If the concentration of DDT is 0.003 ppb in water (parts per billion: one microgram of DDT per litre of water), then the concentration of DDT in zooplankton is 0.04 ppm (parts per million: one milligram of DDT per litre of water). The concentration of DDT in small fishes that feed on the zooplankton is 0.5 ppm. The concentration of DDT progressively increases in the body of large carnivorous fishes which feed on small fishes and reaches 2 ppm.
The DDT concentration ultimately reaches 25 ppm in fish-eating birds through biomagnification.
Regular spraying of DDT for a few years in the Long Islands of the USA, resulted in the declining fish-eating bird population. Studies showed that the concentration of DDT had increased at successive trophic levels in the aquatic food chain. This affected the calcium metabolism in birds, resulting in thinning and breaking of eggshells.
‘A’ in the given image represents large fishes with a DDT level of 2 ppm and ‘B’ in the image represents water with a DDT level of 0.003 ppb.
After adding the labels in place of ‘A’ and ‘B’ the image will be like the one given below.
Figure: Biomagnification of DDT in an aquatic food chain
The process by which a few toxic substances (like DDT) increase in concentration at successive trophic levels in the food chain is known as biomagnification.
Most of the insecticides are non-biodegradable and their residues have a long life. One common example is DDT (Dichlorodiphenyltrichloroethane). It was initially introduced in the 1940s as an insecticide (toxic substance used to kill insects) against mosquitoes.
Normally DDT is sprayed on water bodies to check the growth of mosquitoes. Once it is absorbed by the aquatic organisms, DDT cannot be metabolised, broken down or excreted out and will persist in the body of the organism. DDT normally accumulates in the fat containing tissues of the organisms, as it is highly soluble in fat.
Consider an aquatic food chain: zooplankton → small fish → large fish →fish-eating birds.
It has been observed that the concentration of the DDT progressively increases along the food chain from zooplankton to fish-eating birds through biomagnification.
If the concentration of DDT is 0.003 ppb in water (parts per billion: one microgram of DDT per litre of water), then the concentration of DDT in zooplankton is 0.04 ppm (parts per million: one milligram of DDT per litre of water). The concentration of DDT in small fishes that feed on the zooplankton is 0.5 ppm. The concentration of DDT progressively increases in the body of large carnivorous fishes which feed on small fishes and reaches 2 ppm.
The DDT concentration ultimately reaches 25 ppm in fish-eating birds through biomagnification.
Regular spraying of DDT for a few years in the Long Islands of the USA, resulted in the declining fish-eating bird population. Studies showed that the concentration of DDT had increased at successive trophic levels in the aquatic food chain. This affected the calcium metabolism in birds, resulting in thinning and breaking of eggshells.
‘A’ in the given image represents large fishes with a DDT level of 2 ppm and ‘B’ in the image represents water with a DDT level of 0.003 ppb.
After adding the labels in place of ‘A’ and ‘B’ the image will be like the one given below.
Figure: Biomagnification of DDT in an aquatic food chainSuggest Corrections
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